Analysis Of The Interaction Between Heavy Metal And EPS Isolated From Sulfate Reducing Bacteria

EPS is a macromolecular substance secreted by microbial degradation of organicpollutants. EPS is filled in the internal voids of various microbials aggregates, form ahuge three-dimensional structure and maintain the integrity of the structure and functionof microbials aggregates in waste water reactor. SRB can restore the sulfate to sulfideions during the growth progress. So SRB bacteria are widely used in wastewatecontained sulfate and heavy metal ions. This paper focuses on the interaction betweenSRB EPS and heavy metals. Maincontents and results are as follows:In this paper, the sulfate-reducing bacteria (Desulfovibrio desulfurican) were used asthe test strains to explore the impact of different growth factors on the components ofextracellular polymeric substances and the sorption ability of these extracellularpolymeric substances to the Cu2+. The experimental results showed that the amount ofEPS secreted by SRB were maximum when pH, initial inoculums, the ratio of F/M andCOD/SO42-were7,182mg/L,18.13g/g and3:1g/g respectively. When theseconditions were at8,136.5mg/L,45.33g/g and3:0.3g/g respectively, the EPS weremore easily combined with Cu2+. The FTIR spectrum of unloaded and Cu2+-loaded EPSindicated that protein plays a major role compared with polysaccharide at the process ofsorption.Adsorption characteristic of Cu2+and Zn2+by the extracellular polymeric substances(EPS) extracted from the sulfate reducing bacteria of SRB were investigated. EPS wasmainly composed of protein and polysaccharide. Results showed that Zn2+was moreeasily combined by EPS. FTIR analysis showed protein play a major role in bindingCu2+and Zn2+by EPS. EEM spectra presents that tryptophan-like substances was themain composition existence in EPS and play a important role in EPS combined withCu2+and Zn2+.Gypsum and anhydrite were used as the source of sulfate radical to expore the growthcondition of SRB and the generation of EPS in this condition. Results showed that SRBgrowth better when gypsum was the soruce of sulfate radical and anhydrite was moreeffective in the secretion of EPS. The results of the fuction of EPS and SMP indecomposition of four sulfate minerals shows that both EPS and SMP can promote thisprogress. Gypsum and anhydrite were decomposition easily when EPS exsitence andSMP was play a better role in the decomposition of barium sulfate and lead sulfate.