Thesis (M.Eng.), Memorial University of Newfoundland, 1998. / Bibliography: leaves 86-97.

Thesis (M.S.)--Mississippi State University. Department of Geosciences. / Title from title screen. Includes bibliographical references.

This study describes a laboratory scale development of an in-situ bioremediation method, which uses a water table management system to supply nutrients to subsoil microorganisms, for biostimulation and subsequent biodegradation of pollutants such as fertilizer-nitrate and hydrocarbons (e.g., diesel oils), in the unsaturated zone of the soil. The study, which was divided into two parts: first nitrate bioremediation and secondly diesel biodegradation, was carried out on packed soil columns. / For the nitrate study, different levels of glucose were introduced into packed soil columns, 1,000 mm long x 200 mm, diameter, via subirrigation in order to supplement the organic carbon levels in the soil. Two sandy soils were used, with 1.6% and 3.4% organic matter content, respectively; and the water table in the soil columns was maintained at a depth of 350 mm below the surface. Fertilizer-nitrate was applied to the soil surface at a rate of 180 kg/ha nitrate-N. Simulated rainfall was used to leach nitrates to lower depths. The efficacy of using the subirrigation system, as a method for nutrient delivery in the bioremediation of leached nitrate, was monitored with time and with reference to the nitrate residue, redox potential of the soil solution, and solubilized Fe and Mn. / Leached nitrate was denitrified to less than 10 mg/L nitrate-N, which is the limit permitted in drinking water. The ideal organic carbon range was considered to be the glucose level (20 mg/L glucose-C) that reduced mom nitrate and gave redox potential and soluble Fe and Mn levels, similar to the control soil solution, when subjected to 96 days of subirrigation. Successful delivery of nutrient for the bioremediation of nitrate, within the farm boundaries, will be considered a "break through" toward nitrate residue control if this novel approach to nitrate control is demonstrated in the field. The delivery method will offer a technical solution to on-farm nitrate pollution. It is inexpensive, easy to adopt, and does not require major changes in the current farm practices. / In the second part of the study, a diesel contaminated sandy soil was packed in columns, 2,000 nun long x 200 nun diameter. The subirrigation method was used to supply two different combinations of treatments to the microorganisms in the soil for the biodegradation of the diesel namely: air, water and nutrients (N, P etc.), and air and water. The success of using subirrigation, to deliver nutrients to the soil in the columns, was monitored by measuring the trend in the reduction of soil diesel-TPH (diesel-total petroleum hydrocarbon) residue with time. Results obtained from the treated columns were compared with each other, and with the control columns undergoing passive biodegradation. / The study showed that subirrigation can be used as a method of nutrient delivery in the -bioremediaton of diesel contaminated soil. The TPH in the contaminated soil decreased, from an initial 670 mg diesel TPH/kg soil to an acceptable level of 40 mg diesel TPH/kg soil, in 82 days in the columns subjected to a combination of nutrient, air and water treatments. If this method of delivering biostimulants to the subsoil microbial population is demonstrated in the field, it will be invaluable to in-situ bioremediation of contaminated soils.

The central aim of this study was to determine if indigenous fungi of an oil-contaminated soil could be effectively used in a low-cost bioremediation of the soil. Since some of the contaminant had been present at the site for over two decades, the indigenous microbial species had been subjected to specific selection pressures for a protracted period, thus facilitating key enzymatic capabilities for hydrocarbon degradation. Analysis of the pertinent influential parameters of soil bioremediation indicated that an ex situ technique, utilising the catabolic activities of the indigenous soil fungi, was a feasible low-cost option. Fungi were isolated from the contaminated soil through a variety of techniques. The abilities of these isolates to degrade the contaminant oil and a range of representative hydrocarbon molecules was evaluated by a systematic screening programme. Sixty-two isolates were initially examined for their growth potential on hydrocarbon-supplemented agar. A bioassay, utilising hydrocarbon-impregnated filter paper discs, was then used to examine the abilities of 17 selected isolates to catabolise three representative hydrocarbon molecules (hexadecane, phenanthrene and pristane) in different concentrations. In the same bioassay, the influence of a co-metabolite (glucose) on growth potential was also examined. Eight fungal species: Trichophyton sp.; Mucor sp.; Penicillium sp.; Graphium sp.; Acremoniwn sp.; Chaetomium sp.; Chrysosporium sp.; and an unidentified basidiomycete were then selected. Liquid batch cultures with a hydrocarbon mixture of hexadecane, phenanthrene, pristane and naphthalene facilitated quantitative analysis (HPLC) of the hydrocarbon catabolic abilities of the selected isolates. Ex situ bioremediation was evaluated at laboratory-scale by both bioaugmentation and biostimulation in soil microcosm trials. During the course of the study, total petroleum hydrocarbon (TPH) concentration (U.S. EPA Method 418.1) was used as a simple and inexpensive parameter to monitor hydrocarbon disappearance in response to soil treatments. Soil microbial activities were estimated by use of a fluorescein diacetate hydrolysis bioassay. This was found to be a reliable and sensitive method to measure the activity of respiring heterotrophs as compared with the unreliable data provided by plate counts. In the bioaugmentation trial, the eight selected isolates were individually used to inoculate (30% v/v) the contaminated soil. The highest rate of biodegradation (50.5% > than the non-sterile control) was effected by an Acremonium species after 50 days incubation (25°C). The second highest rate of biodegradation (47% > than the non-sterile control) was achieved with a soil treatment of sterile barley/beer waste only. Comparable rates of hydrocarbon degradation were achieved in simple biostimulation trials. Thus, due to its lower cost, biostimulation was the preferred remediation strategy and was selected for further laboratory investigation. Common agricultural or industrial lignocellulosic wastes such as: wood chips; straw; manure; beer brewery waste; mushroom compost; and spent mushroom substrate were used as soil treatments, either alone or in combination. The effect of the addition of a standard agricultural fertiliser was also examined. The highest level of biodegradation (54.4% > the non-sterile control) was recorded in a microcosm supplemented (40% v/v) with chicken manure. Finally, an ex situ bioremediation technique was examined in a pilot-scale field trial. Wood chips and chicken manure were co-composted with the contaminated soil in a low-cost, low-maintenance bioremediation system know as passive thermal bio venting. Extensive monitoring of the thermal environment within the biopile was made as an indirect measure of microbial activity. These data were then used to optimise the composting process. Three-dimensional graphical representations of the internal temperatures, in time and space, were constructed. From these graphs, it was determined that an inner core region of approximately 500 cm3 provided a realistic simulation of conditions within a full-scale biopile. During this trial a TPH reduction of 68% was achieved in 130 days. The findings of this research suggested that the utilisation of fungal catabolism is applicable to soils contaminated with a wide range of hydrocarbon contaminants. Passive thermal bioventing offers a bioremediation strategy which is highly suitable for South African conditions in terms of its low level of technological sophistication, low maintenance design and, most importantly, its relatively low cost. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1997.

