Microbiological fermentation of lignocellulosic biomass: current state and prospects of mathematical modeling

Abstract

The anaerobic fermentation process has achieved growing importance in practice in recent years. Anaerobic fermentation is especially valuable because its end product is methane, a renewable energy source. While the use of renewable energy sources has accelerated substantially in recent years, their potential has not yet been sufficiently exploited. This is especially true for biogas technology. Biogas is created in a multistage process in which different microorganisms use the energy stored in carbohydrates, fats, and proteins for their metabolism. In order to produce biogas, any organic substrate that is microbiologically accessible can be used. The microbiological process in itself is extremely complex and still requires substantial research in order to be fully understood. Technical facilities for the production of biogas are thus generally scaled in a purely empirical manner. The efficiency of the process, therefore, corresponds to the optimum only in the rarest cases. An optimal production of biogas, as well as a stable plant operation requires detailed knowledge of the biochemical processes in the fermenter. The use of mathematical models can help to achieve the necessary deeper understanding of the process. This paper reviews both the history of model development and current state of the art in modeling anaerobic digestion processes.

Breeding maize as biogas substrate in Central Europe: I. Quantitative-genetic parameters for testcross performance

“…Later onset of grain development reduces digestibility of forage maize and the same effect may also apply to MFY. Alternatively, breeders may select for high MFY by paying special attention to the proportion of easily degradable, energy-rich components like starch, sugars, and fat (Lübken et al 2010). Moreover, MFY might also be increased by decreasing the proportion of non-degradable components like lignin, which may additionally inhibit the degradation of other substances in the substrate (Lübken et al 2010).…”

Fungi open new possibilities for anaerobic fermentation of organic residues

“…Piromyces, Neocallimastix [12], Orpinomyces, Anaeromyces [10]) are possessing fibrolytic activity and are able to enhance the digestibility of fibrous feeds as was documented for cattle [34], as well as wild-living herbivores like buffalo [35] and elephants [9]. Celluloses and hemicelluloses are forming plant cell walls, and their penetration and disintegration are the limiting steps in the anaerobic digestion of fibrous material, especially if they are embedded within the lignocellulose complex [36]. The beneficial role of fungi in the anaerobe biogas process is based on their ability to adhere on plant surfaces and to penetrate the cell walls.…”

Upgrading strategies for effective utilization of biogas

“…Biogas is a renewable energy source which consists of 50-70% CH 4 , 25-50% CO 2 , 1-5% H 2 , 0.3-3% N 2 , and some notable impurities such as NH 3 , H 2 S, siloxane, and halides [2]. The concentration of each of these compounds depends on the composition of the raw materials used for the production.…”

“…The concentration of each of these compounds depends on the composition of the raw materials used for the production. Biogas is basically generated through a multistage reaction process where different microorganisms utilize the available energy stored in complex polymers (polysaccharides, lipids, and proteins) under anaerobic condition for their metabolism [3].…”