L’EPURATION DES EAUX USEES AU SERVICE DE L’AQUACULTURE : UN MODELE INTEGRE DE GESTION DES EAUX AU SAHEL

Abstract

The University of Niamey has a site pilot treatment of wastewater from lagooning and reuse of by-products of the wastewater treatment plant for irrigation and fish farming. This site has been made in an extensive program of research/action in partnership between the University Abdou Moumouni de Niamey and the Belgian development NGO's AQUADEV. It allows one hand to test the yields of several variants of stabilization ponds as the lagoon to microphytes, lagooning rooted or floating macrophytes. On the other hand this pilot site is designed to allow reuse of by-products generated from wastewater treatment, so that the problem of wastewater management is not only seen as an issue which would be limited to environmental clean-up, but that would be considered a genuine issue of integrated management of the resource. I.e. taking into account the requirements of the receiving environment and that would meet a real need for social and economic development sustainable in relying on choice of channels of reuse of by-products. The objective of this study is, on the one hand, to verify the treatment capacity of duckweed in Sahelian climate and to assess, to opportunities for direct recovery of the macrophyte for rearing of Tilapia in the clean, from the stabilization ponds of Niamey University.The treatment results obtained through the use of the duckweed show a significant abatement of the pollution load that can reach over 70% for the ammoniacal nitrogen and more than 80% for phosphorus and 70% for the DBO. The reduction of the bacterial load is greater than 4 log units. The biomass of produced water lens was of the order of 700 kg/ha/day of fresh weight. This biomass has allowed the production of approximately 475 kg/ha/month of Tilapia. For a system serving 5000 inhabitants, the potential income, obtained by the sale of Tilapia or lentils, can reach €1000 / month.