Removal of intI1, ARGs, and SARS-CoV-2 and changes in bacterial communities in four sewage treatment facilities

Yovany Cuetero-Martínez; Karen Natalia Villamizar-Ojeda; Margarita Jazmín Hernández-Santiago; Daniel De Los Cobos-Vasconcelos; José Félix Aguirre-Garrido; Yolanda López-Vidal; Adalberto Noyola

doi:10.1016/j.scitotenv.2023.165984

Removal of intI1, ARGs, and SARS-CoV-2 and changes in bacterial communities in four sewage treatment facilities

Sci Total Environ. 2023 Dec 10:903:165984. doi: 10.1016/j.scitotenv.2023.165984. Epub 2023 Aug 17.

Authors

Yovany Cuetero-Martínez¹, Karen Natalia Villamizar-Ojeda¹, Margarita Jazmín Hernández-Santiago², Daniel De Los Cobos-Vasconcelos², José Félix Aguirre-Garrido³, Yolanda López-Vidal⁴, Adalberto Noyola⁵

Affiliations

¹ Subdirección de Hidráulica y Ambiental, Instituto de Ingeniería, Universidad Nacional Autónoma de México, 04510 Cd de, Mexico; Posgrado en Ciencias Bioquímicas, Universidad Nacional Autónoma de México, 04510 Cd de, Mexico.
² Subdirección de Hidráulica y Ambiental, Instituto de Ingeniería, Universidad Nacional Autónoma de México, 04510 Cd de, Mexico.
³ Departamento de Ciencias Ambientales, Universidad Autónoma Metropolitana - Unidad Lerma, 52005 Lerma de Villada, Edo, Mexico.
⁴ Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Autónoma de México, 04510, Cd de, Mexico.
⁵ Subdirección de Hidráulica y Ambiental, Instituto de Ingeniería, Universidad Nacional Autónoma de México, 04510 Cd de, Mexico. Electronic address: noyola@pumas.ii.unam.mx.

PMID: 37574072
DOI: 10.1016/j.scitotenv.2023.165984

Abstract

Currently, discharge regulations for wastewater treatment plants (WWTPs) are based on conventional parameters, but more is needed to ensure safe water reuse. In particular, emerging pollutants, as antimicrobials and antibiotic resistance genes (ARGs), are not considered. This research focuses on the fate of emerging biological contaminants during wastewater treatment in Mexico City. intI1 and the ARGs cphA-02, OXA-10 and sul1 were analyzed by qPCR; pathogenic bacteria species were characterized by high throughput sequencing of complete 16S rRNA gene, and fragments of SARS-CoV-2 were quantified by RT-qPCR. Conventional parameters (chemical oxygen demand and coliform bacteria) were also determined. Two sampling campaigns (rainy and dry seasons) were carried out in four municipal WWTPs in Mexico City, representing five biological treatment processes: conventional activated sludge, extended aeration activated sludge, membrane bioreactor, direct anaerobic digestion, and constructed wetland, followed by ultraviolet light or chlorine disinfection. In most cases, gene fragments of SARS-CoV-2 were eliminated below the detection limit of RT-qPCR. The abundance of intI1 positively correlated with the sul1, OXA-10, and cphA-02 abundances; intI1 and the ARGs here studied were partially removed in the WWTPs, and in most cases, the number of copies per second discarded in the sludge were higher those in the effluent. The treatment processes decreased the abundance of dominant bacterial groups in the raw wastewater, while enriching bacterial groups in the effluent and the biological sludge, with possible pollutant removal capabilities. Bacterial communities in the raw wastewater showed the predominance of the genus Arcobacter (from 62.4 to 86.0 %) containing potentially pathogenic species. Additionally, DNA of some species persisted after the treatment processes: A. johnsonii, A. junii, A. caviae, A. hydrophila, A. veronii, A. butzleri, A. cryaerophilus, Chryseobacterium indologenes, Hafnia paralvei, M. osloensis, Pseudomonas putida and Vibrio cholerae, which deserves special attention in future regulation for safe water reuse.

Keywords: Bacterial pathogens; Effluent disinfection; Emerging biological contaminants; Full-length 16S rRNA sequencing; Wastewater surveillance.