The occurrence of SARS-CoV-2 in Tehran's municipal wastewater: performance of treatment systems and feasibility of wastewater-based epidemiology.

Analyzing municipal wastewater for the presence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) helps to evaluate the efficacy of treatment systems in mitigating virus-related health risks. This research investigates wastewater treatment plants' (WWTPs) performance in the reduction of SARS-CoV-2 from municipal wastewater in Tehran, Iran. SARS-CoV-2 RNA was measured within sewers, at the inlets, and after the primary and secondary treatment stages of three main WWTPs. Within sewers, the average virus titer stood at 58,600 gc/L, while at WWTP inlets, it measured 38,136 gc/L. A substantial 67% reduction in virus titer was observed at the inlets, accompanied by a 2-log reduction post-primary treatment. Remarkably, the biological treatment process resulted in complete virus elimination across all plants. Additionally, a notable positive correlation (r > 0.8) was observed between temperature and virus titer in wastewater. Using wastewater-based epidemiology (WBE) technique and the estimated SARS-CoV-2 RNA shedding rates, the infection prevalence among populations served by WWTPs found to be between 0.128% to 0.577%. In conclusion, this research not only advances our understanding of SARS-CoV-2 dynamics within wastewater treatment systems but also provides practical insights for enhancing treatment efficiency and implementing the feasibility of WBE strategies in Tehran. These implications contribute to the broader efforts to protect public health and mitigate the impact of future viral outbreaks.

Performance evaluation and siting index of the stabilization ponds based on environmental parameters: a case study in Iran.

Stabilization ponds are open pools that remove total suspended solids, organic matters, microbial and pathogenic agents using physical, chemical, and biological processes. If the stabilization ponds are not well designed, they can produce odors, breed many insects, increase suspended solids concentration in the effluent and pollute groundwater. Consideration of environmental factors is critical for operation and maintenance. In this study, first, information on wastewater treatment plants and meteorological parameters were collected, and simultaneously, specialists were selected to score the effect of environmental factors on stabilization pond efficiency. A geographic information system was used to sit for suitable locations for stabilization ponds. The results showed that 23.6 % of Iran's treatment plants are stabilization ponds, which based on climate, evaporation, sunny hours, ice days, wind speed, and temperature parameters, 33.33 %, 37.3 %, 14 %, 50 %, 64 and 26 % of the stabilization ponds have obtained good points, respectively. The results also showed that 50 % of the stabilization ponds obtained an acceptable score considering all environmental parameters' simultaneous effect. A preliminary study based on considering all the environmental parameters showed that the central and southern regions are the best areas for establishing waste stabilization ponds; in contrast, northern and northeastern regions can have high operation and maintenance costs with lower efficiency. This study has shown that setup and design of the new waste stabilization ponds in Iran need to take into account by considering environmental factors because these factors have the main effect on algae growth which are one of main biological treatment.

The presence of SARS-CoV-2 in raw and treated wastewater in 3 cities of Iran: Tehran, Qom and Anzali during coronavirus disease 2019 (COVID-19) outbreak.

This study aimed to identifying the presence of SARS-CoV-2 RNA in raw and treated wastewater during the COVID-19 outbreak in Tehran, Qom and Anzali cities (Iran). From three wastewater treatment plants (WWTPs), 28 treated and untreated wastewater composite samples were collected from April 4 to May 2, 2020. In this study, polyethylene glycol 6000 (PEG 6000) was used through one-step real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) for identification of RNA viruses. SARS-CoV-2 RNA was elicited from wastewater composite samples in all inlet samples taken from the three above mentioned cities. The results of outlet samples were as follows: 1) Results from Qom and East Anzali outlets showed no trace of SARS-CoV-2 RNA despite the difference in treatment disinfection method used (chlorine vs. ultraviolet (UV) disinfection). 2. In Tehran, SARS-CoV-2 RNA was not detected in any of the outlet samples taken from the modules disinfected by UV. Out of the four samples taken from the modules disinfected by chlorine, two were positive for the SARS-CoV-2 RNA which could have been caused by deficiencies in operation and maintenance. It can be concluded that meeting the standards of operation and maintenance (O&M) in WWTPs can considerably ensure that wastewater does not act as one of the roots of transmission for the disease.