Grantee Research Project Results

Final Report: Biodetoxification of Mixed Solid and Hazardous Wastes by Staged Anaerobic Fermentation Conducted at Separate Redox and pH Environments

EPA Grant Number: R825549C031
Subproject: this is subproject number 031 , established and managed by the Center Director under grant R825549
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: HSRC (1989) - Northeast HSRC
Center Director: Sidhu, Sukh S.
Title: Biodetoxification of Mixed Solid and Hazardous Wastes by Staged Anaerobic Fermentation Conducted at Separate Redox and pH Environments
Investigators: Ghosh, Sam
Institution: University of Utah
EPA Project Officer: Hahn, Intaek
Project Period: February 1, 1990 through September 1, 1992
Project Amount: Refer to main center abstract for funding details.
RFA: Hazardous Substance Research Centers - HSRC (1989) RFA Text |  Recipients Lists
Research Category: Hazardous Waste/Remediation , Land and Waste Management

Objective:

The goal of this research project was to develop a staged anaerobic fermentation system for the simultaneous biodegradation of mixed solid and hazardous substances in the separated redox and pH environments of acidogenic and methanogenic bioreactors. A staged fermentation system consists of a solid-phase fermenter operated in tandem with a packed-bed, upflow methanogenic. The specific objective of the first phase of laboratory research was to study simultaneous anaerobic biodegradation of RDF-quality municipal solid waste (MSW), and benzene, toluene, xylene (BTX), and 1,2-dichloroethane (DCA). The capacity of the fermenting bed of MSW to remove heavy metals was also investigated.

Summary/Accomplishments (Outputs/Outcomes):

Significant quantities of hazardous substances are co-disposed with non-hazardous solid wastes of residential, industrial, and agricultural origin in landfills, gob piles, waste heaps, and other deposits of discarded solids. Non-hazardous organic solids, which constitute the major fraction of these solid waste deposits such as landfills, undergo a series of fermentations during which time the hazardous substances may be co-metabolized and converted to non-toxic metabolites and innocuous end products. It is known that organic materials in municipal landfills undergo aerobic biological transformation initially for a limited duration after which time the entrained oxygen resources are depleted, and anaerobic conditions ensue. During the increasing degree of anaerobiosis, various types of anaerobic fermentations predominate sequentially promoting hydrolysis, liquefaction, acidification, and gasification of the landfill constituents. The fermentation environment within the bed of solid deposits also change as indicated by changing redox potential, pH, acidity, alkalinity, gas-phase composition, and other parameters. The fate and biodegradation of the selected hazardous substances (BTX and DCA) under anaerobic fermentation conditions induced by acidic and methanogenic fermentations were studied.

This research was also aimed at developing a two-stage anaerobic bioprocessing system for the simultaneous removal/destruction of hazardous organics and inorganics, and stabilization and gasification of non-hazardous organic wastes. In this study, processed MSW was used as the organic solid waste. The bioprocess system consisted of a solid-phase anaerobic fermenter that could be operated in tandem with a packed-bed methanogenic reactor capable of gasifying the solid-phase leachate. The solid-phase reactor was operated to promote liquefaction and acidification of the MSW. Liquefaction of solids and acidification of the liquefaction products were promoted by intermittent recirculation of the reactor effluent (leachate).

The bioprocess system used in this research was expected to provide ecological niches in which co-metabolism of hazardous pollutants as secondary substrates and/or electron acceptors could occur owing to promotion of hydrolysis, hydration, dehydration, dehydrohalogenation, carboxylation, beta-oxidation, reductive dehalogenation, and other enzymatic reactions.

The project consisted of the following major tasks: development of a two-stage bioprocess system design, installation, shakedown and operation; residence-time distribution studies; preparation of RDF-quality MSW; development of gas chromatographic techniques for measurement of selected hazardous substances; adsorption studies; culture development; solid-phase fermentation runs to study the biodegradation patterns and kinetics of removal of BTX and DCA; and heavy-metal removal studies.

