Thermal hydrolysis is an anaerobic digestion pretreatment process. The thermal hydrolysis process decreases the viscosity of the material and increases volatile solids or organic loading for anaerobic digestion. Increased volatile content entering the digester increases methane production and reduces the amount of biosolids for disposal. Decreased viscosity alters the rheological properties to improve the digested sludge’s dewaterability and improves dry solids concentration. Other benefits of thermal hydrolysis include lowering downstream process equipment requirements, reducing process chemical costs and production of Class A biosolids for ease of disposal and beneficial use as bio-fertilizer.
The Bio Thelys™ thermal hydrolysis process is a batch operated anaerobic digestion pretreatment system. Steam is applied to hard to biodegrade wastewater sludge by the means of a dynamic mixer that instantaneously condenses steam on to the sludge. The use of steam applied to dewatered biosolids and the elevated pressure in the reactors causes the microbial cells to rupture and therefore increases the soluble fraction of COD that is available for anaerobic digestion.
The wastewater facility can benefit from amount of solids that will be reduced; the net result being greater biogas production and lower hauling costs. The sludge viscosity is also greatly decreased such that a 12% solids content can be mixed in a standard anaerobic digester, increasing mesophillic digester capacity by more than 200%. Thermal hydrolysis also reduces the dewatering requirements as post-THP sludge is known to yield higher dewaterability using less polymer, and produce a Class A product.
Combination of Thermal Hydrolysis and Anaerobic Digestion
- Increase the digestion capacity of an existing installation, maximizing existing infrastructure
- Reduce the amount of biosolids produced, offering disposal costs savings
- Meets Class A requirements, providing a marketable end product
- Reduce the anaerobic digestion volume of a new installation by up to 50%, decreasing capital costs
- Increase biogas production, meeting sustainable initiatives
The Veolia Advantage
- Custom designs
- Variable configurations
- Worldwide experience
- Understanding of full sludge treatment plant