Effects of Dissolved Organic Matter on Corrosion of Cast Iron Pipe for Reclaimed Water

A rotating reactor was used to simulate the working condition of cast iron pipes for reclaimed water. The effects of two kinds of dissolved organic matter (DOM), polysaccharide and protein, on the corrosion of cast iron in reclaimed water were studied by means of corrosion weight loss method, scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). The results indicate that both polysaccharide and protein can inhibit the corrosion of cast iron. The cast iron had the lowest corrosion rate when the concentration of polysaccharide was 2 mg/L or the concentration of protein was 6 mg/L. The corrosion products were mainly composed of stable α-FeOOH under the polysaccharide condition, and SiO₂ formed a dense oxide film which can protect the cast iron under the protein condition.