Member of proweps engineering association proweps GmbH (

Anaerobic digestion

Anaerobic digestion AD is an efficient technology well proven in industrial scale to convert organic waste in valuable resources as renewable biogas and biofertilizer.

The AD technology to treat organic waste includes generally following process steps:

Flowchart AD

The key targets of organic waste treatment by AD are high biogas yields as well as the production of high-quality biofertilizers.
Biogas is the most flexible and a storable renewable energy source that is produced continuously and independent from climatic conditions and its utilization on demand is possible if required. Biogas can be used to produce different types of energy as heat, electricity, cool or after further upgrading to biomethane it can be used as biofuel.
It is important to select the most economical way of biogas utilization with the begin of an anaerobic digestion project.

AD plants can be operated energy self-sufficient and have a very high energy surplus. Energy that is not used for plant own consumption is sold and besides the waste tipping fee the key economical driver for the projects. The biofertilizers are nutritious (N, P, K) and can, if hygienized used directly in agriculture to substitute synthetic produced mineral fertilizers.

The production of mineral fertilizers is very energy intensive and therefore the substitution with organic fertilizer is a sustainable way to reduce CO2-emissions. Different types of biofertilizers can be produced according to the market requirements.

AD plants are suitable to treat a variety of waste materials such as:

• Food waste from restaurants, kitchen, supermarkets, vegetable markets
• Packaged food
• Biowaste (mixture of yard and food waste)
• Organic fraction separated from municipal solid waste
• Production residues from the food and beverage processing industry
• Slaughterhouse waste
• Agricultural residues (manure, straw etc.)
• Sewage sludge

Selection of AD Substrates

It is important to select the appropriate AD technology that can handle the substrates although with different compositions related to moisture and level of contamination.

To achieve the best economics of AD plants and that is our claim it is important to consider several parameters in the plant design:
• Low susceptibility to interferences
• Maximal availability
• Treatment of variety of waste substrates
• High energy efficiency
• High fertilizer quality
• Small footprint

Considering the current legal framework conditions as well as the future requirements for efficient, resources preserving and environmentally friendly plants we accompany the AD projects from the basic concept to completion and provide all necessary engineering services.

Our activities include projects based on “wet” or “dry” AD-technologies and our target is to develop the most economic technical solutions for our customers.