Biodegradation of trimethoprim and sulfamethoxazole in secondary effluent by microalgae-bacteria consortium

• Published in: International journal of hygiene and environmental health 2025-03, Vol.264, p.114517, Article 114517
• Main Authors: Rodrigues, Daniel Aparecido da Silva, da Cunha, Camila Cristina Rodrigues Ferreira, Pereira, Andressa Rezende, Espírito Santo, Daiana Rocha do, Silva, Silvana de Queiroz, Starling, Maria Clara Vieira Martins, Santiago, Aníbal da Fonseca, Afonso, Robson José de Cássia Franco
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents; Antibiotics; ARGs; Bacteria - genetics; Bacteria - metabolism; Biodegradation, Environmental; Bioremediation; Emerging contaminants; HPLC-MS; Microalgae - metabolism; Microbial Consortia; qPCR; Sulfamethoxazole; Trimethoprim; Waste Disposal, Fluid - methods; Wastewater; Water Pollutants, Chemical - analysis; Water Pollutants, Chemical - metabolism
• ISSN: 1438-4639; 1618-131X; 1618-131X
• DOI: 10.1016/j.ijheh.2024.114517

Trimethoprim (TMP) and sulfamethoxazole (SMX) are bacteriostatic agents, which are co-administered to patients during infection treatment due to their synergetic effects. Once consumed, TMP and SMX end up in wastewater and are directed to municipal wastewater treatment plants (WWTPs) which fail to remove these contaminants from municipal wastewater. The discharge of WWTP effluents containing antibiotics in the environment is a major concern for public health as it contributes to the spread of antimicrobial resistance. Improving treatment applied in WWTPs is one of the measures to tackle this issue. In this study, a natural microalgae-bacteria consortium cultivated under low intensity LED irradiation was used as a quaternary treatment to assess the removal of TMP alone (50 μg L−1) and also mixed with SMX (TMP/SMX; 50 μg L−1 of each) from real WWTP secondary effluents from anaerobic treatment systems. The removal of the sulfonamide resistance gene, sul1, was also evaluated. This is the first study assessed the removal of TMP alone and TMP associated with SMX in real effluent using microalgae-bacteria consortium without nutrient enrichment. Biodegradation experiments were conducted for 7 days, residual amount of antibiotics were assessed by low-temperature partitioning extraction (LTPE) followed by high-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) and sul1 was analyzed by quantitative Polymerase Chain Reaction (qPCR). Results showed that SMX removal (48.34%) was higher than TMP (24.58%) in the mixture. The presence of both antibiotics at 50 μg L−1 did not inhibit microalgae-bacteria consortium growth. After 7 days, there was a slight increase in the absolute abundance of sul1 and 16S rRNA. The main removal mechanism for both antibiotics might be attributed to symbiotic biodegradation as bioadsorption, bioaccumulation and abiotic factors were very low or insignificant. While the application of a microalgae-bacteria consortium as a quaternary treatment seems to be a promising alternative, further research to improve degradation rate aiming at a global removal >80% as required in the Swiss and European directives is encouraged. [Display omitted] •Enhanced microalgae-bacteria growth observed in the presence of TMP and TMP + SMX.•TMP removal was higher in the presence of SMX after 7 days of biodegradation.•Biodegradation was the main removal mechanism for TMP and SMX.•Symbiotic effects between micro