Comparative Assessment of Different Pretreatment Methods of Municipal Solid Waste for Resource Recovery Using Anaerobic Digestion and Fermentation Processes

The objectives of this study are to investigate the applicability of different pretreatments i.e., chemical, US, and HO on different waste streams including PS, TWAS, and FW to enhance solubilization and consequently biomethane production. In all feedstocks, the US energy of 20,000 KJ kgTS-1 showed the maximum sCOD concentration, the percentage increase in sCOD, and the percentage of solubilization compared to the control. After sonication pretreatment, extremely alkaline and acidic pH showed higher improvement in the characteristics followed by the HO pretreatment, as compared to the control. Regardless of feedstock type, US pretreatment up to consumed specific energy of 5,000 KJ kgTS-1 revealed higher methane yield followed by pH adjustment and HO. This effect was more obvious (32%) in TWAS, which supports the effectiveness of sonication on agglomerated and hard structure substrates. The modified Gompertz model for the effect of different pretreatments on the improvement of biomethane production showed a good fit for the experiment. The biodegradable fraction ranged from 46% to 87%. The lower biodegradable fraction trend regardless of the type of pretreatment belonged to TWAS and the maximum trend belonged to FW. The most percentage of biodegradable fraction (87%) occurred when FW was pretreated with US energy of 5,000 KJ kgTS-1 and the lowest amount (46%) occurred in the control of TWAS without any pretreatment. The results of this study suggested that the application of sonication at the specific consumed energy of 5,000 KJ kgTS-1 is an optimum and effective pretreatment in terms of biomethane enhancement from the studied feedstocks, especially TWAS due to its agglomerated nature and hard structured matter.