Occurrence of pathogenic microorganisms in small drinking-water systems in Costa Rica.

This study describes the quality of drinking water sampled over 2 years (2018 and 2019) from 20 ASADAS (Spanish acronym for Administrative Associations for Water and Sewer Systems) in Costa Rica. The analysis included Rotavirus (RV), somatic coliphages, fecal coliforms, and Escherichia coli. The ASADAS were categorized into three regions as temperate rainy (region 1), tropical rainy (region 2), and tropical rainy and dry (region 3) according to biogeographic classification. The concentrations of fecal coliforms and E. coli were higher in samples from surface water sources from the ASADAS in region 3 compared to regions 1 and 2. RV-positive samples (24/296) were detected in drinking-water samples from regions 2 and 3 during dry and transition seasons, with higher concentrations more frequently in the dry season. In addition, somatic coliphages were detected in samples from the three regions, with higher concentrations in region 2. Furthermore, a statistically significant relationship was found between somatic coliphages and diarrheal cases, classified as outbreaks or alerts in the region. Thus, the results confirmed that somatic coliphages are a good indicator of the presence of diarrhea cases in a specific region.

Coating polystyrene beads with iron oxide for the adsorption of carbofuran from the water supply.

Population growth requires more food production and as a consequence, there is the indiscriminate use of agrochemicals, among them major group are carbamates. At times, runoff of pesticides leads to surface water pollution that serves as a source of public supply. Thus, the presence of these microcontaminants in surface water has become increasingly frequent. The treatment developed in this work uses the principle of adsorption as a technology for the removal of carbamates, more specifically carbofuran. Two methods of coating the polystyrene beads with iron oxide were used to adsorb these microcontaminants from the water. The coating was evaluated through the chemical extraction of iron, analysis by scanning electron microscopy and BET analysis. The metallurgy that presented the best coating was the one that used the ferric chloride. The beads coated by this methodology were used for adsorption tests of carbofuran and showed positive results after verification of the influence of pH on the adsorption process.