Alcohol Ethoxylate Degradation Of Activated Sludge Is Enhanced By Bioaugmentation With Pseudomonas Sp.LZ-B

Alcohol ethoxylates?AE?are classified as nonionic surfactants?NS?and are widely used in industrial applications in the production of pesticides,pharmaceuticals,paints and cosmetics,as well as in mineral separation,resulting in the release of large amounts of AEs into the aquatic environment.The toxicity of AEs poses a risk to aquatic organisms,and due to its toxic nature and extensive use,it has caused widespread concern.Physical and chemical methods can efficiently remove surfactants from wastewater.However,these methods may cause secondary pollution and are very costly.Therefore,bioremediation being a low-cost and environmental friendly method could be preferred,but the application of conventional activated sludge technology to a single microbial strain would be difficult.Hence,it is urgent to develop an efficient bioremediation technology for removing AE.Bio-enhancement technology can boost the ability of microorganisms to remove stubborn compounds.If this technique enhances the removal of AEs from wastewater by activated sludge,it will be an important breakthrough for the treatment of AEs.In this study,a highly efficient AEs-degrading strain was isolated from an activated sludge obtained from the municipal sewage treatment plant by enrichment and cultivation.The phylogenetic characteristics of the isolate were identified based on 16S rRNA gene sequencing and was named Pseudomonas sp.LZ-B.The strain was inoculated into MSM medium with AEs as the sole carbon source to detect its degradation performance and optimize degradation parameters.The results showed that the strain LZ-B was able to grow with C₁₂E₄?Alcohol ethoxylates Brij 30?as the sole carbon source that reached a stable phase in 10 hours.It degraded 96.8%of Brig 30?200 mg/L?within 24 hours,and achieved 80%Total Organic Carbon?TOC?removal,which indicates that LZ-B is a strain that efficiently removes and mineralizes AE.The optimum degradation temperature and pH were 37?and 6.0,respectively.In addition,the strain was able to degrade five AEs with different molecular weights,within 5 days.The AEs degradation pathway was analyzed by liquid chromatography-mass spectrometry?LC-MS/MS?.The results showed that AEs were dispersible,and the main metabolites of degradation were polyethylene glycol?PEG?and carboxylated AE chains.The strain LZ-B was inoculated into an activated sludge reactor to strengthen the activated sludge,and the ability of the biologically enhanced activated sludge to remove various AEs in urban sewage was examined.The study found that strain LZ-B was successfully colonized into activated sludge.When the hydraulic retention time?HRT?was 10 h,the AE removal efficiency increased to over 95%,and the removal of Chemical Oxygen Demand?COD?and NH₄⁺-N in wastewater was also significantly improved.Studies have shown that biofortification changes the microbial community in the activated sludge.When the strain LZ-B cleaves the AE chain,the microbial community can more easily use the PEG fragment,thereby promoting the complete degradation of AE.This is the first research to study the degradation of AEs by biofortified enhanced activated sludge systems.LZ-B is a potential approach to enhance the capability of activated sludge for the removal of complex AEs from the municipal wastewater.Biofortification may be a viable method of biodegradation complex AEs in municipal wastewater.