|The extended drought observed in Cyprus in the last decade of the 20th century which resulted into an unsatisfactory storage of water in the dams, necessitated the creation of Sea Water Desalination Plants aiming to make the supply of drinking water to the large urban and tourist centres independent of rainfall. Presently, four Desalination Plants are in operation in Cyprus, at Dhekelia, Limassol (Episkopi), EAC Vassilikos and Larnaca, while the construction of a Desalination Plant in Paphos is in progress, expected to start operating at the end of 2019.
The contribution of the Desalination Plants in the solution of the water problem that affects our country is huge. The Desalination Plants in Dhekelia and Larnaca satisfy a great part of the drinking water requirements of the Districts of Nicosia, Larnaca and Free Famagusta with a production capacity in total, of a minimum quantity amounting at 32.8 MCM per year. The Desalination Plants in Limassol (Episkopi) and Vassilikos satisfy a great part of the drinking water requirements of the District of Limassol and part of the requirements of Free Famagusta, with a production capacity, in total, of a minimum quantity also amounting to 32.8 MCM per year.
Information on Desalination Plants
Dhekelia Desalination Plant
The Contract for the construction and operation of the Plant was awarded in 1996 following the submission of bids, to Joint Venture CARAMONDANI BROS LTD and CARAMONDANI DESALINATION PLANTS LTD, at a price of £0,54/m3. The Plant started to operate in April 1997 with a capacity of 40.000 m3/ day and it was acquired by the Government in 2005 making use of a specific term in the contract. Subsequently, the Government proceeded with a call of tenders for the Renovation, Operation and Maintenance of the Plant and Sale of Water to the WDD for a period of 20 years. The contract was awarded to CARAMONDANI DESALINATION PLANTS LTD at a price of £0,376/m3. The Plant was renovated in 2005 and the 20 year period started in May 2007. The contract is expected to expire in May 2027. Since July 2008, its capacity increased by 10.000m3/ day and since April 2009 by another 10.000m3/ day with its total capacity presently amounting to 60.000m3/ day. The Dhekelia Desalination Plant covers for the drinking water requirements of the Free Famagusta area and part of the requirements of Larnaca.
Limassol (Episkopi) Desalination Plant
The contract for the construction and operation of the Plant was signed in August 2009. The contractor is Joint Venture Ν. LIMASSOL WATER CO LTD which is composed of MEKOROT (Israel) and NETCOM (Cyprus) companies and the price of the contract is €0,8725/m3. This contract provides for a 20 year operation which started in July 2012 and is expected to expire in July 2032. The Plant was mainly in reserve until the end of 2015. The capacity of the Plant is 40.000m3/ day with a capacity of extension to 60.000m3/ day. The Limassol Desalination Plant covers for part of the drinking water requirements of the District of Limassol.
EAC Vassilikos Desalination Plant
The contract for the supply of water from Vassilikos Desalination Plant was signed with EAC in February 2010 at the price of €0,813/m3 for a period of 20 years. Despite that the 20 year period started in July 2013, the plant was in reserve until the end of 2015. The agreement is expected to expire in July 2033. The plant is of a capacity of 60.000m3/ day and it covers for the drinking water requirements of communities in the District of Limassol while it supplies the Choirokitia-Famagusta conveyor though the Choirokitia water treatment plant.
Larnaca Desalination Plant
The contract for the construction and operation of the Larnaca Desalination Plant was awarded in 1999 to LARNACA WATER PARTNERS Company (Joint Venture of IDE and OCEANA companies from Israel) at a price of £0,399/m3. This was a 10 year contract and the Plant started to operate in June 2001 with a capacity of 52.000m3/ day. In January 2009, the capacity of the Plant was increased by 10.000m3/ day and reached 62.000m3/ day. The contract expired in July 2011 at which time the plant became property of the WDD. The government called a new Tender and the new agreement for the Renovation and operation of the Plant was signed in January 2012 with MN LARNACA DESALINATION CO LTD company (Joint Venture of Mekorot and Netcom companies), at a price of €0,594/mᵌ. the 25 year period started in July 2015 and it is expected to expire in June 2040. The Plant was mainly in reserve until the end of 2015. The capacity of the Plant is 60.000m3/ day. The Larnaca Desalination Plant presently satisfies to a great extent, the requirements of the Districts of Nicosia and Larnaca.
Paphos Desalination Plant
The construction of the Paphos Desalination plant is in progress, with a capacity of 15.000m3/ day to satisfy the requirements of the District of Paphos. The plant is expected to start its operation at the end of 2019.
Information about the contracts of Desalination Plants
Desalination Plants are constructed using the self-financing method, following a call for Tenders by the Water Development Department. The type of the contracts is BOOT (Built, Own, Operate and Transfer) and contractors/ investors undertaking the construction of the Plants incur all the costs for the construction of the civil engineering works, the supply and installation of the electromechanical equipment and in general, the performance of all necessary tasks for the conclusion of the project. After that, the Plants operate at their own expense for a specific period of time (around 20 years) and sell the water produced to the Government at a determined price, on the basis of which they won the tender. The government undertakes the obligation to receive a minimum quantity of water for the determined duration of the contract. After the expiry of this period the plants automatically become property of the government while there is a right to acquire the plants prior to the completion of this period. There are provisions in the contracts adjusting the price of sale of the contract, taking into account the increases and decreases of the price of oil, electricity and labour costs. Also, there are provisions about the reduction of production or interruption of the operation of the plants and keeping them in a reserve status, in cases of a lot of rainfall where the water of the dams greatly satisfies demand.
Description/ operation of Desalination Plants
Desalination Plants are composed of:
|The various phases from which the water from the sea passes through until it reaches consumers are described below:
Sea water is taken from a point located at a distance of 500-1000 metres from the shore (depending on the prevailing conditions in the sea area). Through a conveyor, it ends to the pumping station located at the beach. After passing through filters to remove solid substances, it is pumped towards the Plant located around 500-800 metres away from the beach. There are 3 treatment stages there, as follows:
(1) Pre-treatment stage:
Micro-organisms must be destroyed and the volatile solids removed so as to avoid the development of microorganisms and the deposit of salt on the membranes, the pre-treatment includes pre-chlorination, accumulation of colloidal organic substances by adding chemicals, filtering through sand filters and addition of sulphuric acid to regulate acidity. Filtered water is pumped in special propylene filters which retain all solid substances greater than 1μm that could cause damage to reverse osmosis membranes. Following that, de-chlorination takes place because the membranes are destroyed in the presence of free chlorine.
(2) Reverse Osmosis Stage
Water is supplied to reverse osmosis membranes using high pressure pumps providing the necessary pressure (around 65-80 atmospheres) so that water passes through the membranes and discharges its salts. Recovery at the membranes is around 50%. In other words, to produce one cubic metre of desalinized water two cubic metres of sea water are required. Sea water, with a double concentration of salts (saltwater) returns through a conveyor back to the sea, after passing through high pressure pumps and gives (due to the pressure it has endured) a part of the energy (around 25-30%) to the pumps. In this manner, electricity is saved.
(3) Final stage of treatment
Desalinized water is now directed for the final treatment at a reservoir where by using chemicals, such as processed lime and carbon dioxide or sulphuric acid, the final correction of acidity is achieved as well as the increase of hardness of the water produced. Finally, water is chlorinated and it is ready for collection by the Water Development Department.
Desalination for the Environment, Clean Water and Energy Conference