Pyrolysis is one of the thermochemical technologies for converting biomass into energy and chemical products consisting of liquid bio-oil, solid biochar, and pyrolytic gas. Depending on the heating rate and residence time, biomass pyrolysis can be divided into three main categories slow (conventional), fast and flash pyrolysis mainly aiming at maximising either the bio-oil or biochar yields. Synthesis gas or hydrogen-rich gas can also be the target of biomass pyrolysis. Maximised gas rates can be achieved through the catalytic pyrolysis process, which is now increasingly being developed. Biomass pyrolysis generally follows a three-step mechanism comprising of dehydration, primary and secondary reactions. Dehydrogenation, depolymerisation, and fragmentation are the main competitive reactions during the primary decomposition of biomass. A number of parameters affect the biomass pyrolysis process, yields and properties of products. These include the biomass type, biomass pretreatment (physical, chemical, and biological), reaction atmosphere, temperature, heating rate and vapour residence time. This manuscript gives a general summary of the properties of the pyrolytic products and their analysis methods. Also provided are a review of the parameters that affect biomass pyrolysis and a summary of the state of industrial pyrolysis technologies.

Lignocellulosic biomass pyrolysis: A review of product properties and effects of pyrolysis parameters

With the rising demand for renewable energy and environmental protection, anaerobic digestion of biogas technology has attracted considerable attention within the scientific community. This paper presents a comprehensive review of research achievements on anaerobic digestion developments for biogas production. The review includes a discussion of factors affecting efficiency (temperature, pH, C/N ratio, OLR and retention time), accelerants (greenery biomass, biological pure culture and inorganic additives), reactors (conventional anaerobic reactors, sludge retention reactors and anaerobic membrane reactors) and biogas AD processes (lignocellulose waste, municipal solid waste, food waste, livestock manure and waste activated sludge) based on substrate characteristics and discusses the application of each forementioned aspect. The factors affecting efficiency are crucial to anaerobic digestion, because they play a major role in biogas production and determine the metabolic conditions for microorganism growth. As an additive, an accelerant is not only regarded as a nutrient resource, but can also improve biodegradability. The focus of reactor design is the sufficient utilization of a substrate by changing the feeding method and enhancing the attachment to biomass. The optimal digestion process balances the optimal digest conditions with the cost-optimal input/output ratio. Additionally, establishment of theoretical and technological studies should emphasize practicality based on laboratory-scale experiments because further development of biogas plants would allow for a transition from household to medium- and large-scale projects; therefore, improving stability and efficiency are recommended for advancing AD research.

Review on research achievements of biogas from anaerobic digestion

Anaerobic digestion is a commercial reality for several kinds of waste. Nonetheless, anaerobic digestion of single substrates presents some drawbacks linked to substrate characteristics. Anaerobic co-digestion, the simultaneous digestion of two or more substrates, is a feasible option to overcome the drawbacks of mono-digestion and to improve plants economic feasibility. At present, since 50% of the publication has been published in the last two years, anaerobic co-digestion can be considered the most relevant topic within anaerobic digestion research. The aim of this paper is to present a review of the achievements and perspectives of anaerobic co-digestion within the period 2010-2013, which represents a continuation of the previous review made by the authors [3]. In the present review, the publications have been classified as for the main substrate, i.e., animal manures, sewage sludge and biowaste. Animal manures stand as the most reported substrate, agro-industrial waste and the organic fraction of the municipal solid waste being the most reported co-substrate. Special emphasis has been made to the effect of the co-digestion over digestate quality, since land application seems to be the best option for digestate recycling. Traditionally, anaerobic co-digestion between sewage sludge and the organic fraction of the municipal solid waste has been the most reported co-digestion mixture. However, between 2010 and 2013 the publications dealing with fats, oils and greases and algae as sludge co-substrate have increased. This is because both co-substrates can be obtained at the same wastewater treatment plant. In contrast, biowaste as a main substrate has not been as studied as manures or sewage sludge. Finally, three interdisciplinary sections have been written for addressing novelty aspects in anaerobic co-digestion, i.e., pre-treatments, microbial dynamics and modeling. However, much effort needs to be done in these later aspects to better understand and predict anaerobic co-digestion.

