Mörbylånga Vattenverk (Mörbylånga Drinking Water Treatment Plant)
Location: Mörbylånga, Sweden
Owner: Mörbylånga Municipality
Operator: Mörbylånga Municipality
Commissioning: 2018
Drivers for development and implementation:
- Drought and water scarcity
- Efficient use of resources
Background:
Due to several years of water shortage, Mörbylånga Municipality in south-east Sweden has commissioned a new drinking water treatment plant (DWTP). The drinking water production will be independent of rainfall and groundwater recharge. Instead it will rely on the desalination of brackish water from wells close to the Baltic Sea, combined with advanced treatment of used process water from a nearby food processing plant (one of the largest producers in Sweden of chicken meat and chicken dishes). The treatment of the brackish water is carried out in a process where permanganate oxidation, ultrafiltration (UF), desalination over reverse osmosis (RO) membranes, remineralisation in limestone contactors and disinfection with ultraviolet light (UV) are crucial elements.
Before the used industrial water is introduced in the DWTP it is treated mechanically, chemically and biologically in an industrial wastewater treatment plant, and also in an advanced water treatment facility called the Mörbylånga Pretreatment Plant (PTP). In the PTP the industrial water undergoes treatment in ultrafilters and with UV light. One of the benefits with blending brackish water with reused water is that the salinity of the industrial water is considerably lower than the salinity of the brackish well water, lowering energy consumption and operating costs.
The production capacity of the water plant is 4,000 cubic meters of drinking water per day, which is approximately 75 % of the daily water demand in Mörbylånga Municipality. Together with the existing drinking water plants this will make the municipality resistant to very long periods of rainfall shortage.
Figure 1: Mörbylånga DWTP in June, 2019.
Financing:
- The investment was financed through a “Green loan” from the Swedish Kommuninvest Green Bonds financing for climate friendly projects.
- The project is financed by raising the water tariff.
- The project received a 50 % financing from the Swedish Environmental Protection Agency [1] for the pilot tests (approx. €169 000).
Project Planning:
- Project planning included pilot testing, design work in 3D, a Quantitative Microbial Risk Assessment (QMRA) [2], a Hazard Analysis and Critical Control Points (HACCP) study [3] and a public procurement processes according to the European Union Directives on Public procurement in the utilities sector.
- The Swedish National Food Agency and the Swedish Environmental Protection Agency were consulted during the planning of the plant.
- Several press releases have been made, together with a leaflet to all municipal drinking water customers. The municipality also has arranged several information meetings.
Type of treatment and capacity of production:
Food processing plant internal WWTP and municipal industrial WWPT:
The treatment includes drum screening, flocculation and flotation, Sequencing batch reactors (SBR) and DynaSand filtration. Capacity 1 800 m3/day.
Reclamation Plant (The Pretreatment Plant):
Ultrafilters and UV light. Capacity 1 500 m3/day of incoming wastewater.
The treated industrial water is then led to the DWTP where it is mixed with brackish well water and treated with ultrafilters, reverse osmosis and UV light.
Performances:
The PTP is still in a testing phase. Initial water samples indicate very low levels of microorganisms already after the PTP. The plant is planned to be fully operational in February or March 2020.
Figure 2: Simplified process diagram of the PTP and DWTP.
Benefits:
Some expected benefits of blending the brackish water with reused water are:
- The salinity of the blended water is lower than in the raw brackish groundwater, which will result in lower energy costs.
- Fresh water is valuable on an island with small amounts of rainfall. By reusing the industrial water, less fresh water will be discharged to the Baltic Sea.
- The need for brackish water desalination will be lower, which also reduces the discharge of brine to the Baltic Sea.
- The plant has been awarded the Water Reuse Europe Innovation Prize 2019, The FEDIL Environmental Award 2019 in Luxembourg (for contractor Apateq PWT S.A., Luxembourg) and the Xylem Water Award 2020 in Sweden.
Challenges:
- Overcoming the general scepticism of water reuse. Proactive and transparent stakeholder engagement (including leaflet drops and information sessions) has produced positive political and local support for the project.
- There are no Swedish regulations on water reuse. Instead, US EPA [4] and WHO [5] guidelines have been used.
Reference:
1. Swedish Environmental Protection Agency, ”Innovations for sustainable cities – Grants for leading-edge technologies and new system solutions,” 2017. [Online].
2. Norconsult, ”Kvantitativ Mikrobiologisk Riskanalys för Mörbylånga Vattenverk,” 2018.
3. Sweco, ”Riskanalys och kritiska kontrollpunkter (HACCP),” 2019.
4. United States Environmental Protection Agency (US EPA), ”2017 Potable Reuse Compendium”, 2017.
5. World Health Organization (WHO), ”Potable Reuse: Guidance for producing safe drinking-water”, Geneva, 2017.
Further Information:
