Antibiotics in nutrient recovery from pig manure via electrodialysis reversal: Sorption and migration associated with membrane fouling

Nutrient (nitrogen and phosphorus) recovery from animal manure using membrane technologies has been well studied, but the migration and accumulation of antibiotics in membrane processes are ignored. This study examined the behaviours of sulfadiazine (SD) and tetracycline (TC) in an electrodialysis reversal (EDR) process designed for nutrient recovery from pig manure. The results showed that SD and TC, two widely used antibiotics for the livestock, were removed from the feed solution but with different mechanisms; SD removal was mainly due to electro-migration and TC removal was due to membrane sorption. SD migrated to the product solution through membranes, while TC remained on the membrane surface and had a spatial association with organic membrane foulants. Particle fouling hindered the migration of SD and TC, which was reflected by 34–67% of SD and TC remaining in the feed solution when treating real manure. After long-term operation, the fouled membranes still showed high sorption capacities to SD and TC, almost identical to the virgin membranes. The sorption and migration mechanisms associated with membrane fouling were then proposed. This study shows that antibiotics were accumulated in the product solution, posing ecological and health risks if the product is used as fertiliser.