Study On The Fermentation Kinetics Of The Strain SHD-1 And The Flocculant Producted By The Compound Bacteria

The oil refinery is the pillar industry in China,but the oil refinery wastewater which includes much emulsified oil, non-biodegradable components and suspension substance, is seriously harmful to the environment. Removing these pollutants as possible by coagulation method is necessary before biologycal treatment. The selecting of flocculant is the key point in the process of coagulation. The traditional flocculants include inorganic macromolecule and synthetical organic macromolecule, which are used extensively in the process of coagulation.These flocculants are harmful to the environment,so the study of the microbial flocculant which is green environmental protection and efficient is the new direction of the flocculant.The study of the fermentation condition optimization,the fermentation kinetics and the low-cost culture medium of the strain SHD-1 producing the microbial flocculant are intended to reduce the production cost of the microbial flocculant. Moreover,aim for improving the flocculation efficiency and enlarging the flocculation scope, the condition optimization of the compound microbial flocculant is studied.At last,the study on the different oil refinery wastewater used to prove the industrial feasibility of the microbial flocculant.The optimum fermentation conditions for the strain SHD-1 were the organic nitrogen source concentration 0.05%,the carbon source concentration 2%, pH 7, the culture volume 10ml for 250ml conical beaker and water 1L.Based on the optimum fermentation conditions,the kinetic equation of the strain SHD-1 was studied.The math models its biomass, polysaccharide production and sucrose consumption were established,and the experiment datas could be well fitted with the model datas.These models offered the evidences for large scale production of the the microbial flocculant. The compound microbial flocculant produced by the strain SHD-1 and the strain 5 had the best flocculation efficiency.Its optimum fermentation conditions were fermentation time 48h,initial pH, the carbon source concentration 2%,the organic nitrogen source concentration 0.05%, and the addition of 0.01 mol·L-1of metallic ion Na+. In addition,Its optimum flocculating conditions were the dosage 60μl,pH 9, the slowly mixing speed 20r·min-1, the slowly mixing time 6min, temperature 30℃, and the addition of 3ml,1mol/L of two-valence metallic ion Ca2+in wastewater. Besides, the compound microbial flocculant could make the sludge reduce.The compound microbial flocculant could flocculate the different oil refinery wastewater,and the flocculation efficiency was similar with polyaluminium chloride and polyacrylamide.The results of the low-cost culture medium about the microbial flocculant show that the soybean dregs and the waste residue of soybean protein processing plant were suitable for the substitute nitrogen source. Furthermore,the flocculation efficiency of the microbial flocculant produced by one strain was better than that produced by the compound bacteria which all cultured with the same medium.