Isolation Of Triazoles Degrading Strains And Its Application In The Bioaugmentation In Wastewater Treatment System

Nitrogen heterocyclic compounds(NHCs)have been widely used in chemical industry,pharmacy industry and pesticide industry.NHCs have been considered to be the major pollutants in the wastewater produced by chemical industry,pharmacy industry and pesticide industry.However,because of the refractory property and high toxicity of NHCs,conventional biological method was limited in the treatment of the wastewater containing NHCs.Currently,physic-chemical methods were widely used in the treatment of NHCs wastewater,which showed high economic cost,high energy consumption and the generation of secondary pollution in the physic-chemical methods.Thus,it is of great significance to develop the biological treatment for NHCs wastewater with low cost,high efficiency and evirtonmental friendness.This study was focused on the treatment of fungicide wastewater.A 1H-1,2,4-triazole(TZ)-degrading strain and a tricyclazole(TC),degrading strain were isolated,the biodegradtion pathway of TZ and TC were proposed and the bioaugmentation feasibility of these strains on the treatment of fungicide wastewater was investigated.Moreover,BioMnOx-BAF system were developed for the further treatment of the secondary effluent of NHCs wastewater.The TZ-degrading strain,which could utilize TZ as the sole carbon and nitrogen source,was isolated from TZ-contaminated soil.The strain belonged to the genus Shinella and was named as Shinella sp.NJUST26.The biodegradation assays suggested that optimal temperature and pH for TZ degradation by NJUST26 were 30? and 6-7,respectively.With the increase of initial TZ concentration from 100 to 320 mg L-1,the maximum volumetric degradation rate increased from 29.06 to 82.96 mg L-1 d-1,indicating the remarkable degradation performance and high tolerance of NJUST26 towards TZ.TZ biodegradation could be accelerated by the addition of organic carbon sources at moderate dosage,but inhibited by the addition of organic carbon sources at high concentration.TZ biodegradation could be accelerated by the addition of NH4+ and NO3-at moderate dosage but inhibited by the addition of NO2-.The main metabolites,including 1,2-dihydro-3H-1,2,4-triazol-3-one,semicarbazide and urea,were identified by GC/MS analysis and HPLC/MS analysis.Based on these results,biodegradation pathway of TZ by NJUST26 was proposed.A TC-degrading strain,which could utilize TC as the sole carbon,nitrogen and sulfer source,was isolated from acclimated activated sludge.The strain belonged to the genus Sphingomonas and was named as Sphingomonas sp NJUST37.The biodegradation assays suggested that optimal temperature and pH for TC degradation by NJUST37 were 30? and 7,respectively.With the increasement of initial TC concentration,the first order degradation rate constants decreased,and half-life of TC increased,indicating the inhibition effect on TC degradation by NJUST37 under high initial TC concentration.In addition,TC biodegradation could be accelerated through the addition of nitrogen sources but inhibited by the addition of organic carbon sources.A possible biodegradation pathway of TC by NJUST37 was proposed based on the density functional theory(DFT)simulation and degradation intermediates identified by GC/MS and HPLC/MS analysis such as 5-methylbenzo[4,5]thiazolo[2,3-c][1,2,4]triazole 2-oxide and toluene.Through the inoculation of NJUST26 and NJUST37 to a activated sludge reactor,the bioaugmentation potential of these strains on fungicide wastewater was evaluated.The removal efficiencies of TZ and TC were remarkably increased from 10%-14%and 10%-15%to 98%-100%and 95%-100%after the inoculation of NJUST26 and NJUST37.The COD and TOC removal and toxicity reduction were also increased after the inoculation.Moreover,The bioaugmented system could maintain a long-term stable performance.These results demonstrated the feasibility of bioaugmentation by NJUST26 and NJUST37 in the treatment of fungicide wastewater.The bioaugmentation would result in an increase of microbial community diversity and a high ability to resist the loadings and shocks.The analysis of microbial community structure indicated that geneus Shinella and geneus Sphingomonas did not become dominant at a long time operation,but the obvious enrichment of the two genera after inoculation showed that the addition of NJUST26 and NJUST37 could result in the succession of indigenous bacteria and the introduction of some functional strains capable of degrading TZ and TC.Moreover,pilot-scale demonstration further illustrated that the removal efficiencies of TZ and TC of bioaugmented reactor effluent were up to 95%and 90%,which were obviously higher than that of control reactor(i.e.10%-35%and 5%-30%).In addition,bioaugmented reactor showed a better performance on COD reduction,biomineralization and detoxification,further indicating the feasibility of bioaugmentation on engineering application.The consortium CS1,which was obtained from soil,was found capable of utilizing Mn2+and yielding BioMnOx.The BioMnOx produced by C-S1 mainly consist of Mn(?)and Mn(IV)and have a poorly crystalline,which was similar to the(100)crystal planes of ?-MnO2 or birnessite consisting of discrete layers or poorly ordered stacking of adjacent layers.BioMnOx-BAF system were developed by inoculation of CS1 to a BAF reactor.The removal efficiencies of TOC and COD were remarkably increased from 7%-13%and]2%-16%to about 30%and about 33%after the inoculation of C-S1,and the toxicity of the effluent was also decreased.These results demonstrated the feasibility of BioMnOx-BAF system on the treatment of secondary effluent of fungicide wastewater.