Study On The Performance Of The Self-inducing Mixing Underwater Aerator

With the continual growth of national economy, the urbanization and industrialization processes have been developing rapidly in recent years, and the water pollution is more serious. The water pollution destroys seriously the ecological balance,affects human health, occupies the precious freshwater resources, restricts the economic and social sustainable development. Therefore, how to realize the efficient treatment of the wastewater has become an urgent problem to be solved in modern society.Activated sludge process is commonly used in the treament of domestic sewage,urban wastewater and organic industrial wastewater, and aerator is the core equipment of this technology. The performance of aerator is directly related to the wastewater treatment effect and processing cost. Therefore, designing and developing an efficient aerator has become an important way for the optimization of the biochemical sewage treatment. At the same time, the efficient aerator also can reduce the cost of wastewater treatment and the total operating cost of wastewater treatment plant.The subject team combines numerous valuable scientific research experience,proposes the new designing program(This program has applied for national patent, its patent number is ZL201420761174.5). According to the new designing program, we make the self-inducing mixing underwater aerator. Compared with the traditional underwater aerator, the self-inducing mixing underwater aerator has many advantages:Its motor stands above the liquid surface, and it’s easy to maintenance and repair; It has mixing and oxygenate function, which can be operated separately. According to the practical situation, it chooses the proper way in order to make the best wastewater treatment effect by consuming less energy; It can automatically suck the air relying on the vacuum produced by the rotation of the aeration impeller, which makes less noise and power consumption; There is no need for placing many pipes in the bottom of the reaction, which makes the gas filling method and machine fixing more simple. Besides,it has less construction cost and the installation cost; Its intake-tube made of plastic,which is easy to change, has high corrosion resistance, saves energy and protectsenvironment.To explore the oxygenation capacity of the self-inducing mixing underwater aerator in different working condition, and to test the situation in the actual application of wastewater biochemical treatment, our suject team conducts two categories experiments respectively: clear water aeration experiments and the sludge cultivation experiment under the 1kgCOD/(m3·d)volume loading level conditions, the results are as follows:(1)The distance between the intake-tube and the water inlet of the aeration impeller called voidage. Only the voidage matches the speed and submerged depth of the aeration impeller can the aerator make the the ideal oxygenation effect. Under the experimental submerged depth and the aeration impeller speed, decreasing the size of voidage properly can increase the oxygenation properties of the aerator;(2) Under the experimental voidage, the critical speed of aeration impeller is directly proportional to its submerged depth;(3)Under the experimental voidage and submerged depth(35cm), the oxygenation capacity of the aerator will ascend up with the increasing impeller speed(The increasing impeller speed are fixed to 1100r/min、1300r/min、1500r/min、1700r/min、1900r/min).However, when the inspiratory capacity of the aerator are increasing slowly, increasing the impeller speed makes little sense to improve the oxygenation properties of the aerator;(4)Under the experimental voidage and the aeration impeller speed(1500r/min),the oxygenation properties of the aerator will decrease with the increasing of submerged depth in some degree;(5)Using self-inducing mixing underwater aerator supplies the domestic wastewater biochemical treatment system with oxygen, the activated sludge has been domesticated successfully under the 1kgCOD/(m3·d)volume loading level conditions.In the domestic wastewater biochemical treatment system, the effluent COD and ammonia nitrogen average removal rate were 90%、97%, both of them can reach the discharge standard, which proved the oxygenation capacity of this aerator, and showing the feasibility of it in the actual operation.