Efficient treatment of oily wastewater by immobilized petroleum degrading bacteria microspheres coupled with industrial waste catalysts

To achieve efficient treatment of oil-containing wastewater and effective use of industrial waste catalysts, two strains of highly efficient petroleum-degrading bacteria were screened from petroleum-contaminated soil. These bacteria were coupled with the spent catalysts from fluid catalytic cracking(FCC) to prepare immobilized composite microspheres by using sodium alginate(SA)/polyvinyl alcohol(PVA), and the removal effects on petroleum pollutants were investigated. The results showed that both strains of petroleum degrading bacteria were Stenotrophomonas pavanii, and the composite microspheres had good mechanical strength and mass transfer properties. After culturing for 3 days under the conditions of microsphere dosage of 20 g/L, temperature of 37 ℃, and pH of 7, the FCC/microbial immobilized composite microspheres achieved the highest degradation rate of petroleum hydrocarbons in simulated oily wastewater (74.06%). Furthermore, the composite microspheres also achieved a removal rate of up to 73% for petroleum hydrocarbons when treating actual oily wastewater. Compared to free bacteria, the immobilized microspheres formed by the coupling of industrial waste catalysts and petroleum degrading bacteria showed significant advantages in the degradation efficiency of petroleum hydrocarbons and the system stability, which was mainly attributed to the unique multi-stage pore structure of the FCC spent catalysts, as well as the potent facilitation effect of high-valent metals on the surface of the FCC spent catalysts to promote the biodegradation process.