Experiments in aerobic and anaerobic biodegradation of trichloroethylene

The removal of trichloroethylene (TCE) from industrial waste has been intensively studied in recent years, Biodegradation has been determined to be an effective treatment for TCE in the environment. Many researchers have studied the biodegradation of TOE and obtained successful results based on the use of specific isolated bacteria. At the NJIT Biotechnology Laboratory, a new method is being developed in which immobilized activated sludge is used to degrade several toxic chemicals in various reactor configurations. The objective of this research is to determine if these methods can be extended to treat TCE. Activated sludge from a wastewater treatment plant was acclimated with TCE and then used in aerobic experi ments. Some commonly and effectively used methods from our laboratory, such as membrane, shaker flask, and microassav reactors were studied with activated sludge. In the membrane reactor experiment, microorganisms from activated sludge were immobilized on microporous plastic sheet (MPS) by attachment. TCE solution was pumped through the reactor containing microorganisms attached on MPS sheet and TCE variation was analyzed with GC. Experiments were conducted in batch recirculation flow mode, A series of shaker flask experiments were constructed to check the result of preinduction for activated sludge with some inducers. The activity of activated sludge was studied by examining the oxygen uptake in a microassay reactor. This reactor has been a valuable tool in the enzyme kinetic studies due to its reproducibility and accuracy of the data acquired. Anaerobic sludge was also used in this study, and taken from a secondary treatment plant. It was digested in an anaerobic digester with a specific nutrient medium and then incubated in an incubator at 37°C for anaerobic treatment. In shaker flask experiments, TCE was degraded by NJIT activated and preinduced sludge with inducers. Biodegradation rates were found to be 0.36, 0.49, 0.44, 0.32 nmol/min per mg of dry biomass with sodium acetate, phenol, toluene, and sodium benzoate, respectively. They are greater than the rates for bacterial strains 46-1, G4, and Alcaligenes eutrophus JMP134 reported in the literature. However, the results of the membrane reactor, the microassay reactor, and the anaerobic experiments indicate that TCE biodegradation rates are far lower than typical biodegradation rate, which is 2.4 nmol/min per mg of dry biomass, for phenol, chlorophenol, and other substrates in NJIT Biodegradation System