Coupling of adsorption, coagulation, and ultrafiltration processes for the removal of emerging contaminants in a secondary effluent

The removal of eleven emerging contaminants (acetaminophen, metoprolol, caffeine, antipyrine, sulfamethoxazole, flumequine, ketorolac, atrazine, isoproturon, 2-hydroxybiphenyl and diclofenac) present in a WWTP effluent by applying several combined treatments has been investigated. These combinations were constituted by PAC adsorption and/or coagulation pre-treatments followed by UF, as well as by an UF treatment followed by GAC adsorption post-treatment. PAC pre-treatment decreased membrane fouling, with the advantage that PAC was separated from the final effluent in the UF step. Low PAC dose in the range 10–50 mg L−1 in the adsorption pre-treatment was enough in order to remove most of the emerging contaminants and to partially improve water quality parameters. However, if the goal is to reach a high improvement of water quality parameters in the pre-treatment step, a PAC dose above 500 mg L−1 was required. Although coagulation pre-treatment did not increase appreciably the permeate flux in the UF step, the final quality of the permeate was improved, especially when the combination Fe(III)/UF was applied. Finally, a significant positive effect of the GAC post-treatment after the UF treatment was appreciated, which led to an increase in the removal of the water quality parameters and a significant elimination of emerging contaminants.

► The removal of eleven emerging contaminants by combined treatments was investigated.
► PAC pre-treatment decreased membrane fouling and improved the quality of the permeate.
► Pre-coagulation with Fe(III) was slightly more favorable than with Al(III).
► The combinations PAC/UF and UF/GAC led to a significant removal of contaminants.