Batch versus continuous feeding strategies for pharmaceutical removal by subsurface flow constructed wetland

This study evaluated the effect of continuous and batch feeding on the removal of 8 pharmaceuticals (carbamazepine, naproxen, diclofenac, ibuprofen, caffeine, salicylic acid, ketoprofen and clofibric acid) from synthetic wastewater in mesocosm-scale constructed wetlands (CWs). Both loading modes were operated at hydraulic application rates of 5.6 cm day−1 and 2.8 cm day−1. Except for carbamazepine, clofibric acid and naproxen, removal in CWs was significantly (p < 0.05) enhanced under the batch versus continuous mode. For all compounds tested except naproxen, values for first-order decay constants (k) for drain and fill operation were higher than that for the continuous mode of operation. Correlation between the distribution coefficient (log Dow) and removal efficiencies of pharmaceutical compounds in the CWs, showed that pharmaceutical removal efficiency was significantly (p < 0.1) and inversely correlated with log Dow value, but not with log Kow value.

► Batch feeding in mesocosm-scale constructed wetlands enhances pharmaceutical removal.
► K values for the 8 pharmaceuticals were in the range of 0.01–0.1 m day−1.
► The pharmaceutical removal efficiency was inversely correlated with log Dow value.