Feasibility of methanolic waste treatment in UASB reactors

Feasibility of methanolic waste treatment in an upflow anaerobic sludge blanket (UASB) reactor operating continuously for a period of more than 400 days was examined. Optimum pH was found to be between 7.0–7.3. In this pH range, there was no excessive build-up of volatile fatty acids and no upset or reactor failure was observed. Elementary pathways of degradation of methanol to methane were shown to be governed by the operating pH. Permissible volumetric loading rate to achieve 80% of TOC removal efficiency was determined to be 8 g-TOC/1•d. Below this value, the effect of hydraulic retention time or loading rate on TOC removal efficiency was not pronounced. Kinetic coefficients of k, Ks, Y and b were determined to be 1.11 g-TOC/g-VSS•d, 0.385 g-TOC/1, 0.213 g-VSS/g-TOC and 0.005 d−1, respectively. Maximum specific methanogenic activity was experimentally found to be 2 g-CH4-COD/g-VSS•d while maximum specific loading rate to achieve 80% of TOC removal efficiency was determined to be 2 g-TOC/g-VSS•d. The results of this study suggest that single-step anaerobic treatment of methanolic waste is highly feasible provided that the pH is maintained close to 7.0.