Biodegradability and toxicity of styrene in the anaerobic digestion process

Start-up and operation of an Upflow Anaerobic Sludge Blanket (UASB) reactor fed with an industrial effluent from a polymer synthesis plant containing 6 mg styrene l(-1) was unstable. In batch assays with 200 mg styrene l(-1), 74% of styrene was degraded at a rate of 7 ml methane g(-)1 volatile suspe nded solids.day, without a lag phase. The toxicity limit (IC50) of styrene was 1.4 mM for the acetoclastic activity, 0.45 and 1.6 mM for the methanoge nic activity in the presence of 30 mM of propionate and ethanol respectivel y. Instability of UASB operation was attributed to other compounds such as acrylates or detergents present in the industrial effluent.