铁电絮凝去除磷酸盐性能及影响因素研究

The removal of phosphate by iron electrocoagulation and its influencing factors

不同水质条件下,铁板作为阳极电絮凝时会产生不同形态的絮体,而絮体种类对磷酸盐去除效果尚不明确.利用铁板作为阳极进行电絮凝,考察溶解氧对电絮凝过程中生成絮体种类的影响,进一步研究电流密度和初始pH值对磷酸盐去除效果的影响.结果表明,低溶解氧(DO)条件下絮体成分主要为磁铁矿,高DO条件下可能为无定型三价铁氧化物/氢氧化物;电流密度越大(2.5、5和10 mA·cm^(-2)),磷酸盐去除效率越高,同时,低DO条件下磷酸盐去除效率高于高DO条件;而初始pH值(4、5、6、7和8)虽不影响不同溶解氧条件下所产絮体的除磷效果,但DO浓度高时,酸性条件下磷酸盐去除效率更高.当前污水处理厂二级出水存在磷浓度较高的问题(TP> 0.5 mg·L^(-1)),采用实际污水在2.5 mA·cm^(-2)电流密度下进行电絮凝,10 min后,初始浓度为1.307 mg·L^(-1)磷酸盐去除效率达98%以上.研究结果将为电絮凝产不同形态铁去除磷酸盐提供理论支持.

Under different water quality conditions,different forms of flocs were generated from iron anode during electrocoagulation.However,the effect of different flocs on the removal of phosphate was still unclear.In this study,the effect of dissolved oxygen(DO)concentrations on the formation of different flocs forms was investigated.The effect of current density and initial pH value on phosphate removal were further studied with iron anode in electrocoagulation process.The results showed that magnetite were mainly formed under low DO condition,while amorphous trivalent iron oxide/hydroxide mainly formed under high DO condition.Higher current density(2.5、5 and 10 mA·cm^(-2))led to higher phosphate removal efficiency.Meanwhile,phosphate removal efficiency under low DO concentration was higher than that under high DO concentration condition.Initial pH(4~8)did not significantly affect the removal efficiency of phosphate by flocs generated under different DO conditions.However,under high DO concentration condition,the removal of phosphate was more efficient with lower pH.At present,the concentrations of phosphate in the secondary effluent from sewage treatment plants are relatively high(TP > 0.5 mg·L^(-1)).In real water,the removal efficiency of phosphate could reach more than 98% at the initial concentration of 1.307 mg·L^(-1) after 10 min treatment under the current density of 2.5 mA·cm^(-2).The results of this study will provide theoretical support for the removal of phosphate by different forms of iron flocs produced by iron electrocoagulation.