Microcosm Tests Research Articles

Degradation of aniline in weihe riverbed sediments under denitrification conditions

Three groups of microcosm tests were conducted to study the possibility of aniline degradation and the effects of organic matter and hydrous metal oxides on the degradation in Weihe riverbed sediments under denitrification conditions. After the riverbed sediments (20 g) and groundwater (800 ml) were put into bottles, aniline, nitrate and other reagents were added, and then the bottles were flushed with N2 for 30 minutes to create microcosms. Samples from the microcosms were employed for the analysis of aniline, nitrate, and chemical oxygen demand (COD). In the first test group, the concentration of aniline remained unchanged when NaN3 (500 mg/L) was added. When there was no nitrate or NaN3, the concentration of aniline also remained unchanged, although COD declined. However, the concentration decreased when nitrate (50 mg/L) was added. Therefore, aniline can be biodegraded under denitrification conditions. In the second test group, when the concentration of nitrate reached 50 mg/L, 300 mg/L or 400 mg/L, either the external or internal organic matter or both of them in Weihe raw sediments inhibited aniline degradation. In the sediments where organic matter alone or organic matter plus hydrous metal oxides were removed, the organic matter still inhibited the degradation when the concentration of nitrate reached 300 mg/L or 400 mg/L, but the external organic matter could accelerate the degradation when the concentration of nitrate was 50 mg/L. The result of the third test group showed that hydrous metal oxides can accelerate degradation. By analyzing the mechanism of the aniline degradation, we conclude that aniline is degradable by microbes in their growth metabolism, in which deamination is involved.

Determination of Electron Donors by Comparing Reaction Rates for In Situ Bioremediation of Nitrate-Contaminated Groundwater

Groundwater contaminated by nitrates occurs frequently. In this research, fumarate, acetate, formate, lactate, propionate, ethanol, and methane were evaluated as a potential electron donor and carbon source by comparing the denitrification rate for the in situ bioremediation of nitrate contaminated groundwater. The denitrification rate for each substance was the quickest in the order of: fumarate > hydrogen > formate/Lactate > ethanol > propionate > methanol > acetate. Microcosm studies were performed with fumarates and acetates. When fumarates were used as a substrate, nitrates were removed completely at a rate of 0.66mmol/day, while the conversion rate from nitrate to nitrogen gas and other by-products was 87%. For the microcosm test, 42 mg of fumarates were needed to remove 30 mg of NO3 −-N/L. When using acetate as a sole carbon source, 31% of nitrates were removed during the initial adjustment period. Among the removed fractions, however, 83% of the nitrates were removed by the cell growth. Overall, the nitrate removal rate was 0.37 mmol/day when acetate was used as a sole carbon source. The acetate showed longer lag time before denitrification occurred, which implied that fumarate would have been a better carbon source compared to acetate as more amounts were utilized for nitrate removal than cell growth.

Long-term aerobic cometabolism of a chlorinated solvent mixture by vinyl chloride-, methane- and propane-utilizing biomasses

The aerobic cometabolic biodegradation of a mixture of chlorinated aliphatic hydrocarbons (CAHs) including vinyl chloride (VC), cis- and trans-1,2-dichloroethylene ( cis-DCE, trans-DCE), trichloroethylene (TCE), 1,1,2-trichloroethane (1,1,2-TCA) and 1,1,2,2-tetrachloroethane (1,1,2,2-TeCA) was investigated at both 25 and 17 °C by means of bioaugmented and non-bioaugmented sediment-groundwater slurry microcosm tests. The goals of the study were (i) to study the long-term aerobic biodegradation of a CAH mixture including a high-chlorinated solvent (1,1,2,2-TeCA) generally considered non-biodegradable in aerobic conditions; (ii) to investigate the efficacy of bioaugmentation with two types of internal inocula obtained from the indigenous biomass of the studied site; (iii) to identify the CAH-degrading bacteria. VC, methane and propane were utilized as growth substrates. The non-bioaugmented microcosms were characterized, at 25 °C, by an average 18-day lag-time for the direct metabolism of VC (accompanied by the cometabolism of cis- and trans-DCE) and by long lag-times (36–264 days) for the onset of methane or propane utilization (associated with the cometabolism of the remaining CAHs). In the inoculated microcosms the lag-phases for the onset of growth substrate utilization and CAH cometabolism were significantly shorter (0–15 days at 25 °C). Biodegradation of the 6-CAH mixture was successfully continued for up to 410 days. The low-chlorinated solvents were characterized by higher depletion rates. The composition of the microbial consortium of a propane-utilizing microcosm was determined by 16s rDNA sequencing and phylotype analysis. To the best of our knowledge, this is the first study that documents the long-term aerobic biodegradation of 1,1,2,2-TeCA.

