Gas Sensor Applications in Water Quality Monitoring and Maintenance

Industrial and population expansion in the last few decades has been a critical contributor to water quality degradation. Some of the gases emanating from water treatment plants are toxic and flammable, which need to be identified, such as hydrogen sulphide, carbon dioxide, methane, and carbon monoxide. Water quality monitoring systems must be developed to meet legal, environmental, and social requirements. Monitoring water quality is difficult due to the variability, nature, and low concentrations of contaminants that need to be detected. The gas emanating from these treatment processes plays an essential role in water treatment, monitoring, and control. Gas sensors can be used as a safety device in the water purification process. The gas sensors receive input signals in chemical, physical, and biological stimulus and convert them into electrical signals. The gas sensors can be installed in different wastewater treatment processes. In this review, we present state-of-the-art progresses, landmark developments, and technological achievements that led to the development of gas sensors for evaluating water quality. The role of gas sensors in water quality maintenance and monitoring is discussed, and different analytes and their detection technologies and sensing materials outlining their advantages and disadvantages have been summarized. Finally, a summary and outlook for future directions of gas sensors in water quality monitoring and maintenance are provided.