Study On The Production Of Lactic Acid By Re - Fermentation Of Naked

With the expanding process scale of Nisin industrial production, the discharge amount of organic effluent increased year by year. In the process of Nisin production, the lactic acid was also produced. In addition, the organic effluent also contains residual sugar, protein, amino acids, inorganic nutrients, and a large number of inorganic salts produced in the extraction process. If these sustances are discharged directly, the environment may be polluted, and the resources may also be wasted. If these substances are transformed into chemical raw materials such as alcohols, ketones, and organic acids by biotechnology, these wastes may be changed into wealth, and the problems of environmental pollution may be relieved.In this study, the Nisin fermentation-produced organic effluent provided by Qiqihar Fengyuan was used as materials, component analysis of these effluent was conducted, which showed that the effluent contained lactic acid, nitrogen, sugar, sodium chloride, lactic acid with corresponding concentrations at 33.55g/L,2.8g/L, 3.45, and 34.59g/L. As such a high-salt environment is not suitable for the growth of lactic acid bacteria, desalination treatment was conducted for the effluent using special electrically driven membrane separation technology, and the desalination conditions were optimized. In such conditions, after desalination for 40 minutes, light room solution’s conductivity decreased from 45ms/cm to 18ms/cm, and the desalination rate reached 60%. Thise organic effluent with different salinity was used for preparation of different culture; then lactic acid strains were domesticated. The vitality of domesticated strain increased. Then the organic effluent with conductivity at about 18ms/cm was used to prepare fermentation medium for lactic acid production. The optimized conditions included medium components, innoculation amount, culture temperature, and the treatment conditions of CaCO3 and NaOH. Under the optimized conditions, the final output of lactic acid reached 100g/L, with corresponding conversion rate at 90%. Finally, the chemical oxygen demand (COD) comparison and amino acid composition analysis were conducted for Nisin organic effluent, the desalination effluent and lactic acid fermentation broth. Results showed that COD value decreased by 2×104mg/L and 3.2×104mg/L in desalination solution and the fermentation broth, respectively.The use of Nisin organic effluent for the production of lactic acid by fermentation can reduce lactic acid production costs while reducing the pollution level on the environment,. With the gradual depletion of fossil resource reserves such as petroleum and a growing environmental pollution problem nowadays, this study has important practical significance.