从磷赋存形态的新视角出发，通过酸性阳离子交换树脂实现废活性污泥中磷的靶向清洁提取：一种创新方法。
Targeted clean extraction of phosphorus from waste activated sludge: From a new perspective of phosphorus occurrence states to an innovative approach through acidic cation exchange resin.
机构信息
State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China.
State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China.
出版信息
Water Res. 2022 May 15;215:118190. doi: 10.1016/j.watres.2022.118190. Epub 2022 Feb 13.
Waste activated sludge (WAS) is an important source of non-renewable phosphorus (P) recovery. Given the factor that the occurrence states of phosphorus in WAS determines its recovery efficiency, the spatial distribution and chemical speciation of phosphorus were comprehensively and simultaneously analyzed by in-situ and step-by-step extraction methods for the first time. It was confirmed that the phosphorus in solid phase of WAS could be mainly divided into three parts: polyphosphate in cells, extracellular polymeric substances (EPS)-bound P, and phosphate precipitated with metals (P-precipitates) in extracellular inorganic minerals. Among these forms, EPS-bound P (mainly orthophosphate, Ortho-P) and P-precipitates (mainly Ca-P, Fe-P, Al-P, and Mg-P) were the major forms of phosphorus in WAS, accounting for 65%-82% of total phosphorus (TP). Owing to the acid solubility of P-precipitates, acid extraction could be a potentially effective means for phosphorus recovery. However, the co-solution of metals may hinder the phosphorus recovery and the EPS-bound P cannot be recovered by acid extraction. To enhance phosphorus release from EPS and reduce metal interference, a targeted clean extraction technology using acidic cation exchange resin (ACER) was also developed. The results showed that a low dosage ACER could effectively extract EPS-bound P and P-precipitates, and the content of phosphorus in the extract exceeded 50% of TP. Compared with acid extraction, the release efficiency of TP increased by 13%-23%, and the dissolved metal content decreased by more than 90% in the extract by ACER. This was attributed to the acidification and metal capture by ACER. Finally, more than 90% of Ortho-P in the extract was recovered as calcium phosphate, which alleviated the depletion of phosphorus resources.
剩余活性污泥（WAS）是一种重要的不可再生磷（P）回收资源。鉴于 WAS 中磷的赋存形态决定了其回收效率，本研究首次采用原位和分步提取方法，全面、同步分析了磷的空间分布和化学形态。结果表明，WAS 固相中的磷可主要分为三部分：细胞内多磷酸盐、细胞外聚合物物质（EPS）结合磷和细胞外无机矿物质中与金属结合的磷（P 沉淀物）。其中，EPS 结合磷（主要为正磷酸盐，Ortho-P）和 P 沉淀物（主要为 Ca-P、Fe-P、Al-P 和 Mg-P）是 WAS 中磷的主要存在形态，占总磷（TP）的 65%-82%。由于 P 沉淀物具有酸溶性，酸提取可能是一种潜在有效的磷回收方法。但是，金属的共溶可能会阻碍磷的回收，并且 EPS 结合磷不能通过酸提取回收。为了增强 EPS 中磷的释放并减少金属干扰，还开发了一种使用酸性阳离子交换树脂（ACER）的靶向清洁提取技术。结果表明，低剂量的 ACER 可以有效地提取 EPS 结合磷和 P 沉淀物，提取液中磷的含量超过 TP 的 50%。与酸提取相比，ACER 可将 TP 的释放效率提高 13%-23%，并且提取液中溶解金属的含量降低了 90%以上。这归因于 ACER 的酸化和金属捕获作用。最后，提取液中超过 90%的 Ortho-P 被回收为磷酸钙，从而缓解了磷资源的枯竭。
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