Economically efficient biogas production from manure fibres and straw

Solutions developed

The BIOMAN-project will develop a so-called ”re-injection loop” with combinations of different types of pre-treatment with i.e. enzymes and physical methods, e.g. division into fine particles and ultrasound. The objective of the treatment is to expand the particle surface in the biomass so the gas producing bacteria can start working. The biomass will come from degassed liquid manure from animals or from energy crops.

Main results

The feed from the HTN biogas plant was used for the pilot scale studies. Initially, the feed consisted mainly of cow manure, but during the course of the project, the percentage of other easily degradable substrates such as organic waste was significantly increased. As a consequence, the possible increment of the Re-Injection Loop was significantly reduced due to the decrease of recalcitrant substrates.
Several attempts were initiated to overcome this, and pilot scale reactors were operated for a longer time than initially planned. The configurations of the pilot scale reactors investigated were as follows: no reinjection; reinjection from solid liquid separation; enzymatic treatment; and the combination of solid liquid separation and enzymatic treatment.