| Abstract [eng] |
About 180 million tons of digestate is produced in the 28 EU countries, and almost half of it is produced in Germany. Most of the digestate (about 120 million tons) is agricultural digestate (a mixture of manure and plants). The rest is obtained by mechanical biological treatment from municipal solid waste, separated biological waste or sewage sludge, and the agricultural/food industry. In the past, this anaerobically degradable biological waste (digestate) was extracted from manure and/or sewage sludge. However, renewable energy policies and subsidies for electricity, gas, and heat production from biomass have improved the economic conditions for the anaerobic digestion of biological waste or food waste in various EU countries. In this way, in addition to energy production from biogas power plants, biogas digestate/fallow is also produced. In 2000, scientific research on digestate was started and it revealed a quite wide field of usage of this product. According to various studies, the fallow of biogas is a product that can be used for plant fertilization, animal feed, extracting water for irrigation, etc. However, it was also noted that a lot of detailed scientific research should be done on risk factors, environmental effects, fertilizer treatment methods, and enrichment during long-term use [1-3]. The aim of this work was to analyze and evaluate the chemical composition of the thick digestate (remaining after separation) in detail and to predict its areas of usage. Digestate obtained from three companies was used for the research (Fig. 1): Agaro riešutas (Biržai), Tvari energija (Vievis), and Kurana (Pasvalys). The concentration of nitrogen, phosphorus, potassium, calcium, magnesium, carbon, trace elements, and heavy metals was determined. Moisture content, pH, and granulometric composition in the initial raw material were also determined. [...]. |
