To date, several methods have been

To date, several methods have been attempted to release the phosphorus in the sludge to promote its recovery. Wet chemical approaches, such as electrochemistry,(6) oxidation,(7) acid–base dissolution,(8) microwave irradiation,(9) and ultrasonication,(10) could release the phosphorus from the microbial cells and EPS in the sludge to the liquid phase, and subsequently separate the phosphorus from metals and metalloids. Unluckily, the recovered phosphorus species could be contaminated by emerging organics under electrodialytic conditions.(11) However, some researchers have paid attention to the thermochemical treatment including incineration and pyrolysis,(12,13) with satisfactory results having been reported.(14) Taking incineration as an example, although most of the phosphorus was retained in the resultant ash, simultaneous enrichment of heavy metals challenged the recovered phosphorus due to the environmental risk.(15)