Among the different available remediation technologies, it is well-known that bioremediation methods which mainly depend on microorganisms to degrade, transform, detoxify or break down the contaminants, they are recognized as cost-effective and environmental-friendly methods. In fact, microorganisms “engine of bioremediation process” carry out their normal duty under aerobic or anaerobic conditions, which without doubt extends and motivates the desires to make use of such abilities to reduce environmental threats caused by various contaminants. However, to achieve satisfactory results during any bioremediation process, providing optimal conditions for microorganisms is considered as an essential/crucial task. Composting as one of the applied bioremediation technologies used to remediate soils contaminated with organic contaminants like PAHs still needs more investigation although a valuable effort has been devoted to elucidate the behaviour of this process in the remediation of PAHs-contaminated soils. However, till recently, anaerobically treatment of PAHs-contaminated soil received less attention as it was believed that PAHs are poorly or even impossible to be degraded under such conditions. Therefore, the present study tried to touch both aerobically bioremediation of PAH-contaminated soil through composting and anaerobically treatment of the same soil under strict methanogenic conditions. For both remediation approaches, the effect of some controlling factors had been also evaluated through experiment design methodology employing central design (CCD) technique. Regarding the composting process, the obtained results demonstrated that this technology is an advantageous and indisputable method to decontaminate PAHs-contaminated soils within short period. Additionally, compost derived from the organic fraction of municipal solid wastes (OFMSW) was found to enhance the contaminants (PAHs) removal rate to high extent. Moreover, a lucid correlation between the contaminants removal rate and the compost stability degree was observed, such that more stable composts better enhanced the remediation process as these composts are believed to have a considerable fraction of humic matter which facilitates the desorption of the contaminants, and get more available as a consequence. At the same time, treatments with stable composts do not produce high temperature during the composting process, and normally they are in the mesophilic ranges which are more favourable for such bioremediation process. Bioaugmentation of the process through introducing white-rot fungi with desired catalytic capacity (Trametes Versicolor) in attempt to accelerate the degradation process demonstrated that no effect or enhancement was achieved through such approach. In the second part of the research, anaerobically treatment of PAHs-contaminated soil has been investigated under strict methanogenic conditions employing two types of inocula; thermophilic and mesophilic. The obtained results demonstrated the effectiveness of such biological treatments in this field. Nevertheless, the process was relatively less effective compared with composting. Furthermore, under these conditions and due to unclear reasons, reversible results were obtained as PAHs concentrations were increased with prolonged incubation, indicating the reversed bioformation of PAHs under such oxygen-deficient conditions. Therefore, future work should be devoted to clarify the reasons behind this behaviour.

Prior to the implementation of an enhanced bioremediation pilot study for a trichloroethene (TCE) source area at an industrial site in the United Kingdom (the Site), laboratory microcosm and column studies were performed. The purpose of this column study was to determine if TCE removal rates could be increased with the addition of partitioning electron donors and bioaugmentation with KB-1® culture. Three 1-meter continuous flow columns were constructed using aquifer solids from the Site and artificial groundwater. A TCE dense non-aqueous phase liquid (DNAPL) zone was emplaced in each column. SRS™, a commercially available emulsified vegetable oil (EVO) product, and n-butyl acetate (nBA) were evaluated as partitioning electron donors, while the third column acted as an unamended control. Both nBA and SRSTM were successfully used in previous microcosm studies with high concentrations of TCE (400 and 800 mg/L) to successfully promote the reductive dechlorination of TCE to ethene. Dechlorination of TCE to cis-1,2-dichloroethene (cis-DCE) with trace amounts of vinyl chloride (VC) and ethene, as well as sulfate reduction, were observed in the SRSTM column effluent while DNAPL was present. A dissolution enhancement factor of 2.1 was calculated. The TCE source zone was depleted after approximately 300 days of column operation. Following depletion of the TCE DNAPL, high concentration (~400 mg/L) of TCE amended artificial groundwater was pumped through the column to simulate high TCE concentrations in a plume down gradient from a source zone. Dechlorination of TCE via cis-DCE and VC to ethene was observed in the column effluent along with increases in Dehalococcoides (Dhc) counts. Sulfate concentrations increased during the plume phase while dechlorination to ethene still occurred indicating that complete dechlorination to ethene was possible in the presence of sulfate. Dechlorination of TCE to cis-DCE was observed, but neither VC nor ethene was detected in the nBA Amended column. The nBA was observed to degrade in the column to butyl alcohol and acetate, neither of which partition as strongly as nBA, and were not retained in the column. A continuous addition of nBA promoted the highest amount of cis-DCE production and sulfate reduction was also observed. Once the continuous addition was stopped, dechlorination and sulfate reduction halted indicating that electron donor retention in the column was not achieved. Dehalococcoides (Dhc) concentrations did not increase in the effluent of this column. A dissolution enhancement factor of 1.2 was calculated for the nBA column.

