Who Can Afford To Save Water?, 1996 Minimum Effluent Mills Symposium Proceedings
George Wohlgemuth - Weyerhaeuser
Eva Mannisto & Heikki Mannisto - EKONO
The technical feasibility of low water use technologies has been proven in both pilot and mill scale. However, although technologies exist, the water and effluent flows are still fairly high in the pulp and paper industry. Obviously economic factors play a key role in the selection of technologies and water use levels. Especially for an existing mill, many technical factors determine the minimum required water usage level. This presentation addresses the economic and technological aspects that have to be taken into account when planning and implementing water conservation measures in an existing mill. The sample cases presented are from an existing bleached kraft mill. Water conservation in existing mills is seldom justifiable based on water price alone, but has to be motivated by other process and environmental benefits, such as reduction in energy costs, chemicals, fiber etc. The optimum water usage level depends on the technologies being used, especially in the pulping and bleaching processes. This level is determined by factors such as effluent temperature, concentrations that can be tolerated in effluent treatment, effluent toxicity and other parameters that may be defined as maximum concentrations.