Wastewater Treatment: Dissolved Air Flotation (DAF) Filtration leads to water savings. DAF pretreatment in the food industry can provide sustainable water cost savings. Stuart Ward of Process Engineered Water Equipment, LLC explains efficient filtration is key. Columbus Salame, South San Francisco CA was established in 1934 to manufacture select quality deli meat Production processing increased dramatically as the company flourished. In 1987 the first wastewater pretreatment plant was installed to meet city discharge requirements. Treatment was variable with modest results. The company continued to grow and in 2008 found it necessary to replace the aging, overrun inefficient system.