The anaerobic treatment of sewage and granule formation in upflow anaerobic sludge blanket reactor

The granulation process was examined using synthetic wastewater containing glucose in a 1 liter laboratory upflow anaerobic sludge blanket (UASB) reactor. The anaerobic biotransformation of glucose was investigated during the granulation process. Anaerobic unacclimated sludge and glucose were used as seed and primary substrate, respectively. Massive initial granules were developed after three months of start-up. The effect of operational parameters such as influent glucose concentrations, pH, Volatile Fatty Acids (VFA) were also considered during granulation. The presence of a large concentration of sulphate in the sludge of a mesophilic (37 degrees C +/- 1 degrees C) UASB reactor treating sewage resulted in severe process disturbance, with a complete inhibition of the propionate-degrading ability of the sludge. Severe inhibition of acetate removal was also observed, with concentrations of propionic acid and acetic acid in the reactor effluent of 1.72% and 18.88%, respectively. Hydrogen sulfide (H,S) is formed from the anaerobic decomposition of organic matter containing sulfate by sulfate-reducing bacteria. This gas is toxic at rate exceeding 2% tolerable by a reactor. The result shows the rate of hydrogen sulfide production was 3.8 %.