Prior to the implementation of an enhanced bioremediation pilot study for a trichloroethene (TCE) source area at an industrial site in the United Kingdom (the Site), laboratory microcosm and column studies were performed. The purpose of this column study was to determine if TCE removal rates could be increased with the addition of partitioning electron donors and bioaugmentation with KB-1® culture. Three 1-meter continuous flow columns were constructed using aquifer solids from the Site and artificial groundwater. A TCE dense non-aqueous phase liquid (DNAPL) zone was emplaced in each column. SRS™, a commercially available emulsified vegetable oil (EVO) product, and n-butyl acetate (nBA) were evaluated as partitioning electron donors, while the third column acted as an unamended control. Both nBA and SRSTM were successfully used in previous microcosm studies with high concentrations of TCE (400 and 800 mg/L) to successfully promote the reductive dechlorination of TCE to ethene. Dechlorination of TCE to cis-1,2-dichloroethene (cis-DCE) with trace amounts of vinyl chloride (VC) and ethene, as well as sulfate reduction, were observed in the SRSTM column effluent while DNAPL was present. A dissolution enhancement factor of 2.1 was calculated. The TCE source zone was depleted after approximately 300 days of column operation. Following depletion of the TCE DNAPL, high concentration (~400 mg/L) of TCE amended artificial groundwater was pumped through the column to simulate high TCE concentrations in a plume down gradient from a source zone. Dechlorination of TCE via cis-DCE and VC to ethene was observed in the column effluent along with increases in Dehalococcoides (Dhc) counts. Sulfate concentrations increased during the plume phase while dechlorination to ethene still occurred indicating that complete dechlorination to ethene was possible in the presence of sulfate. Dechlorination of TCE to cis-DCE was observed, but neither VC nor ethene was detected in the nBA Amended column. The nBA was observed to degrade in the column to butyl alcohol and acetate, neither of which partition as strongly as nBA, and were not retained in the column. A continuous addition of nBA promoted the highest amount of cis-DCE production and sulfate reduction was also observed. Once the continuous addition was stopped, dechlorination and sulfate reduction halted indicating that electron donor retention in the column was not achieved. Dehalococcoides (Dhc) concentrations did not increase in the effluent of this column. A dissolution enhancement factor of 1.2 was calculated for the nBA column.

This thesis describes a laboratory investigation of in-situ treatment of synthetic leachate representative of that generated by a municipal solid waste (MSW) landfill. The overall objective is to evaluate alternative designs and operating procedures for effective leachate collection in conjunction with efforts to accelerate waste stabilization (i.e. leachate recirculation). In the investigation five 15 cm (6) diameter PVC columns were packed with pea gravel and concrete of different sizes; geotextiles were also placed between the packed sections as filter-separators and promoters of bacterial growth. Synthetic leachate was continuously input to the top of the columns and circulated at rates representative of operating field conditions. For each column, effluent was discharged to a nitrification reactor before recirculation. The tests were conducted under anaerobic and unsaturated conditions in the columns. Results indicate about a 97% decrease in COD from the synthetic leachate concentration entering the top of the column, and about 98 % conversion of the ammonia to nitrogen gas. COD depletion and methane production were not significantly inhibited by the denitrification process. Optimum Hydraulic Retention Time (HRT) for the nitrification-denitrification system makes it economically viable for its development at a landfill site. Gas production shows low CO2 values, decreasing the potential of clogging in the Leachate Collection System (LCS) and extending the Landfill Gas (LFG) networks life service by generating a less corrosive environment. The use of concrete as an alternative to the most commonly used natural gravel as leachate collection drains may not be a good option. During the experiment, the leachate that permeated the columns packed with crushed concrete, presented a higher pH than the leachate that permeated the natural stone. At the conclusion of the experiment noticeable weathering was observed when the columns where dismantled. Further studies are recommended until more conclusive evidence as to concrete performance is found. The overall results obtained from the experiment show that in situ passive treatment at landfills is viable.

