Humic Acid Promotes Anaerobic Biodegradation And Mechanism Of Sulfamethoxazole

Humic acid(HA)is a class of organic polymer compounds widely distributed in nature.The structure,composition and composition of humic acid are very complicated because it contains carbonyl,phenol,carboxyl,hydroxyquinone,amino,enol and other functional groups.This structure makes humic acid have surfactant and adsorbent.Characteristics.Sulfamethoxazole(SMX)is a very common sulfonamide antibiotic.Because it is easily retained and enriched in the environment,it has a serious impact on the environmental microecology.In order to investigate the influence of humic acid on the biodegradation of SMX in anaerobic environment,the conversion efficiency and mechanism of anaerobic activated sludge to SMX under its action conditions were investigated.In this study,the use of anaerobic activated sludge with high-efficiency degradation of SMX explored the effect of different HA concentrations on the degradation efficiency of SMX,and explored the relationship between microbial community structure and SMX anaerobic degradation mechanism under HA-mediated conditions.The role relationship further provides a theoretical basis for optimizing the research mechanism of SMX anaerobic biodegradation and HA-mediated anaerobic biodegradation of sulfonamide antibiotics.Under anaerobic conditions,SMX was used as the substrate and electron acceptor,and the activated sludge from the secondary sedimentation tank of the sewage treatment plant was used as the inoculation source of the SMX anaerobic degradation system for enrichment and domestication.Under stable anaerobic conditions,after 90 days of enrichment and acclimatization,the SMX degrading flora reached a stable period,and the degradation rate of SMX was detected to be basically stable at about 40%.From the analysis of the effect of different substrate concentrations,the substrate concentration and humic acid concentration do affect the anaerobic degradation efficiency of SMX.From the experiment,the optimal substrate SMX concentration range is increased from 10 mg/L to 20 mg/L The optimal humic acid concentration for promoting anaerobic biodegradation of SMX is 0.3 mg/L.Both temperature and p H affect the anaerobic biodegradation efficiency of SMX.Low temperature and alkaline environment inhibit humic acid-mediated anaerobic conversion of SMX.Under the action of humic acid,the anaerobic degradation of SMX has a good removal effect.The optimal temperature is 40 ℃ to50 ℃,and the anaerobic degradation of low-temperature SMX is relatively poor.Humic acid promotes the anaerobic degradation of activated sludge.The optimal p H of SMX is 5 to 7.The alkaline environment is not suitable for HA-mediated anaerobic degradation of SMX.It can be obtained from the comparison of the three groups of biodegradation group(Ⅰ),adsorption group(Ⅱ),and control group(Ⅲ).In the SMX anaerobic biodegradation system with humic acid,the removal of SMX by anaerobic activated sludge mainly depends on For the biological function of anaerobic flora with high efficiency of degrading SMX.Without activated sludge,the degradation rate of SMX is low and does not change with time.This shows that when there is no activated sludge,the interaction and influence between SMX and other molecules can be basically ignored.Under the conditions promoted by HA,the predominant phylum in the enriched bacteria in the SMX system are: Proteobacteria,Bacteroidetes,Caldiserica,Chloroflexi,Actinobacteria,Acidobacteria,Firmicutes.The dominant genera are: Sulfurospirillum,Caldisericum,Desulfomicrobium,Desulfomicrobium,others.