|Authors: ||J. Suhl, D. Dannehl, L. Zechmeister, D. Baganz, W. Kloas, B. Lehmann, G. Scheibe, U. Schmidt|
|Keywords: ||decoupled, nitrogen concentration, recirculating aquaculture system (RAS), tilapia, African catfish, sedimentation filter, suction filter|
In contrast to conventional single recirculation aquaponic systems (SRAPS), the innovative double recirculating aquaponic system (DRAPS) provides an opportunity for intensive fish and plant production.
This system is based on two separate recirculating systems, a recirculating aquaculture system (RAS) and a closed hydroponic system, whereby the composition of fish waste water can be optimized for plant growth by the addition of synthetic fertilizer.
However, in the last two years of research it has become apparent that the first approach to DRAPS needs to be reconsidered and further optimized.
In the first implementation of DRAPS, the fish waste water passed a sedimentation filter incorporated in the RAS and then a secondary clarifier, constructed as a three-chamber pit, for deposition of solids before delivery to the hydroponic system.
It became clear that the depletion of nitrogen caused by the secondary clarifier was too high.
Therefore, a new approach was developed and is addressed in the present study: a new suction filter was developed for sludge elimination in the RAS. The first weeks of its use were promising and it is obviously possible to omit the previously used sedimentation filter and leave out the secondary clarifier completely.
With this setup, the fish waste water from the RAS was used directly with a minimum of water losses.
Another advantage was that the nitrogen concentration in the RAS was kept relatively stable by the use of the new suction filter.
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