Study On Development And Flocculating Activities Of Microbial Flocculant BS-5

In wastewater treatment, flocculation is an easy and effective method of removing suspended solids (SS). Although a variety of flocculants, such as inorganic flocculants and organic flocculants have been used due to their effective flocculating activities and low cost, their usage has been restricted because of their neurotoxic and carcinogenic monomers. In recent years, to solve some environmental issues, microbial flocculants have been involved widely due to their some advantages such as easy-biodegradation, innocuity and non-secondary pollution. Microbial flocculants which can agglomerate suspended solids, colloid particles, cells, cell debris, are polymers produced by microorganisms during growing periods. Today, soil, wastewater and activated sludge are considered as the best sources of screening and isolating of flocculant-producing microorganism.In this thesis, it was systematically researched, which includes the screening of the polymer-producing microorganism, the optimization of cultural conditions, the characterization of mechanism of the microbial flocculants and application in wastewater treatmentThrough preliminary researched, a strain of microbial flocculant named BS-5 with had high and stable flocculating activity was isolated from sludge of river. The effects of carbon and nitrogen sources and initial pH on bioflocculant-producing properties of strain BS-5 were investigated respectively, and the optimum cultural conditions was confirmed: 10g soluble starch, 3g NaNO₃, 1.2g K₂HPO₄, 0.5g MgSO₄ · 7H₂O, 0.5g KCl in 1000ml distilled water. When the initial pH value of the medium was adjusted to 6.0, and the microbe was cultured at 30℃ and shaken at 150 rpm in a rotary shaker for 32 hours, the flocculating rate of the MBFBS-5 can reach...