U.S. patent application number 13/071181 was filed with the patent office on 2011-08-11 for method, apparatus and systems for treating contaminants in a waste fluid.
This patent application is currently assigned to ACOS, LLC. Invention is credited to Harry C. Conger, Michael E. Mullins, James W. Muzzy.
Application Number | 20110192807 13/071181 |
Document ID | / |
Family ID | 56290837 |
Filed Date | 2011-08-11 |
United States Patent
Application |
20110192807 |
Kind Code |
A1 |
Conger; Harry C. ; et
al. |
August 11, 2011 |
METHOD, APPARATUS AND SYSTEMS FOR TREATING CONTAMINANTS IN A WASTE
FLUID
Abstract
The invention relates to a method, apparatus and system for the
treatment of organic and inorganic waste in a waste fluid. The
method involves a co-current plug flow of fluid in a reactor in
which ozone mass transfer conforms to the effective life of the
ozone used in the treatment. Hydroxide and hydrogen peroxide can be
added to the waste fluid. The combined fluids to be treated travel
the reactor through a series of surfaces in a packed reactor. The
apparatus includes a diffuser for ozone which assists in the
co-current plug flow of fluids. The diffuser can have a porosity of
about 10 microns. The invention further envisions a compact system
for efficient treatment of waste fluids.
Inventors: |
Conger; Harry C.; (Santa Fe,
NM) ; Muzzy; James W.; (Lakewood, CO) ;
Mullins; Michael E.; (Houghton, MI) |
Assignee: |
ACOS, LLC
Lakewood
CO
|
Family ID: |
56290837 |
Appl. No.: |
13/071181 |
Filed: |
March 24, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11482014 |
Jul 7, 2006 |
7931816 |
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13071181 |
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11027824 |
Dec 29, 2004 |
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11482014 |
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60697856 |
Jul 8, 2005 |
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Current U.S.
Class: |
210/759 ;
210/143; 210/150 |
Current CPC
Class: |
C02F 1/78 20130101; B01J
2208/00725 20130101; B01J 2208/00884 20130101; C02F 1/722 20130101;
B01J 2208/00539 20130101; B01J 8/0457 20130101; B01J 8/0257
20130101; B01J 8/0492 20130101; C02F 1/66 20130101; Y10S 261/72
20130101; B01J 8/0278 20130101; Y10S 261/42 20130101 |
Class at
Publication: |
210/759 ;
210/150; 210/143 |
International
Class: |
C02F 1/78 20060101
C02F001/78; B01D 29/60 20060101 B01D029/60; B01D 29/88 20060101
B01D029/88 |
Claims
1. A reactor for oxidizing waste fluid while enhancing gas-liquid
ozone mass transfer to be comparable to the rate that ozone is
being utilized during oxidation comprising: reactor for treating
waste fluid with hydrogen peroxide, caustic and ozone; the reactor
having a packing comprising a series of surfaces constructed and
arranged for substantially plug flow of fluids under pressure;
waste fluid inlet for receiving at least waste fluid beneath a plug
flow regime in the reactor and reactant inlet for ozone located
beneath the substantially plug flow regime; diffuser device in
juxtaposition to the reactant inlet effecting diffusion of ozone in
the at least waste fluid; continuously supplying ozone gas,
hydrogen peroxide and an effective amount of caustic if needed to
adjust pH with a flow of waste fluid proximate to a bottom end of a
substantially vertical substantially tubular reactor having a
chamber with a packed bed comprising the series of surfaces; the
porosity of the diffuser device and the packing enhance ozone mass
transfer; the waste fluid inlet and reactant inlet constructed and
arranged for co-current substantially non-turbulent, substantially
plug flow of fluids; outlet for treated fluid and off-gas, ozone,
and volatile organic compounds positioned above the substantially
non-turbulent, substantially plug flow regime; wherein ozone mass
transfer design characteristics of the reactor substantially
conform to an effective life for the ozone.
2. (canceled)
3. The reactor according to claim 1, wherein the packing being
raschig rings.
4. (canceled)
5. The reactor according to claim 1, wherein the diffuser device
being a plate with multiple inlets, the ozone inlet being
substantially centered on the plate and the waste fluid inlet being
eccentric, the ozone inlet forming a substantially conical outlet
with the largest dimension covered by a diffuser for ozone and a
baffle located beneath the outlet but over the eccentric inlet to
distribute fluid and promote flow.
6. The reactor according to claim 5, wherein the diffuser is
sintered metal or ceramic article having a porosity between about
0.2 and about 100 microns.
7. The reactor according to claim 6, wherein the porosity is about
5 to about 20 microns.
8. (canceled)
9. (canceled)
10. (canceled)
11. The reactor according to claim 1, wherein the reactor is
designed for a residence time for the ozone of less than about 6
minutes.
12. The reactor according to claim 1, wherein the waste fluid total
contaminant concentration is less than about 3000 parts per
million.
13. The reactor according to claim 1, wherein the reactor is
designed for a pressure less than about 5 atmospheres absolute and
less than about an ignition pressure for ozone.
14-34. (canceled)
35. A system for oxidizing waste fluid while suppressing stripping
of organics and enhancing gas-liquid ozone mass transfer
comprising: a hydrogen peroxide dispenser for storing and
dispensing hydrogen peroxide continuously and a caustic dispenser
for storing and dispensing caustic continuously both into a waste
fluid; an ozone generator adapted to provide an effective amount of
ozone into the waste fluid; an ozone diffuser; at least one
pressurized reactor having packing comprising a series of surfaces
and an ozone diffuser for treatment of the waste fluid; the packing
and porosity of the ozone diffuser enhance ozone mass transfer;
wherein the reactor is designed for co-current substantially
non-turbulent, substantially plug flow of the waste fluid, hydrogen
peroxide, caustic, and ozone during an effective life of the ozone;
continuously supplying ozone gas, hydrogen peroxide and an
effective amount of caustic if needed to adjust pH with a flow of
waste fluid proximate to a bottom end of a substantially vertical
substantially tubular reactor having a chamber with a packed bed
comprising the series of surfaces; and a flash chamber at the top
of the reactor for receiving treated waste fluid and off-gas
wherein off-gas, ozone, and volatile organic compounds are
separated from treated waste fluid.
36. The reactor according to claim 35, wherein the system includes
multiple reactors connected and arranged for series flow of treated
waste fluid and arranged for parallel flow of ozone reactant
through reactor inlets.
37. (canceled)
38. (canceled)
39. The reactor according to claim 1, wherein the reactor is
constructed and arranged for gas-liquid volumetric flow ratios
effective for substantially non-turbulent, substantially plug flow
throughout the reactor.
40. The reactor according to claim 1, wherein the ozone mass
transfer rate is enhanced by increasing the gas-liquid interfacial
area of bubbles traversing a plug flow path through a reaction zone
and maintaining increased gas-liquid interfacial area of ozone
bubbles traversing a reaction zone.
41. The reactor according to claim 1, wherein the ozone mass
transfer rate is enhanced comparable to the rate that ozone is
being utilized during oxidation by maximizing the difference in
concentration of ozone across a gas-liquid interface.
42. The reactor according to claim 1, wherein the size of the
reactor is reduced 1 to 2 orders of magnitude over turbulent,
non-plug flow reactors.
43. The reactor according to claim 1, wherein the liquid residence
time in the reactor is scaled to the useful lifetime of dissolved
ozone.
44. The system according to claim 35, wherein the size of the
reactor is reduced 1 to 2 orders of magnitude over turbulent,
non-plug flow reactors.
45. The system according to claim 35, wherein the liquid residence
time in the reactor is scaled to the useful lifetime of dissolved
ozone.
46. The reactor according to claim 1, further comprising an ozone
mass transfer coefficient between about 0.01 to about 2
sec.sup.-1.
47. The system according to claim 35, further comprising an ozone
mass transfer coefficient between about 0.01 to about 2
sec.sup.-1.
48. The system according to claim 35, wherein the ozone mass
transfer rate is enhanced by increasing the gas-liquid interfacial
area of bubbles traversing a plug flow path through a reaction zone
and maintaining increased gas-liquid interfacial area of ozone
bubbles traversing a reaction zone.
49. The system according to claim 35, wherein the ozone mass
transfer rate is enhanced comparable to the rate that ozone is
being utilized during oxidation by maximizing the difference in
concentration of ozone across a gas-liquid interface.
50. The system according to claim 35, wherein effluent is
recycled.
51. The system according to claim 35, wherein the system further
comprises monitoring and control equipment for the oxidation
treatment.
52. The reactor according to claim 1, wherein the packing being
supported by a screen.
53. A method for treating waste fluid while suppressing stripping
of organics and enhancing gas-liquid ozone mass transfer rate
comprising: continuously supplying ozone gas, hydrogen peroxide and
an effective amount of caustic if needed to adjust the pH with a
flow of waste fluid proximate to a bottom end of a substantially
vertical substantially tubular reactor having a chamber with a
packed bed comprising a series of surfaces; reacting the ozone,
hydrogen peroxide and the effective amount of caustic co-currently
with the flow of waste fluid in the reactor without substantial
back mixing thereof, said co-current flow of ozone, peroxide,
caustic and waste fluid being substantially non-turbulent,
substantially plug flow through the tubular reactor and packed bed,
thereby producing an oxidized flow; maintaining a pH from about 7
to about 11 for the fluid being treated, an effective pressure, and
an effective ozone mass transfer coefficient which complements an
effective life of the ozone; and continuously withdrawing the
oxidated flow from a top end of the tubular reactor.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of U.S.
application Ser. No. 11/482,014, filed Jul. 7, 2006, which is a
continuation-in-part of U.S. application Ser. No. 11/027,824, filed
Dec. 29, 2004, and claims the benefit of the effective filing date
of U.S. provisional patent application 60/697,856, filed Jul. 8,
2005, the entire contents of which are hereby incorporated by
reference.
BACKGROUND OF THE INVENTION
[0002] a. Field of the Invention
[0003] The invention relates to processes, devices and systems for
the highly effective and efficient treatment of waste fluids, and
in particular for the highly effective and efficient oxidation of
contaminates in waste fluid. Oxidation reactions are carried out in
multi-stage, co-current, plug flow reactors.
[0004] b. Background Art
[0005] Organic and non-organic industrial, agricultural and
municipal waste materials are a prevalent and growing problem
throughout the industrial world. For example, industrial chemicals,
pesticides, personal-care products and pharmaceuticals have been
found in wastewater streams throughout the United States. Oil,
mining and chemical refining facilities are key targets. These
organic waste materials present environmental hazards, especially
when the waste levels exceed EPA standards.
[0006] Treating waste materials in a wastewater or waste fluid is
an area of active study. A number of techniques have been developed
for the destruction of organic materials in a waste fluid, several
of which are discussed in greater detail below. Although several of
these techniques have been useful in the partial destruction of
lower organic concentrations, few if any have proven effective or
efficient at treating sources with higher concentrations of organic
waste, for example waste fluids having more than 100 mg/l organic
contaminates.
[0007] U.S. Pat. No. 6,093,328 discloses the use of hydrogen
peroxide and solid particles formed between elemental iron and
sulfur to remove arsenic and total organic carbon from water. The
reaction is carried out at or below about 100.degree. C.
[0008] U.S. Pat. No. 5,928,522 discloses a process for treating oil
refining waste where large particles and waxy materials are removed
and the remaining liquid is drawn off and centrifuged. The residual
cake is treated with hydrogen peroxide and water to form a slurry
which is heated to 100.degree. F.
[0009] U.S. Pat. No. 6,521,290 discloses the use of hydrogen
peroxide in a limited Fenton reaction to treat hydrocarbon ore at
60.degree. C. to 100.degree. C. This results in the partial
oxidation of the hydrocarbons.
[0010] Hydrogen peroxide has further been used in a number of
applications to treat fluids containing various waste materials.
For example, in U.S. Pat. No. 6,051,145, and related U.S. Pat. No.
5,888,389, a multi-stage treatment of sewage sludge is disclosed
using a first stage sub-critical pressure of between about 3,600
psi to 4,500 psi. The second stage is run at a higher temperature
to produce super critical oxidation conditions.
[0011] U.S. Pat. No. 5,240,619 discloses a process characteristic
of a super-critical oxidation. This process utilizes oxygen
containing gas and pressures well in excess of the super critical
pressure, e.g., 350 atm. The super critical pressure is applied in
a first stage reaction at a temperature between 250.degree. C. and
374.degree. C. The second stage reaction is carried out at the same
pressure and temperature between 374.degree. C. and 600.degree. C.
This results in super critical oxidation conditions in the second
stage reaction.
