Impact of wastewater treatment plants on microbiological contamination for evaluating the risks of wastewater reuse

Abstract

Background Wastewater reuse represents a promising alternative source of water supply considering the water scarcity related to climate change. However, if not adequately treated, wastewater represents a source of microbiological health risk. The purpose of this work was to investigate the role of wastewater treatment on microbiological contamination by evaluating the possible risks associated with wastewater effluent reuse, taking into account new EU legislation (2020/741) on minimum requirements for water reuse. E. coli that produce Shiga toxins (STEC) and thermotolerant Campylobacter were monitored using an enrichment step associated with specific PCR, while Salmonella spp. and Legionella were detected with both cultural and molecular methods (PCR and q-PCR, respectively). Culture method was also used for the enumeration of different microbial indicators. The bacteria detection was compared in different wastewater plants with membrane bioreactor (MBR) system or with disinfection step with chlorine dioxide (ClO2). Moreover a comparison between molecular and culture methods was discussed. Results The results obtained showed good abatement performance for WWTPs equipped with MBR. The high concentrations of E. coli (range between 0.88 and 5.21 Log MPN/100 mL) and contamination by Salmonella spp. in effluent disinfected with ClO2 (17% of samples) showed the need to control the quality of this effluent. In addition, despite the absence of Legionella spp. with the culture method required by EU regulation, high concentrations of Legionella spp. (range between 2 and 7 log GU/L) and the presence of Leg. pneumophila with qPCR (15% of samples) highlight the need to carry out further investigations for reuse associated with aerosol formation (e.g. spray irrigation in agriculture). Conclusions The results obtained underline that the MBR technology can be suitable for wastewater reuse applications allowing to achieve the requirement proposed by the new European legislation. More attention should be given to wastewater reuse of effluents treated with ClO2. The use of the molecular methods for pathogens detection in wastewater could allow a more precautionary risks estimation associated with reuse. The overall results highlight that an evaluation of the effectiveness of the wastewater treatments is required for the prevention of a possible risk to public health.

Assessment of wastewater impact on a natural reservoir in Kyrgyzstan

“…S. Bonetta et al (7) emphasise the fact that even in the case of a perfect wastewater treatment system, including biological treatment, all dissolved inorganic substances and about 10% of organic pollutants remain in the treated wastewater. According to the authors, this indicates the need for a radical reorientation of the water use strategy, with the isolation of the anthropogenic water cycle from the natural one, transition to closed water supply, and introduction of low-waste technologies.…”

“…Scientists of Kyrgyzstan pay special attention to the toxic and carcinogenic properties of some components of wastewater from industry and municipal services (4)(5)(6) . Modern scientists S. Bonetta et al (7,8) and H. Hamdhani et al (9) come to the conviction that many destructive changes in aquatic ecosystems, difficult to regenerate, are provoked by large-scale releases of toxic substances from industrial processes. The conclusions of scientists are complemented by a group of researchers led by S. Lu et al (10) and M. Preisner (11) are convinced of the special urgency of the impact on natural reservoirs of new understudied pollutants, which actually cannot be treated even with satisfactory condition of complete wastewater treatment systems.…”

The Fate of Bacteria in Urban Wastewater-Irrigated Peach Tree: A Seasonal Evaluation from Soil to Canopy

“…2). E. coli and TC concentrations are supposed to be strictly dependent on several factors such as the intrinsic characteristic of the wastewater treatment plant (e.g., activated sludge, membrane bioreactor) and, when applied, to the disinfection system adopted (e.g., PPA, hypochlorite, UV) (Bonetta et al, 2022). Indeed, Perulli et al (2021), found E. coli and TC, 1000 and 100 times reduced in a wastewater deriving from a different treatment plant.…”

The role of natural sorbents and piping production waste in the treatment of acid iron-containing waste water

“…Существующие технологии зачастую многостадийны, весьма затратны, требуют применения большого количества химических реагентов, что приводит к вторичному загрязнению окружающей среды. Можно констатировать, что эта проблема актуальна для промышленности всего мира, поэтому исследования проводятся во всех странах [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15].…”