Biogas Production: Microbiology and Technology

Abstract

Biogas, containing energy-rich methane, is produced by microbial decomposition of organic material under anaerobic conditions. Under controlled conditions, this process can be used for the production of energy and a nutrient-rich residue suitable for use as a fertilising agent. The biogas can be used for production of heat, electricity or vehicle fuel. Different substrates can be used in the process and, depending on substrate character, various reactor technologies are available. The microbiological process leading to methane production is complex and involves many different types of microorganisms, often operating in close relationships because of the limited amount of energy available for growth. The microbial community structure is shaped by the incoming material, but also by operating parameters such as process temperature. Factors leading to an imbalance in the microbial community can result in process instability or even complete process failure. To ensure stable operation, different key parameters, such as levels of degradation intermediates and gas quality, are often monitored. Despite the fact that the anaerobic digestion process has long been used for industrial production of biogas, many questions need still to be resolved to achieve optimal management and gas yields and to exploit the great energy and nutrient potential available in waste material. This chapter discusses the different aspects that need to be taken into consideration to achieve optimal degradation and gas production, with particular focus on operation management and microbiology.

QTL Mapping of Wood FT-IR Chemotypes Shows Promise for Improving Biofuel Potential in Short Rotation Coppice Willow (Salix spp.)

“…Anaerobic digestion to biogas, in contrast to ethanol production, proceeds through a series of reactions involving different microbial groups, including microorganism having hydrolytic activity [61]. Thus, lignocellulosic materials such as willow can be degraded without a preceding sacharification, as required for ethanol production.…”

“…Willow is characterized by a high C/N quota as well as low levels of buffering components and possibly also trace metals, essential for microbial activity, and thus without complementary material the biogas process would fail due to nutrient deficiency [61]. Still, willow has a high energy content per mass and can thus be used as a complement to less carbon-rich and more diluted material, such as manure [63,64].…”

Socio-technical systems analysis of waste to energy from municipal solid waste in developing economies: a case for Nigeria

“…WtE is the generic term for a process by which energy is generated from waste materials Average waste generated (kg/capita/day) [27] Average organic fraction of waste (%) [27] Average organic waste generated (kg/day) [4] in the WtE market, it is no surprise that developing economies like Nepal and China are tapping into this modern technology development [30]. This form of WtE technology is thriving, and according to Schnürer and Jarvis [31], various types of waste can be reduced and stabilised, during digestion to produce renewable and environmentally friendly energy, called biogas. Also, it is arguably a more versatile renewable energy source, in comparison to the wind and solar energy, due to its determinate energy value and non-dependence on geographical locations and seasons [32].…”

Anaerobes in Industrial- and Environmental Biotechnology

“…Anaerobic microorganisms, present in different ecological niches deficient in free oxygen ranging from compost heaps and mammalian gut (see [1]) to deep sea sediments (see [2]) and volcanoes, play important roles in global carbon, nitrogen and sulfur cycles, and in extracting energy from organic matter [3][4][5]. The earliest industrial applications of anaerobes have been in the production of foods such as bread, yoghurt, cheese and sauerkraut, and wines and beer.…”

“…In the current trend in shift from fossil-based to biobased economy, anaerobes are attracting increasing interest as tools for transformation of renewable resources such as biomass and gases (e.g., synthesis gas [9] into diverse chemicals and both liquid (this chapter and [9]) and gaseous biofuels [3,4]. They serve as sources for enzymes catalyzing the degradation of complex biomass or the uptake of gases such as CO, CO 2 , and H 2 , and of metabolic pathways for different products in both wild type and engineered microbial hosts.…”