Association of natural lagoons and infiltration-percolation: pilot test results and perspectives

Abstract

Many small French communities have been equipped with Waste Stabilisation Ponds. Their effluent quality is relatively good for N and P but is known to be poor regarding organic matter. Pilot trials show that it is possible to decrease 50 % of the outlet SS and to obtain an additional nitrification thanks to one additional filtration on a 25 cm sand height. The follow-up of a self-priming siphon shows its capacity to function with only 1 cm height of tidal range. The owner of Aurignac accepted to built a demonstration WSP plant, followed by Intermittent Sand Filters. The primary sludge, which accumulates at the inlet of the 1st pond will be spread each day on four Sludge Dewatering Reed Bed Filters. He submitted in November 2001 this project (capacity of 300 PE) to the EEC in the LIFE-environment program. This paper gives the results of pilot trials and of the siphon functioning. It explains the demonstration plant design basis and explains our objectives.