The appearance of two duckweed species in sewage effluents in Yaounde (Cameroon), and their possible use for sewage treatment and feed production

1 The ecological and the economic significance of the spontaneous occurrence of Lemna aequinoctialis and Wolffia arrhiza (Lemnaceae) in some sewage effluents in Yaounde is studied. 2 Physico-chemical analyses and laboratory scale experiments revealed the suitability of the effluents in supporting the growth of the two plant species. The standing biomass of the species was 5-12.5 kg fresh weight m super(-2). 3 The nutrient contents of the Lemnaceae suggest their ability to produce biomass of good quality in these effluents. Farming of such crops will serve both as cost-effectively treatment of domestic sewage and provide cheap animal feed.