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

Heavy metals and nutrients are among pollutants in the United States, which enter soil and water through urban runoff, and landfills. The removal of contaminants particularly heavy metals and excess nutrients from natural resources including groundwater, surface water and soils has been increasingly receiving attention of researchers due to the toxicological problems caused by the contaminants to the ecosystem and to human health in the recent years. Among the various methods, application of adsorbent has been proven to be an efficient technology while its large-scale application is limited by the high material cost. Currently, several promising biomass-to fuel approaches, produce biochar as the major byproduct indicating a large amounts of biochar will be available in the near future due to increasing importance of green biomass fuel as an alternative energy. Biochar, derived from various biomass sources by pyrolysis under anoxic conditions 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 better growth rate thus faster uptake of atmospheric CO₂via photosynthesis.

Several column experiments were conducted to study the sorption of Zinc (Zn), Copper (Cu), Cadmium (Cd), Lead (Pb), Arsenic (As) and fertilizer nutrients including nitrate (NO₃), phosphate (PO₄), ammonium (NH₄) on relatively cleaner commercial biochar. Prior to the column experiments, biochar, soils and sands were screened for elemental abundance by using handheld Thermo Niton’s XL3 hand-held X-Ray Fluorescence (XRF) spectrophotometer at York. Physical and chemical parameters including pH, ORP, conductivity, temp., heavy metals, nutrients were monitored in inflow and outflow by using YSI multi-probe, DPCSV (Differential Pulse Cathodic Stripping Voltammetry, Chemetrics and Lachat multichannel FIA nutrients analyzer at York. Preliminary investigation on an oak derived commercial biochar (<250 µm) duly amended by sea washed sand (1:1) indicated significant sorption of heavy metals including Zn, Cu and limited sorption of nutrients except phosphate at circumneutral pH. An improved understanding of these physico-chemical factors has broad implications for contaminated water and soil remediation.