[0012] U.S. Pat. No. 6,080,309 discloses a process for the
separation of impurities from liquids. In this process, a
centrifuge is used to achieve temperatures and pressures which are
no lower than 705.4.degree. C. and 3,208 pounds per square inch.
Such conditions exceed the super critical pressure and temperature
of water. After reaching super critical conditions, oxygen in any
form is introduced into the suspension. An oxidizing reagent such
as hydrogen peroxide may be used.
[0013] The chemistry of advanced oxidation reactions can be quite
complex.
[0014] U.S. Pat. No. 3,782,163 relates to a process for the ozone
treatment of liquid material. The process includes introducing a
major part of the liquid into a first ozonation zone and
introducing the remainder into a second ozonation zone. The
oxidation apparatus comprises two packed columns. The packing
material can be raschig rings. The waste flow within the reactor is
countercurrent with the flow of ozone within the reactor. The pH of
the waste streams is at least about 12. The two reactors are
necessary to complete the oxidation reaction.
[0015] U.S. Pat. No. 4,028,246 is directed to a liquid purification
system. The system includes an airtight casing having a plurality
of panels dividing the interior on the casing into a plurality of
sections to form an ozone liquid contact chamber. The liquid runs
down the panels and casing walls in a falling thin film. Ozone is
introduced in the casing under pressure between 2 and 10 psi. The
ozone flow contacts the liquid running over the panels. The flow of
ozone and liquid is moving from the top of the casing to the
bottom. No packing material is disclosed.
[0016] U.S. Pat. No. 4,229,296 describes a wet oxidation system
employing a gas separation reactor. A waste water flow is directed
to a bottom region of a first vertically elongated reaction zone at
a first flow rate. An oxygen containing gas is charged to a bottom
region of the reaction zone at a second flow rate. A lower liquid
phase is separated from an upper gas phase. An aqueous liquid
effluent is removed from the middle region of a plug flow type
reaction zone wherein mixing in a traverse reaction zone occurs but
which allows for no diffusion in the flow direction. The flow rates
of the waste water in the oxygen containing gas are not the same.
Composition of the reactant mixture varies along the flow path. The
reactor is directed to operate at temperatures ranging from about
350.degree. to 600.degree. F. at pressures ranging from about 800
to 2200 psig. Waste water contains from about 0.8 to 3 weight
percent of organic matter on a 100 weight percent basis. The
reactor does not have a diffuser plate or a series of surfaces
packed inside the reactor.
[0017] U.S. Pat. No. 5,364,537 discloses injection of hydrogen
peroxide and ozone in flow direction co-current with circulation of
water to be treated. The patent does not disclose a packed reactor
or plug flow.
[0018] U.S. Pat. No. 5,851,407 claims a water decontamination
process. The process comprises injection pressurized flow of
hydrogen peroxide and ozone in a flow of contaminated water. The
ozone and hydrogen peroxide are injected at velocities and
directions matching those of contaminated water flow. The system
for decontaminating water includes a high intensity mixer. The
patent does not disclose a packed reactor.
[0019] U.S. Pat. No. 6,024,882 is a continuation-in-part
application of U.S. Pat. No. 5,851,407. The '882 patent discloses a
process and apparatus for exposing water to oxidizing conditions
under pressure. A combination of ozone and single dose of hydrogen
peroxide is added to the water but, under pressure, at an acidic pH
and with high intensity mixing. The disclosure is focused on the
control of bromate contamination in the water.
[0020] U.S. Pat. No. 6,054,057 is directed to a method for
processing a feed material. The feed material can include an
oxidant such as hydrogen peroxide, oxygen and air. The method
includes initiating reaction by jet mixing the feed material in a
back-mixing section of a reaction chamber, carrying out an
additional reaction in the reaction stream in a plug flow section
of the reaction chamber. Injection of feed material is through the
top of the reaction chamber. The patent does not claim co-current
flow of waste material.
[0021] U.S. Pat. No. 6,214,240 discloses that reaction in an ozone
treatment using ozone mixed with hydrogen peroxide is very complex,
because many reactions simultaneously take place and the reactions
interfere with each other. The disclosure is directed to a computer
simulation model and apparatus. It claims the use of a mixture of
hydrogen peroxide and ozone for the ozone treatment of an effluent.
Ozone concentrations are below 300 mg/l. The process is based on a
volumetric mass transfer coefficient. The patent does not disclose
the structure of the reactor or co-current flow of ozone and
effluent. It does not teach a mass transfer of kinetics and
oxidation rate in terms of time versus volume and time.
[0022] Ozone treatment of effluent using ozone mixed with hydrogen
peroxide is a very complex reaction. A variety of apparatus and a
variety of methods have been utilized as a result of the complexity
of the reaction process. Applicants have advanced the treatment of
such complex reaction systems by utilizing co-current flow of
fluids in the substantial absence of back mixing during the
effective life of ozone. Applicants now describe their invention in
greater detail.
BRIEF SUMMARY OF THE INVENTION
[0023] This invention relates to a reactor for treating a waste
fluid comprising reactor for treating waste fluid with hydrogen
peroxide, hydroxide and ozone; the reactor having a series of
surfaces constructed and arranged for plug flow of fluids under
pressure; waste fluid inlet for receiving at least waste fluid
beneath a plug flow regime in the reactor and reactant inlet for
ozone located beneath the plug flow regime; diffuser device in
juxtaposition to the reactant inlet effecting diffusion of ozone in
the at least waste fluid; the porosity of the diffuser device and
the series of surfaces effect an ozone mass transfer coefficient
between about 0.05 to about 2 sec -1; the waste fluid inlet and
reactant inlet constructed and arranged for co-current plug flow of
fluids; and outlet for treating fluid and off-gas, ozone, and
volatile organic compounds positioned above the plug flow regime;
wherein the ozone mass transfer characteristics of the reactor
substantially conform to an effective life for the ozone.
[0024] This invention also relates to a method for treating waste
fluid comprising reacting ozone, hydrogen peroxide and hydroxide
co-currently with a flow of waste fluid without substantial back
mixing thereof; and maintaining a pH between about 7 and about 11
for the fluid being treated and a pressure effective for an ozone
mass transfer coefficient between about 0.05 and about 2 sec -1
which complements an effective life of the ozone.
[0025] This invention further relates to a method for treating
waste fluid comprising feeding under pressure a co-current
segregated flow of ozone, hydrogen peroxide and hydroxide with
waste fluid into a reactor; reacting a segregated flow of ozone,
hydrogen peroxide, hydroxide and waste fluid for an effective life
of the ozone; and recovering treated liquid and gas from a
reactor.
[0026] This invention additionally relates to a method for treating
waste fluid comprising feeding a co-current flow of waste fluid,
ozone, hydrogen peroxide, and hydroxide without substantial back
mixing into a reactor; the flow of fluid being under sufficient
pressure, temperature and pH to effect an ozone mass transfer
coefficient between about 0.05 and about 2 sec -1 which complements
an effective life of the ozone; and recovering oxidized liquid and
gas.
[0027] This invention relates to a system for treating waste fluid
comprising a hydrogen peroxide dispenser for storing and dispensing
hydrogen peroxide continuously and a hydroxide dispenser for
storing and dispensing hydroxide continuously both into a waste
fluid; an ozone generator adapted to provide an effective amount of
ozone into the waste fluid; at least one pressurized reactor having
a series of surfaces and an ozone diffuser for treatment of the
waste fluid, the series of surfaces and the porosity of the ozone
diffuser effecting an ozone mass transfer coefficient between about
0.05 to about 2 sec -1; wherein the reactor is constructed for
co-current flow of the waste fluid, hydrogen peroxide, hydroxide,
and ozone without substantial back mixing during an effective life
of the ozone; and a flash chamber at the top of the reactor for
receiving treated waste fluid and off-gas wherein off-gas, ozone,
and volatile organic compounds are separated from treated waste
fluid.
[0028] This invention relates to a reactor for treating a waste
fluid comprising reactor for treating waste fluid with hydroxide
and ozone; the reactor having a series of surfaces constructed and
arranged for plug flow of fluids under pressure; waste fluid inlet
for receiving at least waste fluid beneath a plug flow regime in
the reactor and reactant inlet for ozone located beneath the plug
flow regime; diffuser device in juxtaposition to the reactant inlet
effecting diffusion of ozone in the at least waste fluid; the
porosity of the diffuser device and the series of surfaces effect
an ozone mass transfer coefficient between about 0.05 to about 2
sec -1; the waste fluid inlet and reactant inlet constructed and
arranged for co-current flow of fluids; outlet for treated fluid
and off-gas, ozone, and volatile organic compounds positioned above
the plug flow regime; and wherein the ozone mass transfer
characteristics of the reactor substantially conform to an
effective life for the ozone.
[0029] This invention also relates to a method for treating waste
fluid comprising reacting ozone and hydroxide co-currently with a
flow of waste fluid without substantial back mixing thereof; and
maintaining a pH between about 7 and about 11 for the fluid being
treated and a pressure effective for an ozone mass transfer
coefficient between about 0.05 and about 2 sec -1 which complements
an effective life of the ozone.
[0030] These and various other features and advantages of the
invention will be apparent from a reading of the following detailed
description and review of the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1 is a flow diagram for a treatment process of a waste
fluid in accordance with an embodiment of the present
invention.
[0032] FIG. 2 is a diagram of a reactor for the treatment of a
waste fluid in accordance with an embodiment of the present
invention.
[0033] FIG. 3 is a diagram that illustrates a co-current flow
arrangement of the waste fluid and ozone into a reactor in
accordance with an embodiment of the present invention.
[0034] FIG. 4 is a diagram of an off gas treatment system for the
separation of treated waste fluid from off gas and the further
destruction of the off-gas in accordance with an embodiment of the
present invention.
[0035] FIG. 5 is a schematic for a waste fluid treatment system in
accordance with an embodiment of the present invention.
[0036] FIG. 6 is a perspective view of a waste fluid treatment
system in accordance with an embodiment of the present
invention.
[0037] FIG. 7 is an illustrative plot showing acetone levels over
the course of an removal/degradation reaction in accordance with
the present invention.
[0038] FIG. 8 is an illustrative plot showing acetonitrile levels
over the course of an removal/degradation reaction in accordance
with the present invention.
[0039] FIG. 9 is an illustrative plot of indigo dye concentration
as a function of residence time in a reactor or reactor column in
accordance with the present invention. For a residence time of 85
seconds, the mass transfer coefficient was adjusted to match the
observed outlet concentration of indigo. Concentration (gmol/l) vs.
time (sec.). C.sub.SL--liquid phase indigo, C.sub.O3L--Liquid phase
ozone, C.sub.O3g--Gas phase ozone.
[0040] FIG. 10 is a black and white photograph of indigo dye fading
reaction with ozone to measure mass transfer coefficients in a
packed column.
[0041] FIG. 11 is an illustrative plot of atmospheric pressure
ozone destruction (O.sub.3-4%) in accordance with the present
invention. Concentration (gmol/l) vs. time (sec.). C.sub.Sg--gas
phase organic, C.sub.SL--liquid phase organic, C.sub.O3L--Liquid
phase ozone, C.sub.O3g--gas phase ozone.
[0042] FIG. 12 is an illustrative plot of pressurized ozonation
system (4% feed at 3 atm) in accordance with the present invention.
Concentration (gmol/l) vs. time (sec.). C.sub.Sg--gas phase
organic, C.sub.SL--liquid phase organic, C.sub.O3L--Liquid phase
ozone, C.sub.O3g--Gas phase ozone.
[0043] FIG. 13 is an illustrative plot of pressurized ozonation
system (4% feed at 3 atm) in accordance with the present invention.
Concentration (gmol/l) vs. time (sec.). C.sub.Sg--gas phase
organic, C.sub.SL--liquid phase organic, C.sub.O3L--Liquid phase
ozone, C.sub.O3g--Gas phase ozone.
[0044] FIG. 14 is an illustrative plot detailing a concentration
profile from a second reactor in series for the pressurized
ozonation system (4% feed at 3 atm) in accordance with the present
invention. Concentration (gmol/l) vs. time (sec.). C.sub.Sg--gas
phase organic, C.sub.SL--liquid phase organic, C.sub.O3L--Liquid
phase ozone, C.sub.O3g--Gas phase ozone.
[0045] FIG. 15 is an illustrative plot detailing a segregated flow
reactor model. Concentration (gmol/l) vs. time (sec.).
C.sub.Sg--Gas phase ozone.
DETAILED DESCRIPTION OF THE INVENTION
[0046] The present invention provides process, reactors and systems
for the treatment of contaminates in a waste fluid. The present
invention provides enhanced treatment of contaminates over other
conventional waste treatment techniques, especially where the
destruction of high levels of contaminates in a waste fluid is
required. The present invention provides enhanced oxidation
reaction kinetics and mass flow transfer in order to have a waste
fluid treatment environment for highly effective and efficient
destruction of contaminates.
