Selection and pre-treatment of biomass


Selection of biomass

The selection of proper substrates is essential for an efficient process. Thus, biomass with a preferably high gas yield and a preferably low cultivation effort is eligible amongst others. In addition, alternatives that make the biomass production possible without using agricultural land are being investigated to avoid the competition with food production.

Selected publications:

S. Schwede: Untersuchung und Optimierung des Biogasbildungspotentials der marinen Mikroalge Nannochloropsis salina. Dissertation, Bochum (2013).

S. Schwede, M. Gerber, A. Kowalczyk, R. Span: A semi-continuous long term study for the comparison of algal biomass and maize silage as substrates in anaerobic digestion. Proc. 13th World Congress of Anaerobic Digestion, Santiago de Compostella, Spanien, (2013). 


Besides optimal process conditions, a balanced nutrient supply for the microorganisms is necessary to ensure a high biogas output. To compensate deficits of macro and micro nutrients, additives can be added or appropriate biomasses selected by their composition can be chosen and combined.


Selected publications:

L. Aliaga, N.D. Jablonowski, M. Gerber: Development of the “Bionutrator”, an online-tool to find optimal substrate mixtures based on their nutrient composition. Proceedings of the 14th World Congress on Anaerobic Digestion, Chile (2015).

S. Schwede, A. Kowalczyk, M. Gerber, R. Span: Anaerobic co-digestion of the marine microalga Nannochloropsis salina with energy crops. Bioresource Technology, Vol. 148, 428-435 (2013).

E. Harnisch: Untersuchung von synergistischen Effekten in der Kovergärung von Algen und Maissilage zu Biogas. Masterarbeit, Bochum (2012).

Biogas yield (YBG) resulting from the co-fermentation of algal biomass (A) and maize silage (MS) (source)


Pre-treatment of biomass

To achieve a higher biogas yield, substrates can be pre-treated by means of mechanical disintegration, thermolysis, freezing, microwaves, ultrasound or French press. With those treatments cell walls can for example be destroyed, which enables the microorganisms to reach nutrients easier. If the biomass contains a lot of fibres, a pre-treatment is used to minimize the particle size in order to provide a larger surface for the microbiological degradation.

Selected publications:

E. Spielmann, R.Span, M.Gerber: Einfluss der Extraktion von Wertstoffen auf die Vergärung der Mikroalge Nannochloropsis salina. 2. Hammer Bioenergietage, Hamm (2017).

K. Kwiatkowski: Untersuchung des Einflusses der Fest/Flüssig-Trennung auf die Biogasbildung. Masterarbeit, Bochum (2017).

S. Schwede, Z.-U. Rehman, M. Gerber, C. Theiss, R. Span: Effects of thermal pretreatment on anaerobic digestion of Nannochloropsis salina biomass. Bioresource Technology, Vol. 143, 505-511 (2013).

O. Budde: Energetische und wirtschaftliche Betrachtung der Vorbehandlung von Algenbiomasse durch French Press und Mikrowellen für den Einsatz in Biogasanlagen. Semesterarbeit. Bochum (2013).

S. Schwede, A. Kowalczyk, M. Gerber, R. Span: Influence of different cell disruption techniques on mono digestion of algal biomass. Proc. World Renewable Energy Congress, Vol. 1, Linköping, Schweden (2011).

Microscopic pictures of algal biomass after a thermal pre-treatment (B & C)
in comparison to an untreated reference (A)