Development of a two-stage bioprocessing system. A two-stage bioprocess system consisting of two jacketed and hermetically-sealed cylindrical reactors, each equipped with automated feeding, effluent-collection, and effluent-recycling systems; automated gas-collection and recording devices; automated temperature control system; and on-line probes for redox measurement was custom-designed, fabricated and installed. The first-stage solid-phase reactor could accommodate about 14 liters of processed MSW. The second-stage, packed-bed methanogenic reactor (anaerobic filter) was filled with 5/8-in die Pall rings to support acetogenic and methanogenic biofilms grown on the solid-bed leachate substrate. The field capacity of the MSW solid bed was measured. The porosities of the MSW solid bed and the Pall ring-packed methane reactor were determined by analyzing the breakthrough patterns of a salt tracer.

Reactor residence time. The top 80 percent of the MSW-packed solid-bed reactor exhibited plug-flow behavior. The packed-bed anaerobic filter exhibited nearly ideal plug-flow characteristics at all depths at flow-through rates higher than that corresponding to a nominal hydraulic detention time (HDT) of seven hours; complete-mix conditions prevailed in this packed-bed reactor at lower HDTs.

Preparation of RDF-quality MSW. Raw MSW received at the Ogden, Utah landfill was processes by shredding, magnetic separation, hydrapulping, and dewatering to obtain an organic-rich fraction. The processing was done by Biomass International, Ogden, Utah.

Gas chromatographic methods development. One of the major challenges of this project was the development of gas chromatographic (GC) methods for the analyses of BTX and DCA in the gaseous and liquid effluents of the bioreactors. Considerable effort was directed to this end.

Adsorption studies. Hazardous substances present in MSW are partitioned between solid and liquid phases owing to adsorption of these compounds on solid adsorbents. Adsorption experiments were conducted at 22?C at pHs between 4.2 and 5.3 with BTX and DCA as adsorbates to determine the adsorptive capacities of MSW adsorbent, and to develop information on the partitioning of these hazardous substances between solid and aqueous phases. Several techniques including the use of flow-through columns and batch tests with gyrating shake f1asks were employed to conduct the adsorption tests. Sterilized MSW was used in these tests to preclude any adsorbate removal by biodegradation. The adsorption apparatus was maintained in sterile conditions. The data showed DCA adsorptions to range from 9.6 mg/g (dry) to 499 mg/g (dry) at equilibrium concentrations between 170 mg/l and 700 mg/l. The DCA sorption data could be best fitted by the Freundlich isotherm model; model constants were n = 0.528 and Kf = 0.0006 mg/g (dry). Benzene adsorption by MSW could also be fitted by the Freundlich model; the model constants were n = 0.528 and Kf = 1.210 mg/g (dry), which were very similar in magnitude to those of benzene adsorption by activated carbon (n = 0.625, Kf = 1.000 mg/g). The adsorption data indicated that MSW could be a significant sink for hazardous organics.

Culture development. An acidogenic culture was developed in the solid-bed reactor by inoculating the MSW bed with anaerobic digester effluents, and recirculating the percolating bed leachate intermittently at a flow rate of 1.5 pore-volume displacement per day to promote accelerated biodegradation of the bed substrates. Progression of culture development was monitored by measuring the pH, ORP, and volatile acids and COD concentrations in the bed leachate. Gas production from the bed was measured. The gases were analyzed for the contents of carbon dioxide, methane, nitrogen, and hydrogen. The solid bed was maintained at a temperature of 25?C.

Biodegradation studies. Benzene, toluene, o-xylene, and 1,2-DCA were introduced into the solid bed reactor after acidogenic conditions were established as indicated by a pH of 5.5, an ORP of -175 mV, and a bed-liquid volatile acids concentration of 2200 mg/l. The data indicated that 58 percent of the added benzene, 88 percent of the added toluene, 91percent of the added xylene, and 100 percent of the added DCA were removed initially by the MSW bed. DCA was not detected in the reactor liquid or gas phase because the DCA adsorptive-capacity of MSW was more than double the observed removal of this compound. Ortho-xylene was detected in the gas phase, but not in the liquid phase. Liquid-phase concentrations of benzene and toluene declined by more than 70 percent during the first nine days of bed operation indicating that significant biodegradation of these substances occurred at 25?C under conditions of nutritional deficiency. Complete disappearance of benzene and toluene occurred in about 40 days and 10, respectively. The depletions of these compounds could be described by the following kinetic model: K.ln[SO/S] + [SO - S] = k.t, where K is the half-velocity constant, t is time, k is a rate constant, SO is the initial concentration of benzene or toluene, and S is the concentration of benzene or toluene at any time, t. The following kinetic constants were evaluated: for toluene, k = 14.4 mg/l-day and K = 55.6 mg/l; for benzene, k = 8.8 mg/l-day and K = 46.2 mg/l. These data indicated that toluene degradation was considerably faster than that of benzene under the prevailing acidogenic condition characterized by a pH of 5.5 and an ORP of -175 mV.

