To assure that the input substrates will have no adverse effect on the process, several parameters need to be analyzed, providing a first impression of the suitability of a product for anaerobic digestion.

Selection test

In case the waste contains impurities (e.g. municipal solid waste), a thorough pre-treatment will be necessary. A selection test will allow to evaluate this pre-treatment by sorting the waste in different fractions (plastics, glass, stone, sand, organics). This selection test provides the necessary info to decide what settings of the pre-treatment facility result in the most suited waste composition for AD.

Lab-scale silage test

Many input substrates are not year-round available for anaerobic digestion. In order to still allow for a continuous feeding to the AD-process, storage of these input substrates is necessary. Ensiling is a technique which has been successfully used in agriculture for many decades to preserve e.g. maize and grass.

OWS has developed a test that simulates the silage process on a small scale, which allows to investigate the effect of different silage conditions and additives for a specific substrate or combination of substrates. Also the effect of the silage process on the biogas and methane yield can be evaluated.