Direct-utilization of sewage sludge to prepare split tiles

As a type of solid waste with large quantities of pollutants, municipal sewage sludge (MSS) itself and its reclamation are becoming a growing concern of governments. In this paper, the direct-utilization of MSS to prepare split tiles is proposed and tested. Without any pretreatments such as thermokinetic drying, the crude MSS from domestic wastewater treatment plant is directly incorporated into the batch mixtures, and then wet ball-milled, filter-pressed, pug-milled, extrusion-formed, dried and fired to obtain split tiles. A series of formulation experiments and physical and chemical characterizations were carried out; the results show that the feasible maximum content of the crude MSS is as high as 60 wt%, and corresponding bending strength and water absorption of split tile samples fired at 1210 °C are 25.5 MPa and 1.14 wt% respectively. TCLP test reveals that the samples are environmentally compatible. The prospective industrial application of MSS to produce split tile will help to significantly reduce its environmental impacts.