34 research outputs found
A global multinational survey of cefotaxime-resistant coliforms in urban wastewater treatment plants
The World Health Organization Global Action Plan recommends integrated surveillance programs as crucial strategies for monitoring antibiotic resistance. Although several national surveillance programs are in place for clinical and veterinary settings, no such schemes exist for monitoring antibiotic-resistant bacteria in the environment. In this transnational study, we developed, validated, and tested a low-cost surveillance and easy to implement approach to evaluate antibiotic resistance in wastewater treatment plants (WWTPs) by targeting cefotaxime-resistant (CTX-R) coliforms as indicators. The rationale for this approach was: i) coliform quantification methods are internationally accepted as indicators of fecal contamination in recreational waters and are therefore routinely applied in analytical labs; ii) CTX-R coliforms are clinically relevant, associated with extended-spectrum β-lactamases (ESBLs), and are rare in pristine environments. We analyzed 57 WWTPs in 22 countries across Europe, Asia, Africa, Australia, and North America. CTX-R coliforms were ubiquitous in raw sewage and their relative abundance varied significantly (<0.1% to 38.3%), being positively correlated (p < 0.001) with regional atmospheric temperatures. Although most WWTPs removed large proportions of CTX-R coliforms, loads over 10 colony-forming units per mL were occasionally observed in final effluents. We demonstrate that CTX-R coliform monitoring is a feasible and affordable approach to assess wastewater antibiotic resistance status. [Abstract copyright: Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.
A global multinational survey of cefotaxime-resistant coliforms in urban wastewater treatment plants
The World Health Organization Global Action Plan recommends integrated surveillance programs as crucial strategies for monitoring antibiotic resistance. Although several national surveillance programs are in place for clinical and veterinary settings, no such schemes exist for monitoring antibiotic-resistant bacteria in the environment. In this transnational study, we developed, validated, and tested a low-cost surveillance and easy to implement approach to evaluate antibiotic resistance in wastewater treatment plants (WWTPs) by targeting cefotaxime-resistant (CTX-R) coliforms as indicators. The rationale for this approach was: i) coliform quantification methods are internationally accepted as indicators of fecal contamination in recreational waters and are therefore routinely applied in analytical labs; ii) CTX-R coliforms are clinically relevant, associated with extended-spectrum β-lactamases (ESBLs), and are rare in pristine environments. We analyzed 57 WWTPs in 22 countries across Europe, Asia, Africa, Australia, and North America. CTX-R coliforms were ubiquitous in raw sewage and their relative abundance varied significantly (<0.1% to 38.3%), being positively correlated (p < 0.001) with regional atmospheric temperatures. Although most WWTPs removed large proportions of CTX-R coliforms, loads over 103 colony-forming units per mL were occasionally observed in final effluents. We demonstrate that CTX-R coliform monitoring is a feasible and affordable approach to assess wastewater antibiotic resistance status
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An Investigation of the Alternatives for Wastewater Disinfection: Economic, Social, and Technical -- A Theoretical and Experimental Investigation of the Dynamics of Breakpoint Chlorination in Dispersed Flow Reactors
The dynamics of breakpoint chlorination were examined in three continuous dispersed flow reactors. The reactors were comprised of 1/2, 2 and 3 inch PVC pipe, which were 730, 41, and 23 feet long, respectively. Chlorination of ammonia a various chlorine to ammonia ratios were investigated over the pH range of 6.5 to 7.5.Seventeen experiments were performed in the three reactors over the course of the experimental investigations. Chlorine residuals, including free, monochloramine, dichloramine, and nitrogen trichloride, and ammonia were analyzed simultaneously.To quantitatively characterize the breakpoint reactions, a mathematical model, consisting of eight simultaneous, quasi-linear, partial differential equations was developed. The model was solved using an implicit finite difference technique. The reaction rate coefficients were treated as parameters, and were estimated using a search technique to minimize the sum of squares of the difference between the expected and measured values.The model can now be used to simulated continuous flow chlorination processes in order to develop process operating strategies to maximize of minimize any given experimental objectives