Identification of opportunities to save water in a beet sugar factory

A typical water and waste water system in a beet sugar factory consists of three interacting subsystems. First the main water and waste water circuit incorporating fresh water intake, beet fluming and washing, water regeneration by soil separation and waste water treatment, and waste water discharge. Second, the water circuit of the sugar manufacturing and power generation processes; its functions include discharging low pressure vapors that carry waste heat. And third, the barometric circuit incorporating condensation of low pressure vapors in mixing condensers and dissipation of waste heat from cooling water circulated through cooling towers.

The functioning of the water and waste water system can be analyzed by considering interconnected water-using and -regeneration operations, and optimized by using the “Water Pinch” approach. A water and waste water system equipped with a biological waste water treatment plant is considered. Its characteristics are assumed to match the data taken from a real Polish sugar factory. Taking two impurity indices, that is, Suspended Matter and Chemical Oxygen Demand into account, the minimum consumption of fresh water is calculated. The results indicate that by rearranging water flows within the system – without changing the water-treatment technology – the amount of fresh water taken in, and water discharged, can be significantly reduced.