污泥厌氧消化液中磷的去除效果与机制研究基于离子交换与改性水滑石吸附法

Study on efficiency and mechanism of phosphorus removal from supernatant of anaerobically digested sludge—based on anion exchange and modified hydrotalcite adsorption methods

  • 摘要: 以磷酸铁污泥厌氧消化液为研究对象,选用强碱性阴离子交换树脂(IRA402-Cl)、弱碱性阴离子交换树脂(DOWEX66)和改性水滑石开展磷酸根去除试验,探索3种材料在富铁富磷溶液中去除磷酸根的效果与机制。试验结果表明:(1)由于DOWEX66树脂具有与磷酸根( \rmH_2\rmPO_4^- )结合力较强的叔胺官能团,相同固液比(3.0 g/L)条件下DOWEX66树脂除磷效率(33.3%)优于IRA402-Cl树脂(14.2%)。(2)固定床动态吸附试验结果显示DOWEX66树脂对磷酸根的吸附穿透点约在5个柱床体积处,表示其在富铁溶液中除磷能力有限且缓冲溶液体系更有利于树脂与磷酸根的离子交换过程。(3)300 ℃煅烧的水滑石在模拟溶液中表现出优良的磷去除能力,在投加量为2.0 g/L时磷去除率达到最高,且具有较好的铁磷分离效果,可作为污泥厌氧消化液中磷元素回收的潜力材料。

     

    Abstract: This study selected supernatant of anaerobically digested ferric phosphate sludge as the research object and investigated the phosphorus (P) removal effectiveness and mechanisms of three types of materials, including strong base anion exchanger (DOWEX66), weak base anion exchanger (IRA402-Cl) and modified hydrotalcite. The experimental results demonstrated that (1) The DOWEX66 showed higher P removal efficiency (33.3%) than IRA402-Cl (14.2%) at the same solid to liquid ratio (3 g/L) because DOWEX66 resin has tertiary amine functional groups with strong binding force to \rmH_2\rmPO_4^- ; (2) The breakthrough profiles of phosphate uptake by raw DOWEX 66 resin in column test indicated that the breakthrough point of phosphate adsorption was located at around 5 bed volumes, which suggested that anion exchange resin has limited P elimination ability and buffer solution system is beneficial to ion exchange between resin and phosphate; (3) The 300 ℃ calcined hydrotalcite showed efficient P removal ability in the iron and phosphorus concentrated solutions and reached the highest removal ratio of 89.0% ratio at solid to liquid ratio of 2 g/L. The 300 ℃ calcined hydrotalcite also showed good performance in separating iron and phosphorus elements, indicating that modified hydrotalcite can be applied as potential material to remove and to recycle phosphorus from sludge anaerobic digestion supernatant.

     

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