[0047] As used herein, waste fluids include, but are not limited
to, the following sources: waste fluids from gas and oil related
processing, including waste pits, drilling muds and refinery waste;
waste from the chemical industry, including organic and
petrochemical waste; waste from other industrial sources, such as
waste metal, waste paint, waste solvents and waste pulp and paper;
waste from mining operations; flue gas contaminates, for example
from electrical power generation; waste from municipal sewage;
waste from coal processing; waste from agricultural sources; and
waste from dredging operations of harbors, channels and rivers.
Several illustrative organic contaminates found within these waste
fluids include: sulfides, disulfides, sulfites, mercaptans,
mercaptans (thio), polysulfides, phenols, benzenes, substituted
phenols, alcohols, glycols, aldehydes, ethylmercaptans, ethylene,
oils, fats and grease.
[0048] Other industrial manufacturing processes require the use of
ultra high purity water either as a direct process fluid or as a
major component of a fluid product. The pharmaceutical electronic
and electrical utilities industries are exemplary. Use of pure
water in the pharmaceutical industry is apparent in view of the
human use of products in that industry. The pharmaceutical industry
requires use of water essentially free from insecticides,
herbicides, chlorinated hydrocarbons, phenols, colorants, aroma
substances and flavorings and other substances harmful or
disagreeable to humans. Governments also frequently demand from
such industrial sites that harmful organic components are removed
from industrial effluents. Similarly, treatment of dermal disorder
products and microbiocidal health and beauty care products require
the use of water and products such as creams, gels, lotions,
powders, tooth and other paste, suppositories, body and hair
shampoos and rinses, oral hygiene rinses and other products for
human use. The electronics industry requires pure water or fluid as
a result of the continuously greater miniaturization in the
manufacture of electronic devices on semi-conductor substrates such
as crystal silicone wafers. Impurities cause defect in devices
manufactured in that industry, and can effect long term reliability
of the manufactured product. Impurities such as bacteria, bacterial
fragments, inert debris and other microorganisms require treatment.
The utility industry has needs as a result of degradation of high
pressure steamed containment vessels and heat exchangers and a
variety scaling and metallurgical problems associated with
silicates and other metal corrosion problems.
Processes for the Destruction of Contaminates in a Waste Fluid
[0049] The processes of the present invention are based on the
treatment of a waste fluid under conditions, and within an
environment, that facilitates the destruction of contaminates. This
enhanced destruction of contaminates in a waste fluid, in
accordance with the present invention, occurs by a novel
combination of increased mass transfer of the reactants in the
waste fluid and by increased reaction rates of the reactants within
the waste fluid. The combined factors of increased mass transfer
and increased reaction rates allows for an extremely time efficient
treatment process for the destruction of up to 99+% of
contaminates, i.e. degradation of contaminates to below 1 mg/l, in
a waste fluid.
[0050] Processes of the present invention involve partial to
complete oxidation of contaminates in a waste fluid. Oxidants for
use in the invention include ozone or ozone in combination with
hydrogen peroxide. Ozone concentrations for use in the present
invention are usually from about 4% to about 6% by weight. The
dosage of ozone can be about 1,000 g/hr. The volumetric ratio of
ozone to liquid is typically around 2:1. In addition, where
hydrogen peroxide is used in combination with ozone, the maximal
percent hydrogen peroxide feed solution is about 30% by volume.
[0051] Processes of the present invention are typically performed
under pressures of between about one and four atmospheres and are
preferably performed at pressures of between about one and three
atmospheres. It is noted, however, that when ozone and hydrogen
peroxide are combined in the oxidation reactions, reaction
pressures should be kept below 5 atmospheres, based on the data
shown in the Examples. Pressure for the reactor would be less than
that which could prompt explosive characteristics for the oxidation
reaction, particularly with regard to ozone. Note, however, that
although not optimal, slightly higher pressures could be used in
the system and embodiments of the present invention and these
pressures are envisioned to be within the scope of the present
invention.
[0052] Processes of the present invention are typically performed
in a waste fluid having a pH of between about 7 and about 11, and
usefully about 10 where the combination of ozone is used with
hydrogen peroxide. Preferred materials for adjusting the pH of the
waste fluid includes NaOH, when the waste fluid is below 7, and HCl
or H.sub.2SO.sub.4, when the waste fluid is above 11.
[0053] In addition, process temperatures are typically modified to
be about between ambient to about 100.degree. C. Note that for
purposes of the present invention, ambient temperature is typically
between about 20.degree. C. and about 30.degree. C., although it is
noted that an ambient temperature is the temperature of the
environment or room that exists in accordance with the present
invention.
[0054] Applicants summarize certain process parameters. K.sub.1A
ranges between about 0.01 to about 2.0 sec -1, alternatively
between about 0.02 to about 1.0 sec -1 and usefully between about
0.05 to about 0.5 sec -1. Liquid residence time is between about
0.5 to about 6 min, alternatively between about 1 to about 4 min,
and usefully between about 1 to about 3 min. Gas residence time is
between about 0.5 to about 4 min, alternatively between about 0.5
to about 3 min, and usefully between about 0.5 to about 2 min.
Ozone (gas) concentrations is between about 1 mg/l to 500 mg/l,
alternatively between about 5 to about 250 mg/l, and usefully
between about 10 to about 200 mg/l. Alternatively, ozone
concentration is from about 6 to about 8% by volume. An ozone
utilization rate is between 100 and 1000 grams per hour. Organic
(liquid) concentrations is from about 0 to about 1000 ppmw,
alternatively from about 0 to about 800 ppmw, and usefully from
about 0 to about 600 ppmw. Effective life of ozone is determined
from an ozone utilization factor. That factor is determined from a
first order decomposition rate for ozone in the water to be
treated. Typical factors range from about 0.05 sec -1 to about 2
sec -1. Ozone loses its effectiveness when 90+% of ozone has
reacted.
[0055] The processes, reactors and systems of the present invention
are useful in the destruction, i.e., partial to complete oxidation,
of organic and/or inorganic contaminates, i.e., up to and exceeding
about 3,000 mg/l. Contaminates can be in solution or suspended as
solids within a solution. Note that processes of the present
invention can be performed and repeated until the level of
contaminates within the waste fluid is at an acceptable,
pre-determined level. Note that embodiments of the present
invention provide a significant time benefit for the amount of time
required to treat a waste fluid, a benefit not available with other
conventional oxidation-based technologies, i.e., destruction of
contaminates in minutes and not hours.
[0056] FIG. 1 is a flow diagram of one embodiment of the general
process of the present invention. A waste fluid is provided 100 for
treatment in accordance with the present invention. The pH and
temperature of the waste fluid is adjusted, if necessary, to a pH
adjustment 101 of between about 6 and about 10, and more likely
from about 8 and about 10, and to a temperature of between about
ambient temperature and about 100.degree. C. In embodiments of the
present invention that utilize hydrogen peroxide, the hydrogen
peroxide 102 is added to the waste fluid. The waste fluid may also
be diluted with water to obtain the proper viscosity or contaminate
concentration. Each of these reaction parameters may be monitored
during the waste fluid treatment process and further adjusted to
maintain the parameter within the appropriate range, as described
above. An appropriate catalyst optionally may be added to the waste
fluid to enhance potential oxidation reaction rates within the
waste fluid.
[0057] The waste fluid then proceeds to an oxidation reactor 103
where ozone 104 and waste fluid are added to the reactor
concurrently or via a "co-current flow," that is, the waste fluid
and ozone move through the reactor in the same direction. The
co-current flow of ozone and waste fluid provides maximal contact
between the contaminates in the waste fluid and the ozone. The
co-current flow within the reactor is substantially laminar, a plug
flow of co-currently introduced fluids. To facilitate plug flow
within the reactor, a series of surfaces are provided to limit
dispersion flow within the reactor, these surfaces also serve as
mass transfer sites within the reactor for oxidation reactions to
occur.
[0058] Processes of the present invention provide that reactor
pressures may be modified to optimize treatment of the contaminates
from between about one atmosphere and about five atmospheres, and
typically from between about one atmosphere and three atmospheres.
Treated waste fluid 105 and gas 106 exit the reactor, where the
waste fluid may be treated in another oxidation reactor 107
connected in series with the first oxidation reactor. As with the
initial oxidation reactor, ozone is added concurrently to the
second oxidation reactor with the once treated waste fluid. The
processes of the present invention recognize that the number of
oxidation reactors for use with the present invention is dependent
upon the level of contaminates within the waste fluid; a sufficient
number of reactors may be utilized to treat a particular waste
fluid until the contaminate level within the waste fluid is deemed
acceptable by the user.
[0059] As the waste fluid is being sufficiently treated to limit
the level of contaminates in the waste fluid, the off-gas is
treated in an off gas treatment system 108. Off gas treatment
systems of the present invention separates entrained waste fluid
from off gas, where the off gas is further treated via bi-metallic
catalytic destruction. A further description of the off gas
treatment system is provided hereafter.
Reactors for the Destruction of Contaminates in a Waste Fluid
[0060] The present invention provides embodiments of a plug flow
reactor in accordance with the present invention. Reactors of the
present invention provide highly effective and efficient oxidation
of contaminates in a waste fluid. Reactor designs of the present
invention are based on the following interrelated conditions: (1)
using a plug flow or laminar flow of the waste fluid through the
reactor, this provides for non-turbulent flow within the reactor,
i.e., as compared to dispersion flow, which calls for turbulent
flow or back mixing throughout the reactor; (2) using pressures of
between about one and about three atmospheres within the reactor,
this facilitates bubble contact with the waste fluid by limiting
the size of the oxidant bubbles and increases mass transfer and
limits sparging of ozone and volatile organic compounds (VOCs); (3)
using a co-current flow model of the waste fluid and oxidant
through the reactor, this facilitates the amount of time that the
oxidant and waste fluid are in contact within the reactor, i.e.,
the waste fluid and oxidant enter at approximately the same area of
the reactor and flow in the same direction; and (4) providing
conditions that maximize mass flow transfer within the reactor by
modifying the waste fluids pH (for enhanced oxidation reaction
kinetics), providing surface areas for the oxidation reactions, use
of the co-current flow, use of catalysts, etc.
[0061] Referring to FIG. 2, a reactor diagram is shown in
accordance with the present invention. In one embodiment, a reactor
200 includes a housing 201 with a first end 202, a second end 203
and a middle portion 204. The housing 201 defines a chamber for
containing a waste fluid and oxidant, which typically is
cylindrical in shape. The inside chamber wall is typically smooth
to limit the formation of turbulent flow conditions within the
location of the reactor housing, but rather represent the zones
found at typically opposite locations of the housing. An inlet port
205 is located toward or at the first end of the housing and an
outlet port 206 is located toward or at the second end of the
housing. The inlet port receives pH adjusted waste fluid. Hydrogen
peroxide also may be combined with the waste fluid. Gas inlet port
207 is used to introduce ozone, its precursors and reaction
complements to reactor 200. The outlet port at the opposite end of
the reactor releases treated waste fluid from the reactor. The
inlet and outlet port can be located at the first and opposite ends
respectively, but alternately can be located elsewhere in the
reactor or otherwise associated with the reactor commensurate with
the reaction mechanism. Also note that although only one inlet and
outlet port are disclosed in FIG. 2, it is envisioned that multiple
ports can be included in the housing as long as the reactor
comports with the functions discussed above, especially in relation
to the co-current flow and plug flow of waste fluid through the
reactor.
[0062] A diffuser device 208 is located in the middle portion 204
of the housing 201 between the first 202 and second 203 ends. The
diffuser device 208 conforms to the shape of the chamber walls so
as to form a barrier within the chamber between the first and
second ends of the housing.
[0063] The diffusion device 208 is a diffuser plate having a
plurality of small openings for release of ozone gas into the waste
fluid. Diffuser plates can be a screen or made of sintered metal,
ceramic or other material. The diffuser device 208 is logically
located approximate to the bottom end of the reactor. The plate can
be sintered material with porosity between about 0.2 and about 100
microns of about 5 to about 20 microns with 10 microns being
useful.
[0064] The middle of the reactor 204 is typically packed with a
series of surfaces, usually a series or arrangement of Raschig
rings or similar articles known in the art to provide surfaces for
the oxidation reactions and to facilitate and promote plug flow of
fluid through the reactor.
