Study Of Synergistic Interaction Of Efficient Purifying Aquaculture Wastewater In Immobilized Bacteria-algal System

In recent years, the sewage of aquaculture, the characteristic of which is high content of organic matter, nitrogen and phosphorus, less inorganic pollutants and heavy metals is concerned. The method of sewage treatment by system of bacteria-algae not only solves environmental problems, reduce energy consumption and is easy to operate, but also achieves waste reuse. Based on this theory the immobilized bacteria-algae technology gradually developed. However, the physiological characteristics of microorganisms immobilized are still insufficient.The purpose of this thesis is to reveal the synergy in immobilized bacteria-algal system, which contains Nitrobacter, Bacillus licheniformis, Selenastrum capricornutum and Scenedesmus quadricanda. Establishing the model of material transfer and transformation in immobilized bacteria-algal system by comparing the removal effects of nutrients in sewage which are dealed with by immobilized bacteria-algae and free state of bacteria-algae, and it provides theoretical basis for purifying water by bacteria-algae system. If the technology is widely used in practice, it should regulate the best ratio combinations for different environmental factors.The results of this study are summarized as follows:1. The results show that bacteria-algae system removes nitrogen and phosphorus effectively.2. Through the comparative studies, the bacteria, algae and bacteria-algae system under immobilized state in water purification system are better than free state. The nitrogen removal rates are 57.5%,53.7%,90.4%,14.4%,50.0%,76.5%; the nitrate removal rates are49.8%,61.3%,62.1%,27.4%,34.7%,43.6%; the dissolved phosphorus removal rates are 32.3%,48.5%,72.5%,32.1%,59.6%,82.3% under immobilized state. This article concludes that the presence of bacteria in the bacteria-algae system is important to remove NH3-N and NO3--N, and the presence of algae is the most important factor of removing NO3--N and DP. Bacteria-algae system in the removal nutrients reaction follows first order reaction.3. In different environment factors, comparing different experimental groups shows that the efficiency of immobilized bacteria-algae in wastewater is relatively stable, and the removal rates of nutrient in test group has little difference. Immobilized bacteria-algae has the optimal effect in dealing with sewage under the conditions of the ratio of N and P is 12.5, temperature is 30℃, light intensity is 35001x, fixed brightness ratio is 2:1.