Study On Degradation Characteristics Of Sludge And The Final Method Of Chlorophenol Acclimation

Chlorophenols are a kind of persistent organic pollutants,which have strong biological toxicity,bioaccumulation and persistence,and pose a serious threat to human health and ecological environment.Anaerobic biodegradation of chlorophenols has the advantages of low cost,high efficiency,low energy consumption,easy operation and no two pollution.But it also has some limitations,such as the dechlorination function of substrate specificity,mechanism of chlorine removal and dechlorination of relation between function and microbial population composition is not clear,anaerobic dechlorination methods still need further optimization.In this study,the anaerobic biological technology by acclimated activated sludge enriched sludge in anaerobic degradation of chlorophenols under anaerobic conditions.Exploring the degradation of chlorophenols acclimated sludge reduction dechlorination pathway,metabolic characteristics,influencing factors,population structure.Exploring the dechlorination mechanism,which provide a theoretical basis for the complete mineralization of accelerating reduction method,realize the dechlorination Chlorophenol and practical application..In this study,activated sludge was acclimated to 2,4,6-TCP two times,and obtained 2,4,6-TCP acclimated sludge 1# and 2#.The results showed that there were significant differences in the degradation characteristics of the 2,4,6-TCP.1# sludge can quickly achieve the initial degradation of 2,4,6-TCP,but can not degrade the intermediate products 4-CP and phenol,these products continue to accumulate,can not achieve the ultimate degradation,resulting in two pollution.To optimize the culture conditions such as temperature,anaerobic conditions,2# sludge can not only degrade 2,4,6-TCP,2,4-DCP,4-CP,but also degrade phenol and phenol,67μM 4-CP and 25μM can be degraded within 20 h,and the 2,4,6-TCP degradation was not affected by 4-CP concentration.The results show that the 2# sludge has a compound dechlorination.There were significant differences in the effects of NaCl on the twokinds of sludge.When the concentration of NaCl as high as 32 mM,the effect of 2# on the dechlorination of 1# sludge was promoted.However,the degradation effect of low concentration NaCl.Analysis of flora differences found in the use of high-throughput sequencing technology,1# sludge and 2# sludge bacteria species vary greatly,1#containing sulfate salt tolerant species and quantity of more reducing bacteria than 2#,such as Desulfobulbus,Desulfovibrio,Dechloromonas,Desulfomicrobium,Geobacter,Clostridium and Treponema,so 1# sludge can tolerate high salt environment,and 2#can not tolerate high salt environment.In order to optimize the degradation effect of 2,4,6-TCP acclimated sludge,the effects of some environmental factors on the degradation were investigated.It was found that the effects of different antibiotics on the degradation of 2,4,6-TCP acclimated sludge were different.50mg/L ampicillin or 50mg/L chloramphenicol had a certain inhibitory effect on the degradation of 2,4,6-TCP acclimated sludge,while50mg/L vancomycin had no effect on the degradation of 2,4,6-TCP acclimated sludge.Na2 S is a kind of oxygen absorbing substance commonly used in anaerobic reaction,and the existence of 5mM Na2 S has no effect on the degradation of 2,4,6-TCP acclimated sludge.Many researchers have proposed to increase the alkalinity can improve the anaerobic degradation,but this research shows that adding 0mM,0.3mM,0.7mM,1mM,2m M,5mM NaHCO3 did not significantly improve the effect of removing chlorine 2,4,6-TCP acclimated sludge.2,4,6-TCP acclimated sludge had resistance to KCl,low concentration of KCl has little effect on the degradation of2,4,6-TCP,when the concentration of KCl reached more than 16 mM,KCl can inhibit the 2,4,6-TCP activity of sludge,reduce the degradation rate of 2,4,6-TCP.Acclimation of sludge to obtain highly efficient degradation of 4-CP acclimated sludge by 4-CP.The results showed that 4-CP acclimated sludge could degrade2,4,6-TCP,2,6-DCP,2-CP and 4-CP,and could completely degrade 10μM 2,4,6-TCP in 25 h,and completely degrade 40μM 2,6-DCP in 50 h.When 2-CP and 4-CP were present in the system,4-CP acclimated sludge could completely degrade 30μM 4-CP in 60 h,and 40μM 2-CP could be degraded completely within 72 h,and the intermediate product phenol was degraded by 51.5μM in 96 h.The priority level of dechlorination of 4-CP acclimated sludge is that the position of chlorine is greater than that of ortho chlorine.It can be seen that the acclimated sludge of 4-CP enriched the flora with complex function,and had good degradation effect on chlorophenols with different chlorine substitution positions.Using UASB reactor to inspect the degradation characteristics of 4-CP,found that in stable operation of the UASB reactor,the residence time of 43 h,the initial concentration of 4-CP was 50μM,and the 4-CP removal rate was over 90%,the intermediate product of phenol residues rarely,within 3.8μM,most of which have been removed completely.The removal rate of COD can reach more than 95%,gas emissions and pH constant,no greater volatility,indicating that UASB reactor system has good stability,and can not only achieve the final degradation of chlorophenols,but also a more thorough methanation of organic matter.Analysing microbial population structure of degradation by 4-CP batch and UASB reactor showed that UASB reactor flora species of dominant populations and significantly increased the number,such as Longilinea,Saccharibacteria and Smithella were significantly increased,and there is a close relationship between the population and the effect of degradation.