Effect Of Tetracycline Antibiotic On Biogas Production And Microbial Community In Anaerobic Wastewater Treatment

Wastewater treatment is an essential component of the recycling of water resources.There are plenty of biogas generation in the process of anaerobic treatment,such as phosphine,hydrogen,methane and carbon dioxide.These biogas plays an important role in the biogeochemistry circulation of phosphorus,the recovery of energy,and the stability of climate system.However,an emerging contaminant,antibiotics,has been frequently detected in water environment.The pollution of antibiotics in water environment has been a problem that not allow to ignore.In the process of anaerobic wastewater treatment,the presence of antibiotics in wastewater will have a great effect on the microbial community and further influence the production of biogas.Therefore,studies on the influence of antibiotics on the production of phosphine,hydrogen,methane,etc.and the microbial community in anaerobic wastewater treatment are desperately needed.Tetracycline(TC)was choosen as the model pollutant in our study,a lab-scale anaerobic baffled reactor(ABR)with three compartments was employed to simulate the process.After getting stabilized,the reactor was operated in the absence of TC(TC-absence)and the presence of 250 ?g/L TC(TC-presence)synthetic wastewater for 90 days,respectively.The production of phosphine(two different forms,free gaseous phosphine(FGP)and matrix-bound phosphine(MBP)),hydrogen(H2),methane(CH4),carbon dioxide(CO2),and the total biogas production in each compartment were monitored in the two operational conditions.Illumina Mi Seq high-throughput sequencing was used to analyze the change of microbial community simultaneously.The main results of the present work are as follows:(1)Results showed that the removal rate of TC was 14.97%-67.97% in the reactor.In the presence of TC,pH decreased and ORP increased,COD remove efficiency increased in the first two compartments but decreased in the last compartment,TP showed a decrease tend,the activity of dehydrogenase had a very significant increase while the activity of acid phosphatase showed an inverse respond.(2)The production FGP decrease at the initial operation of TC-presense wastewater.As time went on,both the production of FGP and MBP was enhanced with TC exposure.(3)The methanogenesis process was sensitive to TC,while the acidogenesis process was insensitive to TC,which resulted in the increase of VFAs accumulation and H2 production,but reduced the production of CH4 and CO2.Total biogas production sharply decline under TC exposure.(4)The microbial diversity and the similarity of microbial among compartments suffered a shock loading effect upon TC exposure,followed by a gradual recovery.Sequence analysis obtained 16 genera in the reactor,among which Treponema,Syntrophobacter,Desulfovibrio,W22 presented TC resistance,and the resistance performance of some genera increased after a long-term TC exposure.The canonical correlation analysis(CCA)showed that the production of H2 and PH3 was positively related with each other,similar positive relationship could be observed between the production of CH4 and CO2,but no distinct correlation observed between these two groups.TC had the largest effect on the production of MBP in the system of our study.Desulfovibrio had an intimate correlation with the enhanced PH3 production in the TC-presence wastewater.