Chemical stability and sanitary properties of pelletized organo-mineral waste-derived fertilizer

Abstract

Different types of organic waste can be used as fertilizers or soil improvers, but such materials are susceptible to chemical and biochemical decomposition, and their storage can entail a deterioration in their quality. Evaluation of the influence of water content and ambient temperature on the chemical and microbiological properties of pelletized organo-mineral fertilizer produced on the basis of digestate from biogas plant and ashes from biomass combustion was the aim of the study. The results of the short (one month’s storage in the – laboratory silo) and long-term (one year’s storage in – unheated compartment) studies showed that the quality of the fertilizer depends on the temperature, fertilizer humidity, and air accessibility. The growth in the temperature from 20 to 30°C decreased the content of total and ammonium nitrogen, while the increase in water content stimulated the development of the fungi in fertilizer stored at 20 and 30°C. The access of the ambient air resulted in the increase of moisture and volatile solids content in the fertilizer. It was stated that fertilizer should be stored without access to the atmospheric air, at the temperature below 20°C to ensure their long-term chemical stability and microbial safety.