Study On The Anaerobic Biodegradability Nitrophenols

In this study, The Anaerobic toxicity assay (ATA) and the degradation kinetics of nitrophenols are carried out at the temperature of 35℃±1℃and in anaerobic batch assays. The Anaerobic toxicity assay (ATA) of 3-NP (3- nitrophenol), 2,6-DNP(2,6- dinitrophenol) and 2,4-DNP(2,4- dinitrophenol)are investigated by using glucose as co-substrate.Accumulative methane production and relative activity (RA) are used to judge the inhibition level of nitrophenols on methanogenic bacteria. After that, three inoculative sludges are used to study the degradation kinetics of nitrophenols both in the presence of co-substrate and with nitrophenols as the sole carbon source ,these three inoculative sludges are unacclimated anaerobic granules, acclimated anaerobic granules and anaerobic suspending sludge. One degradation kinetic model is proposed to describe the degradation of nitrophenols and the kinetic model parameter : maximum degradation rates (R_m) , saturation coefficients (K_s) and inhibition coefficients (K_i) under any experimental condition are estimated by non-linear curve fit. The following achievements are the main obtained.(1)Anaerobic toxicity assay demonstrates that The 50% relative inhibition concentrations of 3-NP ,2,6-DNP and 2,4-DNP for 24-hour reaction is 672mg/L, 53mg/L and 13mg/L respectively.The inhibition order of the three nitrophenols to decrease is 2,4-DNP>2,6-DNP>3-NP.(2)Anaerobic degradation kinetics assay demonstrates that nitrophenols and glucose can be degraded by the bacteria simultaneously, addition of nitrophenols effected glucose degradation obviously. the addition of glucose accelerate the degradation of nitrophenols and increase the degradation rate and ratio of nitrophenols; In the range of selected concentrations (2,6-DNP concectrations≤30mg/L,2,4-DNP concectrations≤35mg/L) ,the effect of glucose on nitrophenols degradation was minimal.