Fate of heavy metals in acidogenic solid bed. The metal-removal capability of the acidogenic solid bed was investigated in a separate run in which copper was introduced into the acidogenic bed. The data indicated an initial immediate adsorption of 35 mg Cu/g MSW (dry), which was followed by a gradual removal pattern exhibiting second-order kinetics indicating that copper uptake was strongly dependent on its concentration. Copper sorption kinetics were very rapid initially at high concentrations, and thereafter the removal rate declined. The initial sorption mechanism appeared to be quite different from that responsible for the slow uptake of copper during the later stages of removal.

The results have been presented at professional meetings, and they have been communicated to other interested parties.

Journal Articles:

No journal articles submitted with this report: View all 1 publications for this subproject

Supplemental Keywords:

anaerobic biodegradation, acidogenic, methanogenic., RFA, Scientific Discipline, Waste, Water, Geographic Area, Contaminated Sediments, Remediation, Environmental Chemistry, Geochemistry, Municipal, Analytical Chemistry, Hazardous Waste, Bioremediation, Ecology and Ecosystems, Hazardous, EPA Region, fate and transport, adsorbent regeneration, hazardous waste treatment, hydrolysis, heavy metals removal, anaerobic treatment, contaminated sites, fate and transport , hydrodynamic modeling, biodegradation, cometabolism, anaerobic biodegradation, chemical transport, hazardous organic contaminants, contaminated soil, anaerobic digestion, municipal waste, Region 7, Region 8, biodegradable materials, biochemistry, hazardous organic compounds, solid waste, anaerobic fermentation, anaerobic biotransformation, municipal solid waste, hazardous waste characterization, hydrodynamics, supercritical fluids, redox, heavy metals, groundwater

Relevant Websites:

http://www.engg.ksu.edu/HSRC Exit

Progress and Final Reports:

Original Abstract

1990

1991

Main Center Abstract and Reports:

