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Due to the extension of cities and industries and population growth, environmental pollution has become noteworthy. Heavy metals are pollutants produced by industrial factories. Therefore, wastewater should be purified and treated, and returned to natural water circulation. This research investigated the removal of heavy metal zinc (Zn) at high concentrations in Esfarayen Steel Industrial Complex and the performance of the integrated system including activated carbon adsorption column (as pretreatment) and reverse osmosis membrane system under different operating conditions. The variable parameters are pH (4.5, 6.5, 7, and 9), pressure (5, 7, 9, and 11 bar), and zinc concentration (30, 50, and 70 mg/l) to obtain zinc removal efficiency, turbidity dissolved solids (TDS), electrocoagulation (EC), and turbidity (TU) at constant temperature and flow rate. The results show that the integrated system efficiency at 9 bar pressure and pH of 7.5 is optimal as to water outlet quality. The removal efficiencies are 98.1%, TDS; EC, 97.4%; Zinc, 100%; and TU, 95.3%, which is desirable. Moreover, system efficiency at a high concentration of zinc is evaluated. According to the results, the integrated system is resistant to probable shocks, high concentration and has desirable efficiency with all parameters almost above 90%.