Waste ashes from burned sunflower hulls as new fertilising materials

Abstract

Closing the loop – An EU action plan for the circular economy identified the Fertilisers Regulation revision as a key legislative proposal to boost the market for secondary raw materials. The European Commission has adopted recently EU Fertilising Products Regulation EU 2019/1009 expanding its scope to secondary-raw-material-based products (from biogenic wastes and other secondary raw materials). During the industrial processing of sunflowers, sunflower husks used as alternative fuels resulting in the generation of waste ash. Sunflower ash is a known material as a good and cheap source of potassium. In present study the tested samples of ashes is characterized as a starting raw material for the producing fertilizers in an accredited and authorized Laboratory for fertilisers quality. The tested samples is not loaded with heavy metals and the risk of recycling contaminants has not been assessed. According to the content of available (water-soluble) elements, the content of soluble phosphorus and micronutrients is very low, while potassium is completely water-soluble (40 to 50% K2O m/m), therefore, the tested ashes can be regarded as a good raw material as a source of potassium component in the final product. The pH reaction of the samples is extremely alkaline, therefore it is necessary to neutralize pH reaction in the industrial processing of this raw material, or to restrict the final product for use on acid reaction soils.