A new plan from the Spanish government could see water recycling and reuse more than double by 2015. Carlos Martin looks at how the country is coping with drought and why a combined treatment process using ultraviolet technology and chlorine dioxide could help secure water supplies in years to come.
Global capital expenditure on advanced water reuse will grow at an annual rate of 19.5% up until 2016, industry forecasts suggest. Four major factors have been cited that will lead to such growth in the water reuse sector:
– Pressure on the world's water resources driven by climate change and population growth
– Growth of cities, creating greater stress on water resources and sanitation systems
– Environmental concerns have curtailed other solutions to water scarcity, including the construction of large dams and desalination
– New technologies that have proven to safely treat reclaimed water to be blended in reservoirs or aquifers for potable purposes.
Nor is it just the traditional agricultural market that is taking the lion's share of reused water. Increasingly, urban water reuse is helping to reduce urban water stress and is providing a higher return on investment to users of water reuse technologies.
Water reuse in Spain: a burgeoning market
Among EU countries, Spain is one of the most severely affected by water shortages due to drought. Global Water Intelligence ranks the country as the fifth leading market for advanced water capacity – as measured by 2009–2016 capacity estimates – behind the United States, China, Saudi Arabia and Australia, and ahead of countries such as Mexico, the United Arab Emirates and India.
Population growth, economic expansion, tourism and agriculture are the major drivers for rising demand. After investing heavily in national wastewater treatment and sanitation and purification plans, the Spanish government will put forth a new plan for water reuse and recycling in 2010. As a result, reuse and recycling is expected to increase from 368 million m3/yr by the end of 2009 to one billion m3/yr by 2015.
While urban water reuse is on the rise globally, agriculture remains the leading application for reuse in Spain, representing 75% of the usage volume. Other reuse applications include recreational/golf courses (12%), urban watering/cleaning (six%), aquifer recharge (4%) and industrial (3%).
Challenges in implementing reuse projects
Local and regional efforts to address water shortages in Spain through wastewater reuse date to the 1970s, though reuse did not become a national priority until 2005 with the Spanish government's AGUA program. The program's goal was to guarantee the supply of fresh drinking water to the country's water–stressed Mediterranean coast. Initially, the program gave priority to the expansion of desalination capacity. By 2008, however, investment priorities switched to reuse due to its superior financial viability.
TETRA Denite technology is used in water reuse applications, a growing market in Spain
In 2007, the Spanish National Sanitation Plan was introduced establishing a basic legal framework for the use of reclaimed wastewater, as the government aimed to more than double levels of wastewater reuse by 2015. The national water reuse and recycling plan that the Spanish government is due to release this year will provide further guidance on reuse/recycling goals and available funding through 2015.
Global analysts Frost & Sullivan project a compound annual revenue growth rate in reuse and recycling treatment technologies of 11% from 2008 to 2015 – down from the annual growth rate of 45% in 2007, but still representing a strong commitment to reuse and recycling. In the meantime, a variety of challenges – geographic, climatic, financial and cultural – are delaying the implementation of many reuse projects.
Taking into account geographic and climatic factors, Spain has an extremely diverse geography and experiences widely varying climatic conditions. Annual rainfall ranges from 2000mm in the northwest to less than 200mm in the southeast. The number and water quality of the country's rivers also vary significantly, providing different sets of opportunities or challenges for individual provinces.
Financially, as vast portions of the world have experienced an economic recession since 2008, so, too, has the Spanish economy. Recession–driven financial constraints have postponed and will continue to delay many new water and wastewater treatment projects. These delays are expected to continue through 2010 and perhaps into 2011. Access to EU funding for water and wastewater projects also has been eliminated due to the recession, further delaying planned projects.
Cultural factors include that the legislative concerns of Spain's 17 provinces are driven by varying local needs. These provinces feature strong regional identities and different languages (at least five different languages and several dialects are spoken in the country).
