Case study of waste water minimization at a general electric manufacturing plant

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AbstractThis paper describes the process of converting an existing industrial water system at a General Electric manufacturing plant towards zero discharge. A plan to significantly reduce waste water to the publicly owned treatment works (POTW) is presented. The first phase, which should reduce water discharge by 90% compared to 1992 rates, involves three major steps. First, a vibrating membrane filter machine will be used to treat the tumbler machine waste water, which accounts for about half of the plant's total water usage. The suspended solids in the waste water will be removed and disposed of as non‐hazardous waste. The water will be reused in the tumbler room and in other processes throughout the plant. Second, effluent from the waste water treatment plant will be recycled to the maximum extent possible. Third, steps will be taken to minimize water usage in rinsing operations. When the first phase is completed, the water quality in the plant will be expected to change. In particular, the salt concentration will increase, and the temperature of the water may rise. With careful monitoring of the water quality, input rates of city water, and discharge rates, a zero‐discharge system can be defined. The key to achieving zero‐discharge will be selecting a technology to remove salts from the water. The likely candidates are reverse osmosis, electrodialysis, or ion exchange, perhaps followed by evaporation to reduce the brine volume. A preliminary design for a zero‐discharge system is presented; however, the first phase of the project will be implemented and studied before the appropriate salt‐removing technology is selected.