J.S. Bonner

Degradation of petroleum hydrocarbons by facultative anaerobic bacteria under aerobic and anaerobic conditions

Abstract Nitrate-reducing bacterial strains ( Pseudomonas sp. BS2201, BS2203 and Brevibacillus sp. BS2202) isolated from petroleum-contaminated soil were capable of degrading petroleum hydrocarbons under aerobic and anaerobic conditions. Under aerobic conditions (a 10-day experiment in liquid media) the strains degraded 20–25% of the total extractable material (TEM), including up to 90–95% of all alkanes analyzed ( n -C 10 –C 35 ). Under anaerobic conditions (a 50-day experiment) these organisms degraded 15–18% of the TEM, 20–25% of some alkanes, and 15–18% of selected polycyclic aromatic hydrocarbons. The strains also degraded saturated hydrocarbons under anaerobic conditions in the absence of nitrates as electron acceptors.

Biodegradation of phenolic wastes

Phenolic biodegradation kinetics were determined in bioreactors with large solids retention times (SRT). Long term kinetic experiments were conducted in pulse-fed batch reactors for single substrate (phenol) and multiple substrates (combinations of glucose, phenol and pentachlorophenol). Short term initial rate experiments were also conducted on the single and multiple substrate reactors. Results indicate that phenol is metabolized at a maximum rate of 0.55 h−1 with a half saturation coefficient of 10 mg/1. Phenol concentrations in excess of 50 mg/1 inhibit the biodegradation rate. Our results also indicate that pentachlorophenol is cometabolized in the presence of phenol. It can be concluded that biodegradation of phenolic waste is a viable treatment option because the organisms, through their metabolic processes, reduced the waste concentrations below our detection limits.

Nutrient Dynamics in Marsh Sediments Contaminated by an Oil Spill Following a Flood

Flood waters during October, 1994, ruptured a group of pipelines that released gasoline, diesel fuel and crude oil into the San Jacinto River near Houston, Texas. This mixture traveled downstream where it ignited inside a flooded house. The resulting fire burned for seven days. A petroleum-contaminated wetland, designated as a research area, received no cleanup during the spill response. Sediment samples collected over a period of one year were analyzed for nutrients and petroleum hydrocarbons. Natural levels of the nutrient analytes were estimated by monitoring the values over a year following the event. Nutrients monitored include ammonium (plus ammonia), nitrate (plus nitrite), available phosphorus, total Kjeldahl nitrogen and total phosphorus in Kjeldahl digest. Available nutrient concentrations were initially high and then declined to presumable background levels of approximately 10 ppm P, 5 ppm N, and 0.5 ppm N for available phosphorus, ammonium, and nitrate, respectively. Average ammonium concentra...

Degradation of 2,4,6-trinitrotoluene (TNT) in an aerobic reactor

Abstract Microbial mutagenicity tests and chemical analyses were employed in this study to monitor the detoxification of 2,4,6-trinitrotoluene (TNT) in liquid phase bioreactors. To investigate the ability of various bacterial strain treatments to metabolize TNT, pure TNT was placed in a liquid medium in a bioreactor with four different strains of bacteria. The culture fluid from each bioreactor was collected after various periods of incubation and was extracted. The extracts from each sampling time were tested in the Salmonella /mutagenicity bioassay to determine how metabolites produced by each bacterial strain affected the mutagenicity of each TNT extract. Results showed that all strains reduced the mutagenicity of TNT. HPLC analysis of the culture fluid extracts confirmed that although some bacterial strains (such as I-15) metabolized TNT quickly, the extracts remain mutagenic. The data indicate that the pathway utilized for biological transformation of TNT will have a significant impact on the rate of detoxification.

Transport of sewage sludge in a mixed water column

Abstract Sewage sludge from four publicly-owned treatment works was sampled and characterized in terms of parameters affecting transport at the 106-mile deep ocean disposal site as part of the US Environmental Protection Agencys site monitoring programme. Samples from treatment plants in Passaic Valley, Rahway, and Elizabeth, New Jersey and New York City were characterized in terms of dynamic size distribution, suspended solids and density. the transport characteristics of sludge particles were measured using a 2 metre computer-interfaced laboratory settling column. Experiments were conducted at constant salinity (35 ppt) while varying hydrodynamic mixing, sludge type and concentration using a modified factorial experimental design. Hydrodynamic power dissipation was varied so that the vertical dispersion and rms fluid shear rate ranged between 0-6 cm2S−1 and 0-30s−1 respectively. Results indicate that at least 80% of suspended sludge particles will eventually settle under mixed conditions. the average s...

Microbial degradation of hazardous wastes to non-toxic end-products

Abstract The generation of large quantities of toxic wastes in the form of phenolic compounds, halogenated hydrocarbons, and volatile organic chemicals has resulted in requirements for new and environmentally safe methods for elimination. One method used to reduce the volume of toxic waste chemicals is the construction of microbial reaction systems that are capable of degrading toxic chemicals and discharging non-toxic or less toxic products. The applicability of biological fermentation processes for the degradation of phenol, pentachlorophenol, and toluene to non-toxic end-products has been investigated for its potential use as a large-scale unit process. Acclimatization of the batch reactors has been achieved for phenol concentrations ranging from 50 mg/l to 300 mg/l, 1 mg/l pentachlorophenol, and a complex chemical mixture consisting of: 50 mg/l phenol, 1 mg/l pentachlorophenol, and 390 mg/l glucose. Decay rates for a reactor containing 350 mg/l phenol and 150 mg/l glucose have been established and compared to literature values for batch reactors containing 350 mg/l phenol. Future work includes determining decay rates for pentachlorophenol for a concentration of 5 mg/l, identification of the biodegradation end-products, and determination of a kinetic model for each toxicant.

In situ soil reclamation by air stripping and sludge uptake

A laboratory-scale study was conducted to evaluate the feasibility of an in situ reclamation technique for contaminated soils by combining soil stripping techniques and in situ soil surface biodegradation. By pumping air at the base of a test column, a volatile organic compound (VOC) in the soil was mobilized through the soil and trapped in a thin layer of dried activated sludge. The contaminant, once trapped in the sludge blanket, would be available for biological degradation by the sludge microorganisms. Test soil consisted of a homogeneous sand with a moisture content less than 0.5% and particle diameters smaller than 0.84 mm. Dried sludge, obtained from a municipal waste-water facility, was blended until the particle size characteristics were consistent with the sand. Experiments were initiated by passing air saturated with toluene throught the soil column until equilibrium. The initial concentration of toluene was approximately 700, μg per gram of sand. Clean air was then forced through the system to mobilize the toluene at rates which ranged between 1 and 2.7 pore volumes per minute. Over 95% of the particle-bound toluene was removed from the sand within six hours of stripping. On a mass-per-mass basis, the sludge sorbed approximately 70% of the mobilized toluene. The combination of air stripping techniques and use of a sludge blanket to reduce volatile emissions from the soils is feasible and merits further research. Studies to investigate the biodegradation potential of the sludge blanket for toluene and trichloroethylene will be the subject of investigation for future research.