Effect Of Phenol Disinfectant On Wastewater Treatment By Anaerobic Digestion

The use of phenol disinfectants was gradually increased,and the sources of the phenol disinfectants wastewater were from medical wastewater,disinfectants enterprise wastewater and food industry wastewater,etc.Anaerobic digestion technology was a biological treatment method that could both degrade organic pollutants and generate bio-energy,with the characteristics of low energy consumption,low operating cost and energy recovery,it was considered to be a sustainable wastewater treatment technology.However,the effects of phenol disinfectants on anaerobic digestion were still not clear,and the effects of disinfectants on hydrolysis,acidification,methanogenesis and microbial community during anaerobic digestion needed further study.Previous studies were mainly focused on the impacts of single substances or major components on the anaerobic digestion,however,the actual phenolic disinfectants were still not systematically studied.In this study,the typical phenolic disinfectant was selected to explore the effects of phenolic disinfectants on wastewater treatment by anaerobic digestion.The main research conclusions were as follows:（1）Different concentrations of phenol disinfectants on wastewater treatment by anaerobic digestion were studied.The results showed that the cumulative methane yield decreased with the increase of the disinfectant.It was found that no significant difference was found in the cumulative methane yield by different concentration of disinfectants of 0.04、0.2、0.4 and 0.8 m L/L（P≥0.05）.However,the methane yield decreased of 69.98%（P<0.05）and100%（P<0.05）when the disinfectant concentration were 1.6 and 2.4 m L/L,respectively.The addition of phenol disinfectant could accumulate volatile fatty acids（VFA）,affect the secretion of extracellular polymeric substances（EPS）and the construction of anaerobic sludge.With the increase of disinfectant concentration,the activity of acetate kinase and coenzyme F₄₂₀were decreased.Microbial community analysis indicated that the dominant bacteria were Firmicutes,Chloroflexi,Actinobacteria and Proteobacteria.The growth of Methanosaeta and Methanobacterium was inhibited by the disinfectant addition.In addition,the high concentration of disinfectant could inhibit acidification and methanation process during the anaerobic digestion（AD）process,and the inhibition was higher in the methanation stage than the acidification stage.（2）Ultrasonic,titanium dioxide and biochar were selected to disinhibit the phenol disinfectants on anaerobic digestion.The results showed that all three methods had certain promoting effect on the improvement of methane production.The final methane yield of ultrasonic method,titanium dioxide method and biochar method was 388.16 m L,456.05 m L and 527.26 m L by the 0.4 m L/L disinfectant addition,which was 22.01%,43.40%and65.72%higher than the control,respectively,indicating that biochar had the better performance than titanium dioxide and ultrasonic.It was found that the pretreatment can reduce the accumulation of VFA while increase the activities of dehydrogenase,acetic kinase and coenzyme F₄₂₀.By the infrared spectrum,mass spectrometer and high performance liquid chromatography analysis,it was found that there method had little effect on the composition of the solution in the system,the main substances were p-chlorophenol,lactic acid and calcium sulfate.It was found that biochar had the best removal effect on phenolic substances when studing the change of the main components of disinfectant.The analysis of microbial community showed that the dominant microorganism were Bacteroidetes,Chloroflexi,Firmicutes and Proteobacteria,and the relative abundance of Methanomassiliicoccus was increased under three methods.（3）The upflow anaerobic sludge bed（UASB）reactor was used to treat phenol disinfectant wastewater by anaerobic digestion.The results showed that the presence of disinfectants could reduce methane generation and the inhibition effect of methane became more significant with the increase of the disinfectants concentration.In order to remove the inhibition of methane generation,appropriate biochar addition can increase the methane yield.The daily average CH₄yield of UASB in stage S2 decreased by 30.63%,46.9%and 68.13%compared with A2,respectively,while the methane production increased by 61.7%when 5g/L of biochar was added in stage S3.The change of enzyme concentration indicated that biochar enhanced the activity of acetic kinase and F₄₂₀.Microbial abundance analysis showed that the addition of biochar changed the microbial community,Bacteroidetes,Candidatus＿Saccharibacteria,Methanomassiliicoccus and Methanomassiliicoccus was increased.