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Item Biodegradation of ametryn and dicamba in a sequential anaerobic-aerobic batch reactor: A case study(IWA Publishing 12 Caxton Street London SW1H 0QS, 2019) Mahesh, G.B.; Manu, B.Agricultural runoff often contains persistent halogenated herbicide compounds like 2-(ethylamino)-4-(isopropylamino)-6-(methylthio)-s-triazine (ametryn) and 3,6-dichloro-2-methoxybenzoic acid (dicamba). These can enter the food chain through drinking water, causing serious effects for people and the environment. A sequential anaerobic reactor followed by an aerobic reactor was operated and investigated for herbicide removal efficiency at constant, three-day, hydraulic retention time (HRT) and organic loading rate (OLR) of 0.2025 kg-COD/m3/d. The effect of the herbicides on anaerobic bacteria was evaluated based on total biogas production and bacterial activity, which indicated that there was no inhibition on the acclimated biomass. The sequential reactor pair removed 72% of ametryn and 78% dicamba, with COD removal efficiencies of 86% and 85% respectively. The different high-performance liquid chromatography (HPLC) peaks indicate that the compounds are biotransformed and this was confirmed by gas chromatograph high resolution mass spectrometry (GC-HRMS). © IWA Publishing 2019.Item Removal of ametryn and organic matter from wastewater using sequential anaerobic-aerobic batch reactor: A performance evaluation study(Academic Press, 2019) Mahesh, G.B.; Manu, B.The present study was aimed to investigate biodegradation of 2-(ethylamino)-4-(isopropylamino)-6-(methylthio)-s-triazine (ametryn) in a laboratory-scale anaerobic sequential batch reactor (ASBR) and followed by aerobic post-treatment. Co-treatment of ametryn with starch is carried out at ambient environmental conditions. The treatment process lasted up to 150 days of operation at a constant hydraulic retention time (HRT) of 24 h and an organic loading rate (OLR) of 0.21–0.215 kg-COD/m3/d. Ametryn concentration of 4 and 6 mg/L was removed completely within 48–50 days of operation with chemical oxygen demand (COD) removal efficiencies >85% at optimum reactor conditions. Ametryn acted as a nutrient/carbon source rather causing toxicity and contributed to methane gas production and sludge granulation in the anaerobic reactor. Biotransformation products of ametryn to cyanuric acid, biuret, and their further conversion to ammonia nitrogen and CO2 are monitored during the study. Adsorption of ametryn on to reactor sludge was negligible, sludge granulation, presence of ANAMMOX bacteria, and low MLVSS/MLSS ratio between 0.68 and 0.72. The study revealed that ametryn removal occurred mainly due to biodegradation and co-metabolism processes. Aerobic post-treatment of anaerobic effluent was able to remove COD up to 95%. The results of this study exhibit that anaerobic-aerobic treatment is feasible due to easy operation, economic, and highly efficient. © 2019 Elsevier Ltd