ABSTRACT
M .A. Md Yunus School of Engineering and Advanced Technology, Massey University, Palmerston North, New Zealand
S.C. Mukhopadhyay Control and Instrumentation Engineering Department, Universiti Teknologi Malaysia, Skudai, Malaysia
ABSTRACT: A low cost system that measures impedance (real part and imaginary part) was used along with a planar electromagnetic sensor to estimate the amount of nitrate con tamination in natural water sources. The system can generate alternating 10Volt peak-to-peak sine waveform signals at frequencies of 164kHz, 260kHz, 350kHz and 800kH z. The design and operating principle of the low cost system as well as the different design o f planar elec tromagnetic sensors have been reported in this paper. Every sensor was tested with nitrates forms namely, sodium nitrates (NaNO )^ and ammonium nitrates (NH4N 0 3), each of differ ent concentration between 5mg and 20mg dissolved in 1 litre of distilled water and the real part and imaginary part of the sensors impedance were observed and analyzed using elec trochemical impedances spectroscopy approach. For every aqueous solution type (sodium nitrates (N aN 03) or ammonium nitrates (NH4N 0 3)) a semi-empirical equation based on multilinear regression model was determined from the percentage changes of real part and imaginary part values as compared to the mean real part, Rtotal and imaginary part, X total calculated from mili-q water at the frequencies 260kHz and 800kHz and estimated concen tration (EC) values. The semi-empirical equation could be used to determine the predicted concentration (PC) values of nitrates contamination (sodium nitrate or ammonium nitrate form) in natural water source. From the results and MLR models o f the sensors, the best sensor was determined and selected to be used in detecting nitrate contamination of nitrate in the form of sodium nitrate and ammonium nitrate individually. The system and approach presented in this paper has the potential to be used as a useful tool for water sources monitor ing in water sources.
