Process water management

Water management addresses the problem of optimal allocation of reusable water among different water-using operations. Wastewater management deals with optimal design of effluent treatment units to respect environmental norms. However, optimal design of effluent treatment units should be solved in conjunction with the problem of optimal allocation of water among different processes that use water. A new methodology for targeting minimum effluent treatment flow rate satisfying minimum freshwater requirement is proposed in this paper. The proposed methodology can be applied to fixed-flow-rate as well as fixed-contaminant-load problems having a single contaminant. A source composite curve is proposed for directly targeting generation of wastewater. Freshwater can be indirectly targeted using overall mass balance. To target distributed generation of wastewater, wastewater composite curve is proposed. On the basis of this wastewater composite curve, targets for effluent systems can be set. All these targets can be set on a single concentration-contaminant load diagram before designing the detailed water-allocation network. Analytical algorithms are proposed to solve the integrated water and wastewater management problem. The minimum contaminant removal ratio of the effluent treatment system and the minimum number of required effluent treatment units are also reported in this paper.