Isolation, Identification And Biodegradation Characteristics Research Of Strains For Phenol And Thiocyanate Degradation

Phenolic and thiocyanate are mainly inorganic pollutants in coking wastewater. Itnot only contribute to the main control indexes such as COD and ammonia nitrogen forcoking wastewater but also interact with other pollutants, and affect the degradationefficiency of various pollutions in coking wastewater. Biological treatment occupied animportant position in the wastewater treatment, but phenolics and thiocyanate havestrong toxicity. Therefore, it is practical significance to develop a highly efficient way toremove phenolics and thiocyanate.In this study, phenol was used as sole carbon source, thiocyanate was used as solecarbon and nitrogen sources, and two high efficiency bacteria were isolated fromactivated sludge in coking plant aeration tank. In order to provide theoretical foundationfor high efficiency degradation on phenol and thiocyanate by microbial in cokingwastewater, the following research were carried out. First, morphological, physiologicaland16S rDNA sequence were analyzed to identify the strains. Then, further study aboutgrowth and metabolism characteristics, the concentration of tolerance, the range ofsubstrate degradation and the effect of additional carbon/nitrogen source on thedegradation were conducted. Finally, the degradation characteristics of single and mixedstrains in real coking wastewater were investigated.The main research conclusions of this study are as follows:1. The high efficiently phenol degradation bacteria ph-6and thiocyanatedegradation bacteria k-2were isolated from activated sludge in coking plant aerationtank. The two strains were identified as Bacillus sp. through morphology observation,physiological and biochemical characteristics test and16S rDNA molecularidentification.2. The growth and degradation characteristics of ph-6and k-2were investigated,the optimum initial pH, temperature and loaded liquid for ph-6was pH8.0~10.0,30~37℃,volume from75to125mL, the phenol concentration which ph-6could toleratewas up to1840mg/L, in the optimum condition, the ph-6could completely degradeabout550mg/L phenol in36h; the optimum initial pH, temperature and loaded liquidfor k-2was pH7.0~9.0,30~35℃,volume from75to125mL, in the optimum condition, the k-2could completely degrade about300mg/L thiocyanate in95h.3. It has influence on the degradation of phenol and thiocyanate while addingdifferent carbon and nitrogen source, lactose and ammonia sulfate significantly promotephenol degradation, while glucose and toxic substances has negative effect ondegradation of phenol. The amount of addition also affect the degradation of targetsubstances, the degradation of phenol was significantly improved more than13%whilethe addition of lactose was0.1~0.2%and ammonia sulfate was0.2~0.4%, it played apromoting role in the degradation of thiocyanate when the addition of glucose was0.3%and ammonium sulfate was0.4%.4. The results of the study about the range of substrate degradation showed that thestrain ph-6could degrade phenol derivatives such as o-cresol, p-cresol and resorcinolbesides phenol, the degradation of them all higher than80%in28h.5. The results of bioaugmentation in real coking wastewater with singal strain forphenol and thiocyanate showed that strains could coexist with the other kinds ofmicroorganism in activated sludge, and it has a positive effect for the degradation ofphenol and thiocyanate in coking wastewater, and the treatment efficinency in complexsystem was significantly higher than that of single strain.6. The results of bioaugmentation in real coking wastewater with mixed bacteriawhich constitute of ph-6and k-2showed that the phenol removal efficiency was higherthan single strain, the effluent COD also decreased and the removal rate reached up toabout80%.