We have developed the "mass exchange network (MEN)" synthesis concept to provide solutions for waste-minimization problems. Often, waste reduction problems require the removal of multiple toxic species from plant streams. Aside from the transfer of multiple chemical species multicomponent problems also encompasses simultaneous heat and mass exchange. To address this problem, we employ the recently proposed "State Space Approach." The State Space Approach decomposes the network synthesis problem into the evaluation of an operator-where the actual unit operations abe defined, and the distribution network-which contains all the flows to and from the operator. The entire network is optimized simultaneously. The use of distinct subnetworks for the flows and unit operations gives complete flexibility to choose over all possible configurations. The proposed approach is illustrated through as example from recycle-reuse tasks : the removal of nitrogenous compounds from the waste streams of a fertilizer plant.