Isolation And Degradation Of Dominant Bacteria Of Two Aromatic Compounds In Refinery Wastewater

Refinery wastewater is generated by the industrial processes of crude oil fractionation, re-fining, cracking, etc. Compared with the other industrial wastewater, refinery wastewater is dif-ficult to treat. And it has a great amount of different organic pollutants with high concentration,environmental hazards and other characteristics.The composition of refinery wastewater is very complex. In addition to high amounts of oil,phenols, prostates, sulphides, it also has a lot of aromatic compounds, aromatic amine com-pounds, aliphatic compounds and heterocyclic compounds.To meet the detection result of GC-MS to the biochemical treatment effluent of refinerywastewater treatment plant of Wuhan Petrochemical Plant, we chose p-xylene and o-cresol as theresearch subjects. Two strains which could respectively use p-xylene or o-cresol as the sole car-bon and energy source were isolated from the activated sludge of biochemical pool. Physiologi-cal characteristics and16S rDNA sequence analysis of the two strains showed that the twostrains were Pseudomonas sp. We named the two strains P5and JF2respectively.This study researched the degradation characteristics of the two strains, investigated the ef-fect of initial concentration, bacteria adding percentage，pH, temperature, shaking speed and saltconcentration(NaCl) on the strains’ degradation abilities. We studied the biodegradation kineticsof the two strains by tested the degradation curves in different substrates of the two strains. Wealso fostered the two strains in the coked wastewater or refinery wastewater containing the cor-responding substrate, to test the degradation abilities of the two strains in actual wastewater.The results showed that the optimal degradation conditions were as followed: initial pH7.5,temperature30℃,shaking speed150rpm, bacteria adding percentage5%for P5; initial pH7.0,temperature30℃,shaking speed150rpm, bacteria adding percentage5%for JF2. Both of thetwo strains have good tolerance to salt, with little difference in degradation rate when the con-centration of salt below10%. Kinetics analysis showed that the degradation curves of the twostrains agreed well with Zero-order kinetics equation. And the Vmaxof P5was18.43mg/(L.h) ata substrate concentration of800mg/L. JF2agreed well with Zero-order kinetics characteristics ina low concentration of substrate（<400mg/L）, and we could describe the kinetics curves as asegmented Zero-order kinetics in a higher concentration of substrate with Vmaxreaching to69.08mg/(L.h). The two strains were fostered in the coked wastewater or refinery wastewater contain-ing the corresponding substrates. The batch test showed that the two strains could survive in theactual wastewater and remove the substrates effectively, which implied the two strains have agood prospect in application.Our study will help to obtain the fundamental information and theoretical foundation for thetreatment of refractory organics by the bioaugmentation technology, and provide a reference forfurther research and application.