The Study Of Structure And Function Of Microbiology In The Coking Wastewater OHO Biological Treatment System

Coking wastewater,a refractory toxic industrial wastewater,has complex composition,high concentration of contaminants,difficulty to handle.The discharged coking wastewater with national standard is important to human health and ecological environment.Biological treatment process was considered to be an effective method to remove pollutants from coking wastewater.The novel OHO(Oxic bioreactor 1,Hydrolytic bioreactor,Oxic bioreactor 2)biological treatment system can efficiently remove carbon-and nitrogen-contaminants,but the structure and function of microorganisms involved in this system is still very limited.In-depth exploration of the composition,function and influencing factors of microbial communities in activated sludge of different OHO bioreactors and the analysis of functional genes and metabolic pathways of microbial communities can improve the degradation performance of bioreactors in OHO treatment system.The distinct OHO bioreactors may containe unique microbial resources,which has important theoretical and practical significance.In this study,the microbial community in the activated sludge of different bioreactors in the novel full-scale OHO biological treatment system of Guangdong Shaoguan iron and steel coking wastewater treatment plant was taken as the research object.Firstly,the removal efficiency of pollutants was analyzed by standard methods.Secondly,metagenomic sequencing technology and bioinformation analysis were used to analyze the composition and function of microbial community in the activated sludges.Finally,the correlation between environmental factors and microbial community composition was analyzed.The main findings are as follows:(1)Coking wastewater OHO biological treatment system has stable and efficient decarbonization,denitrogen,and desulfuration performance.Bioreactor O1 mainly removes phenols,sulfides,thiocyanates,cyanides and other pollutants through aerobic oxidation.Bioreactor H mainly uses denitrification and anaerobic ammonia oxidation to denitrogen,as well as hydrolytic acidification to break refractory contaminants,and improve the biodegradability of coking wastewater.Bioreactor O2 mainly removes ammonium-nitrogen through complete nitrification and accompanies with further residual organic pollutants degradation.(2)Based on the results of metagenomic sequencing,different microbial community composition of activated sludge in OHO biological treatment system was revealed.The main genera in bioreactor O1 are Thauera(7.86%),Immundisolibacter(3.95%),and Acidovorax(3.77%);the main bacterial genera in bioreactor H are Nitrospira(12.51%),Nitrosomonas(3.24%),and Thiobacillus(2.89%);the main bacterial genera in bioreactor O2 are Thauera(38.15%),Tepidiphilus(10.34%),and Thiobacillus(5.22%).(3)The KEGG results revealed that the pyruvate metabolism,the nitrogen metabolism,and the sulfur metabolism pathways were the main pathways for the degradation of carbon,nitrogen,and sulfur pollutants in the coking wastewater OHO biological treatment system,respectively.Among them,pht5,nor B and TST genes were the main functional genes for the degradation of PAHs,nitrogen-,and sulfur-containing pollutants,respectively.(4)The orthologous groups egg NOG functional annotation results indicated that replication,recombination and repair,amino acid transport and metabolism,and energy production and conversion account for a high proportion in the OHO biological treatment system of coking wastewater,which verifies the high efficiency of microbial metabolism and energy conversion in the process and reflects the excellent performance of OHO biological treatment system in removing pollutants from coking wastewater.(5)The carbohydrate-active enzymes CAZy results showed that the relative abundance of glycosyl transferases and glycoside hydrolases accounted for 88.64% of OHO bioreactors,while the relative abundance of auxiliary activities,polysaccharide lyases,carbohydrate esterases,and carbohydrate-binding modules only accounted for 11.36%.Furthermore,the relative abundances of GH13 and GT4 genes were higher in anaerobic and aerobic bioreactors,respectively.(6)The results of the correlation between environmental factors and main bacterial genera showed that ammonium-nitrogen,hydraulic retention time,sulfides,total soluble solid,and total phosphorus were the main factors affecting the composition of bacterial community.The results of this study showed that the OHO biological treatment system of coking wastewater had the ability to remove pollutants stablely and efficiently,such as carbon-,nitrogen-,and sulfur-contaminants.The results provided a new theoretical basis for improving the biological treatment efficiency of coking wastewater.