Jesus Andres Cacho Rivero Born in Laredo (Cantabria) Spain M.S and B.S. Chemistry. University of Valladolid. Spain PhD Student since 2000 in Dr. Suidan Research Group Department of Civil & Environmental Engineering Anaerobic Digestion of Excess Municipal Sludge. Enhancement of Solids Destruction

Production of excess municipal sludge is increasing with increases in population, industrial activity, and the level of treatment. There is an urgent need to develop technology that permit for safe and efficient disposal of this sludge. Anaerobic digestion is an environmentally friendly and economically sustainable technology for the disposal of excess municipal sludge. This technology, however, suffers from the fact that a maximum of only 50 % of the organic solids are destroyed during treatment. The objective of this study, which is being performed in the Civil and Environmental Engineering Department of University of Cincinnati, is two-fold: Perform fundamental research to determine the effect of the sludge retention time and the hydrodynamics on digestion. Select and optimize a co-treatment system to enhance the performance of solid destruction during the anaerobic digestion process.

Experimental Set-Up Twelve well mixed lab-scale anaerobic reactors set up in a constant temperature (37°C) room Versatility to conduct simultaneous parametric studies

Theoretical Studies  Solids Removal as a function of Sludge Retention Time (SRT) Four different retention times (5, 10, 20 and 40 days) were evaluated in triplicates. The solids removal obtained was modeled as a function of the SRT Model:  Evaluate the benefit of reactor staging Multiple stage configurations were compared to single stage reactors having the same SRT. Staging resulted in increases in solids removal ranging from 2 to 5 %. Proposal Treatments Studies  Thermal, Oxidative and Thermo-oxidative treatment of excess municipal sludge The use of low temperature (below 100°C) and hydrogen peroxide was evaluated as pretreatment and co-treatment options of anaerobic digestion Results:

Model Where: k = 1 st order reaction constant f = fraction non biodegradable  = retention time Back to Previous

Summary of Results Stress Unit Two Stages. Co-treatment Stress Unit Pre-treatment Stress Unit Recycle: 20 % Reactor Volume Single Stage with Recycle Back to Previous