Preparation of poly ferric sulfate and the application in micro-polluted raw water treatment

Abstract

Poly ferric sulfate (PFS) is a kind of polymeric coagulants widely used in China in the past 20 years and reveals certain advantages in advanced treatment of wastewater. In this paper, three samples were synthesized by different methods: sodium nitrite catalytic oxidation method (PFS-1), one-step method (PFS-2) and nitric acid oxidation method (PFS-3). The raw material for PFS-3 was the by-product of (NH4)2SO4 manufacturing, which makes this method conducive to the full utilization of resources. The products were characterized by scanning electron microscopy and Fourier transformed infrared spectroscopy. Their coagulation performances in micro-polluted raw water treatment have been evaluated by jar tests. When the coagulation dosage was 0.1 mmol L−1 as Fe, the turbidity removal rate was around 84% and the removal rate of natural organic matter (NOM) was 35%–40%. The water treated by PFS was much closer to neutral but fluctuated from 7.9 to 7.2 at dosages of 0.05–0.3 mmol L−1 as Fe, which showed similar pe...