Upgrading the WWTP to Provide Treated Wastewater Effluent for Agricultural Purposes in Cyprus
Cyprus, with a limited surface area, faces growing water needs alongside overexploited groundwater resources. As part of a complex programme to meet growing water demand in Cyprus, the EU Urban Waste Water Directive was implemented to make treated wastewater effluent from the public WWTPs usable for agriculture purposes. This required the installation of advanced tertiary treatment phases. The government provides subsidies to cover the investment costs of the tertiary treatment phase, after which local sewerage boards can sell the effluent to end users at a discount compared to the price of the fresh water resource.
Cyprus is a heavily water-stressed country, and recurring drought periods (such as a four-year period from 2008) make the situation more severe. The year 2008 revealed the vulnerability of a strategy that relied heavily on increased dam capacities (from 6 million m3 in 1961 to 332 million m3). Recent weather patterns (average precipitation between 1971–2008 was 461 mm) show a decline in precipitation compared to the previous period (1901–1970) when the annual average was 541 mm. For domestic, agricultural and industrial purpose, an average sustainable yield of 235 million m3 of surface water and 110 million m3 of subsurface water is available, but the latter, heavily used by agriculture, is overexploited by 29 million m3, resulting in a continuous decline of the water table. Desalination started in 1997, supplementing domestic consumption which is based on dams. (Sofrinou 2014)
Water use shows an agriculture-dominated pattern (64 percent), while domestic use accounts for 28 percent, tourism 5 percent, and industry 3 percent. During the last decades, water demand increased for all sectors (from 132 million m3 in 1996 to 275 million m3 in 2012) due to population growth (660,000 to 850,000), improved living standards and tourism developments. Drought frequency has also increased. (Sofrinou 2014)
Recently, wastewater reuse changed the overall picture; 15-16 million m3 (primarily for agricultural purposes) and 2.5 million m3 for groundwater recharge. (Lazarova, 2013)
The reuse of wastewater has substantially decreased the quantity that is discharged to the sea, thus contributing towards full compliance with the EU Bathing Water Directive (2006/7/EC) for 2010.
Conflicts arising from the baseline situation
Shrinking volumes of surface and groundwater storage due to decreased precipitation and increased use results in shorter retention periods and deterioration of water quality. (Sofroniou)
Overexploitation of subsurface resources resulted in saline water intrusions. Desalination is process that involves high, non-fully recoverable cost (there is a dependency on oil price changes), emits CO2, and presents difficulty with brine disposal if the quantity of desalinated water increases. (Sofroniou)
In 2008, water portioning for farmers and domestic use was introduced, and highly expensive transport of water from Greece was also necessary.
Agriculture uses 64 percent of water resources, but contributes to just 3 percent of the GDP (2006) — a pattern observed in many other MENA countries. (Sofroniou)
Description of the applied measure, its introduction and operation
Wastewater treatment plants need to improve the quality of effluent if EU Water Framework Directive (WFD) standards are to be achieved. While this is a requirement (Lazarova), the process itself has led to an increased use of better treated sewerage. The treated effluent is of better quality than the required WFD standards (Papaiacovou 2001). The financial arrangement (described below) reflects that the tertiary treatment phase is partly an additional element (i.e. above and beyond the legal obligation), but also makes the treated water useable for agriculture and aquifer recharge.
The Water Development Department of the Government of Cyprus is responsible for the collection and distribution of treated water to users, as well as for developing the necessary distribution infrastructure for reuse.
The government is focused on the advanced use of public facilities, which treat 90 percent of wastewater. There are many other small facilities that are run by tourist resorts, army camps and hospitals that operate outside of the wastewater reuse scheme. (Lazarova)
The use of reused water for irrigation purposes is limited to seasonal and permanent tree crops. No vegetables or crops that are directly ingested are irrigated with reused water.
Physical and ecological impacts of the measure
- Domestic: the supply of fresh water is more reliable because agriculture uses less of it.
- Agricultural: water resources, no longer dependent on weather, are more reliable. There also savings on fertilisers and increased crop yields.
- Environmental: there is reduced discharge of effluents into the environment, improved groundwater recharge, and controlled seawater intrusion.
