Process intensification by thickened biomass

From left: activated sludge; return sludge after InDense; excess sludge after InDense;

The forces acting on the sludge particles in this process simultaneously aid their clumping and can lead to the formation of aerobic granular sludge.

The advantage of InDense technology is its easy installation and implementation into the existing technological scheme of the wastewater treatment plant. Only the InDense unit and the necessary pump are included in the installation. The technology can be installed directly on the sludge removal pipe from the settling tank, or as a separate assembly installed at the sump with the sludge drawn.

Ephrata Borough has faced chronic sludge settling problems at the WWTP since BNR technology was installed in 2011 to meet the new limits. During the winter months, the sludge index reached values of up to 300 ml/g.

The chart below shows the performance of the system before and after installing the InDense process. As soon as the InDense system was put into operation, there was an immediate decrease in sediment volume (SSV) and sludge index (SVI) with an increase in sludge concentration (MLSS). Due to InDense technology, the sludge index is consistently in the range of 70-80 ml/g. Thanks to the selection and recirculation of thickened biomass, significantly lower sludge index values can be achieved steadily.

It combines the BIOCOS cyclic activated sludge process with an anaerobic selector and InDense technology. Selection and recirculation of the thickened biomass made it possible to reduce or stabilize the sludge index during the trial period. At the same time, the interaction between settling properties and bio-P-activity can be observed During a transition period lasting approximately half a year, the measured sludge index dropped from the original 140 ml/g (see figure: cyclone installation on February 17) to about 60 ml/g, while the phosphorus removal efficiency increased from about 60% to more than 80%.

Selection of concentrated biomass makes it possible to reduce or stabilize the sludge index during the operational period. At the same time, an interaction between settling properties and bio-P-activity can be observed.