TKI- Wetlands as pre-treatment for mild desalination
Dow, Evides and HZ University of Applied Sciences are working on a TKI subsidized project aiming to investigate how a combination of wetlands as pre-treatment and desalination processes can effectively remove micro-pollutants, nutrients and salinity from wastewater treatment plant effluent. The hypothesis is that wastewater treatment plant effluent is one of the most difficult streams to treat for removal of micro-pollutants and nutrients, so if it can be achieved on this stream then it can also be applied to other streams such as (brackish) surface water. It is believed that the micro-pollutants will be adsorbed in the root zone of the wetland vegetation and the nutrients will be taken up by the plants, meaning that the remaining impurities such as salts are removed with a combination of ultrafiltration (UF), ion exchange (IX) and reverse osmosis (RO).
Research on the wetlands alone is carried out independently from summer 2019 to summer 2020. Research on the “brackish water line”; namely the treatment train consisting of ultrafiltration, ion exchange and reverse osmosis in sequence, began in January 2020 and will run until summer 2020 when the wetlands will be connected to the brackish water line as a pre-treatment step. A polishing step such as a mixed bed which would be needed to achieve demi water quality is out of the scope.
The influent water used in the research consists of effluent from a local Membrane Bio Reactor (MBR) and effluent from an industrial wastewater treatment plant (Biox). These influents will be tested separately and also as a mixed stream, with and without wetland treatment.