Experimental Study On Disintegration Of Excess Sludge With Stirred Ball Mills Method

A large amount of excess sludges will be produced in the process of treating municipal°and industrial wastewater by the method of activated sludge process. The treatment and disposal of the excess sludge has become a difficult problem in sewage treatment due to the large volume, complex components of sludges. In this paper, stirred ball mills method is used to disintegrate the excess sludge of urban sewage, 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 research commonly used spin crusher as disintegration device with glass beads, quartz sands and building sands as abrasive matters. The influence on disintegration of excess sludge with stirred ball mills method from three aspects such as time, quality, and particle size of abrasive matters was investigated.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 experimental results showed that stirred ball mills method had certain effect on excess sludge.Through the variation of Soluble Chemical Oxygen Demand, nucleic acids of sludge supernate and other parameters.It showed that the collision of abrasive matter had a certain impact, and also showed that the glass beads effect was best along three abrasive matters.It showed that if the quality and size of mill beads were fixed, the added value and dissolution rate of SCOD was higher; the TP and nucleic acid density of sludge supernate was at maximum after15minutes’ disintegration. That is15minutes was the optimization time for excess sludge disintegration. When the mill beads quality and time were fixed, the experiments result showed1-1.43mm was the best particle size to disintegrate the excess sludge for quartz sands from the variation of the nucleic acid, TN and TP density of sludge supernate.When the size of mill beads, disintegration time and sludge the volume were fixed, the study showed that15g was the best quality to disintegrate the excess sludge for glass beads in a range between0and25g;25g was the best quality to disintegrate the excess sludge for quartz sands in a range between0and25g from the variation of nucleic acid density.