Abstract 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 concentra-tions 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
Keywords Gas sensor/Water quality/Water treatment/Wastewater/Chemical oxygen demand/Biological oxygen demand
Introduction
One of the most significant environmental issues facing humanity is the growing global pollution of water supplies with thousands of natural and industrial compounds. It has been more prominent in recent decades due to globaliza-tion, industrialization, and sudden increase in population. Around 3.4 billion people have no access to clean drinking water, which is correlated with more than 35% of all deaths in developing countries [1]. The term wastewater is used for water that contains human waste, household, animal waste, fats, soap, and chemicals. The term sensor is derived from “sentio”, the Latin word for perception or observation . A sensor is a device used to detect the analyte of interest and responds to the presence of a contaminant or analyte present in the environment. Over the years, humans have advanced water quality detection methods to identify bacteria, organic, and inorganic chemi-cals and other parameters (e.g., pH, hardness (dissolved Ca and Mg) and turbidity (cloudiness). The sensors are used to maintain and monitor water quality and protect water users. These sensors may be placed at appropriate places, centrally within, inside or even on the point of use of a water treat-ment facility. The water quality can be monitored online or offline with the help of sensors. These days, online monitor-ing of water is preferred due to the fast response of these type of systems. There is a lack of appropriate sensors which can be used for proper real-time monitoring for maintenance and water quality monitoring. One of the most used water treatment techniques is sequencing batch reactors . It is an activated sludge system that is used for enriching the sludge with phosphate accumulating organisms. Most of the reactors are operated based on offline steps, which means that data sampling is low frequency and that the results are delayed. It is an obstacle to the proper management of systems and makes
Post time: Dec-19-2024