Analysis Of Microbial Structures And Functional Potentials Of Activated Sludge By High-throughput Sequencing Technology

Biological treatment of wastewater is the use of microbial metabolism to degrade organic pollutants in dissolved or colloidal state in wastewater.So that wastewater purification and recycling can be achieved.Because microorganisms are very sensitive to temperature,which directly affect the amount and activity of microorganisms in the activated sludge,thus affecting the removal efficiency of pollutants in the wastewater.In this study,three different temperature strategies were established to study the effects of temperature changes on the efficiency and variation of activated sludge wastewater treatment,and high-throughput sequencing and metagenomic methods were used to analyze microbial community structure and gene function in activated sludge.The results show that the overall trend of pollutant removal efficiency in the range of 5-35°C is that the community structure would change correspondingly with the increase of temperature;the activity of activated sludge microorganisms under low temperature conditions is severely inhibited,and the removal efficiency of TN and HN₃-H were greatly reduced,but the TP removal rate remained at a high level.Within a certain range,the temperature had a great influence on the microbial community structure and wastewater treatment effect of activated sludge.The extracellular polymeric substances?EPS?in the activated sludge had a negative correlation with temperature.And experiments showed that the activated sludge EPS was closely related to sludge settling,and there was a positive correlation between these two parameters.High-quality data was obtained for metagenomic analysis by DNA extraction,database construction,sequencing and data filtering of activated sludge samples in each typical cycle.Through the comparison of genes and various functional databases,a total of 147 phyla,2162 genera and 13015 species were identified.The dominant gates include:Proteobacteria,Actinobacteria,Bacteroidetes.By comparing the number of genes in the Venn diagram,the relative abundance of phylum level and the clustering heat map of the genus level,we find that higher temperatures help promote the diversity of microbial communities in activated sludge systems and improve wastewater treatment efficiency,while the low temperature condition has a good maintenance effect on the stability of the community structure.By comparing Unigenes with the KEGG database,the results show that the activated sludge microbial functions are mainly concentrated in the four major aspects of Metabolism,Genetic Information Processing,Environmental Information Processing,and Cellular Processes,and the difference in activated sludge function of each sample is small.It shows that the diversity of microorganisms helps to maintain the stability of the activated sludge system function within a certain temperature range,and when brought back to 20?,helps to stabilize activated sludge after big temperature swings.