都市廃棄物のザッピングが貴重なリン肥料の回収に役立つ(Zapping municipal waste helps recover valuable phosphorus fertilizer)

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2023-06-28 ワシントン大学セントルイス校

◆リンは人類にとって貴重な肥料ですが、現在の方法では廃水処理施設の汚泥からの回収が困難です。ワシントン大学の研究チームは、電気化学デバイスを使用して固体廃棄物からリンを回収する方法を開発しました。
◆この方法は、化学物質を追加せずにリンを分離・回収することができます。実験では驚くほど効率的にリンを回収できることが示されました。
◆この技術は持続可能なリンの再利用に向けた重要な進歩であり、農業や工業などで広範な応用が期待されています。将来的には実用化に向けた工学的な課題が残されていますが、エネルギー消費量の削減などの改善が進められる見通しです。

<関連情報>

電気化学的浸出と沈殿による消化液全体からのリン回収 Phosphorus Recovery from Whole Digestate through Electrochemical Leaching and Precipitation

Zixuan Wang, Daran Anand, and Zhen He
Environmental Science  Published:June 26, 2023
DOI:https://doi.org/10.1021/acs.est.3c02843

都市廃棄物のザッピングが貴重なリン肥料の回収に役立つ(Zapping municipal waste helps recover valuable phosphorus fertilizer)

Abstract

Phosphorus (P) recovery from biosolids can play an important role in a circular economy. Herein, an electrochemical phosphorus recovery cell (EPRC) was proposed and examined to recover P from municipal whole digestate via simultaneous leaching and precipitation. The anode of the EPRC released P as aqueous PO43––P through acidification, achieving the highest leaching efficiency of 93.3% under a current density of 30 A m–2. When the leached P solution was treated in the cathode, native metals including Ca and Fe facilitated electrochemically mediated PO43––P precipitation (EMP) and precipitated ∼99% of the leached P in the cathode chamber. Around 54.3–78.7% of total P existed in two harvestable forms: suspended solids in the cathode effluent and immobilized P in the cathode chamber. The solid products contained 28.42–33.51% of P2O5, comparable to the high-grade phosphate rock. Higher current densities reduced cathode scaling and resulted in a lower content of heavy metals in the solid products. An acidic solution was reused three times and effectively maintained cathode performance during a 42-cycle operation, achieving a consistent P recovery efficiency of nearly 80%. Those results have demonstrated the feasibility of the EPRC for recovering P from P-rich solid wastes.

廃水汚泥からの電気化学的リン放出と回収: レビュー Electrochemical phosphorus release and recovery from wastewater sludge: A review

Zixuan Wang,Fubin Liu & Zhen He
Critical Reviews in Environmental Science and Technology  Published:06 Feb 2023
DOI:https://doi.org/10.1080/10643389.2023.2172928

Graphical abstract

Abstract

Phosphorus (P) is abundant in wastewater sludge and can be a secondary P source that will contribute to a circular economy. Electrochemical systems are an emerging technology that can be used to release and recover P from wastewater sludge. This paper introduces and analyzes the state-of-the-art electrochemical methods for P release and recovery from wastewater sludge, both qualitatively and quantitatively. Electrochemical P release, which involves mobilizing P from the solid phase into the aqueous phase, is categorized into three major mechanisms, electro-biological release, anodic P release, and cathodic P release. Anodic P release has been most widely studied with a median P release rate of 92.4 mg d−1. Correlation analysis revealed that the type of feed sludge, sludge P contents, sludge loading rate, and current density have a significant impact on the P release performance. The released P is subsequently separated from the heavy metal laden sludge and then recovered via different electrochemical systems such as three-chamber cells, two-chamber cells, and their variations. Those systems can achieve P recovery efficiency of 50 ∼ 80% and a recovery rate of 2.0 × 102∼1.8 × 103 mg P d−1. Energy consumption of electrochemical P recovery is estimated at 50 ∼ 200 kWh kg−1 P but only 27.3% of literature reported such data. This work provides insights into the development and challenges of electrochemical P release & recovery from wastewater sludge and discusses the challenges that need to be addressed to advance the viability of electrochemical P recovery approach.

0505化学装置及び設備
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