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 (agriculture).
In addition, the treatment adjusts the rheology to such an extent that loading rates to sludge anaerobic digesters can be doubled, and also dewaterability of the sludge is significantly improved. The first full-scale application of this process for sewage sludge was for the city of Hamar in Norway in 1996. Since then, there have been over 30 additional installations globally.
Commercial Application at a Wastewater treatment plant
Wastewater treatment plants, such as Blue Plains in Washington DC, have adopted thermal hydrolysis of sewage sludge in order to produce commercially valuable products (such as electricity and "class A" biosolid fertilizers) out of the wastewater. The full-scale commercial application of thermal hydrolysis enables the plant to utilize the solids portion of the wastewater to make power and fine fertilizer directly from sewage waste.
30 Largest Thermal Hydrolysis Plants
|Plant||Capacity (TDS/A)||Commission Year||Thermal Hydrolysis Supplier|
|Blue Plains, Washington DC, USA||130,000||2014||Cambi|
|Davyhulme, Manchester, UK||91,000||2012||Cambi|
|Ringsend, Dublin, Ireland||56,000||2002||Cambi|
|Tees Valley, UK||37,000||2008||Cambi|
|Bruxelles Nord, Belgium||20,000||2007||Cambi|
|Cotton Valley, Milton Keynes, UK||20,000||2007||Cambi|
|NOSES, Aberdeen, UK||16,500||2001||Cambi|
|EGE Waste Treatment, Oslo, Norway||15,000||2012||Cambi|
|Oxley Creek, Brisbane, Australia||12,900||2006||Cambi|
|Anersfoort, Holland||9,000||2014||SH+E Group|
- "Thermal Hydrolysis: The Missing Ingredient for Better Biosolids?". Water World.
- "DC Water adopts system for making power and fine fertilizer from sewage". Washington Post.
- "From toilet to turbine". Washington Post.