Energy Efficacy to Score Organic Refuses Pretreatment Process for Hydrogen Anaerobic Production

The present paper reports the results of experimental tests on hydrogen production under Anaerobic Digestion (AD) in order to verify the efficacy of several pretreatment processes. The majority of carbon in Organic Wastes (OW) could be present in form of carbohydrates, celluloses or lignocelluloses, with different degree of digestibility. Three types of waste were tested with different C structures to have a large representation of the OW. The selected wastes were: Sweet Product Residue (SPR), confectionary residue taken from the market after the expiry date, Organic Waste Market (OWM) refuses from a local fruit and vegetable market and Coffee Seed Skin (CSS) a waste of coffee production plant. Several pretreatment processes have been tested: chemical, thermal, ultrasonic and a combination of the afore mentioned. To score the different pretreatment process, two parameters were used: the efficiency (x ) that takes into account the produced energy compared to the available one embedded in the refuse and the efficacy (h ) that compares the efficiency obtained in using the pretreatment with that obtained without pretreatment. In the case of SPR, the best result was obtained for the basic pretreatment on its own with h =6.3. In the case of OWM, the best results was for a combination of alkaline/thermal processes with h =9.9. Finally, using CSS, the ultrasonic pretreatment resulted the most efficacy, h =5.2.