Study On The Anaerobic Toxicity And Anaerobic Biodegradation Of Nitrophenols

In this study,the anaerobic toxicity assay (ATA) and the degradation of nitrophenols are carried out at the temperature of 35℃±1℃and in anaerobic batch assays. The anaerobic toxicity assay (ATA) of 2-nitrophenol(2-NP),3- nitrophenol (3-NP), 4-nitrophenol (4-NP), 2,4-dinitrophenol(2,4-DNP)and 2,6- dinitrophenol(2,6-DNP)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 of nitrophenols both in the presence of co-substrate and with nitrophenols as the sole carbon source and in different co-substrate,different co-substrate concentrations, different sludge concentrations .these three inoculative sludges are unacclimated anaerobic granules, acclimated anaerobic granules and anaerobic suspending sludge.The following achievements are the main obtained.(1) Anaerobic toxicity assay demonstrates that the 50% relative inhibition concentrations of 2-NP,3-NP,4-NP,2,4-DNP and 2,6-DNP for 24-hour reaction is 270mg/L, 120mg/L ,175mg/L,20mg/L和40mg/L respectively.The inhibition order of the five nitrophenols to decrease is 2,4-DNP>2,6-DNP>3-NP>4-NP>2-NP.(2)Anaerobic degradation 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 ratio of nitrophenols.(3) To 3-NP and 4-NP,the sludge degradation order to decrease is acclimated anaerobic granules〉unacclimated anaerobic granules〉anaerobic suspending sludge.To 2-NP,2,4-DNP and 2,6-DNP, the sludge degradation order to decrease is unacclimated anaerobic granules〉anaerobic suspending sludge〉acclimated anaerobic granules.(4)Glucose was a better co-substrate than sodium acetic acid.(5)The best co-substrate concentrations for the degradation of 2-NP, 3-NP, 4-NP are 2500mg/L, 2000mg/L, 2000mg/L. The best co-substrate concentrations are 1000mg/L when the 2,4-DNP concentration is below 20mg/L, 1500mg/L when the 2,4-DNP concentration is between 20mg/L and 40mg/L, 2500mg/L when the 2,4-DNP concentration is above 40mg/L. The best co-substrate concentrations are 1000mg/L when the 2,6-DNP concentration is below 20mg/L, 3500mg/L when the 2,6-DNP concentration is above 20mg/L.(6)The best sludge concentrations for the degradation of 2-NP, 3-NP, 4-NP, 2,4-DNP, 2,6-DNP are 3000mg/L, 1500mg/L, 3000mg/L, 4500mg/L, 3000mg/L respectively.