EDTA对剩余污泥磷释放及MAP法磷回收影响

Effects of EDTA on phosphorus release in excess sludge and phosphorus recovery by MAP

探究乙二胺四乙酸(EDTA)的添加对剩余污泥厌氧过程中磷释放及后续鸟粪石(MAP)法磷回收的影响.根据EDTA添加量对污泥上清液中总磷(TP)、蛋白质、多糖、DNA和SCOD的影响确定了最优释磷条件,采用响应曲面法(RSM)构建MAP磷回收的二次多项式模型并验证了模型的有效性.结果表明:EDTA添加量为5mmol/L,厌氧5d时预处理效果最佳.污泥SCOD破解度(DD)和TP、DNA、蛋白质及多糖均有显著相关,其中TP相关性最强,皮尔逊相关系数为0.866.MAP磷回收的最佳工艺参数是:pH=9.5,n(Mg):n(P)=1.6,搅拌时间22min,此时磷回收率可达95.68%,形成晶体的主要成分为磷酸铵镁(MgNH_4PO_4×6H_2O),纯度为79.19%.

The effects of EDTA on phosphorus release from excess sludge during anaerobic digestion, and on the phosphorus recovery by magnesium ammonium phosphate (MAP) precipitation were investigated. The pretreatment condition was optimized by the variety of total phosphorus (TP), protein, polysaccharide, DNA and SCOD in sludge supernatant under different EDTA concentrations during anaerobic digestion process. Furthermore, the prediction model of MAP phosphorus recovery rate and MAP purity was set up by utilizing the response surface methodology (RSM). The results indicated that the optimum additive dosage of EDTA was 5mmol/L, and optimal anaerobic reaction time was 5d;DD had significant association with TP, DNA, protein and polysaccharide, in which the maximum correlation coefficients 0.866was between DD and TP;The optimal process parameters of MAP phosphorus recovery was: pH=9.5, n(Mg):n(P)=1.6, stirring time =22min, under this circumstance MAP phosphorus recovery rate was 95.68% and purity was 79.19%.