[0065] It is also envisioned that in embodiments of the present
invention, a diffuser device would not be located within the
housing of a reactor. Rather, ozone would be diffused into the
waste fluid just prior (outside) to entrance into the reactor (not
shown). A device such as an eductor or other like device can be
used to diffuse the ozone into the fluid. These reactor embodiments
therefore, would include a single chamber for performing the
processes of the present invention, there being no requirement for
a diffuser device. Other like devices can also be used to
accomplish ozone diffused into the waste fluid wherein such devices
effect the reaction kinetics, reaction rates and efficiencies,
residence time, flow dynamics, mass transfer and gas/liquid
interface characteristics according to the present invention.
[0066] FIG. 3 shows an illustrative embodiment of a reactor having
an inlet port 300 located at a first end of the reactor. A module
301 is positioned within the reactor for receiving ozone. The
outside wall of the module forms an annular zone inside the
reactor. Untreated waste fluid is more uniformly distributed within
the reactor by baffle 302 and over the module wall. A packing
screen keeps Raschig rings from entering the module or annular
zone.
[0067] Ozone is received in the module through inlet port 303. A
diffuser device 304 releases small bubbles of ozone into the
passing waste fluid in a co-current flow. The co-current flow inlet
arrangement maximizes plug and co-current flow of the waste fluid
and ozone throughout the reactor. The embodiment minimizes
turbulence of the waste fluid above the diffuser device.
[0068] Packed Raschig rings provide numerous surfaces or a series
of surfaces for the mass flow transfer reactions of the present
invention as well as facilitate plug flow of the waste fluid and
ozone gas through the reactor. Other like materials can be used in
place of the Raschig rings.
[0069] The following parameters illustrate the present invention.
The reactor is designed to have the waste fluid reside within the
reactor housing for less than five minutes, the flowrate through
the reactor is about 5-50 gallons per minute. An example for a 10
gpm reactor, the reactor housing would be about 25 cm in diameter
by eight feet in length. The reactor would be packed with 0.5 inch
ceramic Raschig rings.
[0070] In another embodiment, reactors of the present invention are
connected to an off gas treatment system 400. As shown in FIG. 4,
the off gas treatment system 400 of the present invention has a
flash chamber 401 in gas communication with a bimetallic catalyst
treatment chamber 402.
[0071] Flash chamber embodiments of the present invention include a
treated waste water inlet 403, an outlet 404 for waste water that
has been substantially separated from gas within the treated waste
fluid, a barrier 405 to facilitate release of the gas from the
treated waste fluid, and an off gas outlet 406 for release of off
gas from the flash chamber and into the bimetallic catalyst chamber
402. The system can include a back pressure regulator 407, a
condensate trap 408 and a dehumidifier 409.
[0072] In more detail, the flash chamber 400 receives treated waste
fluid from a reactor or reactors. The treated waste fluid enters
the chamber through an inlet 403. The inlet 403 is in fluid
communication with the outlet port (not shown in this figure) of
the reactor. Waste liquid is separated from gas. Gas is available
for release from the flash chamber into a bimetallic catalyst
treatment chamber.
[0073] Other devices can be used in place of the flash chamber for
separating bubbles out of liquid, for example, a scrubber.
[0074] Off gas treatment in the bimetallic catalyst treatment
chamber is accomplished by contact of the off gas with a
combination of bimetallic catalyst, for example, a bimetallic
combination of platinum (Pt) and palladium (Pd). Other bimetallic
combinations or metallic material are envisioned for use within the
present invention. Off gas is heated to about 150.degree. C. in the
bimetallic catalyst treatment chamber.
Systems for the Destruction of Contaminates in a Waste Fluid
[0075] The present invention provides embodiments of waste water
treatment systems in accordance with the present invention.
Treatment systems of the present invention provide cost effective
treatment, especially in relation to conventional techniques, of
contaminates in a waste fluid. Treatment systems of the present
invention provide the combination of devices necessary to practice
process embodiments of the present invention and incorporate the
reactor embodiments of the present invention.
[0076] The systems (and processes) of the present invention can be
designed as stand-alone units, i.e., provided at the source of the
waste fluid and release treated waste fluid into a predetermined
site. However, the systems of the present invention may also be
adapted for use with existing water treatment facilities or plants
as a "turn-key" or "bolt-on" process that, for example, focus on
the removal of bacteria and particulates fi0m.a water source. As
such, the present invention may be added to existing water
facilities as a first treatment, intermediate or final step to
destroy contaminates within the waste fluid prior to treatment of
the waste fluid within a waste treatment facility. Note also that
the systems of the present invention are portable and can be
designed for transport in trailers or other like platforms to
contaminated sites, for example to a well located in a high organic
contaminated ground water area.
[0077] Referring to FIG. 5, a system 500 is shown in accordance
with the present invention. In one embodiment, waste fluid can be
stored 502 or obtained from a source. Typically, waste fluid for
treatment by systems of the present invention can have contaminate
levels as low as 1 mg/1 and as high as 3,000+mg/l. Note that any
level of contaminates in a waste fluid can be treated by the
systems of the present invention, where additional capacity, i.e.,
reactors, can be added to a system in accordance to the amount of
waste fluid to be treated, the time requirement for the treatment
of the waste fluid, and the contaminate levels within that waste
fluid. As such, a system designed to treat a lower level of
contaminates may only require one or more in-series reactors
whereas a system may also be designed to treat a higher level of
contaminates by placing up to six reactors in the system in
series.
[0078] Waste fluid is pumped by a pump 504 to a mixing vessel 506.
In one embodiment of the system, hydrogen peroxide is stored in a
storage vessel 508 for addition via a pump 510 to the waste fluid
in the mixing vessel 506. Mixed waste fluid is monitored for pH and
appropriate amounts of either sodium hydroxide 512 (or other like
base) or hydrochloric acid (or other like acid) are added to the
fluid 514 to maintain a pH of between 7 and 10, and alternately
between 8 and 10 within the waste fluid. Temperature of the waste
fluid is between about ambient temperature and about 100.degree. C.
If the temperature adjustment is needed a heat/cold device can be
used (not shown).
[0079] Optionally, a control panel 516 monitors and controls the
amount of waste fluid passing through the system, the amount of
hydrogen peroxide added to the waste fluid, the temperature of the
waste fluid, and/or the pH of the waste fluid. As discussed in
greater detail below, the control panel also offers monitoring and
control over the addition of ozone from an ozone source 518, via an
ozone generator 520, to the waste fluid. An instrument panel 522
can provide the system operating parameters for visual
inspection.
[0080] Temperature, pH and hydrogen peroxide adjusted waste fluid
moves through the monitoring point 524, where the waste fluid
parameters are displayed on the instrument panel 522. Data from the
monitoring point is relayed to the control panel for either
automatic or manual mediated control over the parameters. For
example, waste fluid that passes the monitoring point with a pH of
5 will indicate to the controller at the control panel 516 to
increase the amount of base added to the waste fluid.
[0081] The waste fluid then moves to a first reactor 526. As
discussed in detail above, the waste fluid enters the reactor at a
first end 528, the first end logically located at the bottom of the
reactor. Ozone 518 is added to the waste fluid either just prior to
entering the reactor 526 or via an inlet 530 into the reactor
located at a point to maximize the concurrent flow of the waste
fluid and ozone through the reactor. Treated waste fluid exits the
first reactor via a second end 532, the second end logically at the
top of the reactor. Treated waste fluid can optionally be treated
in a off gas treatment system, as illustrated by arrow 334 (Offgas
Treatment).
[0082] A sampling point 536 is optionally located in-line with the
treated waste fluid from the first reactor. Systems of the present
invention are designed to incorporate as many as in-series reactors
as are required to destroy the contaminates present in the waste
fluid. Waste fluid treated in the first reactor would next be
received at a first end 538 of a second reactor 540, and as above,
a fresh supply of ozone would be added to the waste fluid to
maximize concurrent flow of ozone and waste fluid through the
second reactor. Third 542 and fourth 544 reactors are shown with
appropriate sampling points 546 to illustrate that a plurality of
reactors may be incorporated in-series for the treatment of waste
fluids. Once waste fluid has been treated and the off gas destroyed
via an offgas treatment system (see above), the waste fluid is
exited from the system for downstream use, or alternative
treatment, for example the treatment of the waste fluid for
destruction of bacteria.
[0083] Determination of the number of reactors can be determined
via computer modeling under conditions as described in Example 3.
In addition, system parameters for a particular waste fluid source
may be determined through experimentation and pilot based trial
runs to optimize system parameters.
[0084] Note that additional ozone and hydrogen peroxide may also be
added to the waste fluid in-between each reactor or alternatively
every other reactor run (not shown in FIG. 5). In this way, ozone
and hydrogen peroxide concentrations can be maintained at the start
of each reactor run.
[0085] The invention will now be described with respect to its
operation according to the present invention utilizing the present
apparatus. FIG. 1 shows a flow diagram of the present invention.
Contaminated water in unit 100 is pumped to the reactors.
Containers 101 and 102 supply a pH adjustment vehicle, for example,
hydroxide, and hydrogen peroxide to the contaminated water to
facilitate treatment in reactor 103. Ozone is supplied to a desired
reactor from supply unit 104. These fluids, that is, the liquid and
the gas enter co-currently to reactor 103. Gas is disbursed in
liquid and the fluid flows through the center of the reactor
column. Liquid is separated from the gas. Liquid exits the reactor
at 105 and gas exits the reactor at 106. Gas can exit to the
atmosphere or be recycled for use in the reaction while condensate
is collected. Multiple units are envisioned but the number of units
is reduced compared to known processes as a result of the improved
efficiency of the reaction. Effluent from outlet 105 can be
processed in a series of reactors in sequential fashion. The ozone
can be supplied to such reactors in parallel as shown in FIG. 1.
Substantially contaminant free effluent can be collected at unit
109.
[0086] The reactor is depicted in detail in FIG. 2. Contaminated
waste water containing hydroxide and hydrogen peroxide enter
beneath the baffle plate facilitating its distribution. Ozone
enters a diffusion device 208 through inlet 207. The contaminated
waste water and additional components combine with the diffused
ozone uniformly in the manner which avoids back mixing. The
diffusion device includes a porous portion having a porosity in
microns facilitating an increase in the interfacial surface of the
bubbles developed by the gas passing through it. Such a portion can
be made of metal or ceramic sintered or otherwise constituting the
diffuser. The combination of fluids proceeds through the reactor in
plug flow. FIG. 10, discussed in greater detail hereafter, pictures
that flow through the reactor column. As shown, it is substantially
horizontal in cross section passing from bottom to top of the
reactor column. This shows the substantial absence of back mixing
which defines the plug flow regime through the central portion of
the reactor 204. FIG. 10 shows laminar flow of the combination but
also plug flow of the combination. The combination has a uniform
horizontal movement of the combination of liquid and gas and that
horizontal uniformity continues vertically through the reactor.
[0087] The reactor has a series of surfaces which facilitates this
plug flow. The residence time of the combination is increased and
the reaction is thereby facilitated. The series of surfaces can be
raschig rings or equivalents therefore.
[0088] The reactor is typically under pressure and that pressure is
less than 3 atm. The pressure increases the gas holding time,
reduces ozone bubble size, increases oxidation reaction kinetics,
and reduces the ozone and the VOC stripped out of the liquid. This
reaction occurs during the useful life of the ozone which
necessitates ozone mass transfer characteristics to conform to that
lifetime. The inter-relationship of foregoing characteristics
permit the physical size of the devices to be substantially reduced
compared to that used in conventional treatments. Thereafter, gas
and liquid are separated. Off gas exits at 206 and treated water
exits both beneath it.
[0089] Pressure increases the gas holding time, reduces ozone
bubble size, increases oxidation reaction kinetics, and reduces the
ozone and the VOC stripped out of the liquid. This reaction occurs
during the useful life of the ozone which necessitates ozone mass
transfer characteristics to conform to that lifetime. The
inter-relationship of foregoing characteristics permits the
physical size of the devices to be substantially reduced compared
to that used in conventional treatments. Thereafter, gas and liquid
are separated. Off gas exits at 206 and treated water exits at 209
both beneath it.
[0090] FIG. 3 shows the diffuser device which includes in that
figure a sintered metal ozone diffuser plate. This exploded view of
the schematic representation of the diffuser device 208 in FIG. 2
shows waste fluid hydrogen peroxide and hydroxide or caustic
entering beneath a baffle 302 which facilitates uniform dispersion
of that liquid combination. FIG. 3 further shows ozone inlet 303
which enters a conical portion having the baffle 302 attached to it
and the diffuser plate sitting thereabove enclosing the end of the
device. The device coordinates the movement of fluid and gas
bubbles as they enter the reactor and proceed through the center
portion of the reactor. A system layout and commercial systems are
shown in FIGS. 5 and 6 respectively. FIGS. 7 and 8 show the percent
reduction of contaminants to be on the order of about 99%.
