Haarslev’s Continuous Hydrolysis System (HCHS) with Cooler

In the Class A thermal hydrolysis process, the combined bio solids are dewatered to 17 – 22% and treated with saturated steam at a pressure of 6 bar (87 psi) with a temperature of 150‑170 °C (302-338 °F).

Following the hydrolysis stage, a sudden decompression (or flashing) causes a destruction of the cell walls and frees the intracellular material for higher efficient digestion. Finally the sludge temperature is reduced to the mesophilic range by a second flash stage which results in further evaporative cooling.

 

Haarslev’s Continuous Hydrolysis System (HCHS) without Cooler

For Class B applications, the hydrolysed secondary sludge can be mixed with cold primary sludge to adjust the digestion tempera­ture thereby substantially reducing heating costs.