Removal of hardness and COD from retanning treated effluent by membrane process Original Research Article

The use of membrane separation process integrated with conventional tannery wastewater treatment was studied in order to reuse the treated effluent in the retanning process. Laboratory scale tests were performed to find a suitable membrane for the process and to define pretreatment, fluid dynamic conditions and membrane cleaning procedures. Hardness levels restrict effluent reutilization on the process. The effects of the addition of lime, soda, Na2CO3 and EDTA to the primary stage of wastewater treatment plant to reduce hardness levels were presented in a previous work. The results obtained are reported and discussed. It was observed that the membrane MX07 (Osmonics) reached hardness retention values of 54%, obtaining soft permeate which is suitable to the process. The permeate will be used in retanning, partially closing the water cycle, and after that, the exhausted baths will be sent to the wastewater treatment plant.