Development of a sensor array based measurement system for continuous monitoring of water and wastewater

Non-specific sensor arrays provide a simple, non-invasive technique for monitoring changes in water and wastewater quality. An on-line measurement system that incorporated an array of conducting polymers was tested for continuous analysis both in a laboratory, and in the field. The headspace gas, generated from a sparged liquid sample within a temperature-controlled flow-cell was directly transferred to the sensor chamber for analysis. Experiments were statistically designed to investigate the reproducibility of the sensor responses due to humidity effects. The combined effect and interactions of temperature throughout the system, gas flow rate and sparger porosity were evaluated. An optimal sampling methodology was developed for water and wastewater samples. Selected methodologies were applied to a continuous monitoring system. Results showed high-resolution profiles from laboratory and field trials underlining the potential of the technique for the detection of sudden changes in the odour profile. The interest of appropriate data analysis protocols and of a general quality index for real-time monitoring of water and wastewater is also discussed.