Primary Sludge Fermentation – Results from two full-scale pilots at South Austin Regional (TX, USA) and Durham AWWTP (OR, USA).

Both Enhanced Biological Phosphorous Removal (EBPR) and Nitrogen Removal require a sufficient supply of readily biodegradable carbon. Volatile fatty acids (VFA) are often referred to as the critical substrate, especially for EBPR. VFAs are generated through fermentation under anaerobic conditions and are typically present in treatment plant influent. However, in most cases concentrations are insufficient for reliable EBPR and nitrogen removal and/or in high percentages year around. Primary sludge fermentation can provide a cost effective alternative to increase the VFA supply and has been used successfully at many facilities.