Evaluation of IMET technology for enhancement of wastewater sludge digestion

Abstract

This study evaluated the IMET[superscript TM] technology for the enhancement of sludge digestion in comparison to the existing aerobic digesters at the Columbiana WWTP, where the study took place. This evaluation was based on changes in solids and organic matter, and the fate of nutrients, in an IMET pilot plant system. For a study period of eleven weeks, samples were collected from seven different locations in the IMET system, on a weekly basis, and were tested for various parameters included under the study's scope of work. The analysis of data focused on sludge digestion in three process tanks that contained IMET bioreactor modules, and the process of biosolids breakdown in the system's solubilization tank. The results of this study showed decreases of less than 2% of all solids and organic matter parameters in the IMET process tanks, which were considered statistically insignificant by the t-test for paired observations. Weak evidence was shown that the system's venturi and/or ozonation units had some impact on the solubilization of biosludge. Small decreases in nutrient concentrations (< 10.0%) were observed and deemed statistically plausible by the t-test for paired observations, thus, showing signs of biological activity in the IMET process tanks. A comparison between the IMET system and the aerobic digesters, at equivalent detention times, showed a slightly higher reduction of total COD and VSS in the IMET system. This difference was deemed statistically insignificant, after calculating confidence intervals for the mean values of IMET system's outflow concentrations, at confidence levels as low as 20%.