Trichloroethene (TCE) and tetrachloroethene (PCE) are among the most commonly detected groundwater contaminants, and are often difficult to remediate due to their presence as dense non-aqueous phase liquids (DNAPLs) in the subsurface. The objective of this study was to assess the potential of using a passive in situ carbon/hydrogen releasing barrier system to bioremediate TCE-contaminated groundwater. The slow carbon/hydrogen releasing material would cause the aerobic cometabolism and reductive dechlorination of TCE in aquifer. The carbon/hydrogen releasing materials would release carbon when contacts with groundwater and release hydrogen after the anaerobic biodegradation of released carbon, thus cause the reductive dechlorination of TCE. Results from the microcosm study indicate that the addition of emulsified substrate, cane molasses, Simple GreenTM (a biodegradable surfactant), or lecithin would enhance the biodegradation rate of TCE under anaerobic conditions. However, addition of multivitamin would increase the bacterial population in the media but would not be able to enhance the TCE degradation rate. Results show that a significant pH drop was observed due to the production of organic acids after the aerobic biodegradation process of cane molasses and lecithin. This also caused the inhibition of microbial growth in microcosms. Results reveal that higher TCE removal efficiency was observed in microcosms with Simple GreenTM addition followed by the addition of cane molasses, lecithin, multivitamin, emulsified substrate, groundwater (without substrate addition). Results from the microcosm study indicate that the addition of emulsified substrate would enhance the biodegradation rate of TCE under anaerobic conditions. However, appearance of high nitrate concentration would inhibit the TCE degradation process due to the occurrence of denitrification. Compared with nitrate, high sulfate concentration would not have significant impact on the reductive dechlorination of TCE. Results reveal that higher TCE removal efficiency was observed in microcosms with emulsified substrate addition followed by the addition of high sulfate concentration, high nitriate concentration, groundwater (without substrate addition). Results from the gene analysis show that phenol monooxygenase, toluene monooxygenase, and toluene dioxygenase were observed in the microcosms with lecithin, cane molasses, Simple GreenTM, and emulsified substrate. This indicates that the addition of substrates would induce the potential of TCE-degrading enzyme. Addition of emulsified substrate and emulsified substrate in nitrate or sulfate-rich media would stimulate Dehalococcoides sp. to induce tceA, bvcA, and vcrA, enzymes for TCE reductive dechlorination.

