Inhibitory effects of phosphate on zero-valent iron (ZVI) dissolution have been studied mainly focusing on a single chemical system. Little is known about inhibitory effects and the mechanism of phosphate on ZVI dissolution within a bioreactor during long-term operation. This study demonstrates the feasibility of achieving energy recovery from phosphate-containing domestic sewage using an efficient anaerobic reactor with micro-sized or nano-sized ZVI addition. The results indicate that the chemical oxygen demand (COD) removal and methane production are enhanced by ZVI addition. A maximum COD removal efficiency of 89% and methane content of 60% was achieved. However, the strengthening effect of ZVI on methane production is weakened by the presence of phosphate in domestic sewage. Analyzing the variations of Fe²⁺ ions and phosphate concentrations and characterizing the micro-morphology of corroded ZVI proved that the generated Fe²⁺ ions reacts with phosphate and forms a passivation layer on the ZVI surface, inhibiting further dissolution of ZVI. As an improved alternative, we chose the double layered core-shell structured ZVI@carbon composite as an excellent candidate to reduce the inhibitory effects of phosphate on ZVI dissolution. In this way, the direct formation of precipitates on the ZVI surface can be avoided due to the protective carbon layer which adjusts the ion transfer. Adding ZVI@carbon composites accelerate the methane content by 16%. To our knowledge, this is the first report on adding ZVI@carbon composites to promote the anaerobic metabolism in studies, which are focusing on reducing the inhibition of ZVI by phosphate.

已经研究了磷酸盐对零价铁（ZVI）溶解的抑制作用，主要集中在单一化学体系上。长期操作期间，关于抑制作用和磷酸盐对生物反应器内ZVI溶解的机理知之甚少。这项研究证明了使用添加了微米级或纳米级ZVI的高效厌氧反应器从含磷酸盐的生活污水中回收能量的可行性。结果表明，通过添加ZVI可以提高化学需氧量（COD）的去除和甲烷的产生。最大的COD去除效率为89％，甲烷含量为60％。但是，由于生活污水中存在磷酸盐，削弱了ZVI对甲烷生产的强化作用。分析Fe ²⁺的变化离子和磷酸盐浓度以及腐蚀的ZVI的微观形貌证明，生成的Fe ²⁺离子与磷酸盐反应并在ZVI表面上形成钝化层，从而抑制ZVI的进一步溶解。作为改进的替代方法，我们选择了双层核-壳结构的ZVI @碳复合材料作为降低磷酸盐对ZVI溶解的抑制作用的优秀候选者。这样，由于调节离子转移的保护性碳层，可以避免在ZVI表面上直接形成沉淀物。添加ZVI @碳复合材料可使甲烷含量提高16％。据我们所知，这是关于添加ZVI @碳复合材料以促进厌氧代谢研究的第一份报告，该研究的重点是减少磷酸盐对ZVI的抑制作用。