EVALUATION OF THE SORPTION CAPACITY OF BIOCHAR AMENDED SEDIMENTS: AN EFFECTIVE WAY TO REMOVE CONTAMINANTS FROM NATURAL RESOURCES AND TO REDUCE CARBON EMISSION

Water-soluble inorganic pollutants including heavy metals and nutrients may comprise an environmental toxicity problem if their movement through soils and potential transfer to plants or groundwater is not captured. Biochar, derived from various biomass by pyrolysis can immobilize heavy metals due to its high porosity, cation exchange capacity and charge density. Further, its ability to improve nutrient retention in topsoil results faster uptake of atmospheric CO₂ via photosynthesis. The study reports the results from series of column experiments to evaluate the biochar’s ability to adsorb and retain the heavy metals including arsenic (As), lead (Pb), cadmium (Cd), copper (Cu), zinc (Zn) and fertilizer nutrients including nitrate (NO₃), phosphate (PO₄), ammonium (NH₄). An improved understanding of these physico-chemical factors has broad implications for contaminated water and soil remediation. Sediments were amended with finely crushed and sieved (<250μm) biochar in a 4:1 ratio by volume. The mixture was packed into chromatography columns and leached against the gravity using a peristaltic pump. Metals and nutrients were measured in all leachates using Ion- chromatography, spectrophotometer and Echo-Chemie. Preliminary results showed significant sorption of metals and limited sorption of nutrients. An obvious competition between heavy metals and nutrients on sorption sites were also observed.