lou ana foods, inc. , operates a medium-size vegetable oil refining and processing plant in opelousas, louisiana. the plant is operated continuously except for shutdown on major holidays. the treatment system was designed to handle three categories of water effluent from manufacturing operations: process wastewater; rainwater runoff; non-contact cooling water. the sequence of processes in the treatment train is ph adjustment, gravity separation of floatable oils, flow equalization, neutralization, dissolved air flotation, biological treatment and clarification. each process is described in some detail, and the cost of the treatment system project and the annual operating expense are given. system performance can be further improved by optimizing treatment conditions for each type of vegetable oil refined. wastewater from cottonseed, corn, soybean and sunflower seed oil refining/acidulation relatively easy to treat. coconut and peanut oil wastewater being more emulsified is more difficult to treat