Investigation On Gradient Acclimation And Performance Of Bacteria Degrading-polyacrylamide

This work focused on low degradation rate and poor adaptation ability tohigh concentration of polyacrylamide-containing wastewater showed by bacteriain degrading PAM(polyacrylamide), which perplexed the treatment technique inPAM-containing wastewater from oil field. Bacteria with high ability to degradePAM were isolated from the activated sludge containing polyacrylamide in oilfield. Then the bacteria were acclimated and mixed cultivation to get the bestsynergism, improving their polyacrylamide-resistant properties andbiodegradation efficiency. Finally, to study the enforced biological effect of thebacteria on degrading PAM the mixed bacteria presenting the best synergismwere added into the biological aerated filter (BAF) which ran normally.In this study, four PAM-degrading bacterial strains named PM1, PM2, PM3and PM4were isolated from the activated sludge containing polyacrylamide.16S rDNA analysis demonstrated that they belong to Enterobacteriacea,Enterobacter cloacae, Bacillus megaterium and Enterobacter hormaeche,respectively.Following PAM gradient acclimation and mixed cultivation were applied toimprove their polyacrylamide-resistant properties and biodegradation efficiency.The results showed that the concentration of polyacrylamide which bacteria couldgrow well increased from200mg/L to400mg/L after gradient acclimation,which was significantly higher than that got before gradient acclimation and thebiodegradation efficiency for400mg/L PAM increased from29.8%,30.9%,40.1%,33.4%to36%,40.1%,54.7%and42.7%, respectively. Furthermore, thedegradation rate of PM2&PM3for400mg/L PAM with4%inoculums (volumeration) was up to67%, which increased67.5%compared to the value got fromthe reference (40%). The optimal mixed bacteria PM2&PM3were used in the BAF which rannormally. The result showed that the efficiency of degrading PAM in BAFincreased from30%to50%, and the efficiency of COD removal in BAFincreased from50%to70%. The microbial community structure was analyzed byT-RFLP. The results presented that the diversity of microbial community structurein BAF decreased after the inoculation and the optimal mixed bacteriaPM2&PM3grew well and occupied the dominant role in the system.