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Thirasia Water Network

A plot of land in the area of Agia Irini (Riva) of Thirassia, owned by the Municipal Water Supply and Sewerage Company of the Municipality of Thira (100%), hosts the installation of desalination units of the island of Thirassia. It is located in the area of the Municipal Community of Thirassia in the Municipality of Thira with coordinates X = 619969,908 and Y = 4035303,200.

The desalination plants installed supply water to the settlements of Rivas, Manolas, Potamos, Korfu and Agrilia. Two (2) desalination units of 120 m3/d and 200 m3/d are operating on the site. The first unit has exhausted its economic lifetime and is located inside a container (white in colour) 6 m long, 2.5 m wide and 2.5 m high. The second newer and larger unit is also prefabricated, inside a container (white in colour) 12 m long, 2.5 m wide and 2.5 m high with a minimum drinking water production capacity of 200 m3/d.

The installation of a new desalination unit with a drinking water production capacity of 200m3/day is expected, which will include a photovoltaic park for energy production.

Both units include the main stages of seawater treatment by reverse osmosis, i.e. pre-treatment, main treatment and post-treatment, The units are fed by suction of seawater from the existing plastic sea tanks (painted white) with a total capacity of 40 m3. The produced water is piped through suitable taps to the new potable water tank (1 metallic tank with a capacity of 1000 m3 painted white) and the old potable water tank (1 concrete semi-subterranean tank with a capacity of 1000 m3).  The brine is led to the existing brine well and from there to the sea through suitable pipelines. The sea tanks are fed from the 3 existing drillings.

The operation of the plant includes the following stages:

1. Supply of seawater
From the sea tank with pumps inside the container, the sea water will feed the pre-treatment system.

2. Pre-treatment
Pre-treatment comprises the following stages:
- filtration with a turbidity retention filter (multi-layer filter)
- Addition of an anti-fouling agent
- filtration through cartridge filters

3. Reverse osmosis system.
The reverse osmosis system consists of the following components:
- High-pressure rotary pumps with energy recovery system. In order to keep the electricity consumption at a minimum level

-Membrane containers
- Reverse osmosis membranes

4. Reverse osmosis auxiliary systems
The operation of the plant includes the following additional auxiliary systems
- Automatic membrane rinsing system
- Membrane chemical cleaning unit, which can be shared with the membrane rinsing system
- Automatic multilayer filter rinsing system.
- Marine tank
- SCADA system

5. Post processing
Post-treatment includes the following stages:
- Adjustment of hardness

- Adjustment of pH
- Chlorination

In the area there is also a small house where a multilayer filter for sea filtration has been installed as well as a second house that serves as a storage room.

Next to the stone tank there is a stone-built house where the drinking water pumping station is located, which with pumps and a suitable delivery pipeline channels the drinking water to a tank in Manolas from which all Thirassia is supplied with water.

Finally, a small house has been built in the area surrounding the desalination units, which houses the central power supply panels of the units and an electrical generator to support the installation.

In accordance with Order No. YPEN/ESPAPER/6732/59 of 20/01/2023, the Municipality of Thera is included in the "Water Management" Programme of the EEA 2014-2021 for the "Supply and installation of a desalination plant on the island of Thirasia with Renewable Energy Sources".


The physical scope of the project provides for:

- Upgrading the facilities of the desalination units of the Municipality of Thera with the installation of a new desalination unit in Thirassia, with a capacity of 200m3/day, in which the consumed power, together with the accompanying drilling pumps, is approximately 5kW.

- The coverage of the major part of its consumed energy from renewable energy sources (photovoltaic system with a nominal power of 60kW and a total annual production of about 80,000kWh.


The partner from the donor countries is the University of Stavanger in Norway, which will contribute to improving the efficiency and reliability of the infrastructure mentioned.

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