**4. Conclusions**

Tabu search is a stochastic optimization method used to solve global optimization problems. The effectiveness of tabu search for modeling and optimization is explored with the applications concerning to chemical and environmental systems of varying complexities. The meta heuristic Tabu search (TS) is designed and applied to determine the optimal control policies of a SAN copolymerization reactor and inverse modeling of a biofilm reactor. The computational efficiencies of TS are evaluated in terms of execution times, normalized absolute error values and memory storage requirements. The results of polymerization reactor show the usefulness of TS in determining the optimal temperature and feed rate policies to maintain the objectives *MW* and *F*<sup>1</sup> near to their desired values. The results of biofilm reactor explain the efficacy of TS in appropriately configuring the kinetic and film thickness models as a consequence of validation of mathematical models.
