Migration and Conversion of Phosphorus in Hydrothermal Carbonization of Municipal Sludge with Hydrochloric Acid

Phosphate ore is a non-renewable resource, so finding replacement necessary. Municipal sludge has significant recycling potential because of its high phosphorus content and large discharge characteristics. The migration transformation in municipal treated with different concentrations HCl were studied using the standards, measurements, testing extraction protocol from two aspects: complexation mineral form. After hydrothermal carbonization treatment without HCl, hydrochar retained 99.7% sludge, organophosphorus percentage was about 30%. In addition 0.5–2.5% decreased gradually 99.5% (46.18 mg/g) to 91.8% (64.17 that original proportion non-apatite inorganic increased 34% 94%. Hydrochloric acid provides low-pH environment promotes dissolution calcium-related precipitates enhances dehydration reaction. This study technical support for recovery resources sludge.