氯化铁混凝剂中亚铁含量对混凝效果的影响

以城市污水处理厂原水为实验水样,研究了液体FeCl3混凝剂中亚铁含量对其混凝效果的影响。结果表明,液体FeCl3混凝剂中亚铁的含量与其对污水中总磷和COD的去除效果呈非线性相关性,当FeCl3中亚铁含量为25%时,16.0 mg/L的投加量即可使上清液COD降至195 mg/L,去除率达56.7%,总磷降至1.7 mg/L,去除率达70.7%;当FeCl3中亚铁含量继续降低至0.4%时,COD、总磷的去除率仅提高1.1%和1.3%。因此从性价比来讲,FeCl3混凝剂用于污水厂原水混凝时,可适当放宽产品质量标准中亚铁含量限值的规定,有利于降低氯化铁混凝剂的生产成本。

Effect of ferrous iron content in ferric chloride on coagulation efficiency

Based on the raw sewage of municipal wastewater treatment plant, the effect of ferrous iron content in ferric chloride on the coagulation efficiency was studied. The results showed that it is not a linear correlation between the ferrous iron content in liquid ferric chloride coagulation and the removal efficiency of the total phosphorus and COD. When the iron content in FeCl₃ was 25%,the dosage of 16.0 mg/L can make the COD and total phosphorus decrease to 195 mg/L and 1.7 mg/L, respectively, at the same time, the removal rates were up to 56.7% and 70.7%. As the ferrous iron content reduced to 0.4%,the COD and total phosphorus removal rates only increased by 1.1% and 1.3%, respectively. Considering cost performance, it is propitious to relax the limit value of ferrous iron content in the products quality standard when choosing FeCl₃ as coagulant, thus the production costs can be reduced.