Biomass Production and Nutrient Removal Potential of Water Hyacinth Cultured in Sewage Effluent

Growth and nutrient uptake of water hyacinth (Eichhornia crassipes [Mart] Solms) cultured in sewage effluent were measured over a period of 1 year in a prototype wastewater treatment system which has been in operation at Walt Disney World near Orlando, Florida. Annual productivity of water hyacinth cultured in primary sewage effluent (Channel II) was found to be in the range of 5 to 27 g dry wt m⁻² day⁻¹ (23.6 dry tons acre⁻¹ yr⁻¹). Average growth rate during the months of May through October 1982 for hyacinth cultured in Channel II (primary sewage effluent) and Channel I (treated primary sewage effluent leaving Channel II) was about 16 g dry wt m⁻² day⁻¹ (27 dry tons acre⁻¹ yr⁻¹), compared to the growth rate of 13 g dry wt m⁻² day⁻¹ (22 dry tons acre⁻¹ yr⁻¹) for hyacinths cultured in secondary sewage effluent. Plants cultured in secondary sewage effluent generally had longer roots than the plants cultured in primary sewage effluent. A significant relationship was observed between the growth rate of hyacinth and the solar radiation. Nitrogen and P concentration of the plant tissue were higher in the hyacinths cultured during winter months compared to the plants grown in summer months. Average N and P concentration of the plants cultured in primary sewage effluent were found to be 3.7 percent N and 0.94 percent P, respectively, while the plants cultured in secondary sewage effluent had a total N and P content of 2.8 percent N and 0.79 percent P. Nutrient ratios of the major plant nutrients were found to be approximately the same as the nutrient ratios in the sewage effluent. Annual N and P uptake rates of hyacinth cultured in sewage effluent were found to be in the range of 1176 to 1193 kg N ha⁻¹ yr⁻¹ and 321 to 387 kg P ha⁻¹ yr⁻¹, respectively.