Overview of waste stabilization with cement

Cement can treat a variety of wastes by improving physical characteristics (solidification) and reducing the toxicity and mobility of contaminants (stabilization). Potentially adverse waste-binder interactions are an important consideration because they can limit solidification. Stabilization occurs when a contaminant is converted from the dissolved (mobile) phase to a solid (immobile) phase by reactions, such as precipitation, sorption, or substitution. These reactions are often strongly affected by pH, so the presence of components of the waste that control pH are critical to stabilization reactions. Evaluating environmental impacts can be accomplished in a tiered strategy in which simplest approach would be to measure the maximum amount of contaminant that could be released. Alternatively, the sequence of release can be determined, either by microcosm tests that attempt to simulate conditions in the disposal zone or by mechanistic models that attempt to predict behavior using fundamental characteristics of the treated waste.

Assessment of biogeochemical natural attenuation and treatment of chlorinated solvents, Altus Air Force Base, Altus, Oklahoma

Biogeochemical reductive dechlorination (BiRD) is a newly recognized method for the remediation or natural attenuation of chlorinated solvents. Chlorinated solvents are rapidly treated by abiotic reaction with reduced mineral iron sulfides. Iron sulfides are formed by naturally occurring sulfate-reducing bacteria when sufficient SO 4 2− and organic carbon are present or supplied to sediments containing mineral iron. An example of site characterization focusing on BiRD is presented focusing on mineral phases. Methods demonstrated here may be employed at other sites to evaluate naturally occurring BiRD or to evaluate an engineered BiRD remediation. A field investigation was performed at a TCE contaminated site at Altus AFB with naturally high concentrations of SO 4 2− and Fe(III) minerals and where an accidental fuel spill provided organic carbon. In the area of this fuel spill significant mineral iron sulfides were found, sulfate was almost completely removed, and TCE was absent. Only small amounts of daughter products were found, further indicating that the BiRD pathway was operative. Mass balance data indicates all of the remaining TCE (182 kg) could be treated by the remaining FeS (66.5 kg) in the upper aquifer; however, the FeS was not co-located with TCE to enable complete reaction. Laboratory microcosm tests with FeS amended and FeS-rich sediment from Altus AFB also suggest that BiRD is capable of destroying TCE. The results suggest that an engineered BiRD treatment is possible for this site.

Effects of carbon source amendment on the anaerobic degradation of 1,1,1-trichloroethane (TCA) in a contaminated aquifer

We conducted a 10-month anaerobic microcosm test and a 15-month field test to investigate the effects of carbon source addition on the in-situ 1,1,1-trichloroethane (TCA) degradation in a polluted aquifer at an industrial site near Antwerp, Belgium. In the microcosms TCA decreased from 15000 μ g/L to 1500 μ g/L. 1,1-Dichloroethane (DCA) end-concentrations were about the same as the concentrations at the start of the tests (1500 μ g/L). 1,1-Dichloroethene (DCE) decreased from 1200 μ g/L to 800 μ g/L. Carbon source unamended and amended microcosms showed equal concentration trends. Neither chloroethane (CA) nor vinyl chloride (VC) were produced in the microcosms. In the field test TCA dropped from 15000 μ g/L to below 2000 μ g/L. Upstream, TCA levels remained elevated proving that the C-source injection had stimulated degradation. Sulphate reducing bacteria were stimulated; FeS was produced in the microcosms and aquifer. Dehalococcoides species were stimulated in some microcosms and in the HRC-amended aquifer. Neither sulphate reducers nor Dehalococcoidesspecies are however believed to be responsible for the observed TCA degradation. The carbon source injection however did yield environmental conditions that increased TCA degradation.

