Absorbing oxygen carrier induces phosphorus enrichment in sludge: Preparation and screening

Abstract

Phosphorus recovery from sludge is considered a feasible approach. By combining the oxygen carrier gasification technology and microwave heating, an absorbing oxygen carrier (AOC) is used in this study to successfully induce phosphorus enrichment in sludge char. The AOC, which is based on iron and supported on SiC, has been prepared via ultrasonic impregnation. The effects of preparation conditions (particle size of SiC and loading of iron) on the phosphorus enrichment characteristics, thermal reaction performance of the AOC and sludge, and the wave absorption performance of the AOC were investigated. The results show that the AOC prepared using a SiC particle size of 36 mesh and iron loading of 10% can achieve a phosphorus enrichment of 91.30% in the sludge char when the temperature of the microwave reactor is 600 °C. In the thermal reaction test, AOC can effectively increase the rate and depth of sludge gasification reaction in the medium- and high-temperature reaction stages. Iron-based is loading on the SiC surface and has a good wave absorption performance (RL = -16.28 dB; effective absorption width is 3.54 GHz). Overall, this study provides a new and effective approach for utilizing sludge.