Study On Anaerobic Degradation Characteristics And Sulfate Effects Of 4-Chlorophenol Batch/UASB

Chlorophenols are hard-to-degrade organic substances,causing serious harm to the environment and human safety.Chlorine atoms are prone to nucleophilic substitution under conditions of low oxidation-reduction potential.Therefore,it is economical to treat chlorinated wastewater with anaerobic biological methods.Has no secondary pollution and other characteristics.However,anaerobic biological treatment of chlorine-containing wastewater also has certain limitations.For example,the intermediate products produced by the dechlorination of high-chlorophenols are diverse,and the intermediate products are easy to accumulate.The accumulation of4CP and phenol is not easy to be degraded,resulting in difficulty in subsequent dechlorination.The dechlorination mechanism is different;the dechlorination method needs further optimization;the relationship between sulfate reduction and dechlorination is more complicated.In this study,4CP acclimated sludge was used in UASB continuous flow to study the effect of dechlorination and the dynamic characteristics of microbial community in the UASB reactor,which provided the theoretical basis for the practical application of the UASB reactor in the treatment of chlorophenol-rich wastewater.Simultaneously studied the domestication of sludge with 4CP,4CP/SO₄^2-,and SO₄^2-three different target substances to study the effects of domesticated sludge from different methods on the degradation characteristics of 4CP,and explored the relationship between microbial community structure and dechlorination.to provide a reference for the treatment of 4CP biological.To further study the effect of SO₄^2-p-chlorophenol intermittent and UASB continuous flow anaerobic degradation,to explore the relationship between sulfate reduction and dechlorination.The sludge acclimated by three different methods showed that:4CP with 4CP domestication,the initial concentration of about 4?mol/L4CP can achieve good dechlorination effect,4CP experimental group achieved complete dechlorination within 96h;4CP/SO₄^2-combined experimental group Complete dechlorination was achieved within 120 hours;while 4CP/TCP combined experimental group failed to achieve complete dechlorination within 120 hours.Therefore,this study found that the domesticated sludge with 4CP/SO₄^2-has obvious advantages,and can be enriched with high-efficiency dechlorination microorganisms,and achieve rapid and complete dechlorination and phenol degradation.Further analysis of the microbiological structure revealed that:Actinomyces,Bacteroides,Green Bacteus,Thick-walled Bacteria,and Helicobacter were present in the 4CP/SO₄^2-combined domesticated sludge,with a large proportion of them.At the same time,a large number of archaea such as methane appeared.The proportions of Bacteroides,Methanoregula,M.genus,and M.sarcosum,including Bacteroidetes,Methanosarcina,and Unclassified WCHA1 57,accounted for 26.01%,34.76%,and4.84%,respectively,much higher than 4CP and SO₄^2-acclimation sludge.The proportions were 12.86%,29.09%,1.61%and 14.48%,9.52%,and 0.63%,respectively.These microorganisms are closely related to dechlorination and methanation processes.Using UASB to acclimate sludge with 4CP,rapid and complete dechlorination of4CP and TCP and further conversion of intermediate phenol can be achieved.The removal rate of COD is as high as 90%or more.The pH of the inlet and outlet water is basically stable,and the cumulative amount of gas accumulation is evenly and steadily increased.When the HRT was 26h,the initial concentration of 4CP domesticated sludge,4CP influent concentration was 20⁴0?mol/l,the removal rate of 4CP was lower,and phenol was completely degraded.When the reaction system is stable,gradually increase the concentration of 4CP influent to 66.4?mol/l and run continuously for 100 days.There is almost no 4CP and phenol residue in the discharged water.When the UASB reactor is operated stably,the HRT is shortened to17h,and the treatment effect of 4CP is slightly reduced.The UASB reactor continuously and stably operated for 361 days and changed the HRT for 19h on the278th day.The addition of TCP and gradual increase of the TCP influent concentration gradually increased the initial concentration from 6.16 to 15.1?mol/l to51.73?mol/l.There is still no TCP residue in the water.In the initial stage,the degradation of 4CP by TCP was slightly inhibited,the inhibitory effect was not obvious,and the residual amount of phenol was significantly increased.At the later stage of operation,TCP had almost no effect on the degradation of 4CP.Phenol was completely degraded,and TCP had no residue during the whole operation period.It can be seen that the decontamination of various chlorophenols can be achieved by enriching the functional microorganisms with 4CP acclimated sludge.Further analysis of the microbiological structure revealed that,in the UASB operation stage,methane bacteria,methane strains,Methanoregula,Methane bacteria,and bacteria in the archaea were long lines,genus Bacillus,anaerobic lines,and green beetles The door occupies a large proportion,and the number of bacteria species is basically stable.These genus bacteria are closely related to the dechlorination of chlorophenols and the mineralization and methanation processes of phenols.In the study of the relationship between SO₄^2-reduction and dechlorination,it was found that SO₄^2-in batch experiments slightly inhibited the degradation of 4CP,TCP,and their intermediates,whereas in UASB continuous flow experiments,the degradation of low concentrations of SO₄^2-to 4CP was almost No effect.