During primary treatment at a wastewater treat-
ment plant, inorganic and organic suspended solids are removed from plant influent by screening, and settling. The decanted effluent from the primary treatment pro- cess is then subjected to secondary treatment, which involves biological decomposition of organic material and settling to further separate water from solids. If a wastewater treatment plant is not equipped to per- form advanced treatment, water is disinfected and dis- charged to natural water bodies following secondary treatment.