Anaerobic Digestion & Sludge Management

Anaerobic digestion & sludge management

What is Anaerobic Digestion?

Anaerobic digestion is a series of biological processes in which microorganisms break down biodegradable material in the absence of oxygen. One of the end products is biogas, which is combusted to generate electricity and heat, or can be processed into renewable natural gas and transportation fuels.

The process of biogas production takes place in four phases:

  • hydrolysis stage: where large, complex polymers like carbohydrates, cellulose, proteins and fats are broken down by hydrolytic enzymes into simple sugars, amino acids and fatty acid]
  • Acidogenesis, or the acidification phase: where simple monomers are broken down into volatile fatty acids)
  • Acetogenesis: where products of the Acidogenesis are broken down to what is commonly termed Volatile Fatty Acids (VFA).  In addition, carbon dioxide and a little hydrogen and ammonia are also formed. The optimum pH for this part of the process is 5.0-6.5
  • Methanogenesis: or the creation of methane, is the final phase of the process.

The biogas is further treated desulphurised, cleaned, and prepared before being used by the CHP (Combined Heat Power) engine.


Our Expertise

Edenviro offers advice and support on all aspects of anaerobic digestion, from feedstock specification and pre-treatment to digestate quality management and enhancement. We will work with you to de-risk and optimize your process, whether you process waste materials or agricultural residues.

We are member of the ADBA (Anaerobic Digestion Biogas Association). Our highly skilled team are experienced in the operation and commissioning of anaerobic digesters.

Contact Us to see how we can help



We worked on the following projects:

  • Food Waste to Energy to energy plant commissioning: The plant was designed to treat 60000 t/year of food waste. Process included Waste reception, soup preparation Pasteurisation plant, Mesophilic AD tanks. Gas treatment and 2CHP (1500 kWe  each).  The digestate was dewatered by Centrifuges with the centrate further treated in Aerobic process and membranes prior to sewer discharge.
  • Optimization and operation of several Thermal Hydrolysis capable to treat from 60 to 100 Tons of Dry Solids/day including the site sampling and analysis for AD plant operation.
  • Thermal hydrolysis is a two-stage process combining high-pressure boiling of waste or sludge followed by a rapid decompression. This combined action sterilizes the sludge and makes it more biodegradable, which improves digestion performance. Sterilization destroys pathogens in the sludge resulting in it exceeding the stringent requirements for land application
  • Process and surface water management for a Farm AD plant Planning Application