Events linked to Geosmin and 2-methylisoborneol (2-MIB) in a Water Supply in the State of Rio de Janeiro, Brazil: a case study

Abstract

Tastes and odors in tap water are problems faced by water companies worldwide, with consumers complaints mainly during summer, when cyanobacterial blooms occur and produce compounds such as geosmin and 2-methylisoborneol (2-MIB). We analyzed the data on taste and odor intensity and total concentration of geosmin and 2-MIB compounds in drinking water and raw water collected by the sanitation company supplying of the metropolitan region of Rio de Janeiro (Brazil) during the 2020 and 2021 water crises. Statistical and metagenomic analyses of the raw water samples of the year 2020, were performed. Organoleptic data allowed to signal the presence of these taste and odor (T&O) compounds in the drinking water, and the mean values of taste intensity were above the maximum allowed value of the Brazilian legislation, on average 37.5 times in 2020 and 5 times in 2021, indicating that the measures did not eliminate the problem. There was a linear correlation of 0.97 between the standard organoleptic taste and the total concentration of T&O in 2020. Metagenomic data, from raw water in the year 2020, for the mtf, mic and glys genes indicated 2-MIB as responsible for T&O. Modifications in the surveillance system of catchment and drinking water quality need to be adopted to circumvent the problems of cyanobacterial blooms in the Guandu basin, as conditions favorable to blooms will occur as long as the sanitation problems in this watershed are not solved.

Segurança hídrica para abastecimento urbano perante condições ambientais e qualidade da água do manancial: o caso da ETA Guandu, RMRJ

“…Há preocupação crescente com a vulnerabilidade de sistemas urbanos de abastecimento de água no Brasil em função de sucessivas crises hídricas desde 2014 em várias metrópoles brasileiras como São Paulo (SP), Rio de Janeiro (RJ), Brasília (DF), Fortaleza (CE) e Curitiba (PR) (ANA, 2016;BRAGA;KELMAN, 2016;CARNEIRO, 2016;DE NYS;ENGLE;MAGALHÃES, 2016;MMA, 2016;SOUZA FILHO et al, 2018;WERNECK-LIMA et al, 2018;ANA, 2019;SOUZA FILHO, 2019;LEMOS et al, 2020). Essa situação de maior risco à segurança hídrica, resultante de profundas mudanças dos usos da terra e de novos estressores climáticos, constitui atualmente um dos maiores desafios para a gestão dos recursos hídricos no Brasil.…”

“…Essa escolha foi motivada pelas crises hídricas sucessivas nos verões de 2020 e 2021 que afetaram o Sistema Guandu, quando se observaram alta turbidez, odor e sabor desagradáveis na água distribuída para a população da RMRJ, associados à presença da substância conhecida como geosmina ou similar, produzida por microrganismos prejudiciais à qualidade para consumo humano (XAVIER, 2020;KLIGERMAN;SANCANARI;NOGUEIRA, 2021;SOTERO-MARTINS et al, 2021).…”