Abstract
Oil-containing wastewater is generated during postharvest processing of crops and during food processing, and the oil reduces the efficiency of wastewater treatment processes and decreases water quality. In Japan, the water quality standard for facilities above a certain scale is set by the Water Pollution Control Law at <30 mg of n-hexane extracts per liter. There are many technologies for separating oil and water, including centrifugation, floatation, flocculation, and absorption. The recovered oil can be used as fuel and as a feedstock in the manufacture of tires, and especially the oil recovered under proper sanitary conditions can be used for cooking. Separation of the oil can also help to reduce the scale of wastewater treatment facilities, leading to a reduction in construction costs. In addition, separation improves wastewater quality and allows for the recycling of water, which is used in large quantities for food processing. In this separation engineering study, Value Function and Separative Work Unit were used to evaluate the economics of introducing oil-water separation technology to a food processing factory. The results, which revealed the economic performance equivalent to the degree to which the separation technology improved the wastewater treatment process, can be used to aid in decision-making regarding the feasibility of introducing oil-water separation technology in food processing facilities.
