Composting process parameters of different types of manure in a bioreactor
¹Poznan University of Life Sciences, Faculty of Environmental and Mechanical Engineering, Department of Biosystems Engineering, Wojska Polskiego 50, PL-60-637 Poznań, Poland
²Polytechnic University of Beja, School of Agriculture, Department of Technologies and Applied Sciences, Apartado 6155, PT7800-295 Beja, Portugal
*Correspondence: wiktor.bojarski@up.poznan.pl
Abstract:
Composting has been practiced since ancient times, where it was used to enhance soil fertility and support crop production. It is therefore regarded as the oldest known method of biowaste treatment. Over time, the process has been systematically optimized through studies on the dynamics of aerobic biodegradation of various organic substrates, making it one of the most extensively investigated biological treatment technologies. Despite this long history, composting remains an important research topic, particularly in the context of circular economy strategies and sustainable development objectives.
The aim of this study was to evaluate the composting dynamics of manure-based substrates differing in manure type, moisture content, and structural properties under controlled aerobic conditions. Experiments were conducted at the Ecotechnology Laboratory of the Poznań University of Life Sciences using four isothermal bioreactors (125 dm³ each) designed for controlled aerobic degradation. The tested materials included cattle manure (≈70% moisture), pig manure (> 80%), a mixture of cattle and pig manure (≈65%), and cattle manure (> 80%). During the process, O2 and CO2 concentrations, temperature, pH, bulk density, and mass loss were monitored, and dry matter, organic dry matter, organic carbon, and ash content were determined.
The results showed clear differences in composting dynamics depending on manure type and moisture content. The cattle manure (70% moisture) exhibited rapid heating and a stable thermophilic phase, whereas highly moist pig manure showed slower temperature increase and lower intensity. The manure mixture demonstrated the highest microbiological activity, while excessive moisture in cattle manure (> 80%) reduced process efficiency. These findings confirm that manure type and moisture are key determinants of composting performance.
Key words:
bioreactor, compost, composting process, manure composting, physico-chemical changes