诱导结晶法回收磷的试验研究

Study on Phosphorus Recovery by Induced Crystallization

以天然方解石为晶种通过诱导结晶法处理模拟含磷废水,考察了水力停留时间(HRT)、钙磷比(Ca/P)和PO34-浓度对诱导结晶除磷的影响。结果表明:HRT对诱导结晶除磷的影响最大,Ca/P值次之,PO34-浓度最小;对PO43-的平均去除率随HRT、Ca/P值和PO34-浓度的增大均有所提高;诱导结晶除磷的最佳HRT为10 min,HRT越长则出水PO43-浓度越低,但试验后期对磷的去除率增幅越来越小;最佳Ca/P值为3,适当增大Ca/P值有利于除磷,但投加的钙盐越多则越易形成均相沉淀,对磷的回收难度就越大;PO34-浓度越高则除磷越易实现,此时宜适当减小Ca/P值(投药量),反之则应适当增大Ca/P值(投药量)。

Simulated phosphorus-containing wastewater was treated by induced crystallization with natural calcite as the crystal seed, and the influence of HRT, Ca/P and concentration of PO4^3-on phosphorus removal by induced crystallization was investigated. The experiments show that the influence of HRT on phosphorus removal by induced crystallization is the greatest, Ca/P is the second, PO3- is the smallest. The average removal rate of PO4^3- is improved with HRT, Ca/P, and concentration of PO3- increased. The optimal HRT is 10 rain, and PO4^3- concentration of the effluent is decreased with the prolonging of HRT, but the removal rate increase gets smaller and smaller. The optimal Ca/P is 3, and the proper increasing of Ca/P is favorable for phosphorus removal, but homogenous precipitation will form as too much of CaCl2 is added, and the difficulty of phosphorus recovery is increased. Phosphorus removal is achieved more easily with high PO4^3- concentration, and Ca/P should be decreased, or Ca/P should be increased with lower phosphate concentration.