Performance Of Biological Aerated Filter(BAF) Bioaugmented By A Yeast Magnusiomyces Ingens LH-F1 For Treatment Of Azo Dye Wastewater

Azo dye is a class of azo compounds which are widely used as chemical products.They are complex in structures,recalcitrant to biodegradation and possess certain bio-toxicity.They will cause serious environmental pollution once being discharged without effectively treatment.Biological processes are efficient,low-cost and environmentally friendly wastewater treatment methods.Furthermore,biological processes with fungi-bacteria co-cultures are paid much attention recently as upgraded version alternatives and will be potentially useful for field application.This work was started from the isolation of efficient azo-degrading fungi.A yeast strain LH-F1 which can aerobically degrade various azo dyes was isolated from the sea mud of a harbor industrial zone in Dalian.The strain LH-F1 was identified as Magnusiomyces ingens?KF443804?on the basis of morphological observation and 26S rDNA sequencing method.The optimum conditions for suspended growing cells of strain LH-F1 and the cells immobilized by calcium alginate were optimized through single-factor investigation method,respectively.The result showed that strain LH-F1 was a typical aerobic and mesophilic yeast strain which preferred neutral and weak acid conditions.Additionally,the degradation pathways of azo dye acid red B?ARB?were speculated as that the processes were all consistentwitha“reductivecleavageofazobondsfollowedbya desulfurization/denitrification and finally a TCA cycle”pathway.Aerobic ARB wastewater treatment by the activated sludge systems which were bioaugmented by strain LH-F1 was investigated through the experiments in flasks for simulating the operation of SBR.Effects of different concentrations of strain LH-F1 were investigated.The results demonstrated that the decolorization efficiencies of bio-augmented systems showed higher decolorization efficiency and stability to shock loading than the non-augmented system.The optimal entrapped density of immobilized LH-F1 was 40 g/L.However,there were optimal decolorization efficiencies between bioaugmented systems with different inoculation size?3-6 g/L,wet weight?of strain LH-F1.The results of PCR-DGGE analysis showed that there were obvious difference between the microbial structures of bioaugmented and non-augmented systems.Furthermore,bacteria were capable of degrading sulfonated azo compounds and denitrifying,as well as fungi that effectively degraded organic pollutants were detected in the bioaugmented system as dominant species.Three BAFs which were inoculated with strain LH-F1,activated sludge and both of them were constructed and operated for further investigation and the whole operation process was divided into four stages with different HRTs.Shifts of ARB concentration,COD,OD₆₀₀ and biotoxicity in influent and effluent were monitored allthrough the whole operation process.The results showed that decolorization and COD removal efficiencies in the BAF bioaugmented by LH-F1 was higher than those of the other two BAFs,meanwhile the turbidity of effluent was much lower.Thus,the bioaugmented BAF showed higher treatment stability,tolerance to shock loading and remarkably better performance for detoxification of ARB wastewater.MiSeq sequencing results demonstrated that microbial communities obviously shifted in the three BAFs when external factors changed.On the other hand,Magnusiomyces was detected in the bioaugmented BAF and became the absolutely dominant fungal genus,which suggested that the bioaugmentation fungus LH-F1 colonized in the microbial consortium.