Study On Multi-phase Anaerobic Degradation Of Organic Wastewater Containing TCP

The biodegradation of chlorophenols has been an important research topic both at home and abroad.Chlorophenols are generally considered to be environmental exotic compounds.Because of the lack of enzyme system suitable for degradation,environmental microbes are difficult to biodegradation.For complex chlorinated compounds,the mineralization process has a procedure of products,each generation are becoming more and more difficult dechlorination,and dechlorinating bacteria and other anaerobic bacteria form syntrophism complex constraints.In the process of anaerobic dechlorination of TCP wastewater,there are no complete mineralization,and there are some intermediate products(4-CP,phenol)accumulation,and the degradation of COD is slow,and so on.The hierarchical anaerobic process can cultivate anaerobic microbial population suitable for different levels of reactor environment according to the matrix composition and specific environmental conditions at all levels.It has great potential for degradation of complex wastewater containing inhibitory,refractory,and refractory compounds(aromatic,lipid and fatty acids).For the non acidification and the wastewater containing mixed VFA,the classified anaerobic system is superior to the first class high load system.In this paper,the characteristics of single stage anaerobic intermittent degradation of TCP,fractionation anaerobic intermittent degradation TCP and UASB continuous flow reactor were studied with TCP as the research object,respectively.In order to provide a theoretical basis for the complete mineralization of TCP and the practical application of technology,the composition of TCP acclimated sludge,the mechanism of deep dechlorination,and the theoretical basis for the anaerobic classification and multiphase treatment of chlorophenol wastewater were explored.Single stage anaerobic batch degradation of TCP showed that 2,4,6-TCP acclimated sludge could completely degrade TCP with initial concentration of 14.5?M in 27 h,and also degrade 2,4-DCP and 4-CP,but it was not easy to degrade phenol and phenol accumulation.It takes a long time to realize the complete mineralization of phenol and the complete methanation of carbohydrates.During the process of degradation,pH showed changes in stages,indicating that the growth and decay ofcompounds in the system and the metabolism of different microbes also changed the environmental conditions.The experiments of intermittent anaerobic degradation of TCP by fractionation showed that in the first stage,TCP acclimated sludge could dechlorate TCP into DCP,phenol and 4-CP quickly.After the transient appearance of DCP,the concentration of phenol was very low and the concentration of phenol was very low,but 4-CP was accumulated,and it was difficult to degrade further.In the second stage,the acclimated sludge can completely degrade the first grade 4-CP and residual phenol in the first stage in 200 h,thus realizing the complete mineralization of TCP.The classification of microbes is significant,and the grading effect of palaeobacteria is more obvious.Bacteria and archaea in grade second detected more OTU.Grading reduced substrate inhibition and improved biodegradation efficiency.The dominant bacteria in the first stage are Unclassified Anaerolineaceae(anaerobes),Saccharibacteria genera incertae sedis and Ignavibacterium.These bacteria have the functions of acid production and dechlorination.In the second level of dominant bacteria Unclassified Anaerolineaceae(anaerobic bacteria rope),Unclassified Bacteroidetes(Bacteroides),Gordonibacter(Gordon coli),these bacteria have the function of producing methane,has close relationship with the degradation of phenol and 4-CP.In the first stage,methanilli accounted for a large proportion,while in the second level,the majority of the eight methancoccus were methane,so the removal efficiency of second level COD was better than the first level COD removal effect.UASB showed that the degradation of TCP continuous flow reactor experiments,UASB reactor has a good effect on the degradation of TCP,with the concentration of TCP increased,only a small amount of residual 4-CP in the effluent,when the influent TCP concentration is as high as 160 ?M,in 1 days can degrade TCP,no matter chlorophenol residues,with high efficiency TCP degradation activity.In the UASB reactor,the effluent pH is slightly larger than the influent pH,the influent pH fluctuates between 7.2~7.6,and the effluent pH fluctuates between 7.4~7.8 and the operation is stable.The removal rate of COD is stable between 79%~97%,indicating that the system has a high COD removal ability,which is beneficial to the methanation of organic matter.The OTU and diversity index of bacteria increased during the operation of UASB;contrary to the bacteria,the OTU and diversity index decreased during the operation of UASB.Syntrophobacter and Smithella are found in UASB,the former is an important bacterium for the thorough mineralization ofchlorophenol,and the latter is an important bacterium for methane production.In the course of the acclimatization of UASB,the dominant population of the germs changed from methantobacilli to methanoform.