In wastewater treatment plants (WWTPs), it remains a challenge to remobilize and recover phosphorus from the insoluble FeP complex which is produced via iron-enhanced primary precipitation (IEPP). This study demonstrated that an electricity-enhanced biological reducing (EEBR) process can efficiently reduce Fe(III) into Fe(II) and release phosphorus from the FeP complex in the post-IEPP sludge. With a fixed potential of 0.35 V, the electroactive biofilm was enriched in the EEBR system and participated in the electron transfer chain for Fe(III) reduction. In the EEBR system, the highest phosphorus release efficiency was 61.6% with a final dissolved total phosphorus of 89.4 mg/L, which was ∼10 times that in a traditional biological system. Kinetic analysis was also conducted in this study, and the Fe(III) reduction in the EEBR system was estimated as a 2/3-order reaction. The overall mechanism was hypothesized to be that the electrons from the electrode were quickly transferred into the FeP complex by the biofilm, which finally reduced Fe(III) and released phosphorus ions. The proposed EEBR process was proved to be efficient, energy-wise, and sustainable, representing promising feasibility for phosphorus recovery from the IEPP sludge in the WWTPs.

中文翻译：

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电增强FeP络合物的生物还原性Fe（III）还原和磷回收：概念验证和动力学分析

在废水处理厂（WWTP）中，从不溶性FeP络合物中迁移和回收磷仍然是一项挑战，该不溶性FeP络合物是通过铁强化的初次沉淀（IEPP）产生的。这项研究表明，电增强生物还原（EEBR）工艺可以有效地将Fe（III）还原为Fe（II），并在IEPP后的污泥中从FeP配合物中释放磷。在0.35 V的固定电势下，电活性生物膜在EEBR系统中富集，并参与了用于还原Fe（III）的电子转移链。在EEBR系统中，最高的磷释放效率为61.6％，最终溶解的总磷为89.4 mg / L，约为传统生物系统的10倍。在这项研究中还进行了动力学分析，估计EEBR系统中的Fe（III）还原为2/3级反应。据推测，其总体机理是来自电极的电子被生物膜迅速转移到FeP络合物中，最终还原了Fe（III）并释放了磷离子。实践证明，拟议的EEBR工艺是高效，节能和可持续的，代表了从污水处理厂的IEPP污泥中回收磷的有希望的可行性。