Produção de hidrogênio a partir de esgoto sanitário com reator UASB

Abstract

The production of hydrogen from renewable and waste sources has become a strategic alternative for energy matrix diversification and waste valorization within the circular economy framework. This study aimed to develop and apply a phenomenological mathematical model to simulate the behavior of an upflow anaerobic sludge blanket (UASB) reactor operated under acidogenic conditions for fermentative hydrogen production from sanitary sewage. The model was computationally implemented in Python, considering the dynamics of substrate consumption (Chemical Oxygen Demand – COD), microbial growth, and accumulated H2 production, incorporating the effects of pH and hydraulic retention time (HRT) on fermentative activity and methanogenic competition. Two operational scenarios were simulated: conventional sanitary sewage (COD of 731.5 mg/L) and sewage with enhanced organic load (COD of 1,045 mg/L), both with COD removal maintained close to 30% to ensure acidogenic conditions. Results indicated that the pH range between 5.0 and 5.4 and HRT between 3 and 4 hours provided the best conditions for hydrogen production, with volumetric productivities on the order of 10−4 mol/(L·h) (5.04 × 10−4 mol/(L·h) in the conventional scenario and 5.67 × 10−4 mol/(L·h) in the enriched scenario) and total accumulated hydrogen production of 2,456.36 mol in the first scenario and 4,167.95 mol in the organic enrichment scenario. Increasing the influent organic load significantly enhanced hydrogen production without altering the relative COD removal efficiency, highlighting the process dependence on the availability of fermentable substrates. It is concluded that the UASB reactor operated under acidogenic conditions has potential as an energy pretreatment stage in wastewater treatment plants, provided it is associated with co-digestion strategies to enable fermentative hydrogen production, aligning with circular economy and energy transition principles.