Effect of thermal and alkaline pretreatment of giant miscanthus and Chinese fountaingrass on biogas production

Effect of alkaline pre-treatment on hydrolysis rate and methane production during anaerobic digestion of paunch solid waste

Paunch is comprised of the partially digested feed contained in cattle or sheep and contributes 20-50% of organic waste produced at red meat processing facilities. Anaerobic digestion has been identified as a promising technology for paunch treatment, however treatment times can be long and when combined with the moderate degradability of paunch this results in high treatment costs that need to be improved. Pre-treatment was investigated as a strategy to improve AD of paunch, alkaline treatment (NaOH or KOH) was selected due to the high lignin content. A range of alkaline loadings (1-20 g 100gTS-1) were tested with an equivalent hydroxide molar concentration of 9-250 mM [OH-]. Alkaline pre-treatment improved both the hydrolysis rate and the overall degradability of paunch solid by up to 4.4 times and 60%, respectively. The enhanced hydrolysis rate and methane yield was correlated to changes in material composition during pre-treatment. While alkaline concentration was an important factor, there were no significant improvements at alkaline concentrations above 12 g 100gTS-1 (150 mM [OH-]).

Recent advancements in strategies to improve anaerobic digestion of perennial energy grasses for enhanced methane production

Perennial energy grasses (PEGs) are supposed to be a momentous heading to the development of biomass energy on account of their characteristic superiorities of high yield, strong adaptability and no direct competition with food crops. Anaerobic digestion of PEGs with great biogas-producing potential occupies an irreplaceable status despite a variety of pathways for conversion to renewable energy. However, efficient digestion of PEGs suffers from severe challenges in connection with feedstock properties such as recalcitrant structures. This review highlights recent research in anaerobic digestion of PEGs and focuses on essential aspects enhancing anaerobic digestion performance: types and properties of grasses, diverse pretreatments, various co-feedstocks for co-digestion, dosing of different additives, and improvements in reactors. General discussions on the future prospects of anaerobic digestion of PEGs are proposed. Overcoming knowledge gaps and technical limitations will facilitate further application of PEGs on an industrial scale.

Overview of pretreatment technologies on vegetable, fruit and flower market wastes disintegration and bioenergy potential: Indian scenario

Disposal of segregated organic fractions of centralized wholesale market wastes (i.e. vegetable, fruit and flower markets waste) in dumpsites/landfills are not only a serious issue but also underutilizes the huge potency of these organic wastes. Anaerobic digestion (AD) is a promising technology for converting organic wastes into methane, as a carbon-neutral alternative to conventional fuels. The major challenges related to the AD process are poor biodegradation of wastes and buffering capacity within the anaerobic digester that lowers the biogas yield. To accelerate biodegradation and to enhance the process efficacy of anaerobic digestion, several pretreatment technologies (mechanical, thermal, biological, chemical and combined pre-treatments) for organic wastes prior to the AD process were developed. This review article presents a comprehensive analysis of research updates in pretreatment techniques for vegetable, fruit and flower markets wastes for enhancing biogas yields during the AD process. The technological aspects of the pretreatment process are described and their efficiency comparison with the resultant process yields and environmental benefits are also discussed. The challenges and technical issues associated with each pretreatment and future research directions for overcoming the field implementation issues are also proposed.