废水中有机物对铁盐除磷的影响

通过批次实验探究了不同有机物对铁盐化学除磷的影响.结果显示,有机物对铁盐化学除磷的不利影响由强到弱依次为柠檬酸、黄腐酸、聚山梨酯-80、牛血清蛋白、葡萄糖、淀粉,柠檬酸的影响程度为其他五种有机物的5~20倍.较之含羟基有机物,含羧基有机物对铁盐除磷的不利影响更大.研究表明：铁盐化学除磷的实质是通过形成铁羟基氧化物（HFO）来除磷.含羧基有机物,如柠檬酸,可与磷酸根竞争HFO,有机物"抢占"HFO表面结合位点导致磷酸盐与HFO结合减少,从而使铁盐除磷效果下降.在所试柠檬酸浓度范围内,铁盐除磷率最高下降了90.70%.

Effects of organic substance on ferric ion-dependent phosphorus removal in wastewaters

Batch tests were conducted to study the effects of various organic substances on ferric ion-dependent phosphorus removal, and to reveal their mechanism. The results showed that the influencing strength of chosen organic substances was in the order of citric acid, fulvic acid, polysorbate-80, bovine serum albumin, glucose and starch. The influence of citric acid was 5 times to 20 times higher than that of the other five organic substance. Compared with organic substances containing hydroxyl, organic substances containing carboxyl had more negative effects on the removal of ferric ion-dependent phosphorus. Tests showed that the HFO was the main intermediate product to react with phosphate when ferric iron was used to remove phosphate. Organic substances with carboxyl, such as citric acid, competed with phosphate to bind to the HFO, which resulted in less combination of phosphate to HFO and decrease of phosphate removal. Among all tests, the biggest decrease of phosphorus removal caused by citric acid reached 90.70%.