Different Strains of Microalgae in a Microbial Consortium Remove Antibiotics from Urban Wastewater in Batch and...

Antibiotics are micropollutants present in aquatic ecosystems, thus causing serious concerns. The presence of mixotrophic microalgae in wastewater biological treatment systems is important for the removal of those micropollutants. This study evaluated the removal efficiency of five different antimicrobials, sulfamethoxazole, trimethoprim, ofloxacin, ciprofloxacin, and enrofloxacin, in batch and continuous photobioreactors by four different Chlorophyceae strains in consortium with autochthonous bacteria. In a batch system, all strains efficiently removed the 5 antibioticsmainly sulfamethoxazole, enrofloxacin, and ciprofloxacin by Desmodesmus sp. (86 ± 2% average removal) and Chlamydomonas sp. (85 ± 1% average removal). In the continuous system, Chlorella sp. also removed the 5 antibiotics, but with better results for sulfamethoxazole and trimethoprim (54 ± 2% and 57 ± 4% average removals, respectively). In the batch system, the highest removal efficiencies were achieved by Chlamydomonas reinhardtii for organic carbon (95 ± 1%) and nitrogen (89 ± 1%) and by Desmodesmus sp. for inorganic phosphorus (91 ± 6%), whereas in the continuous system, 97% organic carbon were removed by Chlorella sp., and better removal performance for four of the antibiotics compared to the batch system. Therefore, microalgae-bacteria consortia are effective for wastewater biological treatment with antimicrobials, a sustainable treatment alternative. Furthermore, this process contributes to the valorization of residues by simultaneously allowing the production of byproducts, such as organic acids and biohydrogen.