Zero-Discharge: An Application of Process Water Recovery Technology in the Food Processing Industry

摘要

Water is a valuable natural resource and the food processing industry has been among the leading industrial water users in California. With support from a major northern California utility and the California Institute for Food and Agricultural Research, Tri Valley Growers (TVG) has successfully installed the first U.S. energy-efficient zero-discharge process water reclamation system at its Oberti Olive processing facility in Madera, California. The advanced zero-discharge system is the largest application in the world of membrane filtration for recovering water from a food processing plant. Previously, the plant discharged an average of 1 million gallons of salty wastewater (brine) a day into 160 acres of evaporation ponds. However, new environmental regulations made the ponds obsolete. The cost of process water disposal using alternate biotreatment system was prohibitive and would make continued operation uneconomical with plant closure and job loss the likely outcome. Through comprehensive pilot testing and subsequent system design and operational optimization, the advanced membrane filtration system with pre- and post-treatment now recovers about 80% of the process liquid in high purity form of water for subsequent reuse at the plant. The solids produced in olive processing, plus concentrated process liquids are used off-site as an animal feed component, thus achieving the plant zero-discharge scheme. The successful implementation of the zero discharge system at the Oberti Olive processing plant has produced energy saving of 3,500,000 kilowatthours and 244,000 therms of gas a year of power as compared to the alternate biotreatment system. It also prevented plant closure and job loss. In addition, water conservation and the discontinuation of evaporation pond use is beneficial to the environment. The project was applauded by the California Environmental Protection Agency as a positive step forward for environmental technology in the agricultural sector in California.