RESEARCH INTO THE THERMAL CHARACTERISTICS OF GRANULAR FUEL MADE FROM SEWAGE SLUDGE

Abstract

Today, the scale of the formation and accumulation of various wastes, in particular sewage sludge (SS) at sewage treatment plants in settlements, continues to grow. This situation leads to the alienation of productive agricultural lands by sludge and environmental pollution, which requires their immediate processing and disposal. One of the effective ways to process SS can be to produce granulated biofuel from it. The paper considers the issue of utilizing SS by producing biofuel pellets from them. For experiments on the production of pellets, samples of sewage sludge from the treatment facilities of regional municipal production enterprise "Dnipro- Kirovograd" in the city of Kropyvnytskyi after centrifugation with 75–80% humidity of two types: raw sediment and excess activated sludge. The experiments were carried out according to the developed research methodology on a specially designed laboratory press device. Due to the high humidity of the sludge sediment samples (75–78%), before making pellets from them, their preliminary preparation was carried out by thermal (drying) and mechanical (grinding) treatment. From the prepared sludge sediments with a humidity of 12–15%, when compressed to final pressures of 130.5…217.5 MPa in a press device with a vertical punch and a closed matrix, pellet samples with a high-quality texture and a density of 1150–1260 kg/m3 are formed, which meets the requirements of European standards ρ ≥1.0 g/cm3. The determined ash content of the manufactured samples of biofuel pellets on dry weight was 24–41%, and the calorific value calculated by the D. Mendeleev formula was 16–20 MJ/kg, which is comparable to the calorific value of briquettes made of wood waste, brown coal, and peat. The obtained results of the conducted experimental studies can be considered as estimative. In general, they confirm the prospect of further research and development in the direction of technologies and equipment for the production of biofuel pellets from sewage sludge and their further utilization through use in thermal power plants.