Influence of the hydraulic retention time on the removal of emerging contaminants in an anoxic-aerobic algal-bacterial photobioreactor coupled with anaerobic digestion

• Published in: The Science of the total environment 2022-06, Vol.827, p.154262-154262, Article 154262
• Main Authors: Ruas, Graziele, López-Serna, Rebeca, Scarcelli, Priscila Guenka, Serejo, Mayara Leite, Boncz, Marc Árpàd, Muñoz, Raúl
• Format: Article
• Language: English
• Subjects: Algal-bacterial process; Biodegradation; Biotransformation; Domestic wastewater treatment; Microcontaminants; Micropollutants; Pharmaceuticals
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2022.154262

This work evaluated, for the first time, the performance of an integral microalgae-based domestic wastewater treatment system composed of an anoxic reactor and an aerobic photobioreactor, coupled with an anaerobic digester for converting the produced algal-bacterial biomass into biogas, with regards to the removal of 16 contaminants of emerging concern (CECs): penicillin G, tetracycline, enrofloxacin, ciprofloxacin, sulfamethoxazole, tylosin, trimethoprim, dexamethasone, ibuprofen, naproxen, acetaminophen, diclofenac, progesterone, carbamazepine, triclosan and propylparaben. The influence of the hydraulic retention time (HRT) in the anoxic-aerobic bioreactors (4 and 2.5 days) and in the anaerobic digester (30 and 10 days) on the fate of these CECs was investigated. The most biodegradable contaminants (removal efficiency >80% regardless of HRT) were tetracycline, ciprofloxacin, sulfamethoxazole, tylosin, trimethoprim, dexamethasone, ibuprofen, naproxen, acetaminophen and propylparaben (degraded predominantly in the anoxic-aerobic bioreactors), and tetracycline, sulfamethoxazole, tylosin, trimethoprim and naproxen (degraded predominantly in the anaerobic reactor). The anoxic-aerobic bioreactors provided removal of at least 48% for all CECs tested. The most recalcitrant contaminants in the anaerobic reactor, which were not removed at any of the HRT tested, were enrofloxacin, ciprofloxacin, progesterone and propylparaben. [Display omitted] •CECs were efficiently removed in the anoxic-aerobic photobioreactor.•Some CECs were effectively removed in the anaerobic digester.•Enrofloxacin, ciprofloxacin and progesterone were anaerobically recalcitrant.•Biodegradation was the main mechanism of CECs removal.•The global removals of CECs were higher than those found in conventional WWTPs.