Domingo Zarzo Martínez is visiting the island to introduce the XIV edition of the international conference ’60 years of innovation in desalination and reuse’. What is the forum about?
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It serves as a meeting point for the sector, which was initially national and is now international (last year’s, the XIII edition, which is held biennially, took place in Granada). The latest developments and trends in desalination are presented at this event. There are highly technical presentations showcasing new products and discussing innovation projects, now more focused on sustainability. There are also presentations related to legal issues, permits, impact studies, and environmental measures. Both public administrations and private companies can share their achievements, highlighting the latest successful cases in water management. We are thrilled to go to Tenerife as it is a global reference in this field, being the place where desalination began in Europe in 1964, specifically in Lanzarote. Furthermore, without the water provided to the islands by desalination and reuse, the development of the tourism industry and agriculture practices would not have been possible. Canary Islands have the highest number of desalination plants with a capacity exceeding 10,000 m3/day (21 in total) in the country, with a desalination capacity of 485,200 m3/day, as well as numerous smaller facilities.
What is AEDyR?
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A non-profit association with over 25 years of history that was established in 1998. Spain holds significant importance in this field, with 8 out of the 20 largest desalination plants being Spanish. AEDyR brings together private and public companies, universities, and research centres. Its aim is to promote the sustainable use of unconventional resources in areas where conventional ones do not reach, which is becoming increasingly common due to the situations of climate change leading to more frequent and longer droughts.
Is desalinated and regenerated water, including treated wastewater, the solution to drought?
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It is not the only solution. The first step is to be efficient in water use, saving as much as possible as it is a very scarce and valuable resource that also comes at a cost – it is not free. The truth is that capturing, treating, and delivering water to homes is a costly process. Secondly, every last drop of wastewater should be reused as it is a waste to discharge it into the sea. Ideally, seawater should be used as an inexhaustible source, but sometimes groundwater or treated wastewater is used in tertiary treatments.
Are you familiar with the water emergency situation in Tenerife?
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The declaration plays a crucial role, especially on an island. I am not familiar with the 75 measures of the Island Water Council in detail, but I know that at least five portable or medium-sized desalination plants are planned. Additionally, there are expansions of the existing four major plants to increase reuse. Expanding on existing plants speeds up the process; the issue is that from the moment a desalination plant is constructed, there are environmental procedures and permits that could extend the timeline to five or six years.
Is the collaboration of municipalities crucial? There are cases like the unused sewage treatment plant in Güímar due to the lack of necessary pipeline infrastructure. What is your opinion?
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I am not familiar with the specific case, but generally, the answer is yes. We all need to work together, including administrations, in a coordinated manner because the responsibility is shared. Political parties should come together and reach a national water pact that is not a political weapon, as we are facing a water crisis that will worsen with the impact of climate change.
There are experts advocating for groundwater (wells and galleries) as the traditional method to combat drought.
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Those of us who support desalination do not believe it is the sole solution. I understand that all methods are valid and can be used as far as possible, but there is a clear reality: seawater is an inexhaustible resource, whereas aquifers can be depleted. Therefore, all resources must be utilised sustainably.
Desalinated water: it is expensive, has a significant environmental impact (waste), consumes a lot of energy (electricity), and there are concerns about its quality. How do you counter these arguments?
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These are common misconceptions. When we talk about 3 kW per cubic metre, it is equivalent to the energy consumption of a refrigerator for a family of four over a year. Viewed in this context, it does not seem excessive. Desalinated water may be costly, but there is no water more expensive than the one that is unavailable. Then there is the concentrate, often referred to as brine, which is essentially concentrated seawater. On one hand, pure water is produced, and on the other, a concentrate containing salts. Environmental impact studies in the plant design anticipate the effects before discharge, and monitoring programmes confirm that everything is done correctly. A diffuser system allows the water to return to normal seawater without chemicals just a few metres from the discharge point. One of the current trends in innovation is exploring the mining of brine to obtain chemicals or salts. The quality of desalinated water is exceptional as it does not contain microplastics or pollutants.
Is it true that the WHO suggests boron levels in desalinated water are above what is recommended?
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Boron passes through membranes in a very small proportion, but a plant that functions well with the renewal of these membranes fully complies with the legislation. The European Union changed it from one milligram per litre in drinking water to 2.5 because it also doesn’t have any special toxicity. For some crops, it needs to be reduced even further, but it is a resolved technical issue. It’s a matter of a little more investment that has almost no impact on the cost of water.
Are the priorities by law human consumption and agriculture in that order?
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Human consumption is always prioritised, followed by its use in agriculture. Another myth is that desalinated water is not suitable for farming because it is too expensive. There are scientific studies that show it actually increases the productivity of many crops. Before 2050, the United Nations proposes doubling production to feed the entire population, which means the need for more water. Where are we going to get it from?
Is public-private collaboration essential?
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Undoubtedly. An example is the case of the Tenerife Island Council. A demand from the sector is that in Spain, our regulations do not favour concession models. In other words, you, the public administration, do not have money now, but don’t worry, we will make the investment along with banks and recover it over 25 years. This is how it works in countries like Saudi Arabia or Australia. The current legal framework in Spain does not support this, and we are trying to change that.
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She is working on a new concept called Water Positive.
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A group of professionals launched the idea a couple of years ago, and we have reached the United Nations. It involves calculating the water footprint of business activities and encouraging large industries to become Water Positive; that is, to generate more fresh water than they consume. How can they do that? By desalinating or reusing water. Companies like Microsoft, Google, or Coca Cola have already expressed their commitment to achieve this by 2030. If they fail to generate this water, they could pay, for example, 10 cents per virtual water to the government. Those 10 cents could reduce the price for the population or agriculture by up to 10%.
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