Modeling trichloroethylene biodegradation: aqueous kinetics and column performance using microbial consortia

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This study investigates the biodegradation of trichloroethylene (TCE) using a microbial consortium composed of 45% Clostridium sensu stricto 7 and 34.5% Dehalococcoides mccartyi , evaluating its performance in both aqueous and micro-pilot column systems. In batch experiments, the presence of polyhydroxyalkanoates (PHAs) as electron donors significantly enhanced the degradation rates of TCE and its by-products, particularly dichloroethylene (DCE), and revealed a selective microbial behavior favoring the reduction of TCE over DCE and DCE over vinyl chloride (VC). This selectivity was incorporated into a kinetic model to estimate degradation rate constants for TCE, DCE, and VC to ethene (ETH). Subsequently, a 1.44 m column packed with 12.9 kg of sand and amended with 4% (w/w) pine wood biochar was constructed to assess the system at larger scale, achieving a pore volume of 3.96 L . A single addition of 250 g PHAs enabled the treatment of 931.9 L of water contaminated with 0.1 mM TCE, while the biochar increased TCE residence time. The selective degradation pattern observed in batch tests was confirmed in the column, and a model was developed to simulate TCE breakthrough curves under both abiotic and biotic conditions, allowing estimation of apparent kinetic constants. PHA consumption notably enhanced TCE reduction rates. These findings provide a framework for designing efficient bioreactors for chlorinated wastewater treatment, emphasizing the importance of residence time and electron donor management to avoid the need for extensive reactive barriers.