[0091] The present invention is directed to the aqueous phase
oxidation of organic aqueous contaminants with minor transfer of
contaminants to the gas phase. The present invention achieves this
oxidation through a mixed phase (gas-liquid) co-current, plug flow
reactor for ozonation reactions. This contacting method reduces the
size of the reactor required by 1 to 2 orders of magnitude over
known systems. The packing material of the column enhances the gas
liquid mass transfer rate to be comparable to the rate of the
oxidation reactions. Where more than one reactor is utilized, each
individual reactor is co-current, with several reactors in series
to achieve complete degradation of the organic. Gaseous ozone is
added in parallel to each reactor with the liquid flowing through
each reactor in series. This creates a unique cross flow type of
reaction geometry. The liquid residence time in each reactor has
been scaled to the useful lifetime of the dissolved ozone,
approximately 2 to 3 minutes. Computer simulations of the systems
indicate that the optimal useful ozone concentration is 6 to 8
volume percent and the system can be pressurized to about 3
atmospheres absolute (about 43 psia) to enhance performance. Use of
pressurized ozone reduces gas phase stripping of organic
contaminants. Use of air tends to enhance stripping of volatile
organics. Gas to liquid volumetric ratio of about 2:1 is useful to
reduce stripping of the organics from water. The use of dilute
hydrogen peroxide (0.5% to 3% by weight) will enhance by about 20
to 50% the degradation rate. Typically, this is most effective if
the pH of the water is mildly basic about pH equal to 10.
[0092] As mentioned, the chemistry of advanced oxidation reactions
can be quite complex. Rate constant for the entire network of
reactions is virtually impossible to decipher. Applicants do not
wish to be bound by a particular mechanism for the present
invention. They purport that an integration of the proper set of
process parts, contacting patterns, residence times, have a
developed an integrated system which makes use of ozone and
peroxide far more effective than that known.
[0093] The mass transfer coefficient is typically described as
K.sub.1A, where the K.sub.1 term is the transfer rate per unit of
interfacial area per unit time (i.e., -1/meter 2min). The A term is
the interfacial surface area in a given volume of reactor (meter
2/meter 3). When multiplied times the concentration difference
across the interface (concentration in the gas--concentration in
the liquid) the mass transfer rate is obtained (moles/min) from one
phase to the other. The mass transfer rate can be increased by
producing more interfacial area (e.g., smaller bubbles, high area
packing), the concentration in the gas phase, or by changing
K.sub.1 via more mixing or higher fluid velocities. The present
invention currently achieves a K.sub.1A of approximately 0.01 to
0.5 sec -1 using Raschig ring packing, but with other, higher
efficiency packings, one might get as high as 2 sec -1. This higher
rate is comparable to the rate of the ozone reactions themselves,
past which point increasing the mass transfer coefficient doesn't
necessarily help. In other words, the present reactor is still mass
transfer limited, but not by a significant amount. This is an
advantageous region to operate in. Secondly, the residence time
(which is directly tied to the flowrate) may be adjusted to most
advantageously fit the overall rate of mass transfer and reaction.
Whereby if all of the ozone is depleted, the reaction come to a
halt. This is overcome in the present system by using a parallel
addition of the ozone to reactors in series. These advantages can
be accomplished in other types of reactors, but usually at the cost
of plug flow, which is equally or more important.
[0094] The present system has an ozone mass transfer coefficient
(K.sub.1) of 0.05 to about 2 sec -1. This represents ozone transfer
in moles/min and consequently a rate of the oxidation reaction.
This level of transfer and reaction rate determines reactor size
and detention time in the reactor. This results in a significant
increase in the present system efficiency. Where mass transfer is
based on volume, transfer of ozone is in liters into a liquid in
liters. This approach assures an adequate level of ozone for
oxidation but does not reflect the rate of oxidation.
[0095] The following relationship is responsible for improved ozone
mass transfer based on reaction rate (time): [0096] 1. In the
present system, the reactor packing serves to improve the contact
of ozone bubbles and liquid by creating good local contact and
shear along the packing surface without creating back mixing [0097]
2. In increasing the gas-liquid interfacial area by making small
ozone bubbles by the porous diffuser plate at the bottom of the
reactor and the elevated pressure in the reactor. The packing keeps
the bubbles from growing in size and a wet surface for bubbles to
pass over. [0098] 3. The ozone mass transfer can be increased by
maximizing the difference across the gas-liquid interface. The
present system does this by operating at an elevated pressure.
[0099] Viewing FIG. 10 which displays plug flow, visual observation
of that experimentation forms a basis to say that the reactants
move homogenously and vertically through the reaction column in
cross section. This flow emanates from the combination of
components established by the manner in which the components are
introduced in the reactor. This suggest that components move
through the reactor uniformly from the time of their introduction.
The combination of components enhances the interfacial area which
traverses through the series of surfaces or packing in the reactor.
The dynamics of the reactor appears to permit maintenance of the
interfacial area and localization of the reaction between gas and
liquid from the time of introduction to the reactor. There appears
to be a timing and rhythm during travels of gas and liquid through
the reactor. Reaction rate appears enhanced and residence time is
increased during the effective life of the ozone. The mass transfer
rates utilized in this invention suggest the improved efficiency.
The dynamics in apparatus essentially avoid back mixing and
recombination or coalescence of gas bubbles in the reactor.
[0100] Having generally described the invention, the same will be
more readily understood by reference to the following Examples,
which are provided by way of illustration and are not intended as
limiting.
EXAMPLES
Example 1
Combination of Hydrogen Peroxide and Ozone in Waste Fluid Partially
Reduces the Organic Waste in a Waste Fluid
[0101] The following example illustrates the effectiveness of the
methods and compositions of the present invention for treating a
waste fluid. Note that the present example utilizes sub-critical
temperatures and pressures to obtain large decreases in the amount
of organic contaminants from a starting waste fluid. Note also that
relative to the amount of oxidizing agents used in connection with
the present invention, large decreases in organic materials from
the waste fluid is achieved. Such dramatic results are attributable
to the formation of hydroxyl radicals in waste fluid that have
enhanced reactivity with the organic contaminates in the waste
fluid.
[0102] Liquid chemical waste obtained from a chemical plant, having
approximately 760 mg/l acetone and 2,100 mg/l acetonitrile, was
treated with hydrogen peroxide and then ozone added over a period
of three hours. Samples were taken every hour to determine
concentrations of acetone and acetonitrile over the course of the
oxidation reaction. Results indicated that the combination of ozone
and hydrogen peroxide were effective at causing oxidation of
acetone and acetonitrile in the waste fluid.
[0103] In more detail, tests were initially performed on the
untreated waste fluid to ensure that other known organic
contaminates were not present, as organic contaminants could
interfere with the interpretation of the oxidation data specific
for acetone and acetonitrile. Gas chromatography and mass
spectrometry confirmed that no other tested organic contaminant (35
were tested) was present in any substantial amount in the waste
prior to treatment using the methods and compositions of the
present invention (data not shown).
[0104] Hydrogen peroxide was added to the chemical waste and
allowed to equilibrate. The waste was tested at ambient
temperatures at approximately 1 atmosphere of pressure. A flow of
ozone was introduced into the bottom of the vessel containing the
peroxide treated waste. The ozone entered through a plurality of
openings in the bottom of the vessel, thereby increasing the
effective concentration of the ozone in relation to the peroxide
treated organic contaminants. The pH was maintained throughout the
run at between 4 and 8.
[0105] As shown in Table 1, compositions and conditions of the
present invention are highly effective at oxidizing organic
contaminants, e.g., acetone and acetonitrile, in a waste fluid.
Under the limited and preliminary design parameters of the present
example, approximately 30-50% oxidation was achieved. Based on
extrapolation of these results, it is highly likely that a
continuous process in accordance with the present invention could
achieve almost up to 99+% oxidation in a relatively short amount of
time, i.e., even as little as five minutes or less.
TABLE-US-00001 TABLE 1 Oxidation of Acetone and Acetonitrile
(Partial Reduction) Oxidation Sample Acetone (mg/L) Acetonitrile
(mg/L) Time (hrs) Untreated 760 2100 -- Treated 740 2000 1 Treated
470 1700 2 Treated 410 1500 3 Total Oxidation 46% 29%
[0106] The preceding results illustrate the utility of the
invention for dramatically decreasing the level of organic
contaminants within a liquid waste sample. The results show that
temperatures and pressures as low as 30-40.degree. C. and 1
atmosphere can be used effectively with hydrogen peroxide and ozone
to produce high levels of oxidation of chemical contaminants. These
conditions show conditions that favor oxidation of organic
contaminates within the waste fluid.
Example 2
Hydrogen Peroxide and Ozone Achieve Total Reduction in Waste Fluid
Levels of Acetone and Acetonitrile
[0107] The following example illustrates the effectiveness of the
methods and compositions of the present invention for treating a
liquid waste having high levels of acetone and acetonitrile. As in
the previous two examples, the present example utilizes
sub-critical temperatures and pressures to obtain near total
reduction in the amount of measured contaminates from a starting
waste fluid. In addition, the present results support a conclusion
that embodiments of the present invention, using continuous flow
conditions, would achieve near total oxidation of contaminates
within a waste fluid in much faster times than achieved using
conventional technologies.
[0108] Seven liters of liquid chemical waste was obtained from a
chemical plant, the waste having approximately 750 mg/l acetone and
2,200 mg/l acetonitrile. The pH of the waste was maintained at
about 7.5 at an ambient temperature. The chemical waste was
continuously injected with ozone (see Tables 2 and 3). Due to the
limitations in this lab-scale reaction, only a certain amount of
ozone could be injected in any given period of time. The known flow
of ozone gas was injected into the known volume of waste fluid. The
concentration of ozone in the "off" gas was measured. The
difference between the input and off gas ozone was the actual ozone
consumed in the reactor.
[0109] Acetone and acetonitrile within the liquid chemical waste
were destroyed by the consumed ozone. A primary design factor for
this example was that the amount of ozone consumed in destroying
the acetone and acetonitrile was determined to be the amount
measured from an initial level, i.e., 750 and 2,100, to a desired
or optimal level. Depending on the level of acetone and
acetonitrile in the liquid chemical waste, the required amount of
ozone was applied to the reactor in a matter of a few minutes or
over many hours.
[0110] The data in Table 3 shows a compilation of raw data points
shown in Table 2. Data from Table 2 is shown as FIGS. 12 and 13.
Note that the raw data shown in Table 3 is obtained from a series
of four runs under the conditions described above and indicated
within the Table 2.
TABLE-US-00002 TABLE 2 Raw Data For Oxidation of Acetone and
Acetonitrile (Example 3) Time Sam- Min- ple Acetone Acetonitrile
COD Ozone ute point Level % Red Level % Red Level % Red mg/L Run 1
0 0 750 2100 4144 30 1 3992 4% 60 2 700 7% 2000 5% 3912 6% 465 90 3
3740 10% 120 4 600 20% 1700 19% 3544 14% 930 150 5 3364 19% 180 6
510 32% 1500 29% 3156 24% 1395 Run 2 0 0 1300 2400 3632 20 1 3820
-5% 40 2 3580 1% 612 60 3 3364 7% 80 4 3224 11% 1224 100 5 3068 16%
120 6 680 48% 1700 29% 2988 18% 1836 120 0 540 58% 1600 33% 3232
11% 140 1 3008 17% 160 2 460 65% 1600 33% 2876 21% 2448 180 3 2736
25% 200 4 320 75% 1300 46% 2508 31% 3060 220 5 2364 35% 240 6 170
87% 1200 50% 2220 39% 3672 Run 3 0 0 950 1300 4148 240 1 230 76%
1100 15% 2644 36% 4200 360 2 81 91% 880 32% 1864 55% 6300 420 3 35
96% 800 38% 1616 61% 7350 480 4 13 99% 730 44% 1352 67% 8400 Run 4
480 0 530 968 8400 540 1 410 68% 686 83% 10050 600 2 250 81% 448
89% 11700 660 3 150 88% 284 93% 13350 720 4 27 98% 110 97% 15000
Note that the bolded data points show selected data used to prepare
FIGS. 7 and 8, also see Table 3
TABLE-US-00003 TABLE 3 Oxidation of Acetone and Acetonitrile
(Example 3) Acetone Acetonitrile Time Ozone Sample (mg/L) (mg/L)
(minutes) (mg/L) Untreated Liquid 750 2,100 -- -- Chemical Waste
Treated 680 1,700 120 1,836 Treated 230 1,100 240 4,200 Treated 13
730 480 8,400 Treated -- 27 720 15,000
[0111] An analysis of the data shown in Table 3 was used to convert
this "batch data" to data illustrating how long it would take to
accomplish the same result using a continuous flow system. The
contaminate data shown in Table 3 in mg/l was then plotted against
actual batch times to determine the consistency of the continuous
flow reaction, i.e., whether the test results were essentially
linear. Test plots indicate that the data for acetone and
acetonitrile have linear slopes, thereby allowing the conversion to
continuous flow results.