Thesis (M.Sc.) - Carleton University, 2006. / Includes bibliographical references (p. 148-160). Also available in electronic format on the Internet.

No description available.

The bioremediation of petroleum contaminated soil in large-scale treatment units was studied in conjunction with Sybron Chemicals Inc., Salem, VA. The soil had been previously contaminated and was spiked with additional petroleum. Water with different characteristics was circulated through the soil in order to evaluate the effect of nutrient enhanced treatment without and with addition of two inoculation materials - Sybron’s ABR Hydrocarbon Degraders and Rhodococcus sp. - on the rate of hydrocarbon degradation. Treatment units without nutrients and introduced organisms served as controls. Total petroleum hydrocarbon concentrations (TPH) were monitored using two alternative analytical methods, infrared spectrophotometry and gas chromatography. The results of the field study and different laboratory experiments, a radiotracer flask assay, static soil microcosms, and soil columns were compared. While nutrient addition did enhance biodegradation, the addition of autochthonous organisms was not found to accelerate hydrocarbon degradation rates in the previously contaminated soil. A significant decline of surface tension in the circulated water after inoculation with Rhodococcus, was thought to be due to microbial production of surfactants, but did not increase TPH degradation. The radiotracer technique and microcosm study confirmed these results. The soil column study indicated that the rapid degradation of soluble and slower degradation of less soluble hydrocarbons occurred in two subsequent phases with approximately zero order rates. Typical degradation rates for the more soluble or degradable petroleum hydrocarbons were approximately 40 ppm/week and for the less soluble and degradable compounds 10 ppm/week. Microcosms were found to successfully predict the degradation rates of the soluble hydrocarbons, while the soil columns simulated degradation of the less soluble hydrocarbons best. The analysis of soil extracts for petroleum hydrocarbon concentrations with infrared spectrophotometry was found to be defective. / Master of Science

A laboratory scale study was conducted to investigate the treatability of petroleum contaminated soils by soil washing and subsequent biological treatment of the different soil fractions. In addition to soils obtained from contaminated sites, studies were also performed on soils contaminated in the laboratory. Soil washing was performed using a bench-scale soil washing system. Washing was carried out with simultaneous fractionation of the bulk soil into sand, silt and clay fractions. Cleaning efficiencies due to soil washing ranged from 60 to 81% for different soils. After washing, the finer soil particles (silts and clays) were found to possess higher concentrations of adsorbed hydrocarbons, thus requiring further treatment. Distribution of n-alkanes was studied to obtain a better understanding of contaminant redistribution and mass transfer during washing. / Master of Science

Soil contamination with petroleum hydrocarbons is a common problem. Toxic compounds such as BTEXs are present in gasoline derivatives. They can move through the soil and contaminate the groundwater, especially if methanol is present. This problem is critical in permeable soil. Although leaching of BTEX compounds from soil to the water is almost temperature dependent, movement of methanol through the soil is not. Methanol can move through the porous soil and reach the groundwater in a short time. It can also dissolve and carry BTEX compounds through the porous soil. Therefore, fast cleanup of the permeable soil which is contaminated with BTEX and methanol is crucial. Chlorine dioxide is an oxidizer, which is easy to use and safe to transport; and may be considered as a treatment technique for soil cleanup. Keywords: Groundwater, soil contamination, BTEX compounds, methanol, chlorine dioxide, soil cleanup

We explored the combination of metagenomic library and DNA microarray technologies into a single platform as a novel way to rapidly screen metagenomic libraries for genetic targets. In the "metagenomic microarray" system, metagenomic library clone DNA is printed on a microarray surface, and clones of interest are detected by hybridization to single-gene probes. This study represents the initial steps in the development of this technology. We constructed two 5,000-clone large-insert metagenomic libraries from two diesel-contaminated Arctic soil samples. We developed and optimized an automated fosmid purification protocol to rapidly-extract clone DNA in a high-throughput 96-well format. We then created a series of small prototype arrays to optimize various parameters of microarray printing and hybridization, to identify and resolve technical challenges, and to provide proof-of-principle of this novel application. Our results suggest that this method shows promise, but more experimentation must be done to establish the feasibility of this approach.