SBR side stream process for high ammonium concentrated effluent treatment: process performance and sizing

The removal of nitrogen represents an important treatment objective for the processing of wastewaters. One significant contributor to the influent nitrogen loads is the recycled digester supernatant, typical after some form of dewatering such as belt filter press or centrifuge. Conventional methods of nitrification and denitrification are then widely implemented in the main liquid line. An interesting alternative for the high ammonium concentrated waters is the ‘nitrate shunt’ process, which allows treatment of this side-stream separately. This article presents the results obtained on an industrial pilot plant processing supernatant coming from digested biosolids and implementing a nitrate shunt treatment. Issues related to installation and biomass acclimation processes as well as regulation of oxygen and denitrification are discussed. Chemical dosage and FISH analysis were performed during the pilot study experiments. Almost one year of operation experience on site allows us to validate the process and discuss design considerations.