氧化镁与白云石石灰对不同来源废水中磷的回收效果
Phosphorus Recovery from Wastewaters of Different Sources with Magnesium and Dolomite Lime
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摘要: 选择有代表性的3种来源废水(养猪场废水厌氧消化液、鸡粪废水厌氧消化液和污泥厌氧消化液),利用MgO与白云石石灰作为药剂进行磷回收试验,研究不同药剂、药剂投加量和反应时间下3种来源废水中磷的回收效果,通过动力学方程模拟2种药剂的除磷速率,并采用XRD(X射线衍射)、SEM(扫描电镜)对沉淀产物进行表征. 结果表明:投加2种药剂均可实现磷的有效去除与回收,反应沉淀物中含有MAP(磷酸铵镁)和CaCO3,MgO的最佳投加量为200 mg/L,当反应时间为4 h时,PO43--P去除率达85.0%以上;白云石石灰的最佳投加量为500 mg/L,当反应时间为24 h时,PO43--P去除率达80.0%以上. 投加白云石石灰的反应速率较慢,并且反应沉淀物中含有更多的CaCO3. 以处理1 m3原水为例,MgO药剂成本为0.80元,白云石石灰药剂成本为0.25元,显示白云石石灰经济成本更低,是较为理想的磷回收药剂.Abstract: The removal and recovery of phosphate from three kinds of typical anaerobic digest wastewater-swine wastewater, chicken manure wastewater and sludge wastewater-with MgO and dolomite lime were investigated. Phosphate recovery efficiencies under different precipitant and reaction time were determined. During the treatment process, the kinetic rates of phosphate removals were determined. X-ray diffraction and scanning electron microscopy were used for precipitates characterization. The results showed that the products consisted of magnesium ammonium phosphate and calcium carbonate. Phosphate could be effectively removed with 200 mg/L of magnesium oxide in 4 h, and 500 mg/L of dolomite lime in 24 h. The removal rates were over 85.0% and 80.0%, respectively. The reaction with dolomite lime was slower, and the solid products obtained in the treatment contained more calcium carbonate than that obtained in the MgO treatment. It was estimated that the material cost for treating 1 m3 wastewater was 0.80 and 0.25 Chinese Yuan (RMB) for magnesium and dolomite lime, respectively. The cost of dolomite lime is lower, making it an ideal chemical.
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