Water Science and Technology Vol 41 No 4-5 pp 469–476 © IWA Publishing 2000
Extensive nitrogen removal in a new type of airlift reactor
C.T. Frijters*, S. Vellinga**, T. Jorna*** and R. Mulder****
*
PAQUES Water Systems B.V., T. de Boerstraat 24, P.O. Box 52, 8560 AB Balk,
the Netherlands. (Phone +31-514-608500. Fax +31-514-603342)
**
PAQUES Water Systems B.V., T. de Boerstraat 24, P.O. Box 52, 8560 AB Balk,
the Netherlands. (Phone +31-514-608500. Fax +31-514-603342)
***
PAQUES Water Systems B.V., T. de Boerstraat 24, P.O. Box 52, 8560 AB Balk,
the Netherlands. (Phone +31-514-608500. Fax +31-514-603342)
****
PAQUES Water Systems B.V., T. de Boerstraat 24, P.O. Box 52, 8560 AB Balk,
the Netherlands. (Phone +31-514-608500. Fax +31-514-603342)
ABSTRACT
A new type of CIRCOX® airlift reactor was started-up treating
anaerobically pre-treated potato-processing waste water. This type of
airlift reactor with biofilms on carrier is an airlift reactor extended
with an anoxic compartment to obtain total nitrogen removal. This type of
reactor was designed in the early nineties and was tested successfully at
pilot-scale on brewery and municipal waste water. The 3 m3
pilot reactor was scaled-up to a size of 130 m3. Both the
hydraulics and the biological performance were studied. High liquid
velocities and equal concentrations of sludge throughout the whole
reactor, indicated that the system was well mixed. Up to 5 kg
COD/m3/day was removed. Ammonia was almost completely removed
(up to 1.0 kg NH4–N/ m3/day in the aerated compartment). The denitrification efficiency was over 90%. The
NOX–N concentration in the effluent never exceeded
6 mg/l. The biofilm layers were extremely dense: 30 g/l of VSS with a
sludge volume of 220 ml/l. Therefore the particles had high settling
velocities and could easily be retained in the reactor. It can be
concluded that this new technology has been scaled-up successfully. With
this an aerobic technology is available in which extended treatment and
nitrogen removal are accomplished in a very compact system.
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