This work evaluates the potential of hydrothermal carbonization (HTC) to valorize the digestate derived from the anaerobic digestion of sewage sludge into useful materials for P and energy recovery. The hydrothermal treatment of digestate at 180–240 °C did not lead to high-rank hydrochars. On the other hand, inorganic P concentration did not change with the temperature, while as the carbonization temperature increased, the organic P retention yield in hydrochar became lower, increasing the total P in the process water obtained at the highest temperature, up to 25.3%. P recovery from acid leaching of the hydrochar obtained at 180 °C, via precipitation with CaO at pH up to 9, led to a brown solid precipitate with total P content close to 42 mg g⁻¹, in the range of low grade phosphorus ores. Moreover, acid leaching reduced by 50% the ash content, yielding lignite-like upgraded hydrochars with higher heating values in the range of 20.5–23.1 MJ kg⁻¹, fairly interesting as solid fuels. Anaerobic digestion of the process water enabled additional energy recovery in form of biogas (325 and 279 mL CH₄ g⁻¹ VS -at standard temperature and pressure; STP- from the process water resulting at 180 and 210 °C, respectively).

这项工作评估了水热碳化（HTC）的潜力，该潜力将污水污泥的厌氧消化所产生的消化物转化为有用的P和能量回收材料。在180–240°C的温度下对消化液进行水热处理不会导致高级炭化。另一方面，无机P的浓度没有随温度变化，而随着碳化温度的升高，有机碳在水焦中的保留率降低，使最高温度下获得的工艺水中的总P升高至25.3％。 。通过在pH高达9的CaO中进行沉淀，从180°C的酸洗过程中酸浸回收的P产生棕色固体沉淀，总P含量接近42 mg g ^-1，属于低品位磷矿。此外，酸浸减少了50％的灰分，产生了褐煤状的高级水煤，具有更高的热值，范围为20.5-23.1 MJ kg ^-1，作为固体燃料非常有趣。工艺水的厌氧消化能够以沼气的形式（在标准温度和压力下分别回收325和279 mL CH ₄ g ^-1 VS ^- STP-分别从180和210°C的工艺水中回收能量）。