Pentachlorophenol (PCP) is a chloride-containing aromatic compound which is mostly used for preserving wood and leather, but still one can easily detect this compound present in the waste water generated by various industries such as petrifaction, oil-refining, and etc. PCP, due to its chemical property of being stable and highly toxic, would cause severe and irreparable environmental pollution once exposed to open air. This study is intended to explore the feasibility of dealing the problem of PCP with biodegradation. The examination results showed that, except for absorption, the suspension of contaminated soil (aerobic incubation), nonetheless, could effectively degrade PCP during a period of 90 days without the aid of any extra carbon source. (0.62 mg/L/day). The degradation rate was further greatly improved by adding sodium acetate, molasses, and sludge cake (sodium acetate added: 4.15 mg/L/day; molasses added: 1.05 mg/L/day; sludge cake added:0.83 mg /L/day). None of four experimental groups of aerobic sludge, anaerobic sludge, contaminated soil (anaerobic incubation), and Fe3+reaction could degrade PCP after 135 days, 174 days, 250 days, and 124 days, respectively, regardless of whether any sources of carbon were added or not. A bacterium which used PCP as the sole carbon source was isolated from the contaminated soil. After 16s rDNA sequence analysis, it had 98% degree of similarity to Pseudomonas mendocina and was designated as Pseudomonas mendocina NSYSU. The PCP (40 mg/L) degradation rate of Pseudomonas mendocina NSYSU was 9.33 mg/L/day, and the degradation rate would slow down as PCP concentration increased. At a PCP concentration of 320 mg/L, PCP degradation was completely inhibited, although an active population of Pseudomonas mendocina NSYSU was still present in these cultures. The study also indicated that the addition of various carbon sources such as sodium acetate and glucose did not facilitate the degradation of PCP with the degradation rate of 8.11 mg/L/day for sodium acetate, and that of 7.55 mg/L/day for glucose. Analysis from examining several environmental factors showed that the optimal condition for PCP degradation is that of 30¢J, pH6, and in the presence of oxygen. The end products of PCP degradation were detected by GC-MS. After 6 days of incubation, PCP was gradually disappeared and the metabolic intermediate product, acetic acid was detected. The chloride ion concentration also increased by 21.8 mg/L, which is approximately equal to the original total chloride content in PCP (66% of chloride content). In conclusion, PCP could be effectively and completely degraded by Pseudomonas mendocina NSYSU.

The purpose of this study was to treat soils contaminated by pyrene through phytoremediation. The plant species selected were Phragmites communis Trin., Typha orientalis Presl, Vetiveria zizanioides, Rohdea japonica (Thunb.) Roth et Kunth, Cyperus malaccensis. Lam. subsp. monophyllus (Vahl) T. Koyama, Bolboschoenus planiculmis (F. Schmidt) T. Koyama and Bidens pilosa respectively. The degradation efficiencies of pyrene in soils and concentration of pyrene in the plant tissues were evaluated in this study. In addition, the change of microbial biota in soils was investigated in the tests of this study. The experimental results indicated that after twenty-two weeks, soils planted with V. zizanioides, R. japonica and T. orientalis have better pyrene degradation efficiencies. Especially, after fourteen weeks the pyrene degradation efficiencies were 86%, 84% and 77% respectively, which showed that the efficiencies 10% to 20% higher than those unplanted control experiments, which was 66%. In addition, the pyrene degradation efficiencies in summer were found to be higher than those in winter. The degradation efficiencies of pyrene in sterilized soil with and without T. orientalis were found equal to 59% and 55%, respectively. These values were found lower than those in the experiment without sterilization, in which the pyrene degradation efficiencies with and without T. orientalis were 77% and 66%, respectively, after the fourteen weeks experiment. Hence the rhizospheric microorganisms had a significant effect on the degradation of pyrene in soils. The pyrene degradation efficiencies were improved with application of fertilizer (HYPONeX No.2, HYPONeX Co., USA). After fourteen weeks, it was found that the experiment with fertilizer and with or without T. orientalis planted were 7% higher, which were 84% and 73% respectively, compared to 77% and 66% with no application of fertilizer. Proper surfactants have positive effect on phytoremediation. In this study, we found that addition of the surfactant Triton X-100 or combined surfactants (Triton X-100, Tween 20 and sodium dodecylbenzene sulfonate) both presented better pyrene degradation efficiencies than the system without adding surfactant. After ten weeks, soils planted with V. zizanioides