Studies On A New-combined Environmental Microbial Agent And Its Effects On Treating Polluted Water

Microbial agents are alive bacterium preparation which are made from several kinds of microorganisms by suitable proportion and fermentation conditions. The microorganisms in agents have strong degrading function and can promote the growth for each other. Microbial agents have been widely used in planting, breeding, food, environmental protection and other fields, with some features such as low-cost, effective, easy to use and so on. As the strains in environmental microbial agents mostly screened from the contaminated environment, the screening process is relatively complex and their biological security and environment property need to be carefully evaluated. To some extent, some new and environment-friendly alternative strains should be found out.Actic acid bacteria, yeasts, Bacillus natto are used in daily foods and drinks commonly; besides, they are widely used in microbial agents. Their application has been very mature. The screening processes of them are simple and the biological security and environment property are better. Studies have shown that the three types of microorganisms all can degrade a variety of environmental pollutants and play a good role in water purification. In addition, some studies have shown that lactic acid bacteria, yeast, Bacillus natto have a symbiotic relationship with the mixed culture.In this study, lactic acid bacteria, yeasts, Bacillus natto were isolated from yogurt, yeast extract and natto separately as strains. Then the mixed culture conditions of them was studied and a compound microbial agent was prepared that cound be used for treating sewage and removing the odor of landfill leachate. Finally, the effects of the agent were examined and analyzed. All studies were carried out is to provide a safe and effective, low-cost, environmentally friendly product for sewage purification and waste treatment. The main results were as follows:1Three strains were isolated respectively from yogurt, yeast extract and natto by traditional methods, and were identified through individual morphological observation, physiological and biochemical characteristics experiment,16SrDNA or26SrDNA sequence compared. The results showed that they were Lactobacillus casei, Candida ethanolica and Bacillus subtilis var. natto.2The mixed culture conditions of the three strains were studied. A new microbial agent was prepared according to the optimal culture condition and the live bacteria in the agent was counted. The results showed that lactic acid bacteria, yeasts, Bacillus natto could grow better together under the condition with temperature35℃,time120h,inoculation ratio2%:2%:1%(lactic acid bacteria:yeasts:Bacillus natto). In the microbial agent made in accordance with this method, the numbers of live cells of the three microbes were respectively:lactic acid bacteria4.79×107cfu/mL, yeasts5.57×107cfu/mL Bacillus natto3.73×10’cfu/mL.3The agent has a role in promoting the removal of COD and ammonia nitrogen in the sewage. In a word, the effect is best with0.5‰microbial agent and two day’s aeration, COD and ammonia nitrogen removal rate increased by11.11%and14.13%. This initially showed that the agent has a better effect for the purification of sewage.4The agent can effectively reduce the threshold odor number of the landfill leachate, inhibit the production of NH3and H2S. So it has a good deodorizing effect on the leachate. As a whole, in order to remain the threshold odor number at a low level and get a good deodorizing effect adding5%o the microbial agent to the landfill leachate every3days is a good choose.This study preliminary proved that the agent prepared with the microorganisms isolated from foods and drinks has a good effect in the field of environment protection, as well as simple technique and low cost. It is hopeful to develop and utilize the agent by further optimizing the proportion of the microorganisms and improving the conditions of mixed culture.