Due to various environmental regulations, 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 environmentally safe discharge limit. An associated graphical representation of the optimization problem is also provided to gain physical insight. In the proposed methodology, the treatment units are modelled either as unit with constant outlet concentration or as a unit with fixed removal ratio. There is flow loss associated with the treatment unit. The flow loss is assumed to be proportional to the inlet flow rate. Applicability of the proposed methodology is demonstrated through examples from water management, volatile organic compound treatment and flue gas desulphurization. (C) 2009 Elsevier B.V. All rights reserved.