Activated Biochar

Biochar is known to be a potential adsorbent material in treating nutrient rich or polluted waters. The biochar’s ability to retain nutrients such as nitrogen and phosphorous from agricultural waters was assessed by performing sorption experiments in the laboratory by Alchemia Nova and Technical Research Centre of Finland. Two distinct biochars were tested. Biochar 1 (B1) is produced by Sonnenerde GmbH from residuals of grain husks, fruit sludge and wood, and is milled down to a grain size of 0-0.2 mm. Biochar 2 (B2) is produced by Charline GmbH from wood and available at a grain size of 0-2 mm. The biochars were tested in the original, commercially available state and as well activated by water vapour. The biochars were added to separate solutions of ammonium, nitrate and phosphorous. The amount of nutrients that can be adsorbed by the char was calculated by measuring the concentration of the solution before and after biochar addition.

Direct benefits of the application are the possibility to apply activated biochar to the field, thus reducing the need for artificial fertilizer, reducing nitrogen leaching and increasing the amount of carbon in the soil and thus the soil structure. Moreover, adsorption capacities for phosphate can be enhanced effectively by chemical modification methods (e.g. doping with iron oxide) to strengthen its surface properties.