(490c) Energy and Fuel Value of Wastewater Sludge Residuals

Disposal of wastewater sludge presents an expensive problem for nearly all wastewater treatment facilities. Due to its high moisture content, energy exploitation is often not considered viable. However, various sludges present useful characteristics, and invite further evaluation.

We have characterized the fuel value in terms of proximate analysis of several dried sludges, including waste activated sludge and digester sludge. The ash content is always quite high, but the volatile component is also high, and may be as high as 60%. Using several solvents, we have identified several chemicals that are present in the sludge in concentrations high enough to merit investigation, including fatty acids and cholesterols.

We describe possible process configurations to make greatest use of sludge, including pyrolysis, gasification, and solvent extraction.