Basic Red 18 is vastly used in various industries including textile and cosmetic industries. Investigations on the removal of dyes have led to the use of biological methods as appropriate removal methods due to their low costs and economic nature. Moving bed biofilm reactor is one of the most economically efficient methods which reach optimal removal efficiency in less retention time. In this study, feed backward/feed forward moving bed biofilm reactor was designed for the first time using the moving bed biofilm reactors and used for wastewater treatment. In this system, two independent variables including retention time (in the range of 2h.10'-7h.50') and input concentration of pollutant (22.47-202.78 mg/l) were measured and the effect of each variable on removal percentage of dye were studied based on Response surface methodology. Following that, modeling and determining the optimum conditions for operating the system was carried out. The results showed that the optimum condition occurred at retention time of 6.21 h and input dye concentration of 74.77 mg/l. Based on this research, retention time has the greatest impact on the removal efficacy of this biological system and this system has a great potential for wastewater treatment containing Basic Red18.
