Optimization of Biological treatment for petrochemical wastewater and development of molecular tools for monitoring functional microorganisms

Abstract

Biological treatment is an economic strategy commonly used for wastewater treatment Petrochemical industrial wastewater usually containing some chlorinated organic compounds may cause environmental issues when being discharged to water bodies without sufficient treatment However the chlorinated organic compounds are usually difficult for microorganisms to degrade resulting high COD in effluents of Petrochemical Wastewater treatment plant (PC WWTP) A full scale PC WWTP was investigated in this study with water quality analyses and molecular biotechnologies to explore the incompletely degradation of COD in biological process In order to find the key factors of COD degradation in the process batch experiments were conducted under different conditions like dissolved oxygen concentration nutrients addition aerobic anoxic different nitrogen sources and the presence of soluble extracellular polymeric substances According to the batch experiments the specific COD degradation rates were higher under aerobic condition which increased 239% when being compared to anoxic condition Specific COD degradation rates could increase by 55% 18% and 7% respectively in the batches with lower EPS content sufficient DO and additional nutrients Moreover changing nitrogen sources from urea to nitrate could also increase 11% of specific COD degradation rate It should be noted that the consumption ration of COD to nitrate in the batch experiments were between 20 to 30 implying that microorganisms in the sludge may use COD as carbon sources nitrate as nitrogen sources and oxygen as electron acceptors From the results of NGS analysis and quantitative PCR hyphomicrobium was found in the sludge and accounted for 16% of the total bacteria Hyphomicrobium was been prove that could degrade nitrate under aerobic condition explaining the nitrate decrease in the system Gene concentration of hyphomicrobium in PC WWTP was strongly affected by influent nitrate concentration The expression of hyphomicrobium also increased with the increase of specific COD degradation rate indicating hyphomicrobium could be benefit to COD degradation

Date of Award	2020
Original language	English
Supervisor	Liang-Ming Whang (Supervisor)