What is EC
Electrocoagulation (EC) is a process using electricity and iron plates (electrodes) to separate water soluble nutrients in the wastewater. These nutrients - like phosphorus, nitrate and ammonium - are not visible. The system works by coagulating pollutants, making them easier to remove from the water.
Potentially harmful bacteria, viruses and algae are also destroyed during the EC process. Larger molecules which form, become visible as sludge, which then settles at the bottom of the settlement tank. After a clarification process, the clean 'wastewater' can be discharged through the wetlands or a subsoil irrigation system on a parcel of land (Discharge to Land). The separated sludge will dry and could potentially be used as fertiliser for farms, orchards and gardens.
At Rāwene, the wastewater from the maturation pond will be pumped through the EC unit, settler tank and screw press. The resulting clean water can go to the wetland or in the future be Discharged to Land.
As part of this transformation project, the EC system is powered by solar energy, making it a sustainable and eco-friendly solution. The solar power system provides electricity throughout the seasons, with minimal costs to ratepayers. This innovative approach not only improves water quality but also significantly reduces carbon emissions, aligning with both environmental and cultural values.
What are the benefits of EC
- Environmental friendliness: EC can be powered by green energy sources, in this case solar energy.
- Cost-effectiveness: EC is economical and has relatively low maintenance costs.
- Efficiency: EC can quickly and effectively purify wastewater.
- Sludge reduction: EC produces less sludge than other methods, and the sludge is easier to dewater.
- Water quality: EC produces clear, odorless, and colorless water.
- Flexibility: EC can be integrated into existing wastewater systems.
- Metals recovery: EC can recover metals from wastewater.
- Arsenic removal: EC can remove arsenic from water without the need for an oxidation step.
What are the benefits of Discharging to Land
EC is potentially a very good pairing with Discharging to Land as it removes a lot of the limiting nutrients such as phosporus and ammonia.
- Discharging treated wastewater to land encourages further treatment through contact with soils and also allows vegetation to uptake nutrients
- Discharging to land stops contaminants entering waterways
- Taking treated wastewater out of waterways helps to restore the mauri of the awa
- Treated wastewater can be re-used for irrigation purposes, which in turn reduces demand on other freshwater sources.