Research On Diatomite-based Porous Ceramic For Sludge Bio-drying

The process of bio-drying could be a good solution for sewage sludgewaste management, allowing the production of fuel with a interesting energycontent. Due to its high moisture content, sewage sludge requires a highmoisture absorbing amendment to evaluate the bio-drying process。In the present study, porous ceramic amendment with high porosity wasfabricated at950℃from diatom ite in w hich pore-forming agent and fluxwere added. The water absorbing rate of porous ceramic amendment is60~130%, density is0.61g/cm3～0.98g/cm3. These characteristics wereinfluenced by modifying the quantity of pore-forming agent and flux. With theincreasing of pore forming agent and diatomite, the water absorbing rateraised but the strength decrease. Increasing flux can efficiently improve thestrength of the product, while water absorption capability gets lower. Inaddition, glass power was wrapped around the surface of the product toenhance its abrasive resistance.Because of the differences of the raw material and production condition,we changed the formula and produce method based on the Laboratoryexperiments. The result showed that besides the raw material and formula, theballing craft had a significant influence to the properties of products. If theadding speed of the binder is too low, the balls would fragile, while higheradding speed would get bigger and heavier products. The longer balling time,the stouter the balls were. If the water and raw material were notwell-distributed when balling, the intensity of the balls would be low andeasily crack while sintering.The porous ceramic amendment was compared with bark amendment forthe sewage sludge bio-drying. Matrix temperature, moisture, oxygen andcarborn dioxide concentrations were measured every12hours. Addition of30%porous ceramic amendment was found to be sufficient to providethermophilic temperatures and high matrix oxygen concentrations. The matrixtemperature can last3days. Moisture content was reduced from78.7%to 62.8%after4days. The porous ceramic amendment can be repeated used forits high strength.