Preparation and wastewater treatment performance of sludge pore-forming ceramic

The purpose of this study was to use dehydrated sewage sludge, zeolite and attapulgite clay to prepare light weight ceramics for bio-filters. Dehydrated sewage sludge was added as pore-forming agent to increase porosity of ceramic. The sludge pore-forming ceramic (SPFC) were experimentally produced with various mass ratios of sludge, zeolite and attapulgite clay, and then the suitable mass ratios and the suitable process were determined. The optimum conditions (sludge, zeolite and attapulgite clay, sintering temperature and duration of heat) used for ceramics were selected by orthogonal experiment L₁₆(4⁴). Physical properties were tested. Furthermore, in the pilot-scale study on treatment of domestic sewage, the performance of SPFC in biological aerated filter(BAF) was also investigated. The results showed that the SPFC used for fillers were light ( bulk density is 700kg/m³, apparent density is 1474 kg/m³), high hydroscopic (water absorption rate in an hour is 28.4%), low broken(the crushing rate is lower than 0.8%), and porous (porosity is 50.2%) and had high adsorption ability (Methylene blue adsorption value is 0.80mg/g, ammonia nitrogen adsorption rate is 28.2%).SPFC was used as fillers in BAF, removal rate of COD was 84.9% and the removal rate of NH₄-N was 52%. Experiments show that the utilization of dehydrated sewage sludge to prepare SPFC is a new effective approach.