No abstract

The concentration of chlorine in water declines as it reacts with various substances, causing decay of the residual free chlorine until its total consumption. In light of the typical characteristics of the water from protected dug wells and tube wells, this study aimed to evaluate the decay kinetics of free chlorine in the water of alternative individual supply (AIS) solutions used in the city of Porto Velho in the Brazilian Amazon region. The free chlorine decay constant in the water was evaluated by “bottle tests,” applying a first-order model. According to the results, the type of well and initial chlorine concentration significantly influences the free chlorine decay speed. The water samples from the tubular wells had lower chlorine demand levels, attributed to their better water quality. The simulation of the residual chlorine decay in the different supply sources is an important tool to support safe disinfection processes.

To monitor safely managed drinking water services, an increasing number of countries have integrated water quality testing for Escherichia coli into nationally-representative household surveys such as the Multiple Indicator Cluster Surveys (MICS). However, plastic waste generated during such water quality testing programs, mostly through the use of pre-sterilized disposable materials, is non-negligible. The objective of this study was to evaluate several re-use protocols for disposable filter funnels used by the MICS water quality test kits. Decontamination and re-use protocols were assessed in centralized laboratory and decentralized field settings and neither yielded positive results. Re-use of 100 mL sterile funnels decontaminated with an alcohol wipe resulted in a higher incidence of false positive results (i.e., positive contamination when processing sterile water), both in the laboratory and field; therefore, a higher proportion of positives tests can be expected if these components are re-used. Further improvements to the decontamination technique and training are needed before material re-use can be reliably adopted. Autoclaving the funnels for re-use is feasible, provided that there is capacity to re-package and distribute funnels in a sterile manner.

Groundwater is heavily exploited for a variety of uses. Depending on their structure, the wells from which water is extracted can act as an entry point/gateway for a variety of microbiological contaminants, which can cause numerous adverse health effects. This study aimed to identify the microorganisms present in the groundwater in the Western Amazonian city of Porto Velho, using a methodology that can be deployed in other city centers. We collected 74 water samples from both dug and drilled wells in March, August and November 2018. Total coliforms were detected in 96% of dug wells and 74% of drilled wells. Thermotolerant coliforms were found in 90% of dug wells and 61% of drilled wells. Biochemical identification indicated 15 genera of bacteria. The genera Escherichia, Enterobacter, Cronobacter and Citrobacter had the highest prevalence. The genera Pseudomonas and Enterococcus were also detected. Thermotolerant coliforms showed higher values when the water flow was higher. Our results indicate high fecal contamination and higher susceptibility to contaminants in shallow wells compared to deep wells. These findings reflect the precariousness of WASH (water, sanitation and hygiene) services and the importance of effective actions to combat groundwater degradation, improve the quality of the environment, and protect public health.