钙基添加剂对污水污泥在水热炭化过程中磷形态及生物有效性的影响

在污泥的热处置过程中，添加剂的存在会改变污泥中的磷形态从而对后续磷的回收利用产生重大影响。本文综合利用化学连续提取（SMT方法）、SEM-EDS、XRD和ICP-MS等分析测试方法，系统研究了CaCl₂在水热炭化过程中对污泥中磷形态及其生物有效性的影响。研究结果表明，水热炭化可以使污泥中有机磷（OP）向无机磷（IP）转化，同时促进污泥中非磷灰石无机磷（NAIP）向磷灰石无机磷（AP）的转化，CaCl₂的适量添加可以促进上述转化过程。经过水热炭化处理后，污泥水热炭中IP和AP的浓度分别提升了35.6%和63.4%，当添加质量分数为20%的CaCl₂时，污泥水热炭中IP和AP的浓度同时达到最大值，分别为79.62mg/g和75.61mg/g。此时污泥水热炭中可溶性磷在2%CA溶液中的溶解度也达到最大的57.02mg/g，在此条件下，污泥水热炭中磷的生物有效性也达到最高。

Effect of calcium-based additive on phosphorus form and bioavailability during hydrothermal carbonization of sewage sludge

During the thermal disposal of sludge process, the presence of additives will change the form of phosphorus, which has a significant impact on the subsequent recovery and utilization of phosphorus. This paper applied SMT method, SEM-EDS, XRD, and ICP-MS to analyze the influence of CaCl₂ on the phosphorus form and bioavailability in sewage sludge during hydrothermal carbonization. The results showed that hydrothermal carbonization could simultaneously promote the conversion of organic phosphorus (OP) to inorganic phosphorus (IP) and non-apatite inorganic phosphorus (NAIP) to apatite inorganic phosphorus (AP) The propriate addition of CaCl₂ could promote the above conversion process. The concentrations of IP and AP in the hydrochar increased by 35.6% and 63.4%, respectively. When the mass fraction of CaCl₂ was 20%, the concentrations of IP and AP in the hydrochar reached the maximum levels, 79.62mg/g and 75.61mg/g, respectively. Meanwhile, the P-solubility of hydrochar in 2% CA solution also reached a maximum level of 57.02mg/g, and the bioavailability of the phosphorus in hydrochar also reached its maximum level under this condition.