Patent ID: 8357305

Claim:
A pre-treatment method for ultraviolet light disinfection of water streams having suspended solids in a liquid fraction with ultraviolet light irradiation from a uv light bank with uv light tubes, comprising: a. injecting sulfur dioxide (SO 2 ) into the water streams before undergoing ultraviolet light disinfection at an injection point before the light tubes to form sulfurous acid, sulfites, bisulfites and free SO 2 at an acid concentration level sufficient to chemically dewater and agglomerate suspended solids, acid leach heavy metals from the solids into acidified liquid fractions and reduce bicarbonate levels to reduce alkalinity scaling and iron deposit buildup on the uv light tubes, b. removing and disposing of the suspended solids from the acidified liquid fraction forming a recovered treated water, c. passing the recovered treated water between the light tubes for exposure to ultraviolet light sufficient for disinfection, producing a disinfected recovered treated wastewater, and d. adjusting the pH of the disinfected recovered treated water with a calcium alkaline source to adjust the pH and calcium ion concentration of soils and applying the disinfected recovered treated wastewater to soils to provide soil Sodium Absorption Ratios (SAIL) less than 15, Electrical Conductivity (EC) less than 2 dS m −1 (m mho cm −1 ), Cation Exchange Capacity (CFC) less than 57.5 centimoles/kg, and a pH less than 8; specific soil ratios and concentration levels selected for raising a particular plant and reduce soil bicarbonates/carbonates to increase soil porosity and improve water penetration.