| In this study, ceramsite was made from sludge and steel slag as main raw material, mixing clay, fly ash and other additives. Technololgical process of preparation was as follows:firstly, mixing; secondly, granulating; lastly, sintering. The study comprehensively analyzed the effect of the ratio of raw materials, sintering temperature, preheating temperature on compressive strength, water absorption and apparent density of the ceramsite. And then, orthogonal test was carried out to determine the technological condition for the preparation of sluge ceramsite. Impacts of sintering temperature, the ratio of raw materials and steel slag content on the performance of ceramsite were studied systematically. Through single-factor test, the optimal technological conditions for preparing ceramsite were determined. At last, ceramsites made from sluge and steel slag, produced under the optimal technololgical condition, were used as filter material of Biological Aerated Filter(BAF) reactor, comparation of wastewater biological treatment utilization performance were conducted between sluge, steel slag ceramsite and commercial ceramsite. The main contents and results were as follows:1. In the experimental study to explore the sludge ceramsite, preliminary optimization of the sintering process was done firstly, then impact of the ratio of raw material, sintering temperature, preheat temperature were studied systematically. The research showed that sintering temperature is the most important effect for producing ceramisite, and then the ratio of raw materials and sintering time are following. Finally, a preliminary technological condition was determined as follows:sintering temperature of1100～1150℃, sintering time of10min, preheating temperature of300℃, preheating time of20min, the ratio of raw materials of sludge:clay:fly ash=3:6:1～5:4:1.2. The study comprehensively analyzed correlative technical parameters of the preparation of high-quality sludge ceram site, the main conclusions were as follows: sintering temperature and ratio of raw materials, as the two most significant factors, were investigated to find out the impact of performance of ceramsite, and determined the optimum sintering temperature of1120℃, ratio of raw materials of sludge:clay:fly ash= 3.5:4:2.5. Steel slag content had a significant impact on the performance of ceramsite, when steel slag content was between5%to15%, with the reduction of content, the performance of ceramsite is getting better. According to the view of basic principle and making full use of waste, the optimum content of steel slag was10%.3. The leaching concentration of heavy metals in ceramsite made from sluge and steel slag were lower than lppm, the curing ratio of heavy metals over80%, the curing ratio of total Pb reached99.3%. Most of heavy metals in sludge were fixed in the new mineral phase by isomorphous replacement. In sewage treatment experiments, solidification of ceramsite met the requirements of ecological security and stability heavy metals. The mineral phase of ceramsite was mainly silicates and alumino silicates. Mineral composition of ceramsite was mostly the SiO2saturated mineral. Because of uneven mixing, there were part of SiO2unsaturated minerals in a local area; part of area precipitated quartz due to SiO2supersaturation.4. The ceramsites, made from sluge and steel slag, prepared under the optimum conditions were applied as filter material of BAF to treat sewage. Through the experimental research for sewage treatment, reactor started using inoculation membrane formation. Starting time was9days. In the steady operation stage, using reactor, the removal effect of various pollutants was good. When inflow discharge was1.0L/h, COD in effluent was26.31～31.34mg/L, concentration of NH3-N1.44-1.92mg/L, SS was less than10mg/L; when inflow discharge was1.5L/h, COD in effluent was33.27-41.23mg/L, concentration of NH3-N2.72～3.24mg/L, SS was less than10mg/L; when inflow discharge was2.0L/h, COD in effluent was43.93-49.98mg/L, concentration of NH3-N3.87-5.14mg/L, SS was less than10mg/L; when inflow discharge was2.5L/h, COD in effluent was52.12～57.44mg/L, concentration of NH3-N6.12-8.45mg/L, SS was less than10mg/L. When inflow discharge was3.0L/h, COD in effluent was58.93～62.21mg/L, concentration of NH3-N8.56～10.08mg/L, SS was less than20mg/L. Along with the filter material layer height increased, concentration of COD and NH3-N increased as the removal rate increased gradually; at the same height of the filter layer, along with the hydraulic load increasing more, the higher concentration of COD and NH3-N in effluent, the smaller removal rate. In addition, removal rate and nitrification performance of NH3-N was affected by the concentration of organic matter in the filter layer. Comparison with commercial ceramsite showed that the ceramsite made from sluge and steel slag also had good physical properties and pollutant removal performance. |
PDF Full Text Request