BIOLOGICAL AERATED FILTERS - AN ADAPTED BIOLOGICAL PROCESS FOR WASTE-WATER FROM COASTAL AREAS

Compact facilities together with modular and environment-friendly appearance are arguments in favour of Biological Aerated Filters (B.A.F.) in coastal areas where the amount of available land imposes strict limitations on technological choices. The operation of B.A.F. in combination with a physico-chemical process was studied using the data obtained from two wastewater treatment plants located in coastal areas (Barcares and Saint Palais/Mer, France). The main conclusions are the following. Effluent quality in terms of COD, BOD5, S.S. proved satisfactory for organic load conditions higher than those applied when using conventional procedures. Adaptation to organic load variations is not a basic problem for this type of coastal community,but hydraulic flow-rate control should be the main concern. Restarting plant operation after a long shutdown only takes a few days. Furthermore technical and economical optimisation required continuous monitoring, especially in the field of washing and aerating control. This type of management involves the use of reliable, high-performance control equipment.