Development of Microcontroller Based Portable Optical Instrumentation System for Measurement of BOD

Abstract

Aims: To design, develop and fabricate a portable optical instrumentation system for the measurement of Biochemical Oxygen Demand. Place and Duration of Study: The design and fabrication of the portable optical instrumentation system was conceptualized at Department of Chemistry and Department of Electrical Engineering J.N.V University, Jodhpur and fabrication was done at M/s Mindfield Technologies Pvt. Ltd., Jodhpur under the Instrument Development Program of DST, New Delhi. Methodology: A portable optical transducer device with microcontroller embedded circuit has been designed for the measurement of dissolve oxygen (DO) and calculation of Biochemical Oxygen Demand (BOD). It comprises of three functional units viz., sensing unit, instrumentation unit and controller unit. A monochromatic light source is used to irradiate the prepared sample solution under test. A part of the incident light is absorbed by the solution under test and intensity of the transmitted light is measured on other end by the optical sensor. The change in light intensity is used to calculate the DO and subsequently report BOD on LCD display. Results: A portable optical instrumentation system has been developed successfully and tested. The performance of the designed system has been assessed by means of statistical approach based on repeated measurement and obtaining standardization curve. The performance of the designed optical instrumentation system was validated by measuring the BOD values for standard Glucose-Glutamic Acid (GGA) solution and comparing them with those obtained from the standard Winkler’s method; the results depicted a close agreement. Conclusion: The developed portable BOD instrument is battery operable and compact for facilitating field use.