[0112] A company that has done this type of oxidation on the bench
scale outlined above was consulted regarding this conversion
process. They had installed several commercial continuous flow
systems, and they found that up to 99+% reduction of contaminates
by oxidation occurred within one to fifteen minutes compared to
batch times of 680 to 720 minutes (see Table 3).
[0113] Based on their experience, as well as some oxidation
modeling, it was determined that each run remained linear when the
time data from Table 3 was divided by a factor of 48, which gave
the time in minutes for continuous flow:
Batch 680 mg/l at 120 minutes/48=Continuous flow 680 mg/l at 2.5
minutes
[0114] This factor will vary dependent upon: (a) the type of
contaminate; (b) the type of reaction used to form the hydroxyl
radical; and (c) the linear trend reaction (.+-.10%).
[0115] This case illustrates that the high level of dissolved
acetone and acetonitrile in a liquid chemical waste can be
destroyed in less than one hour and often within three to fifteen
minutes, as is shown in FIGS. 7 and 8. This data clearly
demonstrates that the methods and compositions of the present
invention provide a vast improvement for the oxidation of
contaminates compared to other conventional technologies, which
take hours to oxidize much smaller amounts of contaminates. The
inventors are not aware of any prior art references showing
ozone/hydrogen peroxide treatment of above 100 mg/l
contaminates.
Example 3
Computer Modeled Reactor Simulations of Ozone-Based Organic
Oxidation
[0116] Having a high quality process model significantly reduces
the number of experiments required to understand reactor
performance, and greatly enhances the reliability of subsequent
scaled-up designs. These simulations of the reactor system reduce
the number of experimental runs needed to define the system, by
better identifying the experimental space where data is needed.
Computer runs are certainly less time consuming than hands-on
experiments.
[0117] Basic computer modeling is developed for the ozone-only
system, and then extending it to an ozone/peroxide combined
system.
[0118] In this work, an early concern about the design was
supplying enough oxidant to the reactor to treat a 1000 ppm organic
stream. With ozone alone, it is a formidable task, and gas phase
stripping of organics appeared unacceptably high. With the addition
of a stoichiometrically similar amount of hydrogen peroxide (30%
solution) plus ozone the total oxidant requirement looks more
reasonable to completely degrade a contaminant in a waste fluid,
such as acetone. Degradation means at least partial oxidation of
the original compounds to partial oxidation products, but not
necessarily complete destruction to carbon dioxide and water. The
key question is how to effectively use the oxidants provided. In
the ozone/hydrogen peroxide system several factors including pH,
the presence of aqueous metals or salts, use of UV light, or solid
phase catalyst are all very important in the oxidation
efficiency.
[0119] The next step was development of a combined ozone/peroxide
model. Due to the contradictory information in the literature about
reaction rates (see for example: Mullins, M. E., "Aqueous Phase
Oxidation of Contaminants," Presented at AIChE Summer Convention,
Philadelphia, Pa. August 1989; Beltrain, F. J., G. Ovejeor, and J.
Rivas, "Oxidation of Polynuclear Aromatic Hydrocarbons in Water. 4.
Ozone Combined with Hydrogen Peroxide," Ind. Eng. Chem. Res., Vol.
35, pp 891-896 (1996); Kuo, C-H., and S. M. Chen, "Ozonation and
Peroxone Oxidation of Toluene in Aqueous Solutions," Ind. Eng.
Chem., Vol. 35, pp 3973-3983 (1996); Beltrain, F. J., J. M.
Encinar, and M. A. Alonso, "Nitroaromatic Hydrocarbon Ozonation in
Water. 2. Combined Ozonation with Hydrogen Peroxide or UV
Radiation," Ind. Eng. Chem. Res. Vol. 37, pp 32-40 (1998);
Beltrain, F. J., J. Rivas, P. M. Alvarez, M. A. Alonso, and B.
Acedo, "A Kinetic Model for Advanced Oxidation Processes of
Aromatic Hydrocarbons in Water: Application to Phanthrene and
Nitrobenzene," Ind. Eng. Chem. Res., Vol. 38, pp 4189-4199 (1999);
Lang. S. et al., "Treatability of MTBE-contaminated groundwater by
Ozone and Peroxone", Journal AWWA, June 2001; Beltrain, F. J., J.
F. Garcia-Araya, V. Navarrete, and F. J. Rivas, "An Attempt to
Model the Kinetics of the Ozonation of Simazine in Water," Ind.
Eng. Chem. Res., Vol. 41 pp 1723-1732 (2002); Acero, J. F. J.
Benitex, F. J. Real, and C. Maya, "Oxidation of Acetamide
Herbicides in Natural Waters by Ozone and by the Combination of
Ozone/Hydrogen Peroxide: Kinetic Study and Process Modeling," Ind.
Eng. Chem. Res., Vol. 42, pp 5762-5769 (2003); a practical
compromise was adopted in the model, in which two independent
reaction terms were assumed: one for the ozone, and one for the
peroxide with a pH dependency. It seems to fit the existing data
well. Once again, this system seems to work better for the higher
pH's (8-10), but has only small advantages for low pH's over ozone
alone.
Model Development
[0120] No quantitative information on pressurized ozone/peroxide
reactors in the research literature or the patent literature was
found, so there was no data available to determine the possible
advantages or disadvantages of operating this system under
pressure.
[0121] It would also be desirable to do sensitivity analysis to
determine the most important variables to exploit (including
pressure). However, no matter how clearly a model is constructed,
to have a confidence in any actual design requires some
experimental validation of the model results.
[0122] A Microsoft Word text version of the MathCAD 11 program is
found below in the section titled: Packed-bed ozone reactor system
model. This is not an executable file. There are 2 models for the
ozone system: a segregated (plug) flow model and a dispersed flow
model at atmospheric operation and two models at high pressure.
Since we are envisioning a packed column system, the results are
not substantially different between the two, but the dispersed flow
model is slightly more accurate if we could experimentally
determine what the dispersion coefficient might be for present
reactors. Those experiments have not been done in present studies
to date.
[0123] Using the model to examine the effect of pressurizing the
reactor (in the range of 2 to 5 atmospheres), the results appear
very promising. There is a strong positive effect of increased
pressure in reducing reactor size, slightly improving mass transfer
rates, and greatly reducing the containment stripping for the
straight ozone in water case. Of course, increasing the pressure
does not improve the oxidation stoichiometry, so a lot of ozone is
still needed. However, pressurization does significantly help the
problem of stripping of the organic at high concentration.
[0124] Using the design objectives, and operating at higher
pressures, the model shows that the number of plug-flow reactors in
series can be reduced to 2 or 3. This is due to the enhanced
reaction rate and because the mass transfer correlation predicts an
increase of the mass transfer coefficient by a factor of 3. This
means the overall size of the system is reduced by at least a
factor of two.
[0125] The chemistry of advanced oxidation reactions can be quite
complex; therefore, a fairly pragmatic approach has been assumed in
that sufficient detail is used to accurately reflect the real
chemistry, but there are not so many reaction variables that they
cannot be obtained for a limited number of experimental studies.
Second order kinetics has been assumed for the oxidation of the
organic, with a variable stoichiometry for the ozone/organic. A
detailed network of all the side oxidation reactions leading to
complete and partial oxidation has not been incorporated at this
point, as those sets of reaction parameters are very compound
specific. For the ozone, all of the reactions leading to ozone
destruction have been lumped into a pseudo-rate constant, w, the
specific ozone utilization rate. Since the ozone is consumed by
many pathways including reaction with the organic and its
decomposition products, self-decomposition, and scavenging by
minerals or ionic contaminants in the water, the reaction rate
expressions quickly become difficult to interpret. From a practical
point of view, the specific utilization rate is easy to determine
from a simple batch test of ozone with the water to be treated;
whereas, the myriad rate constants for the entire network of
reactions is virtually impossible to decipher. In the past this has
been a very successful method for determining the primary rate of
contaminant destruction and the amount of ozone required. For pure
water, the half-life of ozone is on the order of minutes, but even
in tap water, the half-life may be cut in half. Any pH effects are
also contained in the utilization rate for a specific water.
[0126] Several other important features of the computer simulation
should be noted. These include:
[0127] The mass transfer coefficients for both the absorption of
ozone, and the stripping of the organic.
[0128] Many of the variables in the model attached are values for
toluene, but can be readily changed to other compounds of interest.
These include the molecular weight, Henry's law constant, reaction
rate constants, and oxidation stoichiometry.
[0129] The gas and liquid flowrates in the model attached are also
somewhat arbitrary and can be scaled for any desired column
diameter.
[0130] The model, as written, is for co-current flow, but can be
adapted for counter-current flows of gas and liquid if desired.
[0131] It is important to note, that with good data from a bench
scale system, the reaction and mass transfer parameters of the
model can be "tuned" to much more accurate scale up of the reactors
to larger flowrates. Without this "feedback" loop it would be
somewhat difficult to build a pilot scale system based on the model
alone.
[0132] After running numerous studies using this model, some
general conclusions about the results may be made:
[0133] The simple pressure drop calculation included, shows a very
small pressure drop across the column (only a few inches of
water).
[0134] Properly balancing the ozone feed to the reactors will be
extremely important for best efficiency.
[0135] Co-current feed of ozone and water is more efficient in any
case.
[0136] In the case of volatile, sparingly soluble organic
contaminants (e.g. toluene), stripping is a large factor in organic
removal. Lowering the volumetric gas flowrate and increasing ozone
concentration mitigates this to a great extent.
[0137] In the case of most, but not all, contaminants, the reaction
is still largely mass transfer limited! Additional examination of
factors to improve this may help decrease the reactor size even
further.
[0138] For high concentrations of organic (>2000 ppmw), the
column performance becomes limited by the volume of gas containing
ozone required. In other words, if we were to try to oxidize all of
the organics in one column, in the case of toluene we end up adding
so much gas that stripping becomes by far the largest mechanism for
removal of benzene! This is true even for high (8%) ozone
concentrations. There may be other contacting patterns or reactor
configurations that help prevent this problem (although
counter-current flow makes it worse).
[0139] The initial runs of the model with ozone-peroxide kinetics
show that the gas to liquid ratios are much more favorable, but
chemical kinetics used in that model are needed. Additional
experimental data on the ersatz organic/water systems are also
needed to tune the model for proper hydrogen peroxide addition
rates. The practicality of this design is the effective use of all
of the added oxidants towards contaminant destruction.
[0140] Overall, the model results of the pressurized ozone/peroxide
reactor are quite promising. The reaction rates, mass transfer
rates, and magnitude of organic stripping all look very good. The
level and size of suspended solids should not be a problem. Even
the pH of the sample water is in a great range to enhance reaction
rate. A major concern is still the high TOC level (up to 2000 ppmw)
for the industrial waters of interest. Not only does that mean
using large volumetric flowrates of ozone, but for the highest
concentrations enough ozone to completely oxidize the sample is
supplied, there is enough oxidation taking place to heat the water
by 7 to 10 degrees C.
Plug-Flow Ozone Reactor System Model
[0141] The following description provides multi-phase,
multicomponent reactor models for 3 different cases: segregated
(plug) flow, staged mixed reactors, and disperse flow (both initial
and boundary value solutions). A hydraulic model with a single
phase Ergun pressure drop calculation, and both co-current and
counter current solutions are also included. Reactor material
balances are performed for each of the reactants (i.e. ozone and
the organic) in both the liquid and gas phases.
[0142] Ergun equation: The standard Ergun equation is usually
applied to the flow of a single phase fluid, either a liquid or a
gas, through a porous medium. In the operation of a two-phase
reactor, a liquid may flow co-currently or counter current to the
liquid flow through the packing material. The presence of the
liquid reduces the void fraction and increases the gas phase
pressure drop. As the gas rate is increased, the shear forces at
the gas-liquid interface tend to retard the flow of liquid, further
decreasing the void fraction. If the gas rate is increased
sufficiently, a point will be reached where the liquid is retarded
to a degree that it totally fills the packing material at some
point in the tower. This condition is known as flooding.
Pressure-flow relationships for two-phase flow in packed reactors
are complex and semi-empirical correlations must be used. The
following form of the Ergun equation may be used for a single
continuous phase.
[0143] Ergun equation to calculate the pressure drop (DP) for a
given flowrate, where L is the flow path (bed) length, m is the
fluid viscosity, r is the fluid density, e is the void fraction, F
is the partial sphericity (1.0 for spheres), Dp is the particle
diameter, and V is the mean fluid velocity.
