Wastewater is treated through a series of mechanical and biological processes to assist nature with the removal of pollutants introduced by humans during the use of water. Raw sewage is screened by mechanical equipment to remove sticks, plastics, grit and other non-biodegradable matter. The flow velocity is slowed down to settle out un-dissolved organic matter. Most wastewater treatment plants utilize an activated sludge process as the major process for removing dissolved waste materials. Through a carefully controlled process, the water is mixed with air and live bacteria and over time the organics are biodegraded and removed from the water. By adding chlorine or other methods, any remaining bacteria are disinfected before release of the water to the environment.
In 2006, the City made the transition from a lagoon treatment system to a Sequencing Batch Reactor (SBR) Plant using four basins for a total treatment capacity of .8 million gallons per day. Each basin operated independently and treats a batch of raw wastewater by mixing then settling the solids and decanting the clear supernatant. This process reduces the Suspended Solids and Biochemical Oxygen Demand by as much as 98% and the total Nitrogen to less than 10 parts per million. The effluent was then chlorinated for disinfection and discharged to the Main Drain Canal where it flows about 20 miles to Mexico. The WWTP personnel also maintains 12 pump stations and 46 miles of sewer lines throughout the collections system making use of a newly purchased Vactor truck. In 2012 the City of Somerton expanded the capacity of the WWTP to 1.8 MGD and changed the process to a MLE (Modified Ludzack-Ettinger Process)in order to meet current and future demands.