A microcosm test of adaptation and species specific responses to polluted sediments applicable to indigenous chironomids (Diptera)

Chironomids may adapt to pollution stress but data are confined to species that can be reared in the laboratory. A microcosm approach was used to test for adaptation and species differences in heavy metal tolerance. In one experiment, microcosms containing different levels of contaminants were placed in polluted and reference locations. The response of Chironomus februarius to metal contaminants suggested local adaptation: relatively more flies emerged from clean sediment at the reference site and the reverse pattern occurred at the polluted site. However, maternal effects were not specifically ruled out. In another species, Kiefferulus intertinctus, there was no evidence for adaptation. In a second experiment, microcosms with different contaminant levels were placed at two polluted and two unpolluted sites. Species responded differently to contaminants, but there was no evidence for adaptation in the species where this could be tested. Adaptation to heavy metals may be uncommon and species specific, but more sensitive species need to be tested across a range of pollution levels. Factors influencing the likelihood of adaptation are briefly discussed.

Effects of Anthropogenic Estrogens Nonylphenol and 17?-Ethinylestradiol in Aquatic Model Ecosystems

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Potential for bioremediation of the perchlorate-contaminated sediments in the Las Vegas Wash area, Henderson, Nevada

This study investigates the potential for perchlorate biodegradation in the sediments of the Las Vegas Wash area in Henderson, Nevada. The continuous transport of perchlorate from a contaminated seepage to the Las Vegas Wash, Lake Mead, and the Colorado River has resulted in considerable deposition of perchlorate along the sediments of the Las Vegas Wash. The contaminated sediments act as a distributed source of perchlorate, making efforts to stop the flow of perchlorate to the Colorado River very challenging. In this study, perchlorate- reducing bacteria were enumerated and microcosm tests were performed to investigate the role of indigenous microorganisms and the limitations to natural perchlorate biodegradation in the contaminated sediments. The results of microcosm tests revealed that, despite the high number of perchloratereducing bacteria present, natural perchlorate in the area appears to be limited by (1) high salinity levels, the presence of nitrate, and the low perchlorate concentrations present in the sediments and (2) an insufficient carbon source. However, the potential for in situ bioremediation of the sediments along the Wash area is considered to be high due to the presence of significant numbers of perchlorate- reducing bacteria and to the ease in which an additional carbon source could be provided to sustain nitrate and perchlorate biodegradation. The economics of this process are expected to be very favorable; however, detailed cost estimates, pilot-scale testing, and permit applications are required before this concept can be applied. © 2005 Wiley Periodicals, Inc.

제약업종 부산물 및 화장품 제조업 폐수처리오니 처리토양에 대한 유기화합물 및 Bioassay 분석 평가

This study was conducted to assessment organic compound and bioassay (density of inhabited animal, fluctuation of predominant fungi, and survival ratio of earthworm) for finding damage on red pepper by heavily amount application of sludges in soil, which was treated with 3 pharmaceutical byproducts and a cosmetic industry wastewater sludge as raw materials of compost, and for establishing estimation method. HEM contents in the soil treated with pharmaceutical byproducts sludge2 (PS2) and cosmetic sludge (CS) were 0.51, 1.10 mg/kg respectively. PAHs content of PS2 treatment in the soil was 3406.8 ug/kg on July 8. In abundance of soil faunas, the pharmaceutical byproducts sludge2 treatment was the most highest. The next was decreased in the order of pig manure (PM) and the cosmetic sludge treatment. However the other pharmaceutical sludge treatments were remarkably reduced populations of soil inhabited animals. In upland soil treated with organic sludges, the numbers of bacteria and fungi of the pharmaceutical sludge treatment were 736, 909 cfu/g and those of the cosmetic sludge treatment were 440, 236 cfu/g, respectively. The pharmaceutical sludge treatments and the cosmetic sludge treatment in identification of predominant bacteria were not any tendency to compare with non fertilizer and pig manure treatments, but they had diverse bacteria than NPK treatment. In microcosm tests, the survival of the tiger earthworm in five soil samples was hardly affected against the soil of PSI (20%) after three months treated in the upland But after six months, survival of PS1 was 80%. At present, raw material of compost was authorized by contents of organic matter, heavy metal (8 elements), and product processing according to 'The specified gist on possible materials of using after analysis and investigation among raw materials of compost', however, for preparing to change regulation of raw material of compost and for considering to possibility of application, this study was conducted to investigate toxic organic compound and bioassay methods using inhabited animal, fungi, and earthworm without current regulation.

