The Effects Of Salt Tolerant Bacteria On The Operation Of IC Reactor And The Microorganism Community Structure In IC Reactor

The composition of pharmaceutical wastewater is complex.The concentrations of pollutants such as COD,NH₃-N?ammonia nitrogen?and SO₄^2-?sulfate radical?in wastewater are high,which are harmful to the lives of nearby residents and crops.As one of the most common wastewater treatment processes,IC anaerobic reactor has a certain influence on the removal rate of high salinity wastewater.Previous studies have found that salt-tolerant bacteria have high removal efficiency and good effluent effect in the treatment of some high salinity wastewater.Therefore,in this study,we applied salt-tolerant bacteria into IC anaerobic reactor for the treatment of high salinity pharmaceutical wastewater,and found the difference of removal ability between IC anaerobic reactor with salt-tolerant bacteria and common IC anaerobic reactor.Then,high throughput sequencing was used to explore the changes of microbial diversity and community in the two reactors,and the reasons for the different removal capacity of the two reactors were analyzed from the biological point of view.The conclusions of the study are as follows:?1?The reactor with conventional anaerobic sludge was recorded as group A,and the reactor with salt-tolerant bacteria was recorded as group B.The COD removal rate of group A was over 60%on the 53rd day of start-up period and65.44%on the average after stable operation;the NH₃-N concentration of effluent after stabilization was higher than that of influent;the SO₄^2-removal rate was over65%on the 43rd day of start-up period and 70.98%on the average after stable operation.The COD removal rate of group B can reach more than 60%after 37 days of start-up and 80.10%after stable operation;the NH₃-N concentration of effluent after stabilization is higher than that of influent,but slightly lower than that of group A;the SO₄^2-removal rate reaches more than 65%on the 39th day of start-up,and the average removal rate after stable operation is 75.33%.The start-up speed of group A which reactor treated by salt-tolerant bacteria was faster than group B which reactor treated by conventional sludge.After stabilization,in group B,the removal rates of COD,NH₃-N and SO₄^2-were also higher than those of the reactor treated by conventional sludge group A.?2?During the start-up and operation stages of the two reactors,the pH values remained relatively stable.The maximum VFA of the two reactors was 3.5mmol/L in the initial stage of start-up;the VFA changed between 2.0-3.0mmol/L in the middle and late stage of start-up;the VFA was stable between 2.0-3.1mmol/L in the operation period;neither reactor produced acidification.?3?According to the high-throughput sequencing of two groups of reactors at different stages,we found that after adding salt-tolerant bacteria,the OTU number of bacteria decreased to 600,Shannon-Wiener decreased to 3.01,the OTU number of Archaea decreased to 33,Shannon-Wiener decreased to 0.94.The biodiversity of bacteria and archaea in the reactor was lower than that of common anaerobic sludge.?4?After sequencing the bacteria in the reactor,we found that the proportion of Proteobacteria in anaerobic sludge of group A was 28.8%²9.0%,and that in group B was 32.3%³3.2%.The removal rate of COD was increased with the increase of the proportion of Proteobacteria.Chloroflexi in group A was 16.2%¹6.4%,and that in group B was 26.5%²6.7%.The removal rate of COD and SO₄^2-was increased with the increase of the proportion of Chloroflexi.The proportion of Anaerolineaceae in group A was 20.0%and that in group B was 25.1%.The proportion was increased,which increased the removal rate of ammonia nitrogen and COD.?5?After sequencing the Archaea in the reactor,we found that the proportion of Euryarchaeota in group A reached 90.94%,that in group B reached 93.46%.The proportion of Methanomicrobium in group A reached 76.67%,and that in group B reached 83.34%.The proportion of Euryarchaeota and Methanomicrobium in group B increased gradually,which made the removal rate of pollutants in group B reactor increased.