Process-controlled Enzymatic Hydrolysis (PEH)

The degree and rate of degradation of substrates in the biogas process are strongly dependent upon the chemical structures of the materials involved. Whereas fats, proteins, and starch are very rapidly and almost completely transformed into biogas, the fibrous components, and especially the cellulose fraction, pose a challenge for biogas generation. On the one hand, the structure of the cellulose fibres hinders enzymatic hydrolysis; on the other hand, the conditions typically encountered in a biogas digester (pH value, temperature) are unfavourable for cellulolytic enzymes and significantly reduce their activity. Fibrous plant components are consequently degraded only slowly and incompletely in biogas plants.

Against this backdrop, PFI Biotechnology has developed a special pre-hydrolysis process to substantially increase the degree and rate of degradation of the fibrous components. In process-controlled enzymatic hydrolysis (PEH) the biomass is pretreated in a specially designed hydrolysis vessel before it reaches the biogas digester. Optimum pH and temperature condition for the activity of hydrolytic enzymes are maintained in this controlled and sensor-monitored process. After thorough laboratory and pilot-scale testing, the process is currently undergoing full-scale trials (see also Planning).

Thermal Pressure Hydrolysis (TPH)

Use of lignified biomass requires the application of further pretreatment processes, especially if sugar-enriched hydrolysates are to be provided for fermentation.

Here PFI Biotechnology is working hard on a hydrothermal pretreatment process, known as Thermal Pressure Hydrolysis (TPH). The hemicellulose fraction of lignified substrates (such as straw) is extensively hydrolysed in a special batch process and the lignocellulose prepared for subsequent enzymatic hydrolyse (see also Planning).

Another process has been developed specifically for sewage works. It serves to improve the dewatering behaviour of activated sludge and to enhance its biogas potential (see also Planning).