Development of a low-cost portable turbidimeter for chemical processes

Turbidity is a physical property related to the scattering of light by particles that are suspended in a liquid. Measuring turbidity of potable water, fluids from industries, or effluents is a quality control practice. Commercial turbidimeters are priced in the range of hundreds to thousands of dollars. The calibration technique required by standards is also expensive, and difficult to perform. Considering this scenario, it is proposed in this work the development of a low-cost portable turbidimeter for monitoring turbidity in chemical processes. An infrared LED was used as light emitter and an infrared phototransistor as light receiver. The signal processing control unit was developed with the Arduino Uno platform. It was also investigated alternative ways to calibrate the device, by using a random fluid and comparing the results with a calibrated turbidimeter. The calibration of the turbidimeter was done by means of a comparative test in triplicate, using as reference the commercial turbidimeter 2100P, HACH®. The proposed device was able to perform analysis in the range of 100 to 1000 NTU, and within a good price range, costing US$ 46.30.

Keywords: low-cost technology, nephelometry, open-source technology, turbidimeter.