The chemicals and equipment needed to detect pollutants in water can be costly and inaccessible to those in developing regions of the world. Researchers in the field of “frugal engineering” work to develop technology that can be made widely available to those with fewer economic resources. Scientists at the Singapore University of Technology and Design (SUTD) recently developed a method that requires little more than a basic camera phone to detect environmental pollutants in water and assess its drinkability.
The method relies on tracking the movement of microorganisms, specifically Paramecia aurelia, which are found in abundance in freshwater environments and are large enough to be seen at low magnification levels. The researchers used 5x magnification to view the microorganisms in a well containing water and different levels of pollutants for each experiment. The movements of the Paramecia were recorded at a rate of 15 frames per second and swimming speeds were tracked using a simple computer vision method.
The team found that the microorganisms’ speed was significantly and immediately impacted when the concentration of each pollutant hit unsafe levels. The researchers found that the Paramecia were also slowed down at lower pollutant levels; for example, the average swimming speed was nearly halved when heavy metal concentrations were at about half the level considered unsafe. Contaminants tested included zinc chlordie, copper sulfate and erythromycin. The study was published in Scientific Reports.
“Taking a sample of water and measuring the speed of Paramecia can therefore be used as a straightforward method to assess the drinkability of water without the need for specialised equipment or chemicals,” said lead author Javier Fernandez. “Usually, you would need a different test for each pollutant, but Paramecia swimming is a global measurement.”
The setup used by the researchers could potentially be replicated using an inexpensive, low-magnification lens attached to smartphone capable of basic video recording. The researchers say the method could be tested using different types of microorganisms, and data could be compiled to gain a better understanding of the source of different pollutants. In addition to offering a frugal option for those in developing regions, the technique could be used as a fast method to measure toxicity in laboratory environments.
Video Credit: SUTD