The Content of Heavy Metals in Waste as an Indicator Determining the Possibilities of Their Agricultural Use

The aim of the study was to evaluate the available waste in view of the heavy metals and fractions thereof. Three waste materials were analyzed in the work, namely dried, granular sludge, digestate from agricultural biogas plant and ash after combustion of biomass from the combined heat and power plant, in terms of the content of heavy metals in them. Their mobility through fractional analysis was determined and the possibilities of their agricultural use were assessed. The analyzed waste was varied due to the pH. Biomass ashes had the highest pH and it was alkaline. The pH of the dried precipitate was neutral and digestate was slightly alkaline. In the analyzed wastes, the content of permissible concentrations of heavy metals determined in the Regulation of the Minister of the Environment was not exceeded. The content of individual elements varied and depends on the type of waste tested. The conducted sequential analysis showed that various metal fractions are present in the tested wastes. The content of heavy metals in individual factions was varied and the content of mobile and potentially mobile fractions, i.e. metals of fractions I and II, was lower compared to the non-mobile fractions III and IV.