V := 0.1 m s ##EQU00001## .mu. := 0.1 cP ##EQU00001.2## .rho. :=
100 ? kg m 3 ##EQU00001.3## L := 1 m ##EQU00001.4## D p := 0.03 ? m
##EQU00001.5## := 0.3 ? unitless ##EQU00001.6## .PHI. := 1 unitless
##EQU00001.7## ? indicates text missing or illegible when filed
##EQU00001.8##
[0144] The pressure drop across the bed is:
.DELTA. P ( V ) := L 150 V .mu. 1000 .PHI. 2 D p 2 ( 1 - ) 2 3 +
1.75 .rho. V 2 .PHI. D p ( 1 - 3 ) Pa ##EQU00002## .DELTA. P ( V )
= 6.009 .times. 10 3 Pa ##EQU00002.2## Or : ##EQU00002.3## .DELTA.
p := .DELTA. P ( V ) 1.013 10 5 14.69 ? psia ##EQU00002.4## .DELTA.
p = 0.872 psia ##EQU00002.5## ? indicates text missing or illegible
when filed ##EQU00002.6##
[0145] Segregated flow reactor model: in a two-phase reactor,
disperse flow takes on new meaning, in that one phase may be close
to plug flow (e.g. --bubbles in a bubble column, or droplets in a
spray column); whereas the other phase (typically the continuous
phase) may be affected by some degree of mixedness. In some cases
the continuous phase may also be considered segregated, as when the
reactor length is very large as compared to its width, or when
packing is used. In these simplified two-phase reactions, a
continuous flow reactor may be adequately modeled using a
segregated flow model for each phase. This produces a set of
first-order ordinary differential equations that are readily solved
for any order reaction as an initial value problem. The example
below is for an ozonation reactor with a water-phase reactant in a
simple 2nd order reaction for either the co-current or counter
current situation. The oxidation occurs solely in the liquid phase;
however, stripping of the organic into the gas phase is accounted
for.
[0146] The pertinent differential equations for ozone oxidation of
an aqueous organic, S, are:
TABLE-US-00004 Gas phase ozone: d dt O 3 g := k LaO 3 ( O 3 L - O 3
e ) Q L Q G ##EQU00003## Liquid phase ozone: d dt O 3 L := k LaO 3
( O 3 e - O 3 L ) - h l w O 3 I ##EQU00004## Gas phase organic: d
dt S g := k LaS ( S L - S e ) Q L Q G ##EQU00005## Liquid phase
organic: d dt S L := k LaS ( S e - S L ) - h l k O 3 L S L
##EQU00006## Specific ozone utilization rate (sec-1): w := .05
Liquid holdup: h.sub.1 := .91 Organic oxidation rate (gmol/sec) k
:= 300 Henry's law constant h.sub.s := .42 organic: Henry's law
constant, O3: h := 2.8 Organic/ozone .omega. := 1 stoichiometry
Volumetric flowrates (L/sec) Q.sub.G := .5 Q.sub.L:= 1 Column cross
A.sub.c := .3 sectional area (m2) Residence time range (seconds):
t0 := 0 t1 := 50 MW.sub.R := 80 We can use a gas-to-liquid mass
Linear mass flowrates, G.sub.L and G.sub.g (kg/m.sup.2 - s)
transfer correlation we have developed for 2-phase co-current flow
in a packed bed reactor to obtain an estimate of the mass transfer
coefficient, Kla. (Kindt, 1996) (sec-1) G L := Q L 1000 A c G g :=
Q G 1.2 A c ##EQU00007## k.sub.LaO3 := 0.06371G.sub.L.sup.0.3014
G.sub.g.sup.0.4484 k LaS := 48 MW R k LaO 3 ##EQU00008## k.sub.LaO3
= 0.027 k.sub.LaS = 0.016 Initial concentrations ( gmol / L ) :
.lamda. := ( 0.0 0.00333 .00379 0 ) Liquid phase ozone Gas phase
ozone Liquid phase organic Gas phase organic ##EQU00009## Set up
equation matrix for each material balance : D ( t , .lamda. ) := [
k LnO3 ( .lamda. 1 H - .lamda. 0 ) - h l w .lamda. 0 k LaO3 (
.lamda. 0 - .lamda. 1 H ) Q L Q G [ k LaS ( .lamda. 3 h s - .lamda.
2 ) - h l k .lamda. 2 .lamda. 1 ] k LaS ( .lamda. 2 - .lamda. 3 h s
) Q L Q G ] Liquid phase ozone Gas phase ozone Liquid phase organic
Gas phase organic ##EQU00010## Set up solution matrix, Z: Z :=
Rkadapt(.lamda., t0, t1, 1000, D) t := Z 0 C O 3 L := Z 1 C SL := Z
3 C Sg := Z 4 C O 3 g := Z 2 ##EQU00011##
[0147] Dispersed flow reactor model: If some mixing occurs within
the reactor, especially due to the two phase passing through the
packing at different rates, or due to turbulence within the column,
then the plug-flow assumptions do not strictly apply. The chief
parameter defining whether this is important is the Peclet number:
Pe=Lv/Da. Here L is the bed length, v is the linear fluid velocity,
and Da is the dispersion coefficient. The set of resulting
equations are no longer a simple set of first order initial values
equations, but a set of second order equations that must be solved
via a boundary value solution.
TABLE-US-00005 Sample data: Dispersion Coefficient D.sub.a := 10
Volumetric gas V.sub.g := 1 (unitless) and liquid flowrates:
V.sub.L := 1 Interfacial transfer area A := 1 (L/min)
(m.sup.2/m.sup.3)
[0148] The basic differential equations representing the mass
balances for dispersed flow with one gas phase (O) and one liquid
phase (C) reactant over a bed length from z=0 to z=L are:
Gas Phase Reactant Mass Balance Equation
[0149] D a A 2 z 2 C OL ( z ) - V L ( ( z C OL ( z ) ) ) + k LaO A
( C Og ( z ) H - C OL ( z ) ) = k 1 C OL ( z ) ##EQU00012##
Liquid Phase Reactant Mass Balance Equation
[0150] D a A 2 z 2 C CL ( z ) - V L ( ( z C CL ( z ) ) ) - k LaOC A
( C CL ( z ) - C Cg ( z ) h s - ) = h 1 k 1 C CL ( z ) C OL ( z )
##EQU00013##
With the Danckwert's Boundary Conditions:
[0151] ( C O 3 g ( z ) = C O 3 f ( z ) ) - D a A z C O 3 L ( z ) =
V L ( C O 3 f ( z ) - C O 3 L ( z ) ) - D a A z C OCL ( z ) = V L (
C OCf ( z ) - C OCL ( z ) ) ##EQU00014## z C O 3 L ( z ) = 0
##EQU00014.2## z C OCL ( z ) = 0 ##EQU00014.3##
[0152] Since these are second order differential equations, with 2
unknown boundary conditions, a "shooting" method is used to turn
this into an initial value problem. (details of the MathCAD code
are below).
Shooting Method to Find B.C.s:
TABLE-US-00006 [0153] Mass transfer k.sub.LaO := 0.02 coefficients:
k.sub.LaC := .03 Guess v := ( 0.003 .0001 ) ##EQU00015##
Interfacial area A := 1 Liquid holdup: h.sub.1 := .8 h.sub.s := 1
load ( z 1 , v ) := ( 0 0 0.000333 0 v 0 v 1 ) ##EQU00016## D ( z ,
.xi. ) := [ .xi. 0 .xi. 1 k LaC A ( .xi. 4 - .xi. 3 h s ) 1 v g [ k
LaO A ( .xi. 2 h - .xi. 5 ) ] 1 v g V L .xi. 0 + k LaO A ( .xi. 2 h
- .xi. 5 ) - h l .xi. 5 D a A V L .xi. 1 - k LaC ( .xi. 4 - .xi. 3
h s ) - h l k .xi. 4 .xi. 5 D a A ] ##EQU00017## score ( z 2 , .xi.
) := ( .xi. 4 - .00001 .xi. 5 - .00001 ) ##EQU00018## S := sbval
(v, 0, 20, D, load, score) We now have our missing initial
conditions! S = ( 2.092 .times. 10 - 5 9.682 .times. 10 - 6 )
##EQU00019##
[0154] The system of equations now may be solved as an initial
value problem. Convert the second order equations into a set of
first order equations by defining the first derivatives of liquid
phase concentrations for reactor size, z, as shown in the first 2
equations below. The entire set of equations along with any
algebraic constraints and the initial values are also provided:
TsO ##EQU00020## he so ##EQU00020.2## Given ##EQU00020.3## z C O 3
L ( z ) = .chi. ( z ) ##EQU00020.4## z C RL ( z ) = .phi. ( z )
##EQU00020.5## V g z C RL ( z ) = .kappa. LaR A ( C RL ( z ) - C Rg
( z ) h s ) [ V g z C O 3 g ( z ) + k LaO 3 A ( C O 3 g ( z ) h - C
O 3 L ( z ) ) ] = 0 ##EQU00020.6## D a A z .chi. ( z ) - V L .chi.
( z ) + k LaO 3 A ( C O 3 g ( z ) h - C O 3 L ( z ) ) = h 1 w C O 3
L ( z ) ##EQU00020.7## D a A z .phi. ( z ) - V L .phi. ( z ) - k
LaR ( C RL ( z ) - C Rg ( z ) h s ) - h 1 k C RL ( z ) C O 3 L ( z
) = 0 ? ##EQU00020.8## C O 3 L ( 0 ) = 2.092 .times. 10 - 5 C RL (
0 ) = .0000 ? C O 3 g ( 0 ) = .00033 ? C Rg ( 0 ) = 9.682 .times.
10 - 6 ##EQU00020.9## .chi. ( 0 ) = 0.0000 ? ##EQU00020.10## .phi.
( 0 ) = 0.0000 ? ##EQU00020.11## ? indicates text missing or
illegible when filed ##EQU00020.12##
[0155] A pilot scale packed bed ozone and hydrogen peroxide based
reactor was designed to run a basic experimental matrix on several
compounds of interest. The design was prepared to validate the
parameters used in the present model. Of particular importance were
mass transfer rates and destruction rates. The present apparatus
was originally designed to operate at near atmospheric pressure,
but was subsequently modified to operate up to about 40 psia. In
this fashion, a clearer idea of how operating under elevated
pressure will work for ozone alone and for the ozone and hydrogen
peroxide system is obtained.
Experimental Studies and Set-Up
[0156] A pilot scale packed ozone/hydrogen peroxide reactor (one)
was used to analyze the basic experimental matrix on the compounds
of interest, to validate the parameters used in the model and to
help refine the design of systems of the present invention. The
original device used to test was designed to operate at about 40
psia.
[0157] A one reactor system was developed to provide data useful in
the modeling process. The setup was designed to support a glass
column reactor. An inlet source tank was prepared with 40 liters of
distilled water plus chemicals common in industrial waste fluid,
such as toluene, acetone, acetonitrile, and-phenol. The solution
was allowed to equilibrate for 24 hours with constant stirring. The
waste fluid was then pumped through a variable speed gear pump and
liquid rotometer into the bottom end of the reactor column.
[0158] Bottled oxygen with a double-sided regulator was used to
supply gas to the ozone generator and reactor at sufficient
pressure. The oxygen traveled directly to the OREC Ozone Generator
which requires cooling by a circulating water system next to the
source tank. According to calibration test performed with indigo
dye, the gas leaving the ozone generator at the settings employed
was approximately 4% ozone and 96% oxygen. The gas was diffused
into the bottom of the reactor.
[0159] The reactor itself consists of a two foot long.times.four
inch I.D. Pyrex glass column with cast iron flanges and steel end
plates. The bottom four inches contain a porous ceramic diffuser
device for the gas inlet as well as the stand and a screen to
support the packing. The next twenty inches were filled with 1/2
inch glass Raschig ring type random packing which serves to enhance
mass transfer and prevent back-mixing with the reactor.
[0160] Gas and liquid exit the reactor through a single outlet,
which was equipped with a pressure gauge, pressure regulator, and
ball valve. Pressure gauges were also placed on both gas and liquid
inlet line and another back pressure regulator was included
downstream of the regulator. The ball valve was used to pressurize
the reactor during the experiment by restricting exit stream. This
resulted in a higher velocity in the gas/liquid stream as it
escaped, but still left the problem of separating the off-gas from
the treated water. As such, a flash chamber operatively attached to
the treated waste fluid stream.
