Anaerobic treatment of wastewater is a biological method characterized by the production of methane (CH₄).

All the active microorganisms belong to the group of anaerobic bacteria, i.e. bacteria which are able to and in most cases can only exist in an environment which excludes oxygen. In this context, methanogenic bacteria are a key component.

The anaerobic degradation process of organic material occurs stepwise.

Four steps can be distinguished:
• Hydrolysis
• Acidification
• Acetogenesis
• Metanogenesis

The anaerobic process removes the bulk of COD (Chemical Oxygen Demand) from the wastewater by converting it into biogas (= methane + carbon dioxide) at low operational costs.

Why Anaerobic Technology?
• Very small footprint (up to 90% smaller)
• Low operational costs and low maintenance (no air needs = low energy requirements!)
• Reduction of CO₂ footprint
• Reduction of excess sludge production (up to 90% less) – no sludge discharge costs
• Excess sludge has market value
• High applicable COD loading rates 20 – 35 Kg COD/m³ of reactor per day
• Production of about 13.5 MJ CH₄energy/KgCOD removed -> 1.5 kWh electricity (assuming 40% electric conversion efficiency)
• High return on investment
• Quick start-up, using granular anaerobic sludge as seeding material
• High rate systems facilitate water recycling in factories (towards closed loops)