Mass Cultivation Technology Of Microorganism

Research on mass cultivation of microorganism was performed as a part of the study on the microorganism addition to improve the contaminated water quality of Wai Huan River. Large quantity of microorganisms are needed in practical application, so mass cultivation of microorganism was performed to reduce the costs of microorganism cultivation. The feasibility of simulate beer wastewater used as culture medium was investigated. The carbon and nitrogen sources for mass cultivation of yeast was explored and selected. To satisfy the downstream processing, a high density cultivation is required. An airlift bioreactor was designed to take place of the expensive traditional digesting tank.Compared with the traditional culture medium, the simulate beer wastewater culture medium is better for microoganism growth. it was found that: simulating beer wastewater can be used to culture microorganisms, except for microbial flocculant-producing bacteria. Study on the feasibility of corn saccharification liquid and corn steep liquor as carbon and nitrogen source of yeast cultivation was also performed, by comparing with the traditional ones. Higher density yeast and greater degradation rate are achieved in the investigated culture medium. On that basis, optimum program of yeast cultivation was achieved, on the orthogonal experiment principle and considering the wastewater removal rate (CODcr). The optimum medium is one litter of simulating beer wastewater, five milliliters of saccharification, and nine grams of corn steep liquor. The optimum culture condition was carried out by taking100 milliliters to the conical flask of 250 milliliters, before inoculating 15 milliliters of inoculum in it, with the culture medium pH on 4.5, 30℃in cultivation temperature and 220 r/min on shaking speed. After comparing with the fed-batch cultivation, Cyc-cultivation method was adopted to achieve high density cells. From the high density experiment, it was found that: the three times cyc-cultivation have the greatest degradation rate. On the basis of flask experiment, the designed airlift bioreactor experiments are carried through. The validation results show the method is satisfied and the optimum aeration rate is 0.25vvm. From the above researches, the flow chart of microorganism cultivation was designed. At simple analysis on cost of the optimized mass cultivation method show that the medium cost is approximately was done, and the result is: medium cost is 1.7 RMB/kg and the operation cost is approximately 5.31 RMB/kg cell weight.