Experimental Study On Disintegration Of Excess Sludge With Ball Mills Method

With the construction of waste water treatment plants, water pollution was effectively controlled in China. But at the same time, a large amount of residual activated sludge occurred. The residual activated sludge without dispasal would produce serious environmental problems. The minimization and resource utilization of the residual activated sludge is the development trend of the residual activated sludge disposal. In this paper, the ball mills method is used to disintegrate the excess sludge of urban sewage, under the action of mechanical shear power and the collision of abrasive matter, which can destroy structure of the sludge and cell wall. The method can not only reduce the sludge solid capacity, promote follow-up sludge digestion rate, but also improve the sludge dewatering effects, which provide prerequisites for the final disposition of excess sludge.The disintegration device in the experiment of ball mills method is ball mill mixer, with glass beads as abrasive material. The content of the experiment can be divided into two parts: First part, change the mill bead volume, in the different disintegration time, do some analysis. Second, change the mill bead size, and it is necessary to analyze and evaluate the effect.The test items include pH, particle size distribution of excess sludge, and nucleic acid, Soluble Chemical Oxygen Demand, Total Nitrogen, Total Phosphorus, Ammonia Nitrogen density of sludge supernate after disintegration, and finally scan sludge with microscope and electron microscopic, the main conclusions can be obtained as follows:(1) Ball mills method has the best effect on residual sludge.(2)The concentration of SCOD, TN, TP has increased obviously.(3)According to the first part,when mill bead volume occupy20%of all tatal volume, after30minutes, ball mills method works best.(4)It is very best that when mill bead size is hybrid particle size.(5) Through particle size analysis, the size of sludge has change smaller gradually.(6) Through the optical microscope and the transmission electron microscopy that I can see sludge flocculent body is broken. The sludge is dispersed in30minutes, at the same time that the cell wall is broken, a lot of cytoplasm runs off.