BATCH BIODEGRADATION OF INDUSTRIAL ORGANIC-COMPOUNDS USING MIXED LIQUOR FROM DIFFERENT POTWS

This study compared the levels at which organic compounds could be biologically treated by the mixed liquor from different publicly owned treatment works (POTWs). Experiments conducted using several 5-L batch reactors involved degradation of single compounds and mixtures of compounds with two different mixed liquors. One mixed liquor came from a municipal treatment plant with a throughput of 9.5 ML/d (2.5 mil gal/day) of domestic waste; the other came from a plant that treats 9.5 ML/d (250 mil gal/day) of waste that is 55% industrial on a BOD basis, including about 227 kg/d (500 lb/day) phenol (0.25 ppm). Microorganisms from the domestic treatment plant degraded chlorinated hydrocarbons (2-chlorophenol, 2,6-dichlorophenol, and 2,4-D) at rates that were virtually the same as those for the plant handling industrial waste. The phenol degradation rates were the same, even though the latter plant had experienced significant prior exposure. The dominant microbial populations were also similar, both before and after phenolic exposure. Microbial adaption to the compounds was quite rapid, resulting in a two- to five-fold increase in the average degradation rates after only the second exposure in a batch reactor. When multiple substrates were tested, the individual compound degradation rates in the mixture were very similar to the degradation rates as sole carbon source. The amount of throughput and the magnitude of the degradation rates indicate the potential of the plant handling industrial waste to treat significant quantities of the compounds tested.