Various environmental regulations imply that it is important to minimize the cost associated with treatment of different industrial wastes prior to its discharge to the environment. In this paper, an algebraic methodology, based on the principles of process integration, is proposed to target the minimum waste treatment flow rate to satisfy an environmentally acceptable discharge limit. In the proposed methodology, treatment units with fixed outlet concentrations are considered. It is observed that it is not necessary to maximize the usage of the treatment unit with the minimum specific cost. Hence, a prioritized cost for each treatment unit is devised to select appropriate treatment units that minimize the overall operating cost. Applicability of the proposed methodology is demonstrated through examples.