Recovery of Ammonium in Urine by Biochar Derived from Faecal Sludge and its Application as Soil Conditioner

摘要

Recovery of ammonium from source-separated urine was achieved through biochar adsorption. Fecal sludge was used to produce biochar by pyrolysis. This method allows for self-treatment of human excrement. Biochar saturated with ammonium was applied to the soil as a conditioner. Results showed that the adsorption capacity of biochar increased with the decrease in particle size and increase in temperature. Kinetic experiments showed that adsorption of ammonium by biochar was in accordance with the pseudo second-order kinetic model, and equilibrium data agreed well with data from the Freundlich isotherm model. Dynamic adsorption experiments showed that biochar could be effectively used as an adsorbent to recover ammonium from actual urine. When the saturated biochar was used as a soil conditioner, the cation exchange capacity of the soil increased from 8.4 cmol/kg (weak nutrient retention and supply capacity) in the beginning of the experiments to 13.6 cmol/kg (medium nutrient retention and supply capacity) at the end of the experiments (140 days). Soil pH increased by 0.9 units compared with that in the blank test.