Island (Region, Province, Country):
Gran Canaria, Canary Islands, Spain
Budget / cost of the project:
Increase the sustainability and environmental protection of small islands by eliminating the impact of desalination plants brine discharges on marine ecosystems.
Project description of activities and specific interventions:
Brine disposal locally impact benthic fauna and flora communities, if poorly diluted discharge is allowed to flow across the marine bottom.
The Venturi Project (2009-12), funded by the Spanish Environmental Ministry (MAPAMA) and coordinated by the Technological Institute of the Canary Islands (ITC) demonstrated the technical viability of venturi diffusers in the dilution process of desalination plants brine discharges with the aim of reducing its environmental impact in marine ecosystems.
ECOS, an environmental impact consultancy agency focused in the marine sector, which was one of the main participants of the overall project, conducted the installation of two prototypes of the diffusers in 2012 and 2013 on desalination plants located in Gran Canaria, Spain (average brine effluent flow 1.062 m3/h and 583 m3/h, respectively).
Brine dilution efficiency was improved (131% higher than conventional diffusers) resulting in a minimization of the 99% environmental impact associated to the brine and the recovery of fast growing colonizing benthic communities (e.g. Caulerpa prolifera) which was observed after the installation of the device.
Benthic ecosystems at littoral zones as coral reefs, seagrasses meadows and mangroves forests are very sensitivity to changes in the water quality and due to their location are highly susceptible to being affected by brine discharge.
After the Venturi Project, ECOS has developed the Brine V+1, a product which higher efficiency and lower manufacturing costs than the initial prototypes. During 2017 a feasibility study and a market approach were carried out during the European Union Horizon 2020 SME Instrument Phase 1, indicated a few necessary technological improvements before launching it to the international markets.
Those improvements have been developed. ECOS is currently undertaking negotiations with potential partners to test the technology in real conditions thought pilot projects in other islands in the Mediterranean (Italy and Cape Verde) as well as in the Caribbean and Asia Pacific.
This promising technology has the potential to represent a technological leap in tackling one of the most robust environmental barriers for the developing of the desalination industry.
Public outreach, education and awareness efforts and results:
There has been much research and dissemination on the environmental impacts associated with the disposal of brine concentrate, which range in geographic scale from local to regional to global.
The primary environmental impact include increases in the salinity of receiving water bodies (particularly restricted circulation bodies), local impacts of hypersaline brines on marine benthic communities at and near the point of discharge, discharge of chemicals used for pretreatment and membrane cleaning and metals from corrosion (Cu, Fe, Ni, Mo, Cr), impacts to aquifers from leaks from brine pipes, temporary damage during construction and maintenance and permanent damage from emplacement of infrastructure (pads, pipelines, etc.) ECOS has participated in the development of scientific articles which currently are baseline publications in the field.
Nevertheless, there are still a large number of new projects that are being evaluated based on old or misleading assumptions. Many of them located in coastal regions that have not needed much desalination in the past, such as California and Texas in the United States, or parts of Europe and Southeast Asia.
On these regions desalination is being projected to become an integral part of future water supplies, and the need of higher quality and more up to date scientific information is required to assess the projects’ environmental impacts.
Often the environmental government bodies have a lack of awareness or determination on this field, so in many countries the policies restrictiveness is still very lax.
During 2017 and 2018 we have worked on the following different strategies to increase the environmental awareness of this problem and to push the government agencies to act upon it:
o On-site presentations to Government agencies (California, USA and Abu Dhabi, UAE).
o Exploring partnership agreements with renewable energy desalination companies and with technical consultancy agencies that that assist and advise local governments on the development of national desalination plans and projects.
o We have designed a dissemination activities plan to exploit the data that will be generated during the validation and monitoring of the Brine V+1 on the upcoming pilot projects.
Economic value added and how calculated:
Environmental policies regarding brine dilution requirements are increasingly restrictive worldwide. Nevertheless there are still major differences among countries.
In Europe, the direct disposal of brines from desalination plants into water bodies is no longer allowed due to its conflicts with the objectives of the Blue Growth Strategy (COM(2012)494) and both, the Water Framework Directive (2000/60/EC) and the Marine Strategy Framework Directive (2008/56/EC).
Thus, the dispersion and dilution of the brine is currently a top concern for the companies that build and operate desalination plants. New solutions have emerged in the last decade, in order to meet the new requirements.
Currently, the most used method of brine disposal is a discharge pipe with either multiport or rosette diffusers. Diffusers are series of nozzles that increase the mixing of concentrate within the seawater column and prevent accumulation on the seafloor. Taking into account that a kilometer of an underwater pipe costs around 1.5-2 M€, this is an expensive alternative.
Recently, the updated guidelines on the management of desalination activities for the Mediterranean (UNEP(DEPI)/MED WG.439/7) directly address the desalinations plants impact on water quality deterioration and biological effects due to brine discharges and recommends the improvement of diffuser technology to increase the dilution processes during the brine discharge at sea (note 22.d.) The main economic value added by the Brine V+1 comes from its higher dilution capacity, which enables the length of the underwater pipes to be significantly reduced.
Other economic impacts will be achieved indirectly through the protection of benthic ecosystems which protect coastal regions and increase their resilience against the impacts of waves and storms and are fundamental for the balance of marine biodiversity, and consequently a key element for the protection of economic activities like fishing and tourism. Seagrasses meadows are also responsible of the greater percentage of the world CO2 absorption.
The relevance of benthic communities in islands is higher, due to its greater exposure to climate change and the importance of fishing and tourism to sustain their economies.
Ecological and social project outcomes:
Globally, the growing scarcity of freshwater and the climate change (which makes rainfall less predictable and droughts more common) place desalination as a key technology in filling the gap between supply and demand of freshwater.
Brine discharge management is considered as one of the main issues that the industry is facing, being a real bottleneck to speed its growth.
By launching to the international market a cost-effective solution that eliminates the environmental impact of the brine, ECOS is promoting the availability of water resources from desalination plants.
The brine effluent is not merely concentrated salts, as they also include a variety of chemicals that come from the reverse osmosis or distillation processes, such as antiscalants and antifouling, including chlorine and other disinfection by-products that may be toxic, as well as chemicals present in the intake water.
These discharges forms a very dense hypersaline plume (heavier than normal seawater) that spreads over large areas affecting marine ecosystems, especially to seagrass meadows which are one of the most ecologically important ecosystems in islands.
Brine can be diluted by co-discharging it with power plant cooling water, seawater or municipal wastewaters to reduce its salinity before it is returned back to the sea. Currently, the most commonly employed subsea modern outfall design is a discharge pipe with diffusers.
The Brine V+1 diffuser has an estimated the dilution capacity 2,3 times higher than conventional diffusers and it is easily installable in both new and existing submarine outfalls.
ECOS is also undertaking considerable research for further developments of the device and for the improvements of the services offered to the industry which will lead to optimal brine management, including:
o Brine plumes modeling techniques sophistication, allowing better projections to locate the discharge point where a maximum degree of mixing will occur.
o Using cutting-edge oceanographic techniques for a better acquisition of detailed monitoring data on active plumes to assess changes in brine concentration.