A critical review on anaerobic co-digestion achievements between 2010 and 2013

A review on dark fermentative biohydrogen production from organic biomass: Process parameters and use of by-products

This paper presents a review of the turn of events and points of view of biogas in and its utilization for power, heat and in transport in the European Union (EU) and its Member States. Biogas creation has expanded in the EU, empowered by the sustainable power strategies, notwithstanding monetary, ecological and atmosphere benefits, to arrive at 18 billion m3 methane (654 PJ) in 2015, speaking to half of the worldwide biogas creation. The EU is the world chief in biogas power creation, with more than 10 GW introduced and various 17,400 biogas plants, in contrast with the worldwide biogas limit of 15 GW in 2015. In the EU, biogas conveyed 127 TJ of warmth and 61 TWh of power in 2015; about half of absolute biogas utilization in Europe was bound to warm age. Europe is the world's driving maker of biomethane for the utilization as a vehicle fuel or for infusion into the petroleum gas network, with 459 plants in 2015 creating 1.2 billion m3 and 340 plants taking care of into the gas network, with a limit of 1.5 million m3. Around 697 biomethane filling stations guaranteed the utilization 160 million m3 of biomethane as a transport fuel in 2015.

https://www.longdom.org/open-access/biogas-developments-and-perspectives-in-europe.pdf

Biogas Developments and Perspectives in Europe

Pretreatment of lignocellulosic biomass for enhanced biogas production.

Anaerobic digestion of food waste - Challenges and opportunities.

Solid-state anaerobic digestion (SS-AD) has gained increasing attention in recent years, especially for digesting lignocellulosic biomass Compared to liquid anaerobic digestion (L-AD), SS-AD handles feedstocks with higher total solids content, and therefore, performs more effectively at higher organic loading rates and has higher volumetric biogas productivity Challenges facing SS-AD of lignocellulosic biomass are primarily related to its relatively low methane yield, potential instability, and low value end-products These challenges are either due to the inherent limits of SS-AD (eg retarded mass transfer caused by high solid content) or can be attributed to the nature of lignocellulosic biomass (eg components recalcitrant to biodegradation) To address these challenges, a variety of methods, including pretreatment of feedstock, improvement of inoculation efficiency, co-digestion of multiple feedstocks, and upgrading biogas to higher-value transportation fuels, have been examined to enhance the performance of SS-AD and increase the value of the end products This review summarizes these challenges in SS-AD of lignocellulosic biomass and discusses the mechanisms and feasibility of potential strategies for resolving them

Challenges and strategies for solid-state anaerobic digestion of lignocellulosic biomass

Solid-state anaerobic digestion of lignocellulosic biomass: Recent progress and perspectives

With global population growth, the security of food, energy and water is becoming more challenging. Both anaerobic digestion (AD) and composting are waste management methods that are plausible approaches to address this challenge by reusing organic waste and generating value-added products. In this paper, recent research on AD and composting is summarized, and differences in the technical, economic, and environmental aspects of AD and composting, and their potential to improve the sustainability of waste management, are examined. Recent research on AD has focused on process enhancement and valorization of end products, while composting research has emphasized ways to shorten composting period and reduce odor and greenhouse gas (GHG) emissions. Strategies to enhance AD and composting processes are similar, but the operational parameters that affect microbial activity, including inoculation, aeration, temperature, moisture, C/N ratio, and pH, can differ. AD can be economically more advantageous than composting, depending on plant scale and valorization of end products, while composting is more profitable at smaller scales (e.g.

Improving the sustainability of organic waste management practices in the food-energy-water nexus: A comparative review of anaerobic digestion and composting

Fuqing Xu

Papers

Pretreatment of lignocellulosic biomass for enhanced biogas production.

Anaerobic digestion of food waste - Challenges and opportunities.

Challenges and strategies for solid-state anaerobic digestion of lignocellulosic biomass

Solid-state anaerobic digestion of lignocellulosic biomass: Recent progress and perspectives

Improving the sustainability of organic waste management practices in the food-energy-water nexus: A comparative review of anaerobic digestion and composting