Pollution characterization of waste water of an industrial zone - Example of a dairy water clarification

The objective of this study is the estimation of the polluting load generated by domestic effluents added to those of various industries in one of the most important industrial zone in Africa. Analysis of waste water showed strong and irregular pollution which is prejudicial for the aquatic receiving medium (river, sea). This pollution is confirmed among others by COD/BOD ratio which may attain the value of 1.8. Pre-treatment by coagulation floculation of waste water used in a dairy belonging to this industrial zone showed a considerable reduction of the initial pollution by a systematic decreasing of pollution parameters. Aluminium sulphates and iron chloride tested in this experience have reduced considerably all the studied parameters; the organic charge has received a very significant reduction up to 99%. The discharge of treated effluent in the surrounding river or its use for recycling aims is then possible for this industry. However, the formed sludge can be the subject of a suitable treatment for possible agricultural, avicolous valorisation or other. (author)