Study On The Screening And Immobilization Of Efficient Degradation Bacteria In Coking Wastewater

China is a large country of coke in the world.Coking wastewater has the characteristics of large amount of water,high concentration of organic matter,complex components,significant proportion of refractory substances,high content of salt in inorganic components,high content of ammonia nitrogen,and a large number of nitrogen-containing heterocyclic compounds and other toxic and harmful substances.Biodegradation is an economical and effective method to treat and purify these pollutants.In this paper,several strains of nitrogen heterocyclic compounds were isolated and purified from a coking wastewater.However,free microorganisms are easy to be affected by the environment and have poor adaptability.The preparation method of immobilization is simple,which can reduce the inhibition effect of high concentration substrates,enhance the adaptability of microorganisms to the environment,as well as its inherent economic advantages,and greatly improve the bioactivity,stability and reusability of the degrading strain.In this paper,the immobilized materials and operating conditions were optimized,and an optimal embedding strain scheme was selected and the degradation effect was verified.The results show that:1.After screening,5 strains were identified as Rhodococcus ruber,Patulibacter medicamentivorans,Paracoccus acridae,Microbacterium keratanolyticum and Rhodococcus qingshengii by 16SrDNA.2.Morphological observation and degradation characteristics of Rhodococcus ruber were studied.The morphology of the strain was ellipsoid with long tail and gram staining was positive(G+).The optimal degradation pH of the three mixed substrates was 7.0,and the optimal degradation temperature was 30-40?.Three mixed substrates with the degradation degrees of 100mg/L each were used for 12h.Metal ions,such as Zn2+,Co2+,Ni+,Mg2+,Fe2+,Mo6+,Mn2+have certain inhibitory effects on degradation.The auxiliary nitrogen source will reduce the degradation efficiency of the target pollutant.The auxiliary carbon source can improve the degradation efficiency of the target pollutant.3.The optimal immobilization scheme was obtained with the physical properties and degradation effect of the pellet as indicators:100g/L polyvinyl alcohol,10g/L sodium alginate,30g/L SiO2,5g/L CaCO3,5g/L activated carbon and residual deionized water were prepared into composite materials.The bacteria suspension and composite solution were mixed and dropped into the crosslinking agent with a embedding ratio of 20%,and the immobilized degradation pellets were obtained after hardening at 4? for 24h,which proved that the degradation effect was good.