Financial and other impacts of the measure on different stakeholders
The estimated cost of compliance with the EU’s Urban Waste Water Directive is EUR 1.5 billion. The government subsidises the construction and operation costs of tertiary treatment, as well as the sewerage systems in rural areas. Operation and maintenance costs are covered by fees. These developments have increased the sewerage service fee from EUR 2.26 per m3 (2008) to EUR 4.32 per m3 (2012), which reflects an increase in depreciation and financing costs (Lazarova). However, only a small portion of this increase, less than 10 percent, is associated with tertiary treatment methods required for irrigation use of wastewater.
The distribution of treated wastewater is a government responsibility. From a financial point of view, the cost of tertiary treatment is reimbursed to wastewater treatment plants (the producers of the effluent) from the revenue generated by selling the treated wastewater (Lazarova). This also helps to keep the household cost of sewerage service at bay. (Hadjigeorgiou)
Pricing System for Irrigation Water in Cyprus (See table)
The users of treated water pay a reduced price compared to the fresh unfiltered irrigation water. The cost recovery ratio for users of the treated water is around 88 percent, with a total cost EUR 0.152 per m3. (Lazarova)
There is a price differentiation for end users. Water for agricultural activities are cheaper than water use for sport, tourist and leisure activities. Identical differentiation is made for fresh water resources as well. (Hadjigeorgiou 2014)
For agriculture producers, reused water provides a cheaper way to produce fodder crops than importing the water. (Papaiacovou, 2012)
Resilience of achievements, sustainability of results
There was a “confidence building” period during which pilot sites were operated to prove to farmers and the public the viability and health safety of wastewater. Sorghum, alfalfa and corn were produced for two years with treated effluent from the Limassol WWTP on a 30-hectare pilot site. The Agricultural Research Institute monitored the crops and verified that they were not contaminated. (Hadjigeorgiou, 2014)
Continuous monitoring of quality and reviewing of standards is necessary to prevent the accumulation of harmful substances in the soil. (Papaiacovou, 2001)
A remaining challenge is better integration with storm water management and to find additional uses during overflow periods. (Papaiacovou, 2001)
- Secondary use of treated effluent steadily increased, from 1 million m3 in 1998 to 13–15 million m3 in 2012.
- Government-led educational efforts to prove the viability and safe use of the treated effluent (recurring drought periods also proved that this reliable water source is essential).
- Use of treated effluent (14.5 million m3 in 2012).
- Share of agricultural irrigation (72 percent).
- Landscape irrigation (3 percent).
- Groundwater recharge (15 percent).
- Discharge to the sea (10 percent) from the annual quantity.
The key question of replicability is the pre-existence of secondary treatment of wastewater. The cost of advanced tertiary treatment (which enables reuse) is only a small part of the total sewerage cost, which comprises the sewer network and the first two stages of treatment. The extra cost of an advanced tertiary phase and the subsequent distribution infrastructure can be mostly covered by the revenue from the sale of the treated effluent to farmers. It is also important that the price of treated wastewater be lower than the price of fresh water for irrigation
The total cost for the complex water and wastewater development in Cyprus was estimated at EUR 1.5 billion. Regarding the Limassol WWTP development, the unit cost of the whole operation is EUR 4.32 per m3, while the cost of tertiary treatment alone is relatively low at EUR 0.152 m3.
- Iacovos Papaiacovou, Constantia Achileos, Ioanna Ioannidou, Alexia Panayi, Christian Kazner, Rita Hochstrat. “Water Reuse in Cyprus”, http://www.reclaimedwater.net/data/files/225.pdf (accessed July 18, 2016) in the “2012 Guidelines for Water Reuse” http://nepis.epa.gov/Exe/ZyPDF.cgi/P100FS7K.PDF?Dockey=P100FS7K.PDF
- Anastasia Sofroniou, Steven Bishop. “Water Scarcity in Cyprus: A Review and Call for Integrated Policy in Water”, 2014, 6, 2898-2928; doi:10.3390/w6102898
- Panayiota Hadjigeorgiou. “Reuse of Treated Effluent in Cyprus”, presentation at WG PoM 2nd Meeting (March 25-26, 2014), accessed at July 20, 2016 http://www.moa.gov.cy/moa/wdd/wdd.nsf/All/267EB778799 99BBBC2257DE70045AE31/$file/Water%20Reuse_Cyprus%20Case.pdf
- Iacovos Papaiacovou. “Case study: Wastewater reuse in Limassol as an alternative water source”, Desalination, 138 (2001) pp. 55–59
- Valentina Lazarova, Takashi Asano, Akica Bahri, John Anderson. “Milestones in Water Reuse: The Best Success Stories”, Chapter 5, IWA, 2013