污泥水热炭中磷及主要伴生金属元素的浸出行为

Leaching Behavior of Phosphorus and Main Associated Metal Elements from Sludge Hydrothermal Carbon

以水热碳化对市政污泥进行预处理,采用硫酸法对制得的污泥水热炭进行磷提取实验,同时考虑钙、铁、铝的释放,探究硫酸浓度、浸出时间、液固比对磷提取效果的影响。结果表明,水热炭中磷的形态以Ca-P、Mg-P为主,该形态有利于磷的提取利用。磷及相关金属的浸出率随硫酸浓度的增大而升高。长时间浸出会导致溶液形成硫酸钙晶体,降低磷和钙的浸出率,铁和铝的浸出率随着浸出时间的增加而升高,但所需浸出时间较长。液固比通过影响水热炭与酸的接触面积来影响磷及相关金属的浸出效果。在硫酸浓度为0.5 mol/L、浸出时间为120 min及液固比为50 mL/g的条件下,水热炭中磷的浸出效果最好,浸出率为93.8%,钙、铁、铝的浸出率分别为70.4%、54.5%、65.8%。

Municipal sludge was pretreated by hydrothermal carbonization method,and phosphorous was extracted from the sludge hydrothermal carbon by sulfuric acid method.Considering the release of calcium,iron and aluminum,the effects of sulfuric acid concentration,leaching time and liquidsolid ratio on the phosphorus extraction performance was investigated.The forms of phosphorus in hydrothermal carbon were mainly Ca-P and Mg-P,which were conducive to the extraction and utilization of phosphorus.The leaching rates of phosphorus and related metals showed an overall increasing trend with the increase of sulfuric acid concentration.Long leaching time led to the formation of calcium sulfate crystals in the solution,and reduced the leaching rates of phosphorus and calcium.The leaching rates of iron and aluminum increased with the increase of leaching time.However,the leaching time was longer.The liquid-solid ratio affected the leaching performance of phosphorus and related metals by influencing the contact area between hydrothermal carbon and acid.When the sulfuric acid concentration was 0.5 mol/L,leaching time was 120 min and liquid-solid ratio was 50 mL/g,the maximum leaching rate of phosphorus from hydrothermal carbon was 93.8%,and the leaching rates of calcium,iron and aluminum was 70.4%,54.5%and 65.8%,respectively.