Download Bioaugmentation by nitrification with return sludge (BABE

Bioaugmentation by nitrification with return sludge (BABE technology)
PhD-student: Ir. Sonia Salem
Tel: +31 15 278 1482
e-mail: [email protected]
Promotor:
Prof. dr.ir. Mark C.M. van Loosdrecht
Institute:
Delft University of Technology, Department of Biotechnology,
Environmental Biotechnology group (EBT)
Project term: April 2000 – December 2004
Financed by: DHV Water- STOWA
Description
The nitrification capacity of an activated sludge process can be augmented by the addition of
nitrifiers. These bacteria are usually added as cell suspension. An important disadvantage of
adding bacteria in suspension is that they are susceptible to grazing by higher organisms,
and not necessarily adapted to the conditions of the actual treatment process. The so-called
BABE® (Biological Augmentation Batch Enhanced) technology, developed by DHV in cooperation with the TUD overcomes this problem by producing nitrifying bacteria into the
activated sludge flocs. To achieve this, a limited amount of activated sludge from the main
process is recycled over the BABE reactor. The concept has two main goals: biological
treatment of a nitrogen rich side-stream and augmentation of nitrifying bacteria in the main
stream.
In this project, the augmentation technology was proposed and experimentally evaluated.
First, the effect of feeding a normal activated sludge system with nitrifiers enriched in a
separate reactor (the so-called BABE reactor) was studied. A dynamic simulation model was
used for evaluating design criteria. A high-load WWTP (Houtrust in Den Haag) and a lowload (Walcheren), partially nitrifying WWTP were taken as examples. The simulations gave
proper design criteria and showed the advantages of upgrading according to the BABE
concept.
The process was tested at full-scale at the WWTP of Garmerwolde (300,000 PE) in the north
of the Netherlands. These experiments were successfully conducted by DHV and supported
by model-evaluation and FISH analysis at the TU
Delft. In the BABE reactor nitrogen from the sludge
digestion was converted. Moreover FISH analysis
revealed that nitrifying bacteria were being
augmented in the main treatment plant, leading to
increased nitrification capacity.
The simulations have shown that the decay rate of
nitrifiers is a crucial factor for designing the BABE
reactor. Extensive experimental work was done to
evaluate the decay rate of nitrifiers under different
conditions and different temperatures. The sludge
of Den Bosch WWTP was used for experiments
where the first full-scale application of the BABE
The BABE reactor in Garmerwolde WWTP
process will take place.
(300000 p.e.)
Project Outcome:
New process for augmentation of nitrifiers in sludge: BABE
- Salem S, Berends D, Van Loosdrecht MCM & Heijnen JJ. (2003). Bio-augmentation by
nitrification with return sludge. Water Res 37(8) p1794-1804.
Mathematical modeling of the BABE process
- Salem S, Berends D, Van Loosdrecht MCM & Heijnen JJ. (2002). Model based evaluation
of a new upgrading concept for N-removal Water Sci Technol 45(6) p169-176.
- Berends D.H.J.G., van der Kuij R.J., Salem S., Uiiterlinde C. (2002). BABE-technologie
voor volwassen. H2O (in Dutch) 19, 81-83.