Isolation, Identification, Biodegradation Characteristics Of Strains For Phenol And Pyridine Degradation In Coal Tar Wastewater

Coal tar wastewater, containing high concentrations of phenolic compounds,ammonia, nitrogenous heterocyclic compounds, has the characteristics of variety ofpollutants, high concentrations, high toxicity, and biorefractory. The phenolic andnitrogenous heterocyclic compounds have inhibitive effect on common microorganismin wastewater treatment equipment because of their toxicity. Therefore, dominant strains,isolated from contaminated environment through biological means, strengthen theefficiency of wastewater treatment. The research has important theoretic and practicalmeaning.In this study, phenol and pyridine were chosen as target substrates, and twocorresponding dominant strains were isolated from the coking activated sludge. In orderto provide theoretical basis for the application of bioaugmentation treating wastewatercontaining phenolic and nitrogen heterocyclic compounds, the following research werecarried out. Firstly, morphological, physiological, and16S rDNA sequence wereanalyzed to identify the strains. Secondly, further research about growth characteristics,degradation characteristics and kinetics model. Finally, the degradation characteristicsof single and mixed strains in real coal tar wastewater were researched.The major research result of this study are as follows:1. The high efficient phenol-degrading strain P1and pyridine-degrading strain B2were isolated from activated sludge in coking plant. The strain P1and B2wereidentified as Enterobacter sp. and Acinetobacter sp. respectively through morphologyobservation, physiological and biochemical characteristics test and16S rDNAmolecular identification.2. Degradation conditions of strains were optimized through monofactorialexperiment. The optimum initial pH, temperature, inoculum size, and shaking speed forP1was pH=7,35℃,3%,150rpm. The optimum initial pH, temperature, inoculum size, and shaking speed for B2was pH=7,30℃,5%,150rpm. In addition, strain B2couldbe growth in the salt concentration of1%~10%.3. Through the degradation kinetics experiment, when the concentration ofphenol and pyridine wree100~500mg/L and50~400mg/L respectively, the equationsof substrate-degrading of strain P1and B2were satisfied with zero order kinetics model.When the phenol concentration was500mg/L, the degradation rate constant of strain P1was up to43.05mg/(L h), and when the pyridine concentration reached300mg/L, thedegradation rate constant of strain B2was up to21.10mg/(L h).4. The target substrates (phenol and pyridine) could be degraded to providenutrition for the grown of strains P1and B2in coal tar wastewater respectively. Themixed strains (1:1ratio) were added to wastewater, COD could be removed effectively,after96h, the initial COD was538.46mg/L, could be reduced to228.84mg/L, theremoval rate reached57.51%.