Elemental analysis of wastewater effluent using highly sensitive fiber Bragg grating sensor.

Industrial effluent is largely being used for irrigation of crops. Hence, monitoring its pollution level is essential to check its suitability for the purpose. We propose a simple and highly sensitive Fiber Bragg grating (FBG) sensor to determine the concentration of Chloride (Cl) and Lead (Pb) ions present in the treated waste water effluent of sugar factories. It is based on the principle of shift in the Bragg wavelength of an etched FBG with change in the ambient refractive index. The etched FBG was calibrated by known concentration of solutions containing the element under study and then was used to quantify the element in the waste effluent. Proper reagents were used for selective determination of the element. The concentrations of Cl and Pb ions in the effluent sample determined by our designed FBG sensor are 95.73 ppm and 0.008 ppm respectively which are in good agreement with the results obtained by APHA (American Public health association) standard techniques employed for wastewater analysis. Sensitivities of Cl and Pb sensors are calculated as 0.76 pm/ppm and 38.6 pm/ppm respectively. Sensitivity of the sensor for Pb ions being about 50 times greater than that for Cl ions, suggests a higher sensitivity of sensor in lower range of concentration in ppm. Limit of detection of our sensor for Cl and Pb are 1.2 ppm and 0.003 ppm respectively which are lower than that of APHA techniques, suggesting the superiority of our sensors. Simple working, miniaturization, cost-effectiveness and ability of online measurement are the most important features of FBG chemical sensors that give them an edge over existing techniques for continuous effluent monitoring. [ABSTRACT FROM AUTHOR]