For the highest strength wastewater and slurries, Waterleau offers the BIOTIM^® CSTR, a continuous stirred-tank reactor that provides complete mixing and digestion of very concentrated organic streams.

The BIOTIM^® CSTR is essentially an anaerobic digester (often with heating and mixing), where the entire contents are mixed to ensure uniform conditions throughout. This design is particularly suited for extreme COD levels (50 kg/m³ and above) and wastes with significant solids or viscous content.

By continuously stirring, the CSTR prevents settling and can handle substrates like thick sludge, agro-food wastes, manure, or other high-solid organic wastes that might clog or overload other reactor types.

Waterleau’s BIOTIM^® CSTR units often operate in the mesophilic temperature range and can be equipped with heating/co-generation systems to maintain optimal digestion rates for high-strength wastes.

Two-stage anaerobic treatment for liquid and solid waste

In practice, BIOTIM^® CSTR reactors are used for streams such as industrial process slurries, food industry by-products, and municipal sludge. For example, Waterleau’ssolutions for organic solid waste (e.g. kitchen waste or thick sludges) are based on CSTR technology, allowing treatment of wastes with 100–600 kg COD/m³ or high dry-matter content.

In a potato-processing context, extremely rich wastes like potato peels (≈160 kg COD/m³) or concentrated starch water can be digested in a CSTR to maximize biogas output.

The CSTR can be fed in parallel to a BIOTIM^® UASB or tower handling the factory’s wastewater, so that two-stage anaerobic treatment covers both liquid and solid wastes – this approach has achieved up to 90% total organic load removal in large potato processing plants (with the remaining pollution polished by aerobic treatment).