The use of Ecogreen in the selective removal of sodium in reclaimed wastewater
4 June, 2050
Partners 4 Water
Waste water source
Treated effluent is delivered by the urban WWTP of Aquafin located in Mechelen-Noord (province of Antwerpen). The drain water is collected and reused as irrigation water.
Every week 2 to 4 m³ of freshly purified effluent is supplied in cubicle vessels, which are stored under shady conditions. From these cubicle vessels the water is distributed over a greenhouse with a floor area of 160 m².
The greenhouse is furnished as is customary in the practical greenhouses for cucumber cultivation on rock wool substrate (Grodan GT Master). It is equipped with autonomous irrigation, recirculation and climate controls, which can be operated independently.
Waste water treatment description
The WWTP effluent is purified to achieve the minimum water quality standards set for minimum quality requirements for water reuse. For this, a purification train was chosen consisting of sand filtration (suspended particles up to 20 microns), activated carbon filtration (removal of pesticide residues) and ultrafiltration (removal of fungi, bacteria and viruses on carrier). Due to the high sodium concentration, the water of the Aquafin-Na+ treatment was desalted via selective sodium removal based on electrodialysis by EcoGreen (WaterFuture).
The EcoGreen (WaterFuture) is used to prevent the accumulation of sodium and chlorine in the hydroponic system. The technology uses capacitive electrodialysis to remove monovalent elements from the Aquafin effluent.
The pilot EcoGreen capacity amounts 0,5m³/h.
Extent of the agricultural beneficiaries
Within the trial, the supplied Aquafin effluent was purified until the target value of 0.3 mS/cm was reached, which is close to the EC value for the reference treatment. In general, the proposed EC value of 0.3 mS/cm could be achieved. During the treatment with the EcoGreen, an average of 61% sodium was removed and an average of 78% of the chlorine.
The treatment costs and distribution costs will be defined by the end of 2021.
Type of agreement
This demonstration and research takes place within the context of an cooperation between Aquafin (WWTP operator), Imec the Netherlands and The Research Station for the Vegetable Production (PSKW).