Extrahera tungmetaller ur rötrest med naturligt anskaffade ämnen

Sammanfattning: As the demand for biogas increases, so does the amount of digestate produced. Digestate contains large amounts of nutrients and has been introduced in agriculture as an alternative plant nutrient. However, digestate can have a high content of heavy metals which over time increases in soil concentration and can have negative consequences for humans and the environment. Therefore, methods to remove the contaminants in digestate are necessary, while enabling resource recovery that reduces the demand for raw materials and promotes a circular society. In this study, a method was designed and tested that enables the extraction of heavy metals using the naturally sourced substances chitosan and apple cider vinegar. The quantitative part of the study has been carried out in the form of laboratory experiments with solutions of the heavy metals copper(ii)sulphate (CuSO4) and iron(iii)chloride (FeCl3), since the metals are easily analyzed in connection with their strong colors and reflect a typical behavior of heavy metals. The laboratory was divided into two phases where first the method was tested on aqueous solutions with heavy metals and then on biogas digestate. The qualitative part of the study consisted of two interviews with active actors in the field to gain a broader perspective and greater knowledge. The results show that apple cider vinegar and chitosan together enable the removal of heavy metals from polluted water.