Preparation, sintering behavior, and expansion performance of ceramsite filter media from dewatered sewage sludge, coal fly ash, and river sediment

The main aim of this study is to assess the preparation, sintering behavior, and expansion performance of ceramsite filter media (CFM) from dewatered sewage sludge, coal fly ash, and river sediment without using any natural resources. The results showed that the investigated physical properties of lab made CFM met with the China's industrial standard of CJ/T 299-2008 and the concentration of heavy metals in the lixivium was lower than the threshold of GB 5085.3-2007. During the sintering process, the relationships between ignition loss rate, expansion rate, and sintering temperature could be well described simultaneously by the 3-order polynomial fitting curve, with high correlation coefficient values (R-2 > 0.999). The fitting curves of the ignition loss rate and expansion rate had one peak and one valley, respectively, and their cut-off point that is the sintering temperatures were the same (700 degrees C). The whole sintering process could be divided into two stages. The ignition loss rate was gradually increased in both the stages. At the same time, the expansion rate was decreased in the first stage and then increased in the second stage. The significance of this work is to pursue the concept of sustainable development.