Rheological behavior of physicochemical sludges during methanogenesis suppression and hydrogen production at different organic loading rates

ABSTRACT

This study investigated the rheological behavior of raw physicochemical sludges and sludges that were digested at different organic loading rates (OLRs) (1, 5, 10 and 15 gVS L⁻¹ d⁻¹) during methanogenesis suppression to produce hydrogen anaerobically. The Herschel–Bulkley model was used to describe the rheology of these sludges with specific properties. The results indicate that the Herschel–Bulkley model adequately described the rheology ( ≠ 0) of this type of fluids (R² > 0.98). In addition, the raw physicochemical sludges and those that were digested at different OLRs had dilatant behaviors (n > 1), which increased with increasing OLR. These results identified the apparent viscosity, yield stress, pH and OLR conditions that allow for the production and suppression of methane, as well as the conditions that guarantee the production of hydrogen.

KEYWORDS:

• Digested physicochemical sludge
• hydrogen production
• methane suppression
• pH
• rheological behavior

Funding

This research was supported by the Tecnológico Nacional de México (TecNM) through Grant 5596.15-P. López-Escobar acknowledges support from a PhD scholarship from the Council of Science and Technology of Mexico (CONACyT) with CVU (grant holder) 168870/168870.