Xie, J.; Wang, Y.; Peng, Z.; Du, H., and Zhu, T., 2015. Research on influence of ferroporphyrin content on ferric chloride coagulation effect.

This paper tests the raw water sample from the Qingdao sewage treatment plant and studies influence of the ferroporphyrin content in FeCl₃ coagulant on coagulation effect. The results indicate that the ferroporphyrin content in FeCl₃ coagulant is non-linearly correlated with removal effect of total phosphorus and COD_Cr in sewage. When the ferroporphyrin content is 25% in FeCl₃, 16.0 mg/L addition volume can reduce the COD_Cr content in the supernatant to 195mg/L, the removal rate reaches 56.7%, total phosphorus content reduces to 1.7mg/L, and the removal rate reaches 70.7%. When the ferroporphyrin content in FeCl₃ will continue reduction till 0.4%, the removal rate of COD_Cr and total phosphorus are only improved by 1.1% and 1.3%. From the view of the price/performance ratio, when the FeCl₃ coagulant is used as the raw water coagulation in the sewage, the ferroporphyrin content limit regulated in the product quality standard can be properly relaxed to reduce the production cost of the ferric chloride coagulant.