Cast iron valves can be used in sewage treatment In the sewage treatment process, various valves are needed to control the flow and closure of liquids. Cast iron valves are ideal for this area due to their high corrosion resistance and long life. For example, in a sedimentation tank, cast iron gate valves can be used to control the inflow and outflow of water. In filtration systems, cast iron valves can be used to control liquid flow at different stages to achieve efficient sewage treatment.