Composting is a recycling method based on biological degradation of organic solid waste (OSW) by microorganisms under aerobic conditions, resulting in a stable and mature organic compound that can be used as organic fertilizer in agriculture. Several countries have invested in this technology as part of urban solid waste management, since it is considered simple and inexpensive, provided there are parameters controlled during the process such as temperature, humidity, pH, carbon / nitrogen ratio and particle size. The composting process in the reactor system presents some advantages when compared to the traditional process in piles or ponds, as the requirement of smaller area and labor. The objective of this work was to evaluate the chemical stability and maturity of compounds from organic solid waste treatment by composting process in a reactor system. The reactor was constructed and filled with 60 kg of material, being 58% of OSW, 28% of Wood waste-sawdust and 14% of dry leaves. To evaluate the chemical stability of the compound the following parameters were monitored for 120 days: Temperature (°C); pH in 0.01 molL-1 CaCl2 solution; moist at 65°C; carbon/nitrogen Ratio; cation exchange capacity (CEC mmol kg-1); Total Organic Carbon (TOC) and CEC/TOC ratio. Toevaluate the maturity of the compound the following parameters were monitored: Germination index (GI); Electric conductivity (EC); Spectroscopic characterization of humic acids in the ultraviolet-visible region (UV-Vis); Spectroscopic characterization of humic acids by Fourier transform infrared spectroscopy (FTIR) and ash content. It was observed that after 90 days the compound presented stability, with reduction of temperature, moist and Carbon / Nitrogen ratio, increase of pH, CEC and CEC / COT ratio; however, the maturity of the compound was reached at 120 days of the composting. The compound reached stability and maturity at the end of the composting process (90-120 days), indicating that it could be used as soil corrective in agriculture.
KEY WORDS: organic solid waste, composting, stability, mat