Study On Application Of Microbial Flocculants By Multiple Microorganisms

Microbial flocculants which Agglomerate suspended solids, cell debris, colloid particles are the secondary metabolite excreted by microorganisms during growing periods. With the characteristics of biodegradation, nontoxicity, high efficiency and non-secondary pollution, the research and exploration of microbial flocculants has been a hot topic in recent years.Four kinds of flocculating microbes with flocculating ability, namely ZJTL2, ZJSW3, KJTD6 and KTYD1, were obtained by repetitious enrichment and reselection. multiple microorganisms 1 were constructed by ZJTL2 and KJTD6. At the optimum flocculation condition(9.0 for initial pH, 2ml/100ml for the dosage of fermented liquid, 2ml/100ml for the dosage of CaCl₂, 15min for the sedimentation time), multiple microorganisms 1 had the best flocculating rate, the efficiency of which could reach 95.5%.In order to cut down the cultivating cost of multiple microorganisms 1, starch wastewater was tested to replace glucose as the carbon resource and energy resource in the cultivating medium, and the result of experiments confirmed its feasibility. It was studied that starch wastewater concentration, initial pH of culture medium, cultivating temperature, shaking speed and the dosage of inoculation influenced flocculating activity of fermented liquid of multiple microorganisms 1. The optimal culture medium of multiple microorganisms 1 consists of 1L starch wastewater(its CODcr is 4860mg/L), 0.3g urea, 0.6g yeast extract, 5.0g K₂HPO₄, 3.0g KH₂PO₄, 0.3g NaCl, 0.5g MgSO₄·7H₂O. The optimal cultivating condition is listed here: initial pH 7.5, 1.0ml germ solution per 50ml starch wastewater culture medium, cultivating temperature 35℃, shaking speed 160rpm, cultivating time 72h. Under this environment, the flocculating rate of fermented liquid of multiple microorganisms 1 is up to 95.8%.The productivity of the purified is 0.9268g per liter fermented liquid. The main components of the microbial flocculants are polysaccharide. The microbial flocculant is heat-resistant well.MBFL-X produced by multiple microorganisms 1 was used to treat starch wastewater. The optimized mixing procedure is listed here, 600r/min stired 30s, 300r/min stired 30s, 140r/min stired 2min, 50r/min stired 4min. The treating 500ml starch wastewater processing: 7ml microbial flocculants and 9ml l%CaCl₂ solution were put into 500ml starch wastewater and pH of system was adjusted to 9.0.MBFL-X excels at treating printing and dyeing wastewater. The optimized removing CODcr scheme is listed here: 1.6ml microbial flocculants and 3ml 1%CaCl₂ solution were put into 100ml printing and dyeing wastewater and pH of system was adjusted to 9.0.under this condition, the efficiency of removing CODcr and chroma was 77.4% and 85.2%, respectively. The optimized removing chroma scheme is listed here: 1.6ml microbial flocculants and 3ml 1%CaCl₂ solution were put into 100ml printing and dyeing wastewater and pH of system was adjusted to 9.5. under this condition, the efficiency of removing CODcr and chroma was 70.2% and 89.3%, respectively.The multiple microorganisms immobilization was preliminarily studied. PVA and boric acid solution were selected to manufacture immobilization pellet in the experiment. Impact of flocculating activity of multiple microorganisms on immobilization condition was studied.Zhao jun(Environmental Science) Supervosed by Zhao xiao-xiang...