Anaerobic Treatment of Atrazine Bearing Wastewaters

In the present study, performance of mixed microbial anaerobic culture in treating synthetic strong wastewater containing different concentration of atrazine was evaluated (R-1). Studies were also conducted in two hybrid reactors (A-1 and A-2) with wood charcoal as adsorbing matrix along with microbes. All the reactors for the treatment of atrazine bearing wastewater were operated in sequential mode with a Hydraulic Retention Time (HRT) of 5 days. In all the cases, Chemical Oxygen Demand (COD) removal was found to be above 82% within 5 days with an initial COD of above 1000 mg/l. Atrazine reduction was 43.8% and 40% with an initial concentration of 0.5 and 1.0 mg/l respectively in R-1 after 5 days. Maximum atrazine reduction of 33.4% was observed in the same reactor with an initial atrazine concentration of 2.0 mg/l. Acetoclastic methanogenic activity test showed no inhibitory effect of atrazine up to a concentration of 2 mg/l, on methane producing bacteria. The performance of anaerobic microorganisms in removing atrazine in absence of any external carbon source (R-3) and in absence of external carbon and inorganic nitrogen source (R-4) was studied. With an initial atrazine concentration of 1.0 mg/l, R-3 could achieve 61.8% of atrazine removal in 34 days, whereas R-4 could affect only 44.2% of atrazine after 149 days. No further reduction of atrazine was observed on R-3 with time.