Assessing soil ecotoxicity of methyl tert-butyl ether using earthworm bioassay; closed soil microcosm test for volatile organic compounds

An earthworm bioassay was conducted to assess ecotoxicity in methyl tert-butyl ether (MTBE)-amended soils. Ecotoxicity of MTBE to earthworms was evaluated by a paper contact method, natural field soil test, and an OECD artificial soil test. All tests were conducted in closed systems to prevent volatilization of MTBE out of test units. Test earthworm species were Perionyx excavatus and Eisenia andrei. Mortality and abnormal morphology of earthworms exposed to different concentrations of MTBE were examined. MTBE was toxic to both earthworm species and the severity of response increased with increasing MTBE concentrations. Perionyx excavatus was more sensitive to MTBE than Eisenia andrei in filter papers and two different types of soils. MTBE toxicity was more severe in OECD artificial soils than in field soils, possibly due to the burrowing behavior of earthworms into artificial soils. The present study demonstrated that ecotoxicity of volatile organic compounds such as MTBE can be assessed using an earthworm bioassay in closed soil microcosm with short-term exposure duration.

Biocontrol of Rhizoctonia Damping‐off of Tomato by Bacillus subtilis Combined with Burkholderia cepacia

Abstract Bacillus subtilis strain RB14‐C and Burkholderia cepacia strain BY were used in combination to control damping‐off of tomato plants caused by Rhizoctonia solani. Microcosm tests showed complete inhibition of R. solani growth on filter disks buried in soil added with the mixture of both bacteria. Single BY inhibited the fungus, but not completely, and RB14‐C had only slight inhibitory effect on pathogen growth. The efficacy of this combining treatment was checked in pot experiments, where bacteria were applied to the soil in several combinations: RB14‐C and BY together 4 days before seed planting, RB14‐C 4 days and BY 2 days before seed planting, RB14‐C 4 days and BY immediately before seeds. The effect of these treatments on population of R. solani in soil and infection of plants was compared with the activity of single application of each agent. All bacterial treatments significantly decreased damping‐off of tomato plants. The best control was obtained when BY was added 2 days after RB14‐C. In this treatment plant protection was significantly higher than that obtained in other combined applications and obtained by single strains, except BY added to the soil 4 days before seed planting. The lowest suppression indicated BY introduced to the soil before seed planting. RB14‐C only slightly decreased number of R. solani in the soil. In contrast, BY drastically reduced population of the pathogen. However, there was not a clear relation between decrease of pathogen density in soil and the rate of plant infection. The results show that combination of B. subtilis RB14‐C with B. cepacia BY can lead to greater damping‐off suppression than biocontrol exhibited by these strains used separately, but the effect of combining bacterial agents was clearly related to the order in which both agents were introduced.

The uptake of uranium by Eleocharis dulcis (Chinese water chestnut) in the Ranger Uranium Mine constructed wetland filter

Eleocharis dulcis has proliferated in a constructed wetland used to treat uranium mine runoff water, where it rapidly accumulates significant quantities of uranium (U) in its roots and relatively little in its stems. We investigated the mechanism of U uptake and accumulation by E. dulcis using field-sampling techniques and microcosm test work. Results from the microcosm trials and outcomes from statistical tests of field sampled macrophyte, water and sediment indicate that the primary source of U for E. dulcis is the water column. Basipetal translocation of U to the plant's roots was indicated by significant correlations between the U content of stems, taproots and rhizomes and XPS detection of U inside root segments. U sequestering from sediment interstitial water by Fe hydroxides on root surfaces was also evident. No basipetal translocation was evident following the 28-day duration of the microcosm experiments, indicating that it is a longer-term process.

Mobilisation of bacteria in soils by electro-osmosis

A prerequisite for effective bioremediation of contaminated soil is the presence of microorganisms able to degrade the contaminants. If such microorganisms are absent initially, dissemination of bacteria and nutrients becomes necessary; this is a challenge, especially in dense soils. We studied the feasibility of disseminating bacteria by electro-osmosis in three different soil types; garden soil, fine sand, and clay. We tested migration velocities in a horizontal gel electrophoresis setup and used microcosms specially designed with electrodes in order to simulate field conditions. When an electric current is applied, the bacteria co-migrate with water to the cathode. Results were compared to those of controls without electricity, showing that electro-osmosis stimulates bacterial spreading even in low-permeability soil such as clay, although the migration velocity was lower than in the other soils tested. In fine sand, the bacteria migrated ca. 1 cm h −1, in garden soil ca. 0.6 cm h −1, and in clay ca. 0.1 cm h −1. Phenol served as a growth substrate in the microcosm tests; it appeared to improve the migration of bacteria and the number of recoverable bacteria in most tests. In clay, a moisture gradient formed, which is a factor to consider in designing field applications.