and added with surfactants showed the pyrene degradation efficiencies equal to 85% and 87% (combined) respectively, which showed that 4% and 6% higher rate than the system without adding surfactants (81% ). After twenty two weeks, soils planted with V. zizanioides and added with surfactants showed that the pyrene degradation efficiencies were 96% and 96% (combined) respectively. They were all higher than the system without adding surfactants (94%). Soils planted with R. japonica also showed the same results. In this study, it was also found that the degradation efficiencies were higher at the surface layer of the soil than subsurface layer due to better oxygen content there. Hence the activities of microorganisms in the surface layer were higher than those in the subsurface layer of soils. After twenty two weeks, soils planted with V. zizanioides showed the residual concentration of pyrene were 5.7mg/Kg (surface layer) and 10.8 mg/Kg (subsurface layer). The difference between them was about 50%. Soils planted with R. japonica, T. orientalis or unvegetation also showed the same results. The pyrene concentrations of the roots, stems and leaves were analyzed and the results showed that pyrene did not exist in the plant stems or its leaves. Since pyrene could not be absorbed into plant¡¦s tissues by plants, the phytoextraction and phytovolatilization did not occur in this study. It was concluded that the degradation of pyrene in soils was mainly in rhizoremediation. The soils planted with V. zizanioides showed that the inhibition of Lactobacillus sp, while the soils planted with R. japonica and T. orientalis showed unfavorable conditions to Rhibopus sp.. Four weeks after this experiment, both Lactobacillus sp. and Rhibopus sp. were not existent. The soils planted with V. zizanioides, R. japonica and T. orientalis showed an increase of the number of bacteria (CFU), and thus the pyrene degradation efficiency was increased.

Chlorinated organic compounds are widely used in various industrial processes. Due to their high density and low water solubility, they are mainly utilized as cleaning solvents in dry cleaning operations, as well as semiconductor manufacturers. Many chlorinated organic compounds spilled sites contain residuals, which present in a pure liquid phase (dense non-aqueous phase liquids, DNAPLs). Trichloroethylene (TCE) is the most typical compound as a result. In situ bioremediation has been successfully used for the removal of TCE. This process has several advantages, such as relative simplicity, low cost, and potentially remarkable efficiency in contamination removal than others. By using the in situ bioremediation to remediate TCE contaminated groundwater, it must ensure (1) biodegradability of contaminants, and the presence of a competent biodegrading population of microorganisms, (2) presence of electron acceptors, and (3) environment condition and, nutrient sources. A field study for biodegradation TCE through molasses injection was conducted at the industrial trading estate in Kaohsiung City. The study included electronic products, semiconductor, nicety optical industry and so on. Molasses, nitrate and phosphate were introduced from injection well (BW1-1 and BW2-1) into aerobic and anaerobic groundwater contaminated site. In the aerobic zone, there were four wells being monitored: BW1-1, C029, BW1-2 and BW1-3. After 213 days of biostimulation treatment, TCE concentration detection results showed TCE concentrations in all wells monitored. BW1-1 and C029, there was a sharp decrease from 0.0853 mg/L to below the detection limit and from 0.1340 mg/L to 0.0038 mg/L. BW1-2 and BW1-3 showed a slight decrease from 0.0668 mg/L to 0.0211 mg/L and from 0.0323 mg/L to 0.0161 mg/L. After treatments, TCE concentrations in all wells monitored were dropped to 0.05 mg/L. In anaerobic zone, there were four wells being monitored: BW2-1, SW-4, BW2-2 and BW2-3. After 193 days of biostimulation treatment, TCE concentration detection results showed TCE concentrations in all wells monitored. BW2-1, SW-4, BW2-2 and BW2-3 all had a slight decrease from 0.0399 mg/L to 0.0043 mg/L, from 0.14603 mg/L to 0.0687 mg/L, from 0.1030 mg/L to 0.0365 mg/L and from 0.0492 mg/L to 0.0289 mg/L. According to the results from BIOCHLOR modeling, elevated aqueous concentration of chloroethenes with a classical reduction pathway for TCE leading to an accumulation of vinyl chloride and ethane. All the results revealed that bioremediation technology is one of the more feasible approaches to clean up TCE contaminated groundwater in this field.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 160-168). Also available on the Internet.

Thesis (M.S. in environmental engineering)--Washington State University, December 2009. / Title from PDF title page (viewed on Jan. 14, 2010). "Department of Civil and Environmental Engineering." Includes bibliographical references (p. 41-42).