Author(s): Yudai Kohira
Email (s): e21m5811@soka-u.jp
Institution or organization of origin: Soka University
Country: Japan
Abstract
Lake Tana, the largest lake in Ethiopia, has been invaded with a notorious invasive “water hyacinth (Eichhornia crassipes)” since 2011. It is one of the fastest growing aquatic weed causing various social and environmental problems such as blockage of water channels and deterioration of native aquatic plants and lake ecosystem. In efforts to utilize this biomass, pyrolysis (carbonization) of squeezed solid residue of water hyacinth (biochar) has been proposed for energy and adsorbent utilization. Water hyacinth biochars have shown good adsorption capacity for ammonium-nitrogen (NH4+-N), which can be further improved by pre-treatment of feedstock or post-treatment of biochar. Therefore, the objective of this study was to investigate adsorption capacity of water hyacinth biochars treated by different pre- and post- treatments for NH4+-N. Three types of biochars were produced using squeezed solid residue of water hyacinth: untreated (BC), potassium hydroxide pre-treated (KBC), and hydrogen peroxide post-treated (HBC) with the maximum pyrolysis temperature of 350◦C. In the adsorption experiments, the effects of different solution pH and coexisting cations on adsorption capacity, and adsorption kinetics and isotherms were evaluated. Water hyacinth biochars with high adsorption capacity for NH4+-N can be further utilized as soil amendment and alternative nitrogen fertilizer when applied to soil.