THE DENITRIFICATION PROCESS
Denitrification as oxygen-free water filtration removes toxic nitrogen compounds from a (partially)-closed aquaculture facility. In this process, nitrate (NO3) is broken down from the water in the plant with the aid of special bacteria, the denitrifiers. In nitrate respiration, the bacteria use the nitrogen (NO3‑N) bound in the nitrate as well as a carbon source (substrate, e.g. acetic acid CH3COOH) to generate energy and build cell structures. The bacteria extract the nitrogen from the process water, whereas the carbon source must be added as required. This dosage is decisive for stable denitrification. After the conversion of the nitrate, only molecular nitrogen remains. This is harmless to the environment and escapes from the plant as a gas without leaving any residue. As a result, a functioning denitrification leads to a reduced water consumption, because no toxic substances accumulate in the water. Without denitrification they would have to be flushed out of the system with an increased water change.
The required size of a denitrification depends on the daily amount of nitrogen introduced by the feed. Our standard product with a volume of 1000 liters (IBC) is designed for a feed load of around 5 kilograms per day. Other sizes can be offered individually on request. The SEAWATER denitrification comes with built-in automation software with corresponding error and warning systems. It is very well suited for integration into existing process control systems and, if required, also records data from existing measuring devices.
Efficient filling pellets
Optimized filling pellets made of food-safe PP plastic serve as a place for bacterial cultures to settle. They also ensure that the bacteria are well bathed in process water as well as substrate and thus supplied with nutrients.
The SEAWATER software controls the denitrification fully automatically on the basis of a PLC. Depending on the amount of feed, both the supply of nitrogen-rich system process water and the dosage of the carbon source are regulated.
Special substrates are required for a quick start-up and smooth operation of the denitrification. These are the food for the bacteria and are produced by us according to our own recipe and offered for sale.
In recirculating systems, it is important that toxic nitrite does not accumulate in the water. With our denitrification, the nitrate nitrogen content in the water can be kept constant between 50–100 mg / l NO3‑N. These are optimal values for the animal welfare of the fish.