Abstract
In landfilling, biodegradation of municipal solid waste organic fraction (OFMSW) is a major mechanism that governs environmental pollution such as gaseous and liquid emissions. Application of innovative analytical techniques for waste characterization to identify the physicochemical composition and structural changes of the waste involved during the degradation process leading to emissions is important for sustainable management and treatment strategies for OFMSW. The study reports variations in the physicochemical composition of leachate and their relationship with organic matter stability during degradation of OFMSW. A conventional (SLR-1) and a hybrid (SLR-2) bioreactor system were utilized for this study. The OFMSW, including wood, paper, cardboard, kitchen, and garden trash, was collected from Tshwane landfill sites in Gauteng. Biological changes of OFMSW were explored through Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and physicochemical parameters. Progression and dynamics of the degradation processes were reflected by changes in the chemical information relative to the presence of aliphatic (CH), polysaccharidic (CO -C), aromatic (CH) and phenolic (OH) structures. The decomposition state was established by the presence or absence of distinct bands in the spectra. The pH and COD stabilized around 7.98 and 28 000 mg/L, but the COD then declined to <500 mg/L for SLR-2 and <10 000 mg/L for SLR-1. Hybrid operation effectively aided the biodegradation by 11.79 % compared to the conventional operation. These results were confirmed by heat flow curves, reflecting different phases of degradation, which illustrated the change of enthalpies and revealed the status of samples' profile. The acquired results support the concept of a possible relation between the thermal and biological stability of the investigated waste and, therefore, the feasibility of characterizing municipal organic waste stability using thermal analysis. These can also be beneficial in establishing strategies for sustainable management and treatment of OFMSW to reduce its environmental impact.