Researchers in the United States have developed a new, accurate, and economical sensor-based device capable of measuring Escherichia coli levels in water samples in less than 1 to 8 hours could serve as a valuable early warning tool.
The device is described in an article in Environmental Engineering Science, a peer-reviewed journal published by Mary Ann Liebert, Inc.
The device may be a valuable tool in protecting swimmers and suffers in Costa Rica from sea water laced with sewage. Now measurements are in the hands of the Instituto Nacional de Acueductos y Alcantarillados. Typically samples are taken and brought back to the San José lab for culturing.
Current methods to detect Escherichia coli, a bacterium highly indicative of the presence of fecal matter in water, typically require 24 to 48 hours to produce a result.
Costa Rican beaches are vulnerable to contamination because Central Valley sewage flows untreated into the Gulf of Nicoya. In addition, communities like Tamarindo have had serious problems with sewage leaking into the sea.
The article provides a detailed description of the battery-powered device, which contains a prototype optical sensor that can measure changes in fluorescence intensity in a water sample. In the presence of E. coli bacteria an enzymatic reaction will cause an increase in fluorescence.
The device can detect high concentrations of bacteria in less than 1 hour and lower concentrations in less than 8 hours.
Jeffrey Talley of Johns Hopkins University and colleagues with Environmental Technology Solutions and the U.S. Army Corps of Engineers presented the results of a seven-day demonstration project using the device. The detection system developed is able to collect and analyze a water sample every six hours and to employ wireless transmission to send the data collected to remote monitoring stations.