Compared effects of “solid-based” hydrogen peroxide pretreatment on disintegration and properties of waste activated sludge

The effects of two solid-based hydrogen peroxides sodium percarbonate (SPC) and calcium peroxide (CP) on waste activated sludge (WAS) disintegration were investigated. Both oxidants achieved efficient WAS disintegration for the synergistic effect of alkaline and oxidation. The strong alkaline condition led to the leakage of ammonia and the existence of abundant calcium ions accelerated the fixation of phosphorus via precipitation in CP WAS disintegration process. However, the spongy-like layer and low pH condition retarded the release of gaseous ammonia in SPC group. Hydroxyl radical was the main oxygen reactive species in SPC approaches which were more intense than CP by electron spin resonance (ESR) analysis. CP treated WAS contented more small particle size matter and total suspended solids (TSS) increased dramatically. In conclusion, CP pretreated sludge was more suitable for fertilization, while SPC was in favor of anaerobic digestion. This study clarified the differences between these two oxidants and their intermediates on nutrients release in sludge disintegration.