Continuous measurement of pollution due to urban effluents under wet conditions using optical systems

Optical sensors appear well adapted to the pollution measurement of urban discharges during wet weather: they allow a continuous and long time investigation of sudden and highly variable phenomena such as rainfall events. They may also be connected to remote monitoring and sanitary equipment automation systems. This paper deals with the measurement principles and use of this type of equipment: adjustment and calibration, sample collection, equipment maintenance and measurement validation. Taking into account the hydraulicity (flow rate or velocity) allows one to improve appreciably the calibration for runoff waters. Calibration at the laboratory seems better than calibration using registered data on the field, as it makes it possible to eliminate the Suspended Matter under-estimation resulting from sampling/analysis.