Atrazine degradation in anaerobic environment by a mixed microbial consortium.

Atrazine degradation by anaerobic mixed culture microorganism in co-metabolic process and in absence of external carbon and nitrogen source was studied at influent atrazine concentration range of 0.5-15 mg/l. Wastewater of desired characteristic was prepared by the addition of various constituents in distilled water spiked with atrazine. In co-metabolic process, dextrose of various concentrations (150-2000 mg/l) was supplied as external carbon source. The reactors were operated in sequential batch mode in which 20% of treated effluent was replaced by the same amount of fresh wastewater everyday, thus maintaining a hydraulic retention time (HRT) equal to 5 days. In co-metabolic process, 40-50% of influent atrazine degradation was observed. First-order atrazine degradation rate (expressed in day(-1)) was better in co-metabolic process (5.5 x 10(-4)) than in absence of external carbon source (2.5 x 10(-5)) or carbon and nitrogen source (1.67 x 10(-5)). In presence of 2000 mg/l of dextrose, atrazine degradation was between 8% and 15% only. Maximum atrazine degradation was observed from wastewater containing 300 mg/l of dextrose and 5mg/l of atrazine. Influent atrazine concentration did not have much effect on the methanogenic bacteria which was clear from methane gas production and specific methanogenic activity (SMA).