A new biosensor for rapid oxygen demand measurement

A biosensor for the determination of oxygen demand (OD) using bacteria isolated from activated sludge has been developed. This sensor allowed OD measurement with a short response time, an operation stability of 48 days, and a serial coefficient of variation of +/-1.3% when a sample solution with 6.6 mg/L OD was employed. A linear range was obtained up to 32.8 mg/L OD using a glucose-glutamic acid standard solution. Comparable results were obtained for OD values estimated by the biosensor and biochemical oxygen demand (BOD) determined by the 5-day method. The biosensor was applied to on-the-spot estimation of OD for the effluent from wastewater treatment plants.