Biochemical Treatment Of Fur Dyeing Wastewater And Impact Of Bacterial Community In Activated Sludge

Fur dyeing wastewater is a recalcitrant and highly polluting industrial wastewater which makes traditional biochemical treatment somehow inefficient. In this study, some biochemical treatment processes of fur dyeing wastewater were used and on these bases bioaugmentation processes were also used to explore the limit of biochemical treatment processes of fur dyeing wastewater. The influence of the microbial community structure of activated sludge, and the succession of microbial community structure in the process of wastewater treatment were also studied.Three treatment processes under similar operating parameters in this study were adopted to decontaminate fur dyeing wastewater. Chemical oxygen demand(CODCr), biochemical oxygen demand 5-day test(BOD5)and NH4+-N were measured to monitor treated water quality and treatment efficiency while microbial community structures in the treatment were also examined using terminal restriction fragment length polymorphism(T-RFLP). HA(Hydrolysis acidification) and SBR performed the highest removal efficiencies of CODCr, BOD5 and NH4+-N at 92.75%, 94% and 93.59%, respectively. T-RFLP analysis showed Bacteroidetes, following by Firmicutes and Proteobacteria, is the most dominant microbial population in sludge under all treatments,but the percentages were different under different treatment processes. Such as Pseudomonas and Bacillus which were common in activated sludge can effectively survive wastewater treatment and play a positive role. Flavobacterium can withstand such high salinity wastewater grow well while the bacterial community diversity was closely related to the NH4+-N level of the wastewater.Meanwhile, this paper also studied two bioaugmentation processes to use to fur dyeing wastewater.First, nutrients were added to the activated sludge to change the carbon and nitrogen ratio. Then, the result showed that this method could increase the number of microorganisms and changed the microbial community structure in activated sludge, which could promote the effect wastewater treatment. After adding exogenous nutrients with different carbon and nitrogen ratio to the activated sludge, One group which C/N=5:1 had the best CODCr removal, CODCr removal rate reached about 90%. Adding exogenous nutrients could effectively promote CODCr removal of wastewater, and the analysis of the concentration of dehydrogenase and EPS also verified that, higher concentration of dehydrogenase and protein, lower concentration of polysaccharide, waste better water treatment would be..Adding exogenous nutrients to activated sludge during wastewater treatment process could change microbial community structure of sludge, which could increase the number of microorganisms as Pseudomonas, Bacillus, and thus played an active effect in wastewater treatment.Secondly, this paper used the microbial agent for actual fur dyeing wastewater treatment through bioaugmentation process, respectively.By orthogonal experiment, results showed that by one batch addition with amount of 5%(V/V) at 0 h,a C/N of 5:1, initial p H value of 5, the COD removal rate could be more than 90%. Molecular identification of the isolated strains from the treated fluid confirmed the biological stability of the compound bacteria agent in the treatment of fur dyeing wastewater.By T-RFLP analysis, adding microbial agent in the wastewater treatment process, could effectively increase the proportion of Proteobacteria and Firmicutes in activated sludge, thereby increasing the proportion of Pseudomonas and Bacillus, both of this two bacteria were able to play an active role in wastewater treatment.