Preparing Mealy Yeast Microbial Agent By The Technology Of Lyophilization

The water quality of Waihuan River has been heavily contaminated, and needs comprehensive administration urgently. The addition of microbial agent can not only accelerate the degradation of contaminants in the water, but also is helpful to quicken the decomposition and inversion of contaminants in bed mud. It has no secondary pollution to the environment. The yeast has immense potential and broad prospect in the treatment of wastewater. It is an ideal culture of microbial agent. Making the liquid yeast solution into mealy microbial agent by the technology of lyophilization, which can be transported expediently and stored chronically, is the problem needing to overcome for the promotion of microbial agent technology.The centrifugal conditions of thalli and technology of vacuum freeze-drying, optimized and selected compound protectant for freeze-drying yeast, prepared high activated mealy yeast agent, and the best storage mode were investigated. COD degration in Waihuan River water after adding the freeze-drying mealy microbial agent was preliminarily researched.Results indicate that the optimum centrifugal conditions for high centrifugation yield ratio of inoculum cell is under 6000r/min in rotational speed for 10min. Under the above centrifugal conditions, the centrifugation yield ratio of yeast can reach to 78.64%. The optimum compounding of protectant is 5% Glycerol, 5% Skim Milk, 10% Sucrose and 15%β-cyclodextrin. Under the fixed condition of drying temperature and vacuum degree, the optimized mixing condition of compound protectant and yeast are: pH of protectant at 5, mixed proportion of protectant and thalli at 2: 1, 60min of balanced time, 0.5cm of thickness mixture. Water content of thalli cells was decreased by 2.47% after 22h drying time, survival ratio is 84.64%. Products were stored in the borosilicate glass which was sealed by butyl rubber stopper under the condition of vacuum and 4℃. Their activated cells number and water content changed very slightly and thalli cells have high activity and maintain the activated cells number of more than 1×1011cfu/g. The prepared mealy yeast agent was actived 2h by common yeast culture medium before adding to Waihuan River water with a volume ratio of 5: 1000. The highest degradation efficiency of COD reached to 33.33% after 5 days.