Chemistry: molecular biology and microbiology – Process of utilizing an enzyme or micro-organism to destroy... – Treating gas – emulsion – or foam
Reexamination Certificate
1998-09-04
2001-09-18
Redding, David A. (Department: 1744)
Chemistry: molecular biology and microbiology
Process of utilizing an enzyme or micro-organism to destroy...
Treating gas, emulsion, or foam
C435S294100, C210S601000, C210S610000, C210S617000, C210S629000, C210S631000
Reexamination Certificate
active
06291233
ABSTRACT:
FIELD OF THE INVENTION
This invention is directed towards a biological treatment system which is suitable for removing and/or degrading a wide variety of contaminants. The treatment system is able to effectively handle volatile organic compounds (VOCs), volatile organic hazardous air pollutants (VOHAPs), light to middle weight petroleum distillates, and a variety of other organic pollutants. The treatment system is able to effectively treat these pollutants from both gas and liquid waste streams.
BACKGROUND OF THE INVENTION
The Clear Air Act Amendment (CAAA) of 1990 requires industrial and commercial facilities to control emissions of a wide range of Volatile Organic Hazardous Air Pollutants (VOHAP), Volatile Organic Compounds (VOCs), particulates, and gases causing acid rain and precursors for depletion of stratospheric ozone layers. The CAAA contains 10 titles, each addressing specific guidelines and compliance rules for each area of concern.
Title III of the CAAA requires all industrial and commercial facilities located within “non-attainment” areas to reduce their VOC emissions below the threshold value. The term “non-attainment” means areas or metropolis which have not met the National Ambient Air Quality Standards (NAAQS) in terms of ozone, NO
x
and particulate matter.
Title III of the CAAA requires 174 source categories/industry groups requiring control of emissions of 188 Hazardous Air Pollutants (HAPs). Each source category is a specific type of industrial or commercial operations which emits pollutants to the ambient air. A facility becomes a major source when it emits over 10 tons per year of a single HAP, or over 25 tons per year of all HAPs combined into the air.
Further, industry and regions in all parts of the country are undertaking aggressive efforts to limit the release of all types of hazardous materials. Public reporting criteria have increased the scrutiny and public pressure on all industries which generate or release toxic or hazardous materials. As a result, many industries are undertaking renewed efforts to control the production or release of hazardous materials.
Title III of the CAAA exposes numerous industrial emission sources which were not regulated or controlled before. These sources require installation of emission control technologies. At present, many industrial and commercial facilities have turned to aqueous scrubbing techniques or thermal oxidation processes such as incineration to curb their emissions. Incineration, while achieving a high destruction efficiency, is expensive in terms of capital and operating costs. Further, off-site incinerators which may serve many industries, face ever more opposition from citizens who have health concerns over incinerations efficacy and safety. Incineration of halogenated VOCs and HAPs are also extremely corrosive to the contact parts and may produce highly toxic substances such as dioxin.
Aqueous scrubbing technologies for VOC control do not have the corrosion or toxic byproduct formation problems like the incineration technologies. However, the scrubbers can only be effective for hydrophilic VOCs and HAPs and also require effective means for disposal of scrub water. For hydrophobic contaminants, such as the majority of the regulated VOCs and HAPs, aqueous scrubbing is generally not effective for emission control.
Both the incinerator and the scrubber technologies are not well suited or compatible for accepting and treating facility wastewater. In other words, both the technologies are applicable for treatment of only air streams. For hydrophilic contaminants, scrubbers could potentially use facility wastewater. However, since scrubbers merely transfer the contaminants from the gaseous to the liquid phase, and do not destroy, degrade or decompose, other forms of treatment operation(s) are necessary to dispose or discharge the scrub water.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a material and process which effectively treats a diverse group of pollutants.
It is a further object of this invention to provide a material and a process which can effectively remove pollutants from gaseous as well as liquid waste streams.
It is a further and more particular object of this invention to provide an apparatus and process which uses selected sorbents along with bio-solids to first remove (separate/concentrate) and to then degrade contaminants from a waste stream.
These and other aspects of the invention are made possible by features of applicants' AGB (Ashalata, Gostha Bihari) Process which involves the use of a novel bio-reactor utilizing microorganisms embedded in selective sorbents to sorb and bio-oxidize VOCs and HAPs from facility exhausts. As used herein, the term “sorb” includes both adsorptive and absorptive capabilities. In a single operative step, a multistage unit provides for the initial removal and subsequent degradation/detoxification of organic contaminants by utilizing bio-solids, selective sorbents, moisture and micro-nutrients.
Wastewater may be used to provide the moisture and part of the organic (carbon) food sources for the bio-reactor. The wastewater may be sprayed directly over the bio-solids and the sorbents. Depending on its characteristics, the wastewater may be pretreated or conditioned so as to be conducive to the bio-solids and the sorbents. A facilities' gaseous emissions are then passed through a multistage sorption unit of the bio-reactor. Each stage of the sorption unit is stacked with a blended mixture of selective sorbents and bio-solids. Depending on the characteristics of the contaminants, the mixture may additionally contain pH buffering ingredients, surface active agents and boosters to enhance selective metabolic activities. The sorbents and the bio-solids are kept moist by adding preconditioned wastewater in the form of fine mists or globules.
As the contaminated emissions passes through the stages of the bio-reactor, the selective sorbents capture the contaminants. Once captured, the contaminants provide a metabolic source for the microorganisms. Oxygen and micronutrients such as nitrogen (N), phosphorous (P) and potassium (K) are supplied via the wastewater and aids in the process of bioxidation or metabolization which converts the contaminants to CO
2
, H
2
O and trace quantity of mineral salts. The mineral salts are only formed for contaminants containing atoms other than carbon (C), oxygen (O) and hydrogen (H). The treated exhaust exiting the last stages essential contains air, CO
2
, H
2
O vapor, and ultra trace quantities of non-reacted contaminants.
The integrated AGB Process collects the facility wastewater and performs pretreatment or conditioning. The conditioning entails reducing the concentrations of the wastewater contaminants to a level which enhances the subsequent injection into the sorption unit of the bio-reactor. The primary unit operation for conditioning is a stripper cum bio-reactor vessel where the wastewater is pulsated in the presence of sorbents and bio-solids similar to those used in the sorption unit. The pulsation treatment allows the microbes sufficient time to bio-oxidize and reduce the wastewater contaminant concentration. The pulsation also strips (dislodges) the volatile contaminants such that it can be combined with the facility exhaust for passage through a BIO-SORPTION unit. Moreover, the pulsation also suspends and grows the microbes in an aerobic state and stimulates the growth of microbes most conducive for bioremediation of the contaminants.
One part of the wastewater, after pulsation, is generally filtered before injection into the bio-treatment unit. Following filtration, the filtered wastewater is introduced to the bio-treatment unit along with the gaseous emissions. The other part of the pretreated wastewater can either be discharged or reused within the facility.
REFERENCES:
patent: 4168050 (1979-09-01), Serfling et al.
patent: 4662900 (1987-05-01), Ottengraf
patent: 4810385 (1989-03-01), Hater et al.
patent: 5169782 (1992-12-01), Murphy et al.
patent: 5501718 (1996-03-01), Bandurski
Saha Anuj K.
Sarkar Amitava
Dority & Manning PA
Redding David A.
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