Production And Application Of Bioflocculant By Two Strains Of Rhizopus Sp. Using Starch Wastewater As Nutrilite

Flocculation characteristics of complex bioflocculant CMBF917 produced by Rhizopus sp. M9 and M17 were studied, and the culture conditions of the two strains using potato starch wastewater as nutrilite were optimized, then the bioflocculant was used to treat the wastewater and the flocculating conditions were also optimized.The bioflocculant which is a kind of secretion produced by M9 and M17 has characteristics of lower dosage, better flocculation efficiency and thermal stability:The optimal and economical culture conditions for the two strains producing bioflocculant using potato starch wastewater were CODCr of wastewater about 1600mg/L,0.3g/L urea and 0.04g/L potassium dihydrogen phosphate added, no need to add carbon source and adjust pH.60mL/L M9 and 40mL/L M17 were inoculated and cultivated for only 35h, then 5mL/L fermentation broth added to kaolin suspension can make the flocculating rate reach 92.67%. The CODCr and turbidity removal rates of wastewater after microorganism cultivation and bioflocculant extraction were 93.60% and 82.87%, respectively.When the bioflocculant was used to flocculate potato starch wastewater, the optimized flocculating conditions were dosage of 0.1mL/L, no need to adjust pH and 5mL/L 10% coagulant aid CaCl2 added. The CODCr and turbidity removal rates after flocculation were 54.09% and 92.11%, respectively.1.1 g/L proteic substance which can be used for animal feed was recycled from the water.Conventional chemical flocculants AlCl3,Fe2(SO4)3,PAM and remixed between organic and inorganic ones were used to treat potato starch wastewater in this paper. AICl3+PAM which has a better treatment efficiency with lower dosage of flocculant as well as lower cost and sludge was determined as the best flocculation treatment method according to the comparison of treatment efficiency, cost and the flocculation conditions.The flocculating conditions and treatment efficiency of CMBF917 and AICl3+PAM were compared. The conclusion showed that CMBF917 has great advantages according to its simpler process, lower flocculation cost, higher treatment efficiency and economic benefit.