Evaluating the Potential of Pineapple Peel Biochar and Lateritic Soil in the Adsorption of Phosphorous from Human Urine

Abstract

The diminishing phosphate rock reserves and the increasing cost of fertilizer production is a major driver for seeking alternative sustainable sources of phosphate fertilizers to meet the growing food demand. Extracting nutrients from human urine to obtain fertilizers for crop production can contribute in achieving phosphorous fertilizer demand in addition to protection of fresh water bodies from pollution. This study aimed at evaluating the potential of pineapple peel derived biochar (PPB) and lateritic soil (LS) in adsorbing phosphorous (P) from human urine. The effect of contact time and initial concentration of P on adsorption was evaluated. Langmuir and Freundlich isotherm models were employed to correlate the experimental equilibrium adsorption data. The results indicate that PPB adsorbs P from human urine but releases into the solution thus not attaining equilibrium. There was an increase in the amount of adsorbed P on LS upto equilibrium. Langmuir model (R2= 0.984) best described P adsorption on LS with a maximum monolayer adsorption capacity of 45.25 mg/g calculated from the model. These results indicate that LS can hold P for crop use if enriched with human urine whereas the adsorbed P by PPB can be easily leached. Keywords—Equilibrium, Freundlich, Isotherms, Langmuir, Phosphorous