scope:

Scope of application

This guideline can be applied to any organic material whose fermentation is to be tested. The precise area of application is described in the particular sections of the guideline.

Purpose

Guideline VDI 4630 provides rules for assessing the fermentability of organic materials and the necessary equipment and apparatus required for the corresponding test set-ups. Before this area is tackled, however, definitions of important terms are provided. In addition, this guideline will provide information on characterizing - and thus on describing - the substrates and specifies the requirements as to how certain variables characterizing the substrates must be measured in accordance with the current state of knowledge and science if comparability is to be ensured. Furthermore, instructions are also given on how a representative sample should be taken from the various material flows available. In summary, the following aspects are treated in the present guideline:

• Definitions

Brief definitions are provided here of the most important terms found in constant use in the field of biogas production and utilization; this should ensure that all parties involved use specific terms in exactly the same way

• Characterization of the substrates

Following a general characterization and classification into particular groups the possibilities of a basic fermentability of an organic material can be estimated. This will also yield important information about handling the material and about special factors which need to be taken into consideration in the planning of a biogas installation in which materials of this kind are to be used.

• Sampling and preparation of samples

The way in which samples are collected and prepared forms the fundamental basis for a transparent examination of an organic material. The basic rules and a standardized procedure are described.

• Determination of material data

Chemical analysis of an organic material allows a far-reaching assessment to be made of its potential fermentability. Suitable analytical methods for this are suggested and evaluated.

• Batch fermentation tests and continuous fermentation tests

Fermentation tests supply information about the actual fermentability of organic material flows. Depending on what objectives have been defined and on what is actually possible, the gas yield and the course of fermentation can be determined by means of batch fermentation tests or continuous fermentation tests. Methods suitable for this are described.

This guideline is directed at those laboratories, planners, plant constructors and operators of biogas installations who wish to examine the use of organic materials.