Experimental Study On The Effect To Cure Heavy Metals In Sewage Sludge By Firing Ceramsite

Municipal sewage sludge is in the process of urbanization of the solid waste, the municipal solid waste treatment and disposal is a problem that must be addressed. Preparation of the use of sewage sludge ceramsite not only make full use of the sludge organic matter in the roasting process as a foaming agent, but also can be completely inactivated pathogens and keep heavy metals in the ceramsite curing, and eliminate the pollution of heavy metals in sludge problems. At present, the new way of sludge utilization is gradually promoted and apply in a variety of works. Because the heavy metals are difficult to aging and have strong toxicity, Using sewage sludge to make ceramsite can be harm to the environment and the people. So it is greatly significant to make sewage sludge ceramist and use it securely by studying the curing effect to heavy metals in the series course.This study′s raw materials is urban sewage sludge and shale powder with a certain percentage of mix to the dry ceramic material, respectively change different conditions such as the pre-heating temperature,the acalcination temperature and the heavy metal content to make ceramsite, and the X-ray fluorescence spectrometer is used to detect the content of heavy metals such as Cu, Pb, Cr, Zn, Ni in ceramsite and dry sludge before and after firing,then compare and analyze the different curing effect; Leaching toxicity test is made to ceramsite when changing the firing temperature, leaching time, leaching temperature and leaching solution conditions such as pH value, and the atomic absorption spectrophotometer is used to detect the leaching concentration of heavy metals such as Cu,Pb,Cr. The following findings:1.The rate of municipal heavy metal solidification by firing sewage sludge to ceramsite is about 90% and twice than the solidification by firing sewage sludge directly .It is certain that the curing effect of heavy metal by making sewage sludge is better.2.The curing rate before and after ceramsite′s firing is directly proportional to the pre-heating temperature and the calcination temperature, and change little in the temperature of 1050℃, 1100℃, 1150℃and 1200℃, which is associated with the different attributes of element. When increasing the content of heavy metals,the curing rate of Zn and Cu have a little change,and Cr, Ni decreased gradually, while the curing rate of Pb increase gradually. 3.The leaching toxic according to ceramsite is far less than the national standard, and can be used in the production of security.4.The rate and concentration of heavy metals in ceramsite is directly proportional to the leaching time and temperature, and the curing rate change variously at different pH value because they exist in different forms, and the change is generally showed that it is higher under the conditions of alkaline.The results show that the curing effect to heavy metal is better by using municipal sewage sludge and shale to make ceramsite.The ceramic products can be used safely. The results can provide a useful reference to utilization of making municipal sewage sludge to building materials.