Enhancement of Biochar from Waste for Soil remediation in urban areas

Important results from the project

The purpose of this study has been to investigate whether biochar that has been refined, through mechanical post-processing processes and with the adding of other materials, has a better ability to bind environmental toxins compared to untreated biochar. The effect was studied on contaminated soil with moderate to high levels of both metals and polycyclic aromatic hydrocarbons (PAH). At the time of study start, no such soil was available. Thus, two different soils were chosen; one contaminated with copper (Cu), lead (Pb), nickel (Ni) and zinc (Zn) and another contaminated with PAH.

Expected long term effects

Processing of wood chip-based biochar, through the addition of clay or iron oxide, during mechanical post-processing processes, seems to increase the product´s ability to bind organic toxins. The ability of the processed biochar to determine PAH increased up to about 4 times for the 16 studied PAHs when the biochar was mechanically processed in a cyclone with clay admixture (50%) and up to 6 times when the biochar underwent processing. an extruder with iron oxide admixture (50%) and a small proportion of miscanthus (<1%).>

Approach and implementation

To obtain a picture of the mechanisms for the solubility of Cu, Pb and Zn, we used a geochemical model, we used Visual MINTEQ software to perform calculations. The soil without biochar and soil with biochar mixtures aged for two weeks before the various tests were started. All tests were performed in triplicate. The freely dissolved concentration (Cw, freely dissolved) of 16 PAHs in leachate from PAH contaminated soil and soil with biochar mixtures was investigated using the POM method (Arp et al., 2014; Josefsson et al., 2015).