Wastewater surveillance represents an alternative approach for the diagnosis and
early detection of infectious agents of public health importance. This study aimed to
evaluate SARS-CoV-2 and other quality markers in oxidation lagoons, estuarine areas
and seawater at Guayas and Santa Elena in Ecuador. Sample collections were
conducted twice at 42 coastal sites and 2 oxidation lagoons during dry and
rainy seasons (2020-2021). Physico-chemical and microbiological parameters were evaluated to determine organic pollution. Quantitative reverse transcription PCR was conducted to detect SARS-CoV-2. Results showed high levels of Escherichia coli and low dissolved oxygen concentrations. SARS-CoV-2 was detected in sea-waters and estuaries with salinity levels between 34.2-36.4 PSU and 28.8 degrees celsius -31.3 degrees celsius. High amounts of fecal coliforms were detected and correlated with the SARS-CoV-2 shedding. We recommend to decentralized autonomous governments in developing countries such as Ecuador to implement corrective actions and establish medium-term
mechanisms to minimize a potential contamination route.
Especially in small communities, little attention is paid to the hydraulic characteristics of wastewater treatment systems. Motivated by this problem, and using the ANSYS fluid dynamics software, the hydrodynamic evaluation of the residual water flow in a rural plant maturation pond was carried out. For the stationary modeling of the velocity and turbulence fields, the standard k-ε model was used; and for transient modeling of virtual tracer transport, the species transport model without chemical reaction was used. Subsequently, the analysis of the distribution of retention times was carried out, in order to obtain the flow patterns that govern the hydrodynamics of the pond. The results revealed the presence of hydraulic short circuits, stagnant zones, and recirculations, due to design deficiencies and operating conditions over the years. Given this situation, and by bibliographic recommendation, new modified geometries were proposed with longitudinal and transverse baffles at 70 and 90% in relation to the width and length of the pond. As a result, the hydraulic characteristics improved notably in all cases; however, the models configured at 90% achieved higher efficiency.
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