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Publications (3)8.99 Total impact

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    ABSTRACT: A pentachlorophenol (PCP) degrading bacterium was isolated from PCP-contaminated soils and identified as Pseudomonas mendocina NSYSU (P. mendocina NSYSU). The main objectives of this study were to (1) clarify the factors affecting the ability and efficiency of PCP biodegradation by P. mendocina NSYSU, and (2) optimize the use of this bacterium in bioremediation of PCP. Microcosm experiments were conducted to fulfill the objectives. In batch cultures, P. mendocina NSYSU used PCP as its sole source of carbon and energy and was capable of completely degrading this compound. This was confirmed by the stoichiometric release of chloride ion. Moreover, P. mendocina NSYSU was able to mineralize a high concentration of PCP (150 mg/L). Results from the oxygen concentration experiment reveal that the growth of P. mendocina NSYSU was inhibited under low oxygen and anaerobic conditions. Results indicate that the optimal growth conditions for P. mendocina NSYSU include the following: slightly acidic (6<pH<7), aerobic, and relatively moderate ambient temperature (20 degrees C<temperature<30 degrees C) conditions. Addition of extra carbon sources (sodium acetate and glucose) could not enhance the PCP biodegradation. No PCP byproducts were detected after eight days of incubation in this study. This suggests that P. mendocina NSYSU is able to effectively biodegrade PCP and its biodegradation byproducts without the accumulation of inhibitory toxic compounds. Results from this study could be used to assist the optimization of its use in bioremediation of PCP.
    Journal of Hazardous Materials 09/2005; 124(1-3):68-73. · 4.33 Impact Factor
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    ABSTRACT: Pentachlorophenol (PCP) has been used in the past as a pesticide, herbicide, antifungal agent, bactericide, and wood preservative. Thus, PCP is among the most ubiquitous chlorinated compounds found in groundwater contamination. A former pesticide manufacturing plant located in southern Taiwan has been identified as a PCP spill site. In this study, groundwater samples collected from the PCP site were analyzed to assess the occurrence of natural PCP biodegradation. Microcosm experiments were conducted to (1) evaluate the feasibility of biodegrading PCP by indigenous microbial consortia under aerobic and cometabolic conditions, and (2) determine the potential of enhancing PCP biodegradation using cane molasses and biological sludge cake as the substitute primary substrates under cometabolic conditions. The inocula used in this microcosm study were aquifer sediments collected from the PCP site and activated sludges collected from the municipal and industrial wastewater treatment plants. Results from this field investigation indicate that the natural biodegradation of PCP is occurring and causing the decrease in PCP concentration. Microcosm results show that the indigenous microorganisms can biodegrade PCP under both aerobic and aerobic cometabolism conditions. A PCP-degrading bacterium was isolated from the collected aquifer sediments and identified as Pseudomonas mendocina NSYSU via some biochemical tests and further conformation of DNA sequencing. In batch cultures, P. mendocina NSYSU used PCP as its sole source of carbon and energy. The isolated bacterium, P. mendocina NSYSU, was capable of completely degrading PCP as indicated by the increase in biomass formation with the decrease in PCP concentrations occurred in the carbon-free medium simultaneously. Results indicate that the in situ or on-site aerobic bioremediation using indigenous microorganisms or inoculated bacteria would be a feasible technology to clean up the studied PCP-contaminated site. Results from this study will be useful in designing a scale-up in situ or on-site PCP bioremediation system (e.g., on-site bioreactor) for field application.
    Water Research 03/2004; 38(3):663-72. · 4.66 Impact Factor
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    ABSTRACT: Contamination of groundwater by petroleum-hydrocarbons is a widespread environmental problem. Generally in plumes of petroleum-hydrocarbon contamination, the dissolved oxygen (DO) demand imposed by biodegradation of organic contaminants exceeds the DO available creating anaerobic conditions within the plume core and mid-plume areas. Since the petroleum-hydrocarbons are generally degraded faster under aerobic conditions, aerobic bioremediation can be applied to enhance the biodegradation of petroleum-hydrocarbons within of the plume if oxygen can be provided to the subsurface economically. The objectives of this bench-scale study were to (1) develop an oxygen-releasing materials for continuous oxygen supplement, (2) determine the optimal components of the studied oxygen release material, and (3) evaluate the oxygen release rate and lifetime of this material. Moreover, the potential of using a passive oxygen release material to clean up aquifers contaminated by petroleum hydrocarbons was also studied. Bench experiments were conducted to design and identify the components of the oxygen-releasing materials. The mixtures of the oxygen release material were prepared by blending gypsum, calcium peroxide (CaO2), sand, and water together at a ratio of 1�0.5�0.14�0.75 by weight. Cement was used as a binder and regular medium filter sand was used to increase the permeability of the mixture. Calcium peroxide releases oxygen upon contact water (2CaO2 + 2H2O � O2 + 2Ca(OH) 2). The designed material with a density of 1.1 g/cm 3 was made of 3.5-cm cube for the batch experiment. Results show that the oxygen release rate of the material is 0.025 mg/day/g. The oxygen release material is able to remain active in oxygen release for more than three months. With the application of this developed oxygen release material, the contaminated subsurface can remain an aerobic environment for subsequent aerobic bioremediation. For the future field application, the developed materials can be placed in remediation wells, trenches, horizontal wells, or barriers. Thus, the passive biobarrier system has advantages over conventional system including less maintenance, cost-effectiveness, no above-ground facilities, no groundwater pumping and reinjection, no air pollution problems, and groundwater remediation in situ. The proposed treatment system would be expected to provide a more cost-effective alternative to remediate petroleum-hydrocarbon contaminated aquifers. This technology can also be applied for other hazardous waste contaminated sites.