The use of integrated soil microcosms to assess the impact of carbendazim on soil ecosystems.

Our investigation used carbendazim as a representative pesticide for testing an integrated soil microcosm (ISM) test protocol. Microcosms, set up in a greenhouse, consisted of cylinders made from high-density polyethylene (HDPE) pipe, 7.5 cm (i.d.) x 15 cm high. A fine nylon mesh was placed across the bottom of each microcosm for leachate collection. Field soil, (silty clay loam), collected from Flörsheim, Germany, was sieved through a 5 mm screen and mixed thoroughly. Earthworms, enchytraeids, and microarthropods were added to each microcosm. Each microcosm contained five wheat seedlings, and was maintained at a 12 h-12 h light-dark cycle. Artificial rainwater was used to water microcosms as required. Soil microcosms were treated with carbendazim at concentrations 1, 3, 9, 27, and 81 times higher than the predicted environmental concentration (PEC) of 0.76 mg a.i./kg soil dry weight. A water-only control treatment was also used. The key soil processes used as endpoints were microbial activity, nitrogen mineralization. soil enzymatic activity, ammonium and nitrate leaching, organic matter decomposition and biological feeding activity. Key structural parameters measured were microbial biomass, nematode communities, microarthropod populations and diversity, enchytraeid and earthworm populations and plant growth. Pesticide degradation, leaching and uptake into plants and earthworms were also assessed. Carbendazim had significant effects on several key soil processes including soil ammonium-N and nitrate-N concentrations and soil dehydrogenase activity. Wheat growth, nematode and earthworm populations, and invertebrate feeding activity were soil structural parameters affected significantly by carbendazim. Earthworm biomass was the most sensitive parameter measured with an EC50 of 1.9 mg a.i./kg soil dry weight 28 days after treatment. A comparison of these results with results from single-species tests, small microcosms, large terrestrial model ecosystems, and field tests indicated that the ISM protocol may adequately predict environmental effects.

Release of Polychlorinated Biphenyls from River Sediment to Water under Low-Flow Conditions: Laboratory Assessment

The diffusive release of polychlorinated biphenyls (PCBs) from sediments to water under low-flow conditions was measured for surficial sediments with different PCB concentrations collected from the Grasse River near Massena, N.Y. Data on PCB sediment-water equilibrium partitioning and PCB mass release flux from sediments were used to assess the extent and mass transfer rate of PCB release under low-flow conditions in the Grasse River. Microcosm studies were employed to evaluate the release flux of PCBs under quiescent conditions for various river sediments and sediment mixtures. The observed total-PCB release fluxes ranged from about 1 to 20 mg/m2⋅year, showing predominantly dichloro- through tetrachlorobiphenyls. Analyses of water column samples from the Grasse River under low-flow conditions also indicated the predominance of dichloro- through tetrachlorobiphenyls as in the microcosm tests. Data on PCB equilibrium partitioning between water and sediment were used to estimate sediment porewater concentra...

The effect of amount of crude oil on extent of its biodegradation in open water‐ and sandy beach‐ laboratory simulations

We examined the biodegradation of varying amounts of artificially weathered Alaskan North Slope crude oil in laboratory microcosm test systems that use natural seawater and simulate spills in open water and on sandy beaches. The model bioremediation treatment consisted of periodic applications of marine bacteria, selected to degrade n‐alkanes and a range of aromatic compounds, suspended in a salts solution that supplied inorganic nitrogen and phosphorous. Beach microcosms dosed with low and high oiling lost an average of 22.5% and 11.3% oil weight, respectively. Open‐water microcosms dosed with high and low oiling lost 19.1% and 2.9% oil weight, respectively. Thus, the lower doses of oil were more efficiently degraded. The model bioremediation treatment also affected a greater number of selected analytical endpoints in the lower‐oil‐dose than higher‐dose experiments and the former showed more substantial degradation of recalcitrant components. Above a certain threshold oil concentration, bioremediation did not effectively remove oil. Below this threshold the distinction between active bioremediation treatment and intrinsic biodegradation of the controls was less prominent; i.e., fewer of the oil components were statistically depleted by remediation treatment relative to controls. Furthermore, the oil‐dose range over which bioremediation was realized in these systems occurred at very low oiling levels. Thus, under the environmental conditions simulated in these microcosms, the effectiveness of bioremediation peaked over a rather narrow low‐dose oiling range.

