Mise en oeuvre de la turbidimétrie pour évaluer la pollution des eaux résiduaires

Implementation of turbidimetry to evaluate the pollution of waste water

Laboratoire Central des Ponts et Chaussées, BP 4129, 44341 Bouguenais Cedex, France

Abstract

Turbidimetry is interesting for particulate pollution measurement, as its signal is continuous. instantaneous and tele-transmissible. For non-submersible turbidimeters installed on diversion pipes, a water feeding system including a primary circuit fed by a vortex immersed pump (Ø 50 mm) allows to reach a good reliability. Calibrating the device at the laboratory by directly dipping the sensor in the sample just before it is analysed, appears more representative when the signal moves quickly (rainy weather) than calibrating the device with the turbidity recorded in the field. The calibration of Suspended Matter concentrations in relation with turbidity in combined sewers appears rather steady from one site to the other during dry weather, and different but not very variable during rainy weather on the study site.