R825549    HSRC (1989) - Northeast HSRC

Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R825549C006 Fate of Trichloroethylene (TCE) in Plant/Soil Systems
R825549C007 Experimental Study of Stabilization/Solidification of Hazardous Wastes
R825549C008 Modeling Dissolved Oxygen, Nitrate and Pesticide Contamination in the Subsurface Environment
R825549C009 Vadose Zone Decontamination by Air Venting
R825549C010 Thermochemical Treatment of Hazardous Wastes
R825549C011 Development, Characterization and Evaluation of Adsorbent Regeneration Processes for Treament of Hazardous Waste
R825549C012 Computer Method to Estimate Safe Level Water Quality Concentrations for Organic Chemicals
R825549C013 Removal of Nitrogenous Pesticides from Rural Well-Water Supplies by Enzymatic Ozonation Process
R825549C014 The Characterization and Treatment of Hazardous Materials from Metal/Mineral Processing Wastes
R825549C015 Adsorption of Hazardous Substances onto Soil Constituents
R825549C016 Reclamation of Metal and Mining Contaminated Superfund Sites using Sewage Sludge/Fly Ash Amendment
R825549C017 Metal Recovery and Reuse Using an Integrated Vermiculite Ion Exchange - Acid Recovery System
R825549C018 Removal of Heavy Metals from Hazardous Wastes by Protein Complexation for their Ultimate Recovery and Reuse
R825549C019 Development of In-situ Biodegradation Technology
R825549C020 Migration and Biodegradation of Pentachlorophenol in Soil Environment
R825549C021 Deep-Rooted Poplar Trees as an Innovative Treatment Technology for Pesticide and Toxic Organics Removal from Soil and Groundwater
R825549C022 In-situ Soil and Aquifer Decontaminaiton using Hydrogen Peroxide and Fenton's Reagent
R825549C023 Simulation of Three-Dimensional Transport of Hazardous Chemicals in Heterogeneous Soil Cores Using X-ray Computed Tomography
R825549C024 The Response of Natural Groundwater Bacteria to Groundwater Contamination by Gasoline in a Karst Region
R825549C025 An Electrochemical Method for Acid Mine Drainage Remediation and Metals Recovery
R825549C026 Sulfide Size and Morphology Identificaiton for Remediation of Acid Producing Mine Wastes
R825549C027 Heavy Metals Removal from Dilute Aqueous Solutions using Biopolymers
R825549C028 Neutron Activation Analysis for Heavy Metal Contaminants in the Environment
R825549C029 Reducing Heavy Metal Availability to Perennial Grasses and Row-Crops Grown on Contaminated Soils and Mine Spoils
R825549C030 Alachlor and Atrazine Losses from Runoff and Erosion in the Blue River Basin
R825549C031 Biodetoxification of Mixed Solid and Hazardous Wastes by Staged Anaerobic Fermentation Conducted at Separate Redox and pH Environments
R825549C032 Time Dependent Movement of Dioxin and Related Compounds in Soil
R825549C033 Impact of Soil Microflora on Revegetation Efforts in Southeast Kansas
R825549C034 Modeling the use of Plants in Remediation of Soil and Groundwater Contaminated by Hazardous Organic Substances
R825549C035 Development of Electrochemical Processes for Improved Treatment of Lead Wastes
R825549C036 Innovative Treatment and Bank Stabilization of Metals-Contaminated Soils and Tailings along Whitewood Creek, South Dakota
R825549C037 Formation and Transformation of Pesticide Degradation Products Under Various Electron Acceptor Conditions
R825549C038 The Effect of Redox Conditions on Transformations of Carbon Tetrachloride
R825549C039 Remediation of Soil Contaminated with an Organic Phase
R825549C040 Intelligent Process Design and Control for the Minimization of Waste Production and Treatment of Hazardous Waste
R825549C041 Heavy Metals Removal from Contaminated Water Solutions
R825549C042 Metals Soil Pollution and Vegetative Remediation
R825549C043 Fate and Transport of Munitions Residues in Contaminated Soil
R825549C044 The Role of Metallic Iron in the Biotransformation of Chlorinated Xenobiotics
R825549C045 Use of Vegetation to Enhance Bioremediation of Surface Soils Contaminated with Pesticide Wastes
R825549C046 Fate and Transport of Heavy Metals and Radionuclides in Soil: The Impacts of Vegetation
R825549C047 Vegetative Interceptor Zones for Containment of Heavy Metal Pollutants
R825549C048 Acid-Producing Metalliferous Waste Reclamation by Material Reprocessing and Vegetative Stabilization
R825549C049 Laboratory and Field Evaluation of Upward Mobilization and Photodegradation of Polychlorinated Dibenzo-P-Dioxins and Furans in Soil
R825549C050 Evaluation of Biosparging Performance and Process Fundamentals for Site Remediation
R825549C051 Field Scale Bioremediation: Relationship of Parent Compound Disappearance to Humification, Mineralization, Leaching, Volatilization of Transformaiton Intermediates
R825549C052 Chelating Extraction of Heavy Metals from Contaminated Soils
R825549C053 Application of Anaerobic and Multiple-Electron-Acceptor Bioremediation to Chlorinated Aliphatic Subsurface Contamination
R825549C054 Application of PGNAA Remote Sensing Methods to Real-Time, Non-Intrusive Determination of Contaminant Profiles in Soils
R825549C055 Design and Development of an Innovative Industrial Scale Process to Economically Treat Waste Zinc Residues
R825549C056 Remediation of Soils Contaminated with Wood-Treatment Chemicals (PCP and Creosote)
R825549C057 Effects of Surfactants on the Bioavailability and Biodegradation of Contaminants in Soils
R825549C058 Contaminant Binding to the Humin Fraction of Soil Organic Matter
R825549C059 Identifying Ground-Water Threats from Improperly Abandoned Boreholes
R825549C060 Uptake of BTEX Compounds by Hybrid Poplar Trees in Hazardous Waste Remediation
R825549C061 Biofilm Barriers for Waste Containment
R825549C062 Plant Assisted Remediation of Soil and Groundwater Contaminated by Hazardous Organic Substances: Experimental and Modeling Studies
R825549C063 Extension of Laboratory Validated Treatment and Remediation Technologies to Field Problems in Aquifer Soil and Water Contamination by Organic Waste Chemicals