Zhai Yunbo, Xiang Bobin, Chen Hongmei, Xu Bibo, Zhu Lu, Li Caiting, Zeng Guangming
College of Environmental Science and Engineering, Hunan University, Changsha 410082, China and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China E-mail:
Water Sci Technol. 2014;70(6):1108-14. doi: 10.2166/wst.2014.344.
In this paper, the fraction transformation and recovering of phosphorus (P) from sewage sludge (SS) residues, derived from supercritical water process, was investigated by extraction and precipitation processes. In addition, the form of heavy metals existing during the recovery process is also discussed. First, P in the solid residues was recovered by acid leaching with HCl, and then the derived P was adsorbed by activated alumina (Al(2)O(3)). Finally, the Al2O3 was desorbed with low concentration of NaOH. Results showed that 80% organic P was converted into HCl-P. The total P (the chief ingredient of HCl-P) in solid residue increased from 86.1 to 95.6% as temperature increased from 350 to 400 °C. The amount of P in the solid residue that was dissolved by 1 M HCl was 97.8%, and over 95% of P in the leaching solution (15 mg/L for P concentration) was adsorbed after 5.0 g of Al(2)O(3) powder was added. The amount of P desorbed from Al(2)O(3) with 0.1 M NaOH was 98.7%. Ultimately, over 85% of TP in SS was recovered. Moreover, the proportion of Cu, Zn and Pb in the extracted P products was lower than 5%.
本文通过萃取和沉淀工艺，研究了超临界水工艺产生的污泥残渣中磷（P）的分馏转化及回收情况。此外，还讨论了回收过程中重金属的存在形态。首先，用盐酸对固体残渣中的磷进行酸浸回收，然后用活性氧化铝（Al₂O₃）吸附所得的磷。最后，用低浓度氢氧化钠对Al₂O₃进行解吸。结果表明，80%的有机磷转化为盐酸磷。随着温度从350℃升高到400℃，固体残渣中的总磷（盐酸磷的主要成分）从86.1%增加到95.6%。1M盐酸溶解的固体残渣中磷的量为97.8%，加入5.0g Al₂O₃粉末后，浸出液中95%以上的磷（磷浓度为15mg/L）被吸附。用0.1M氢氧化钠从Al₂O₃上解吸的磷量为98.7%。最终，污泥中超过85%的总磷被回收。此外，提取的含磷产物中铜、锌和铅的比例低于5%。
