The field performance of Moving Bed Biofilm Reactors (MBBR) for nitrogen removal on effluent from greenhouses is tested by Proefcentrum voor Sierteelt. The test results from two floristries in Belgium show promising results.
Biofilm for denitrication
Photo 1: MBBR and P filters at Floristry Meuninck with an indication of the water flow
A MBBR is a filter that denitrifies nitrate (NO3) into gaseous nitrogen (N2). The filter tank is filled with special plastic carriers that provide a good surface to grow a biofilm. An air pump with a membrane disc diffuser is working every 3 hours for one minute to create some movement in the carriers and to prevent clogging of the biofilm in the carriers. The residence time of the water in the filter is 8 hours. CarboST is used as C-source and is injected by a dosage pump working together with the influent pump. The COD concentration of CarboST is 1,12 kg O2/L.
PCS has already been testing this MBBR since two years. The system was adapted and simplified and is now ready for evaluation in real-life practice.
In 2019, two MBBR have been installed at floristries. At Floristry Meuninck (Nevele, Belgium), the MBBR installation is in operation since the beginning of August 2019 (Photo 1). At floristry Azaro (Laarne, Belgium) it is in operation since the end of September 2019 (Photo 2).
To enhance the activity of both filters, about 10 L of carriers were taken as inoculation material from the MBBR installation at PCS. On these carriers, the biofilm was already well developed.
Setup at floristry Meuninck
Since a few years, all drain water at Meuninck is collected in a storage tank during winter. In springtime, the water is pumped through 2 P filters (filled with Iron Coated Sand) to remove P. With the installation of the MBBR filter, there is now also a good N removal from the drain water at Meuninck. The MBBR filter has been installed before the P filter because the presence of P in the drain waterhas a positive effect on the operational efficiency of the MBBR (= bacteria need P to grow). Photo 1 indicates the water flow through the different filter systems.
Setup at floristry Azaro
Photo 2: MBBR at Floristry Azaro
At floristry Azaro, water from the container field is pumped through the MBBR filter to remove N. This filtration has only been working since a short period, but the first results of N-removal were as promising as for the other MBBR-filters that PCS tested. One filter can treat 3 m³/day. The cost for a self-maid MBBR amounts up to about € 2700.
els.pauwels[at]pcsierteelt.be or marijke.dierickx[at]pcsierteelt.be,
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