Biokol för rening av kväve och fosfor ur dagvatten i Segeåns avrinningsområde

Sammanfattning: Stormwater from urban areas contain a number of pollutants, among which nitrogen and phosphorous have been of lesser focus. In this study I aim to investigate if biochar has the potential to fill the role as water filter in urban areas, and to pin point what should be experimentally investigated in order to evaluate biochar in comparison to two contemporary filter systems: bioreactors and chalk filters. In natural systems, nitrogen is most efficiently removed from water by denitrification, and phosphorous is removed by adsorption and precipitation. Biochar can facilitate microorganisms and capture materia crucial in the denitrification process and is, if produced in the right conditions, capable of retaining phosphorous with primarily magnesium oxide groups. When treated in slow pyrolysis at high temperatures, oak, sugarcane and rapeseed are good precursors to biochar. In order to get a high amount of magnesium oxides the precursor material of biochar can either be anaerobically digested or pretreated with magnesium. When measuring the potential of biochar to remove nitrogen from water, the experiments should focus on measuring conditions for bacteria, levels of oxygen in the filter and the efficiency by which nitrogen is removed. When measuring the potential of biochar to remove phosphorous from water, the experiments should focus on the efficiency and longevity of the retention capacity. In order to evaluate the potential for phosphorous and nitrogen to be removed in the same filter, the experiment should also focus on if phosphate is removed more efficiently in aerobic conditions than in anaerobic conditions. Biochar has a great potential to fill many roles in our society, removing nutrients from storm water may be one of them. The benefits of having biochar as a filter for stormwater extends beyond the removal of nitrogen and phosphorous, different kinds of pollutants may be caught in the process and eliminated.