• 关键词：水平潜流人工湿地  亚铁离子  含铁基质

• 基金项目：国家自然科学基金(No. 50908090)

• 平安
• 华南农业大学资源环境学院, 广东高校污水生态处理与水体修复工程技术研究中心, 广州 510642

• 种云霄
• 华南农业大学资源环境学院, 广东高校污水生态处理与水体修复工程技术研究中心, 广州 510642

• 余光伟
• 华南农业大学资源环境学院, 广东高校污水生态处理与水体修复工程技术研究中心, 广州 510642

• 梁羽乔
• 华南农业大学资源环境学院, 广东高校污水生态处理与水体修复工程技术研究中心, 广州 510642

• 李俊
• 华南农业大学资源环境学院, 广东高校污水生态处理与水体修复工程技术研究中心, 广州 510642

• 摘要：使用富含铁基质的水平潜流人工湿地,运行过程中,由于内部氧化还原和pH条件的变化,可能会导致基质中铁溶出,致使间隙水中亚铁离子增加,进而影响污水去除效率.本研究以使用富含铁基质的香蒲人工湿地系统为研究对象,分析了其处理富含有机物污水时,内部间隙水的亚铁离子、氧化还原电位(ORP)和pH时空变化特点.研究结果表明,各位点间隙水都含有较高浓度亚铁离子,范围为8.23~462.86 mg · L^-1,远远高于进水中亚铁含量,表明运行过程中,基质铁大量溶出;内部各位点ORP在-236~40 mV之间,变化范围较大,多数位点ORP均为负值,表明整个湿地内部大部分区域处于厌氧状态,是污水中较高浓度有机物降解导致;ORP在水深方向逐渐下降,污水沿程方向是逐渐升高的,夏季ORP整体较高,春秋季较低.亚铁离子变化特点与ORP相反,ORP高的情况下,亚铁离子浓度较低,表明亚铁离子浓度受ORP影响.湿地内部各位点处的pH空间变化范围不大,在6.44~7.97之间,仍维持在中性范围.结合pH和ORP的分布特征可以得知,间隙水中亚铁离子应是基质中铁氧化物特别是三价铁氧物,络合和还原解离共同的产物.

• Abstract：ORP and pH values were unstable in subsurface flow constructed wetland (SFCW) system containing iron-rich substrate when wastewater was treated continuously. The decrease of ORP and pH could result in the extraction and release of oxidative iron from substrate to interstitial water, in which oxidative iron would be transformed into Fe²⁺ and affected the removal efficiency of pollutants in wastewater. In this study, dynamic variation of ORP, pH and Fe²⁺ in interstitial water at different locations of the SFCW system with iron-rich substrate and plant Typha latifolia were monitored within one year. The pH value ranged from 6.44 to 7.97 among different locations, with a decrease along with the flow direction of wastewater and increase from top to bottom in the SFCW system. Inversely, the ORP value unstably ranged from -236 mV to 40 mV among different locations, and gradually increased along with the flow direction and decreased from top to bottom. Furthermore, the ORP value was the highest in summer at all locations. The ORP values at most locations of the system were negative, indicating that the large parts of the system was anaerobic. It was also found that concentration of Fe²⁺ in interstitial water with a range of 8.23~462.86 mg · L^-1 among different locations was much higher than that in the inlet, suggesting that the Fe²⁺ would be produced from the system. According to the changes of ORP and pH values in the system, it could be implied that the Fe²⁺ accumulation might result from complexation and reduction of the oxidative iron, especially Fe(Ⅲ).

• Key words：subsurface flow constructed wetland  Fe²⁺  substrate containing rich iron

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