Modeling wastewater temperature and attenuation of sewage-borne biomarkers globally.

Affiliation

Biodesign Center for Environmental Health Engineering, The Biodesign Institute, Arizona State University, 1001 S. McAllister Avenue, Tempe, AZ, 85287-8101, USA. Electronic address: [Email]

Abstract

Accurate modeling of in-sewer degradation of sewage-borne epidemiological biomarkers requires information on local wastewater temperature. We applied a deterministic, physical model to map theoretical wastewater temperature on a monthly scale worldwide and incorporated in the model estimated changes in the decay rate of 31 biomarkers of public health relevance frequently used in wastewater-based epidemiology (WBE). Over the course of a year, 75% of the world's global wastewater temperatures were estimated to fall into the temperature range of 6.9-34.4 °C. These non-fitted results obtained purely a priori were in good agreement with empirical observations (n = 400), as indicated by coefficients for Pearson (0.81; 0.76) and Spearman (0.86; 0.78) correlations for annual minima and maxima, respectively. Application of the Q10 rule for biochemical reaction rates showed that, depending on wastewater temperature, half-lives of sewage-borne biomarkers will change significantly (range: 27%-7,010%) from the baseline at ambient conditions (21 ± 1 °C; 100%). Importantly, these temperature-related modulations of in-sewer biomarker decay changed the size of the area observable by WBE; in the extreme, changes in the distal reach observable by WBE were predicted to be as large as 49-fold over the course of a year at a given location. This first model of spatial and temporal variability in wastewater temperature has multiple suggested applications, including (i) utility for explaining literature-reported discrepancies in the detectability and levels of sewage-borne biomarkers, (ii) identification of optimal and sub-optimal wastewater-borne biomarkers depending on their varying half-lives over the course of the year at the sampling location of interest, and (iii) estimating the effective size of the sewershed capture zone in WBE studies.

Keywords

Degradation,Global health,Modeling,Population health,Wastewater,

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