Experimental Procedure:
[0161] Several experiments were conducted with the pilot plant to
determine the effect of a number of variables on the destruction of
the chemicals mentioned above. The three most important variables
(flowrates, ozone concentration and pressure) were tested and shown
in Table 4:
TABLE-US-00007 TABLE 4 Experimental Setup Testing Rubric For Waste
Fluid Treatment By Ozone Trial 1 Trial 2 Trial 3 Trial 4 Trial 5
Trial 6 Trial 7 Trial 8 Pressure (psig) 0 0 0 0 15 15 15 15 O.sub.3
Amps (A) 1.00 1.00 2.00 2.00 1.00 1.00 2.00 2.00 Liquid Flow
(L/min) 0.6 1.6 0.6 1.6 0.6 1.6 0.6 1.6 Gas Flow (L/min) 10.0 10.0
10.0 10.0 10.0 10.0 10.0 10.0
[0162] The eight trial ensured that samples were taken at each
combination of two different pressures, two different amperages
(ozone concentrations), and two different liquid flow rates. The
gas volumetric flowrate was held constant for all tests.
[0163] The critical variable to be tested was the pressure in the
reactor, followed by the liquid flowrate and the ozone generator
amperage. Over the complete range of testing, it proved difficult
to operate at constant pressures of 15 psig, however, all tests can
be considered accurate within the range of 15.+-.2 psig. Although
gas flow could also have been included as a variable for these
tests, the benefit would have been minimal in the face of doubling
the number of trials.
[0164] The rubric of Table 4 was first used to evaluate the
destruction of waste fluid having organics acetone and toluene.
Four milliliters of each chemical was added to 40 liters of
distilled water, resulting in 87 ppm toluene and 79 ppm acetone by
mass, or simply 100 ppm each by volume. Samples of the solution
were taken so that concentrations could be determined analytically
instead of relying on complete dissolution and mixing. The samples
were collected in 40 ml vials and 100 ml jars to be tested
respectively for aromatics, i.e., toluene and phenol, volatiles,
i.e., acetonitrile and acetone, and Total Organic Carbon (TOC).
[0165] The rubric of Table 4 was also used to test the pilot plant,
this time with a combined ersatz solution of acetonitrile, phenol,
toluene, and acetone. Concentrations in this solution were 157 ppm
acetonitrile, 170 ppm phenol, 109 ppm toluene, and 99 ppm acetone.
Again, initial samples were taken for analysis, and exit samples
were collected for each trial in succession. With the solution
remaining after these tests, another test was introduced to
determine the effect of hydrogen peroxide in solution and the
peroxone reaction. A 30% hydrogen peroxide solution was used to add
10 ml per liter of the remaining simulated waste fluid. The result
was a solution of about 3.3% hydrogen peroxide and the other
chemicals in their lower concentrations. Trials three and seven
were chosen as representative data points and sampling was
performed at those conditions. With sampling completed, the vials
and jars were tested for TOC, volatiles and BTEX analysis. To
verify these results, several duplicate samples were taken of
trials four and seven during the testing, and these samples were
sent out for independent analysis (White Water Associate, Inc.,
Arnasa, Mich.).
[0166] Representative results for the removal of toluene are shown
in Table 5 below. Note that these results don't represent the
complete destruction of toluene to carbon dioxide and water, rather
they show a combination of the destruction, degradation to other
compounds, plus stripping which may occur. In any case, the removal
numbers are impressive for such a small column and short contact
times.
TABLE-US-00008 TABLE 5 Representative Toluene Removal EPA Method
Toluene Trial 8260B Concentration Reduction % Initial Toluene
12,500 .mu.g/L NA Exit Run 2, Trial 3 Toluene 1,650 .mu.g/L 86.8
Exit Run 1, Trial 4 Toluene 5,030 .mu.g/L 59.76 Exit Run 1, Trial 7
Toluene 2,360 .mu.g/L 81.12 Exit Run 2, Trial 7 Toluene 1,590
.mu.g/L 87.28
[0167] The results from trials 3 and 7 show removal of 80% to 90%
of the toluene, as might be expected for these higher ozone
concentrations and lower liquid flowrates (higher residence times).
Although it would be useful to get a better handle on the total
removed via stripping, it is instructive to compare these
percentages to the TOC removal numbers to understand the relative
amount of materials that must be at least partially oxidized.
[0168] The results of the TOC trials are shown below in Table 6.
The original ersatz mixture of the four chemicals had a measured
TOC of 288 ppm. This may differ from the theoretical TOC based upon
the original mixture as made due to evaporation, etc. Note that
although, the original organic compounds may have been up to 80%
degraded, the TOC is more slowly reduced due to the formation of
partial oxidation byproducts. Although, some of the reduction may
be due to stripping, the reductions are significant for such a
small reactor and contact time.
TABLE-US-00009 TABLE 6 TOC Sample I.D. TOC, ppm TOC, removal (%)
Initial 288 NA exit setting 1 279 3.13 exit setting 2 265 7.99 exit
setting 3 275 4.51 exit setting 4 258 10.42 exit setting 5 282 5.21
exit setting 6 272 5.56 exit setting 7 265 7.99 exit setting 8 272
5.56 Initial with H.sub.2O.sub.2 297 NA settings 3 with
H.sub.2O.sub.2 262 11.78 setting 7 with H.sub.2O.sub.2 272 8.42
Blank 4.7 NA
[0169] It is apparent that there is a large discrepancy between the
toluene removal (>80%) and total TOC removal (approximately
10%). It is believed that these results indicate that stripping of
the organic is present, but small, and that the majority of the
original compounds are being at least partially oxidized. These
experimental values cannot be strictly quantitatively interpreted
unless precisely the identity of the partial oxidation byproducts
is known.
[0170] A few points are apparent from this data: First, generally
the presence of hydrogen peroxide is useful in the destruction of
organics. Second, higher ozone concentrations in the influent are
very beneficial. Third, somewhat surprisingly, the effect of liquid
flowrate (i.e., contact time) is not particularly important,
however, this may be due to the complete depletion of ozone in the
reactor over an even shorter timeframe. Finally, from these
results, one may gather that pressure is important and will also
result in the reduction of stripping of organics at higher
pressures. So overall, the actual destruction of the organics is
probably higher overall. The model developed earlier should be able
to help on the analysis of this data, as discussed more completely
below.
Results:
Fitting the Model to the Experimental Results:
[0171] The segregated flow model of the present invention is a
reasonable representation of the co-current, plug flow system
envisioned. Several aspects of the reaction parameters are under
investigation: reaction parameters associated with the mass
transfer coefficients (kLa's), specific ozone utilization rate (w)
and specific reaction rates (k). It is believed that discussions
that follow provide an accuracy of about .+-.20%.
[0172] Indigo dye fading studies to determine ozone mass transfer
coefficients: Indigo dye reacts stoichiometrically with ozone to go
from a dark blue to colorless in an extremely fast reaction. Indigo
is also a non-volatile solute, so that the reaction is ideal for
determining the rate of ozone mass transfer and for titrating the
amount of ozone being produced. Several flowrates of ozone
containing gas for a given flowrate and concentration of indigo in
waster were run, the results were used to "back calculate" the mass
transfer coefficients by adjusting that parameter in the model to
match the observed indigo outlet concentration.
[0173] An example of a plot of concentration versus reactor contact
time for the indigo-ozone system is shown in FIG. 9. This fitting
exercise confirmed that the mass transfer correlation used is close
to the results of the actual experimental value for ozone, the
model is designed to be a conservative approach to this value. This
data provides confidence in the prediction of the overall model.
Also, by observing the passage of the blue indigo dye through the
packed column reactor (see FIG. 10), the mean residence time of the
water in the bed could be determined. For the data shown herein, at
a flowrate of 3 L/min, the residence time was approximately 85
seconds.
Batch Tests for Determining the Specific Ozone Utilization Rate
[0174] In the following tests, a small closed flask containing
ersatz water with the target contaminates (or the actual waste
water to be treated) is saturated with ozone using a bubble
diffuser. The gaseous ozone is then turned off and the flask
sealed. The liquid phase ozone concentration is then monitored as a
function of time using UV spectroscopy (or colorimetric
techniques). The resulting data is analyzed as a pseudo first-order
reaction, i.e., the log of the normalized concentration is plotted
as a function of time. The slope of the plot is determined via a
simple linear regression and the slope is equal to the specific
ozone utilization rate.
[0175] This batch test is performed, for purposes of this Example,
on any candidate aqueous waste stream to find the correct reactor
residence times, ozone requirements, and flowrates. This rate
constant incorporates both ozone decomposition, reaction with the
target contaminates and the effects of pH and ionic strength.
Although this approach limits the precision model, it is an
excellent compromise between model complexity, the number of
required parameters, and reliability of the model results. Even
distilled water has an ozone utilization rate of approximately 0.05
sec-1, indicating an ozone half-life of only seconds to up to three
minutes. For waste fluids, the values may be as high as 2.0 sec-1,
indicating a half-life of only a few seconds. These rates are
greatly affected by the presence of iron, metals, and articulate
matter. For the ersatz waters, the values range from approximately
0.1 to 0.5 sec-1, but these are likely to be far higher for actual
industrial waters.
Pilot Scale Ozonation of Ersatz Waters
[0176] Ersatz solutions were created, having target contaminates,
by addition of small amounts of the pure chemicals to 40 liters of
distilled water. The compounds selected include acetone, phenol,
acetonitrile, and toluene. The entire experimental matrix is shown
above in Table 1.
[0177] Samples were measured for each specific compound, and for
Total Organic Carbon (TOC), before and after treatment.
Representative results are shown in Tables 2 and 3. Using these
exit concentrations of each component, adjustments were made to the
reaction rate constants in the model to match what was observed. In
this fashion, it was determined that a second order reaction rate
constant for the oxidation of toluene is 147 M-1 sec-1, and that
the specific ozone utilization rate constant (w) is approximately
0.15 sec-1. Similarly, the rate constants for phenol, acetonitrile,
and acetone were fitted to exit data, and values between 75 and 500
M-1 sec-1 were obtained.
[0178] The results for phenol are interesting in that upon
oxidation, the solution turned light brown, indicating that the
phenol may have been polymerizing or undergoing some similar
reaction. This of course removes the original phenol, but likely
does not significantly reduce the TOC.
[0179] Several major observations can be made from these results,
including that ozone is depleted far before the organic, due to
higher reactivity of ozone. Therefore, in some cases, the ozone is
effectively depleted within the first 30 seconds of contact time.
This is more clearly evident for the pressurized reactor case
(FIGS. 12 and 13). Another observation is that in the pressurized
case, the stripping of organics is suppressed. Finally, since the
ozone is depleted very rapidly, it is virtually impossible to lower
the toluene concentration more than 70% at best in one column, but
that subsequent columns (2 and 3) are needed to accomplish the
original design objectives.
[0180] The above results are very instructive. Due to the lifetime
of ozone in water, the maximum destruction that can be anticipated
in a single stage reactor is about 70%, if followed in series by a
second similar stage, 96%, and with a third stage in series, 99%.
Notice that even after 30 seconds of contact time, the ozone is
nearly depleted, and the organic destruction levels off. Once this
has occurred, the remaining oxygen in the gas phase merely serves
to strip the volatile organics up to their Henry's law limit. It is
believed this is also why the water flowrates had little impact on
the observed destruction; the ozone was too readily depleted. This
depletion severely limits the maximum size of each individual
reactor column, and means that fresh ozone feed is required at the
entrance to each column. It is not recommended that ozone be added
midway through the individual reactors due to excess stripping
potential. Based upon the destruction obtained in each column, it
takes at least 3 column runs to obtain complete degradation of the
organics (based on type and level of contaminate). Under less ideal
condition than a distilled water ersatz solution, it may take an
additional column of two. The reduction in TOC at this point will
probably not be 99+%, but on the order of 30 to 60%. To obtain
further total TOC reduction (i.e., 99+%) would require at least two
more columns in series, and the associated increase in ozone and
hydrogen peroxide usage.
Conceptual Design:
[0181] A conceptual design was developed by applying an approach
that was used for an advanced oxidation treatment system for
contaminated waste fluid. A conception design of this system is
provided in FIGS. 5 and 6. Note that the systems shown in FIGS. 5
and 6 could be designed at two systems in parallel and thereby
provide for higher target flowrates. Addition of approximately 10
ml of H.sub.2O.sub.2 (30%) per liter of water to be treated lowers
the TOC by approximately another 20%. It is particularly useful for
some types of polar compounds.
[0182] The foregoing description of the invention is thus
illustrative and explanatory, and various changes in the equipment,
as well as in the details of the methods and techniques disclosed
herein may be made without departing from the spirit and scope of
the invention, which is defined by the claims.
[0183] This specification contains numerous citations to patents,
patent applications and publications. Each is hereby incorporated
by reference for all purposes.
* * * * *