Comparative Evaluation of Effects of .GAMMA.-Rays and Heavy Metals on Mobility of the Water Flea Daphnia magna

The authors comparatively studied effects of γ-rays and some heavy metal treatments on mobility of water flea Daphnia magna according to the OECD Guideline for Testing of Chemicals, which is generally used for ecotoxicity evaluation of chemicals. The 50% effect dose at 24 hours after γ-irradiation (ED50/24h) was 1 600 Gy. The 50% effect concentrations following 24 hours exposure for manganese, nickel and copper (EC50/24h) were 990, 180 and 3.3 μM, respectively. The Gy-equivalent factors (=ED50/24h/EC50/24h) were therefore calculated as 1.6, 8.9 and 480 for manganese, nickel and copper, respectively. These factors indicate that toxicity of these metals to D. magna can be ranked in an order of Mn<Ni<Cu. This toxicity rank shows a similar trend to that evaluated previously in the experimental model ecosystem (microcosm) consisting of three species of aquatic microorganisms. However, there was a noteworthy difference in the toxicity ranks obtained from the D. magna immobilization test and the microcosm test, suggesting that ecotoxicity ranking should be carried out by integrated evaluation on the basis of various ecotoxicity tests.

Planetary Bioresources and Astroecology: 1. Planetary Microcosm Bioassays of Martian and Carbonaceous Chondrite Materials: Nutrients, Electrolyte Solutions, and Algal and Plant Responses

The biological fertilities of planetary materials can be assessed using microcosms based on meteorites. This study applies microcosm tests to martian meteorites and analogues and to carbonaceous chondrites. The biological fertilities of these materials are rated based on the soluble electrolyte nutrients, the growth of mesophile and cold-tolerant algae, and plant tissue cultures. The results show that the meteorites, in particular the Murchison CM2 carbonaceous chondrite and DaG 476 martian shergottite, contain high levels of water-extractable Ca, Mg, and SO 4–S. The martian meteorites DaG 476 and EETA 79001 also contain higher levels of extractable essential nutrients NO 3–N (0.013–0.017 g kg −1) and PO 4–P (0.019–0.046 g kg −1) than the terrestrial analogues. The yields of most of the water-extractable electrolytes vary only by factors of 2–3 under a wide range of planetary conditions. However, the long-term extractable phosphate increases significantly under a CO 2 atmosphere. The biological yields of algae and plant tissue cultures correlate with extractable NO 3–N and PO 4–P, identifying these as the limiting nutrients. Mesophilic algae and Asparagus officinalis cultures are identified as useful bioassay agents. A fertility rating system based on microcosm tests is proposed. The results rate the fertilities in the order martian basalts > terrestrial basalt, agricultural soil > carbonaceous chondrites, lava ash > cumulate igneous rock. The results demonstrate the application of planetary microcosms in experimental astroecology to rate planetary materials as targets for astrobiology exploration and as potential space bioresources. For example, the extractable materials in Murchison suggest that concentrated internal solutions in carbonaceous asteroids (3.8 mol L −1 electrolytes and 10 g L −1 organics) can support and disperse microorganisms introduced by natural or directed panspermia in early solar systems. The results also suggest that carbonaceous asteroids and martian basalts can serve as potential future resources for substantial biological populations in the Solar System.

A microcosm test for potential mineralization of chlorinated compounds under coupled aerobic/anaerobic conditions

In this study, the feasibility of using a mineralization test under coupled aerobic/anaerobic conditions was demonstrated. The coupling of anaerobic methanogenic and aerobic methanotrophic conditions in a microcosm required the presence of both a carbon source for anaerobic metabolism and oxygen for aerobic metabolism. These requirements were fulfilled by using a slow hydrolyzing organic matter along with intermittent addition of oxygen to the bottle headspace. Perchloroethylene (PCE) mineralization tests confirmed the effectiveness of the proposed methodology as well as PCE mineralization under coupled conditions.