this paper, we have presented the solution of the second-order ozone decomposition system with OH radical and microcystin-LR without dissolved organic content (DOC), and claim that one can tackle with such a large problem by the least cost and time. The governing differential system is solved by Optimal Homogony Asymptotic Method (OHAM), and the solutions of the system are illustrated by some plots. تفاصيل المقالة