PI: Prof. Soumyo Mukherji, Department of Biosciences and Bioengineering

Tata Fellow: Jasleen Chabra (2016-18)

Water crisis is emerging as a serious problem all over the world, especially in India. In order to cope with this problem, different solutions for reusing water for household purposes have come up. Reusability of water requires proper treatment and disinfection. Thus, there must be proper quality check before it reaches the end user on a daily basis. To this end, the need for a cheap and rapid sensing platform is of utmost importance. Among the various criteria of quality checks, monitoring bacterial contamination is of primary interest in water and environment quality control for health and safety purposes. Bacteria monitoring in water has been studied previously using various methods i.e., optical, piezoelectric, electrochemical detection. Among the optical techniques, the most common are surface plasmon resonance, fluorescence intensity measurement, evanescent wave based absorbance detection etc., while piezo based methods mostly use the cantilevers and quartz crystal microbalance.

Apart from optical and piezo based methods, one of the most routinely used transduction techniques for detection of bacteria is the electrochemical method. Electrical transduction technique is based on the measurement of current or potential changes occurring at the electrode or sensor-sample interface. This technique offers certain advantages in terms of cost effectiveness, scope for miniaturization, ability to work with turbid samples, low power consumption, applications in point-of-care diagnostics, etc. However, this method has slightly limited selectivity and sensitivity with respect to optical methods of detection. Biosensors based on electrochemical transduction exclude the use of any light source or bulky instruments or mechanical motion, etc.

In this project, we will be aiming at the quality control of recycled grey water using electrochemical impedance spectroscopy. Grey water is defined as any domestic wastewater produced (from bathroom sinks, bath, shower etc.), excluding sewage. Treatment and disinfection of grey water are important to provide water that is both safe and aesthetically appropriate for reuse in toilet flushing, irrigation of plants, etc. Inadequately treated or disinfected grey water presents a risk of infection to end users from pathogens in the reused grey water. Thus there is need for a sensor that can detect the quality of the grey water after the treatment process.

The proposed sensor intends to detect any bacteria present in water and is non-specific in nature. The idea is to determine the quality of the treated grey water as well as efficiency of the treatment plant by using sensors both at the inlet and the outlet of the plant. We also plan to develop a portable device as an alternative to the available bench top setup of frequency response analyzer for impedance spectroscopy measurements, so that it can be used directly in the field.