According to Frost & Sullivan, investment capital for reuse projects that had been delayed by the recession should once again begin to flow more freely by 2011. Industrial users of water and wastewater treatment equipment are expected to continue investing in environmental programs and increased tax revenues will fuel growth of municipal projects.
Current water reuse technologies
Spain's water reuse market has developed over many years, and as a result many technologies are used throughout the country to produce reclaimed water. Most reclamation plants typically employ a pre–treatment phase in which sand and grease are removed through screening. Physical and chemical treatments are used in the primary phase, after which the wastewater is sent to a settling tank. A biological reactor activates the sludge in the secondary phase. The most frequent configuration for tertiary treatment is a three–stage process involving coagulation/flocculation, filtration and ultraviolet (UV) disinfection.
For more than 30 years, a variety of filtration and UV disinfection technologies have been utilised and proven effective in plants throughout the world. For example, in the United States, which has the second largest installed reuse capacity behind China, deep bed denitrification has proven to be a highly effective treatment method to meet low total nitrogen limits. The technology was patented in 1979. Denitrification is the biological process by which nitrate is converted to nitrogen and other gaseous end products, and it can be achieved through chemical or biological methods. Methanol or another readily biodegradable carbon source must be added to wastewater ahead of the filter to enable denitrifying bacteria to grow.
Filtering liquids through deep beds of porous granular media to improve their clarity is widespread in municipal and industrial practice in the United States and is often used in tertiary wastewater filtration for reuse. Additionally, the removal of nutrients provides advanced wastewater treatment quality effluent.
An example of the use of deep bed filtration technology in the denitrification process is the TETRA® Denite® process from Severn Trent Services. As both a bioreactor and effluent filter, the Denite system combines deep bed filtration and fixed–film biological denitrification to achieve a high level of process synergy. Simultaneous removal of total suspended solids and nitrate–nitrogen achieves 1 ppm nitrate–nitrogen and 3 ppm total nitrogen or less.
UV power
The highly effective germicidal effect of ultraviolet light has been known for over 100 years. The first full–scale use of UV for disinfection was in 1910, for a wastewater treatment system in Marseilles, France. UV disinfection works by exposing waterborne microorganisms to UV light at a specified intensity for a specified period of time. This process of producing germicidal UV light renders the microorganism, in effect, "microbiologically dead." It does so by penetrating the cell wall and affecting the DNA in such a way that the cell cannot reproduce. The UV effect is generally referred to as "inactivating" the microorganism
As an alternative or supplement to traditional chemical disinfectants, such as chlorine, an ultraviolet disinfection system offers a number of operating advantages. An ultraviolet disinfection system is safe and easy to operate. The use of ultraviolet does not inject any taste or odour into the processed water, nor does it produce any undesirable by–products.
BESt of both
Earlier this year, Aigues de Reus Empresa Municipal installed Spain's first disinfection treatment system that combined a UV system with chlorine dioxide disinfection. The company's wastewater treatment plant in Reus, Spain, features the MicroDynamics microwave ultraviolet (UV) technology combined with Aquadiox chlorine dioxide generators from Severn Trent Services–Apliclor. The plant, which serves the wastewater treatment needs of communities in the province of Tarragona, has a treatment capacity of 25,000 m3/day, providing water for a variety of municipal reuse applications. The MicroDynamics UV technology works whereby microwaves are used to generate monochromatic UV light from electrodeless lamps. With electrodeless lamps, there are no electrical connections to fail, corrode or leak, which dramatically increases system efficiency and bulb life when compared to traditional UV lamps. The MicroDynamics system does not require the lamps to be submerged in the channel – lamps can operate in the air – thus reducing concerns regarding precise water level control.
As countries throughout the world struggle to address the effects of population growth, economic development and other factors contributing to water shortages, reuse strategies are rapidly gaining favor as cost effective, environmentally conscious and sustainable solutions. In Spain, a variety of challenges – from the global recession to geographic, climatic, and cultural factors – may, for the time being, have slowed the progress of planned reuse programs.
Author's note: Carlos Martin is the Iberian Region sales manager for Severn Trent Services–Apliclor
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