Electrochemical Phosphorus Recovery from Anaerobically Digested Sludge: Improving Product Purity and Concentration

IF 7.4 Q1 ENGINEERING, ENVIRONMENTAL

ACS ES&T engineering Pub Date : 2024-06-28 DOI:10.1021/acsestengg.4c00172

Zixuan Wang, Emma Thompson Brewster, Siyang Xing, Zhen He

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Abstract

Recovering high-concentration and high-quality phosphorus (P) from municipal sludge presents significant technical challenges. Herein, an electrochemical phosphorus recovery system (EPRS) was developed to treat the anaerobically digested sludge (ADS), featuring a leaching unit for P leaching and a recovery unit for P separation. The leaching unit consistently reduced the ADS pH from 7.5 to 3.3 and elevated the dissolved ortho-P concentration from 65.7 ± 19.7 to an average of 215.2 ± 44.6 mg L^–1. The recovery unit achieved a P recovery efficiency of 74.8 ± 7.5% until reaching a maximum ortho-P concentration of ∼4040 mg L^–1 after 33 cycles. This maximum concentration could potentially be increased by adjusting the anolyte pH to 3–4 as predicted by a mechanistic model. Mass distribution analysis revealed that 54% of total P input was in the final anolyte of the recovery unit, which contained less than 1% of Mn, Al, Zn, Cu, Pb, Cd, and Ni that were in the ADS. However, 10% of total As was detected in the recovery unit anolyte, likely because of chemical speciation. The solid product from the EPRS consisted of struvite and magnesium phosphate. Although the leaching unit was the main energy and chemical consumer, it significantly reduced the total coliform levels that satisfied the USEPA Class A pathogen standards.

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从厌氧消化污泥中电化学回收磷：提高产品纯度和浓度

从市政污泥中回收高浓度和高质量的磷（P）是一项重大的技术挑战。为此，我们开发了一种电化学磷回收系统（EPRS）来处理厌氧消化污泥（ADS），该系统包括一个用于浸出磷的浸出单元和一个用于分离磷的回收单元。浸出单元将厌氧消化污泥的 pH 值从 7.5 持续降至 3.3，并将溶解的正磷浓度从 65.7 ± 19.7 升至平均 215.2 ± 44.6 mg L-1。回收装置的磷回收效率为 74.8 ± 7.5%，33 个循环后达到最大正-磷浓度 ∼4040 mg L-1。根据机理模型的预测，将溶解液的 pH 值调至 3-4 有可能提高这一最大浓度。质量分布分析表明，总磷输入量的 54% 在回收装置的最终溶解液中，其中所含锰、铝、锌、铜、铅、镉和镍不到 ADS 中的 1%。不过，回收装置的前溶液中检测到了 10%的总砷，这可能是由于化学式的原因。来自 EPRS 的固体产品由硬石膏和磷酸镁组成。虽然浸出装置是主要的能源和化学品消耗者，但它大大降低了总大肠菌群的含量，达到了美国环保局的 A 级病原体标准。

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来源期刊

ACS ES&T engineering ENGINEERING, ENVIRONMENTAL-

CiteScore

8.50

自引率

0.00%

发文量

期刊介绍： ACS ES&T Engineering publishes impactful research and review articles across all realms of environmental technology and engineering, employing a rigorous peer-review process. As a specialized journal, it aims to provide an international platform for research and innovation, inviting contributions on materials technologies, processes, data analytics, and engineering systems that can effectively manage, protect, and remediate air, water, and soil quality, as well as treat wastes and recover resources. The journal encourages research that supports informed decision-making within complex engineered systems and is grounded in mechanistic science and analytics, describing intricate environmental engineering systems. It considers papers presenting novel advancements, spanning from laboratory discovery to field-based application. However, case or demonstration studies lacking significant scientific advancements and technological innovations are not within its scope. Contributions containing experimental and/or theoretical methods, rooted in engineering principles and integrated with knowledge from other disciplines, are welcomed.