The Study On Wastewater Treatment Using Seires System Of Bacteria, Algae And Daphnia

As the development of social economy, the improvement of living standards and thedramatic increase of world population, the discharge amount of urban sewage increasessignificantly. The main treatment methods of sewage were physical chemical andbiological. Because of the absolute advantage, low energy consumption and nosecondary pollution, biological treatment has been widely used in the urban domesticsewage treatment, and80percent of the treatment uses the activated sludge treatment,which has the main disadvantage of producing large amount of excess sludge. Therefore,the treatment and reduction of excess sludge is the core part of present research.The experiment of this paper is based on the biological treatment of urban domesticsewage. The predation of microorganisms was used to guarantee the treatmenteffectiveness, and at the same time, to achieve the goal of excess sludge reduction. Afterthe processes of start, biofilm formation and steady operation in the biological gravelscontact oxidation tank, the bacteria, algae and daphnia were isolated from the reactiontank and cultivated. The optimal growth conditions of the bacteria, algae and daphniawere studied, and the series system was constituted. The order of the series system wasinlet, the tank of bacteria, the tank of algae, the tank of daphnia and outlet. The symbioticsystems of bacteria-algae, bacteria-daphnia and algae-daphnia and their series systemswere set as control groups, and the water qualities in each reaction tank of all the systemswere monitored. The wastewater treatment effects and advantages of thebacteria-algae-daphnia series system was achieved by comparison. The algae isolatedfrom biological gravels contact oxidation tank were spirulina and chlorella, so thebiological systems of these two algae were comparatively studied.(1)The series system of bacteria, algae and daphnia had the best treatment effect ofdomestic sewage among all the reaction systems.(2)In the symbiotic system without daphnia, the domestic sewage treatment effect ofchlorella is better than that of spirulina, but in the symbiotic system with daphnia, thetreatment effect of spirulina is better than that of chlorella.(3)The symbiotic system of algae-daphnia didn’t need aeration, so the energyconsumption was reduced, and the cost was reduced at the same time.