Effect Of Nitrogen Source And Metal Ions On Microbial Flocculant Synthesis

Microbial flocculant(referred to as MBF)due to its non-toxic,harmless and easy to biodegradation,does not produce secondary pollution and good flocculation effect become research hotspot in the field of environmental engineering.Although both domestic and overseas have found a variety of microbial can produce flocculant,and launched microbial flocculant chemical composition,structure,and the flocculation mechanism of related research,the nitrogen source and multivalent ions mediated microbial flocculant synthesis mechanism of molecular regulation rarely been reported.A study of a strain of efficient flocculant bacteria Bacillus subtilis A9 as the object,systematically study the different nitrogen sources,carbon nitrogen ratio and metal ions on the effect of A9 which can produce microbial flocculant(referred to as MBFA9),to explore the mechanism of regulation and initially used monosodium glutamate wastewater replace nitrogen and carbon source for the preparation of MBFA9 of feasibility study.The main results are as follows.(1)The best nitrogen source conditions of MBFA9.Carbon sourcefixed in this study,through the screening of inorganic nitrogen source,organic nitrogen source and mixed nitrogen sources onMBFA9 synthesis,and eventually optimize selected the best nitrogen source for yeast extract,the amount is 0.033g(m/v),flocculation reaches 94.26%.(2)Studying different C/N ratio onthe effects of MBFA9 synthesis and determine the glucose as carbon source,yeast extract and urea as nitrogen source,C/N ratio is 30:1,the temperature is 30 degrees,shaking speed is 150r/min,inoculation amount is 3%(v/v),pH7to8 in the fermentation culture medium and culturing for 72h,MBFA9 output reach 7.04g/L,36h flocculation rate reach 96.24%.(3)Studying different metal ions on the effects of MBFA9 synthesis and determined glucose as carbon source,yeast extract and urea as nitrogen source,C/N ratio is 30:1,the temperature is 30 degrees,the shaking speed is 150r/min,inoculation amount is 3%(v/v),pH 7 to 8 in the fermentation culture medium and culturing for 72h,when the Mg2+concentration is 0.025mol/L,the yield of MBFA9 reach 8.29g/L,36 h flocculation rate reach 97.34%.(4)Carbon source fixed,use monosodium glutamate wastewater instead of nitrogen and carbon sources,namely:with a 0.22um membrane filtration volume fraction for 10%monosodium glutamate wastewater and other medium composition is the same,without extra addition of nitrogencarbon and source can be as a substitute of medium,in the temperature 30 degrees,shaking speed is 150r/min,inoculation amount is 3%(v/v),pH 7 to 8 in the fermentation culture medium and culturing for 72h,the yield of MBFA9 reach 6.73g/L,36h of flocculation rate can reach 94.71%.(5)Analyzing flocculating constituent of MBFA9 from monosodium glutamate wastewater,and demonstrate the effective component is mainly polysaccharides.