Disintegration of waste activated sludge by a combined treatment of alkaline-modified eggshell and ultrasonic radiation

In order to improve disintegration performance of waste activated sludge, alkaline-modified eggshell and ultrasonic radiation were introduced. Eggshell was subjected to modification treatment to produce calcium oxide (CaO). The calcium oxide was characterized by X-ray diffraction (XRD) and thermogravimetric analysis (TGA). XRD patterns showed CaO intense peaks. TGA profile indicated the components of eggshell were constant at above 850 °C. The alone and combined treatment effects of alkaline-modified eggshell and ultrasonic radiation on the disintegration of waste activated sludge were studied. The combination of alkaline-modified eggshell and ultrasonic radiation treatment processes could enhanced the disintegration of waste activated sludge. Optimum conditions were pH of 12, ultrasonic power of 330 W, and disintegration time of 15 min for the combined treatment process. The disintegration efficiency of waste activated sludge reached 45% under the optimized condition. The combined process of alkaline-modified eggshell and ultrasonic radiation was effective and feasible to disintegrate waste activated sludge.