Membrane (RO-UF) filtration for antibiotic wastewater treatment and recovery of antibiotics

A membrane system including reverse osmosis (RO) and ultrafiltration (UF) was proposed and evaluated for the treatment of an oxytetracycline (OTC) waste liquor. Using RO filtration with a volume reduction coefficient of 3.5, the organic content in its permeate was decreased from COD∼10 000 mg/l to less than 200 mg/l, while OTC was reduced from more than 1000 mg/l to lower than 80 mg/l. Oxytetracycline was concentrated more than 3 times to 3000-4000 mg/l in the retentate. Due to likely the high concentration of large biopolymers interacting with OTC molecules, OTC could not be successfully recovered from the RO retentate by conventional crystallization. With additional treatment of ultrafiltration by 3K membranes, OTC crystallization and recovery from the RO retentate were significantly improved with a recovery ratio of more than 60% and a purity of higher than 80%. Detailed studies indicated that most large biopolymers in the OTC liquor were polysaccharides that would either hinder the growth of OTC crystals or precipitate together with OTC molecules. Removal of these large biopolymers by ultrafiltration could improve the condition remarkably for OTC crystallization. Therefore, the RO-UF membrane process can be developed as an effective alternative for the treatment of antibiotic wastewater as well as the recovery of antibiotics from the waste liquor. © 2003 Published by Elsevier B.V.link_to_subscribed_fulltex