Treatability of atrazine in a simulated DEPHANOX process

Abstract

In this study a simulated DEPHANOX process was used, including anaerobic/anoxic and oxic phases. An upflow anaerobic sludge blanket reactor (UASB), an anoxic sludge blanket reactor (UANSB) and a completely stirred tank reactor (CSTR) were used, sequentially. The atrazine, chemical oxygen demand (COD) removal efficiencies, methane and nitrogen (N2) gas productions and volatile fatty acid (VFA) concentrations were monitored to assess the stability and the performance of anaerobic/anoxic and oxic reactors. The produced intermetabolites were Diaminochloroatrazine(DACT), Desethylatrazine(DEA), Deisopropylatrazine(DIA) urea, ammonia, aromatic amines, Cl− 1 and NO3-N. For maximum atrazine and COD removal efficiencies (86% and 82%, respectively) the optimum atrazine concentrations were between 30-80 mg L− 1. The methane gas percentage varied between 40 and 68% while no N2 production was observed in the anaerobic UASB reactor; 6–10 mg L− 1 of urea, 4–21 mg L− 1 of ammonia, 8–10 mg L− 1 of aromatic amine and 4–6 mg L of Cl− 1 were detected during anaerobic atrazine degradation. 25–45% N2 gas production was observed in the anoxic reactor while the methane gas production was 1–5%. In the aerobic phase COD and atrazine were removed with removal efficiencies of 98% and 99% for initial atrazine concentrations of 0.3 mg L− 1 and 2.5 mg L− 1, respectively.