Effect of output power, target temperature, and solid concentration on the solubilization of waste activated sludge using microwave irradiation

In this paper, we quantify the effect of heating pretreatment on the degree of solubilization of waste activated sludge. The pretreatment process was carried out using a lab-scale industrial microwave unit (2450 MHz frequency). Response surface analysis was applied to determine the combination of output power (400–1600 W), target temperature (60–120 °C), and total solid concentration (1–3% total solid (TS)). The power, temperature, and TS concentration significantly affected the solubilization degree of sludge. Within the design boundaries, the conditions predicted to maximize the solubilization degree of 17.9% were determined to be 400 W, 102 °C, and 2.3% TS.