[Effects of different co-substrates on degradation of nitrophenols using upflow anaerobic sludge bed (UASB) reactors]

The removal efficiencies of 3-nitrophenol (3-NP) and 2, 6-dinitrophnol (2, 6-DNP) were investigated in two lab-scale upflow anaerobic sludge bed (UASB) reactors using two different co-substrates. Initially, glucose was used as co-substrate and followed by sodium acetate. The results showed that glucose was found to be a better co-substrate for 3-NP degradation compared to sodium acetate. While for the degradation of 2,6-dinitrophenol, sodium acetate was better. For the study of 3-NP degradation, input COD concentration was kept as 2,500 mg/L and hydraulic retention time (HRT) was kept as 26 h with glucose as co-substrate. Maximum 3-NP concentration was 254.6 mg/L and 3-NP removal efficiencies were always more than 99.0%. While HRT was 30 h with sodium acetate as co-substrate, maximum 3-NP concentration was 71.6 mg/L and over 90.0% 3-NP removal efficiencies could be obtained. For the study of 2,6-DNP degradation, HRT was 35 h using the same input COD concentration as 3-NP degradation. The maximum 2,6-DNP concentration was 170.0 mg/L and 2,6-DNP removal efficiencies were always more than 98.0% using glucose as co-substrate. While HRT was 30 h with sodium acetate as co-substrate, maximum 2,6-DNP concentration was 189.5 mg/L and over 99.2% 2,6-DNP removal efficiencies could be obtained.