Sensor system using polarization analysis method to monitor oil-on-water in water purification plants and rivers.

Some 80% of accidental pollution in river water is caused by oil spills. Oil spills can cause serious damage such as suspension of water intake at water purification plants and major harm to ecosystems in the lower reaches of rivers. This is because oil-on-water tends to spread easily, quickly exacerbating the damage. To address this problem, an automated, continuous sensor system with high sensitivity can be used for early detection of spill accidents. We have developed a sensor system for detecting oil-on-water based on a polarization analysis method. Its advantages include: a) no direct contact with sample water; b) minimal maintenance; c) largely unaffected by foreign matter and waves on the water surface; and d) much higher sensitivity than simple visual observation. This paper describes the measurement principle and configuration of the sensor system, and discusses the results of sensitivity tests and tests on the influence of water turbidity, foreign matter and waves. We will also consider some of the limitations of the new system.