Study On The Preparation Of Sludge Ceramsite And Application In Wastewater Treatment

The sewage sludge of municipal wastewater treatment plant is solid waste which must be disposed suitably, or else it will bring secondary pollution and waste of resources. In China, the primary treatment methods include incineration, landfill and compost at present, and more or less shortages exist in these methods. So developing a new way of sluge source reuse seems to be particularly importmant.In this study, the sewage sludge of municipal wastewater treatment plant was used as principal material to sinter ceramsite. meanwhile, the fly ash and clay was used as additives. The best mass ratio of raw materials was selected. And the impact of main factors, such as dry time, pretreatment temperature, pretreatment time, sinter temperature, and sinter time, on the characteristics of sludge ceramsite (specific surface area, bulk density, granule density) were studied. Orthorhombic experiment was carried out to determine the best technique conditions for the sludge ceramsite produce. Biological Aerated Filters ( BAFs ) with sludge ceramsite and commercial ceramsite as biofilm media, respectively, were designed to treat the simulated wastewater. And the results showed that the application of sludge ceramsite as biofilm media in wastewater treatment was feasible.Based on the specific surface area, bulk density and granule density, the best mass ratio of raw materials was determined as follows, sewage sludge: fly ash: clay = 2: 3: 1. And the best preparation conditions were also obtained as follows: the dry time was 1h. the pretreatment temperature was 300℃. the pretreatment time was 20min. the sinter temperature was 1100℃. and the sinter time was 8min. Under this condition, the characteristics of prepared sludge ceramsite were as follows: the specific surface area was 4.222 m~2/g. the bulk density was 635 kg/m~3. the granule density was 1146 kg/m~3. Performance of sludge cetamsite was tested and analyzed, and the reaults showed the fittness of sludge ceramsite for the requirements of biofilmcarrier. The contents of metal elements in the lixivium of the sludge ceramsite was within the content range defined in the Chinese standard GB 5085.3-2007. which indicated that the application of sludge ceramsite was feasible and secure for wastewater treatment, but not for drinking water treatment. The sludge ceramsite was used as the biofilm media in BAF to treat the simulated wastewater and actual sewage. The effects of sludge ceramsite both in the process of biofilm attachment and natural circulation were very good, and were better than that of commercial ceramsite.The above results indicated that the sludge ceramsite could be employed as an effective, safe and economically feasible substitute for commercial clay ceramsite or shale ceramsite in wastewater treatment. So the resource reuse of sewage sludge could be achieved.