史可,徐志嫱,李瑶,曹琛洁.EDTA-2Na添加提高污泥热水解磷的回收效率和鸟粪石纯度[J].环境科学学报,2020,40(2):554-562
EDTA-2Na添加提高污泥热水解磷的回收效率和鸟粪石纯度
- Enhancing phosphorus recovery and struvite purity by EDTA-2Na addition during hydrothermal treatment of sewage sludge
- 基金项目：陕西省教育厅重点项目（No.17JS103）
- 史可
- 西安理工大学, 省部共建西北旱区生态水利国家重点实验室, 西安 710048
- 徐志嫱
- 西安理工大学, 省部共建西北旱区生态水利国家重点实验室, 西安 710048
- 李瑶
- 西安理工大学, 省部共建西北旱区生态水利国家重点实验室, 西安 710048
- 曹琛洁
- 西安理工大学, 省部共建西北旱区生态水利国家重点实验室, 西安 710048
- 摘要：污水处理厂剩余污泥因富含大量的磷而成为一种资源.为了提高磷的回收效率和回收产物（鸟粪石）纯度，本文采用响应曲面法、扫描电子显微镜-能量色散X射线光谱法（SEM-EDS），研究了EDTA-2Na的添加对污泥热水解过程中磷的释放和回收效率的影响.结果表明，最佳磷释放条件为：EDTA-2Na浓度9.2 mmol·L-1、pH=3.9、水解温度T=62℃.在此条件下，污泥中磷的释放率为77.9%，远高于未添加EDTA-2Na的磷释放率（39.7%）；在pH=9，Mg/P=1.2：1的条件下进行磷回收，与未添加EDTA-2Na情况相比，污泥中磷的回收率从30.9%提高到70.2%，鸟粪石纯度从32.5%提高到61.3%，回收的晶体沉淀主要成分为磷酸氨镁.由于EDTA-2Na可与金属离子发生络合，同时引起细胞膜和胞外聚合物的破解，使磷的回收效率和鸟粪石纯度均得到提高.
- Abstract：The excessive sludge has become a resource due to its high phosphorus (P) content in wastewater treatment plant. In order to improve the P recovery efficiency and product (struvite) purity, response surface methodology and scanning electron microscopy-energy dispersive X-ray spectrometry were employed to investigate the impacts of EDTA-2Na addition on P release and recovery during the sludge hydrothermal treatment process. The results show that the optimum conditions of P release were:EDTA-2Na concentration of 9.2 mmol·L-1, pH 3.9 and hydrolysis temperature of 62℃. Under optimum conditions, the P release efficiency was 77.9%, which is much higher than that without EDTA-2Na addition (39.7%). Under the conditions of pH 9 and an Mg/P ratio of 1.2:1, the P recovery rate increased from 30.9% to 70.2% compared to the condition without EDTA-2Na addition, and the purity of struvite increased from 32.5% to 61.3%. The main component of recovered crystalline precipitates was magnesium ammonium phosphate. The results suggest that EDTA-2Na could bind with metal ions and break down the cell membrane and extracellular polymer substance, thus enhances the P recovery efficiency and purity of struvite.
