Performance Of Quinoline Degradation Pseudomonas Citronellolis PY1 And Its Bioaugmentation In MBBR

Quinoline as a typical nitrogen-containing heterocyclic compound exists in various natural products.With the development of modern industry,quinoline is also used as an important solvent and industrial raw material.Quinoline-containing wastewater of discharge into water can seriously endangers the growth of animals and plants and human health.Biological method is a common method for the treatment of quinoline-containing wastewater,but the traditional biological is poor treatment to wastewater,and microorganisms or communities of have a good removal ability to the target pollutants are less competitive in the wastewater environment.So,bioaugmentation technology is considered to be an effective way to solve this problem.In this study,a highly efficient quinoline degrading bacterium was selected from coking wastewater.Firstly,the degradation properties of quinoline and the effect of different factors on the degradation properties of quinoline were studied.Then the HPLC/MS was used to analyze the quinoline metabolites of strain PY1.After that,the strain was inoculated into a continuous MBBR reactor as a strengthening bacteria,and its quinoline degradation characteristics were studied from the aspects of quinoline degradation ability,metabolic pathway and microbial diversity.Finally,the degradation performance of the MBBR enhancement system to the actual quinoline-containing wastewater was studied.The results will provide experimental theoretical guidance for the practical application of the strain.The main conclusions were as follows:(1)A strain was newly screened with quinoline as the sole carbon source and nitrogen source from coking wastewater,named PY1.Through 16S rDNA genome sequencing and combined with morphological observation of bacteria,physiological and biochemical characteristics experiments,and the strain PY1was finally identified as Pseudomonas citronellolis.The strain PY1 can completely remove 300 mg/L quinoline within 18 h and have a good removal ability to COD.(2)The optimum conditions for PY1 growth and quinoline degradation are:culture temperature 30-35?,DO 4.69 mg/L and pH 7.0-9.0.Appropriate concentration of applied carbon source can promote the quinoline biodegradation,and there is an optimal concentration,which will no longer be promoted if it exceeds this concentration.Zn²⁺toxicity to PY1 is less than Cd²⁺,and PY1 can effectively remove quinoline under 50 mg/L Zn²⁺and 30 mg/L Cd²⁺,respectively.(3)Analysis of intermediates of quinoline metabolites by HPLC/MS,five main intermediates were identified,based on the analysis of intermediates and gas detection experiments,it is suggested that strain PY1 metabolites quinoline through a typical 8-hydroxy coumarin pathway.(4)The PY1 was inoculated in a continuous MBBR reactor.When the influent quinoline concentration 300 mg/L?HRT 24 h and the temperature 30?,the quinoline removal efficiency of the reactor increased from 65%to more than99.0%,which indicated that the strain PY1 successfully enhanced the quinoline degradation performance of the continuous MBBR reactor.The enhanced MBBR reactor can effectively remove quinoline at pH 7.0-8.0,HRT 24-28h,the influent quinoline concentration 100-700 mg/L,and the removal efficiency of quinoline can reach 90.0%.The enhanced MBBR reactor was used to treat the actual coking wastewater,the removal efficiency of quinoline(about 35 mg/L),phenol(about201 mg/L)and cod(about 1398)could reach 99.9%,99.0%and 89.0%,respectively.(5)The analysis of the intermediates of quinoline metabolites in the strengthening reactor system.There were mainly six intermediates were detected,quinoline,2(1H)-quinolones,8-hydroxy-2(1H)quinolones,8-hydroxy coumarin,2,3-dihydroxyphenylpropanoicacid,2-amino-3-hydroxyphenylpropanal,respectively.The metabolic pathway of quinoline is proposed based on the above study.(6)The community structure before and after strengthening was studied from three levels:phylum,class and genus.Suggesting changes in the community structure after PY1 inoculation,although PY1 lost its advantage after long-term operation,PY1 inoculation plays a key role in the formation of effective microbial communities considering the effective removal of quinoline during long-term operation.