|Sourcebook of Alternative Technologies for Freshwater Augmentation in East and Central Europe (UNEP-IETC, 1998)|
|Part B - Alternative technologies|
|3. Wastewater treatment technologies and reuse|
The technology comprises a number of water savings opportunities which can be realized through the application of alternative technical approaches to the use of water in the power generation industry. For example, the Riga, Latvia, Thermal Power Plant Number l uses a large volume of surface water for cooling, and, after passing this freshwater once through the cooling process, discharges this entire volume of chemically and thermally polluted water to Lake Kiezers, situated in the City of Riga. Based upon the reconstruction experience obtained at the Riga Thermal Power Plant Number 2, it is proposed that this once through system be replaced with a treatment and recycling system that should consume significantly less water. After cooling, the cooling water used at the Number 2 Plant is biologically treated in ponds and recycled. This system is largely closed, with only small volumes of supplemental water being withdrawn from Lake Kiezers.
Extent of Use
Similar projects are under construction, or have been completed, in a few thermoelectric power plants in Poland, Ukraine, and Hungary.
Operation and Maintenance
Use of the treatment and recycling technology is fully compatible with standard operation and maintenance procedures in thermoelectric power plants. However, the recycling system does require some additional maintenance in order to recirculate the treated cooling water and to operate the biological treatment ponds.
Level of Involvement
This technology is generally implemented at the company level.
Costs are difficult to identify, and depend on scale of the project.
Effectiveness of the Technology
At Riga, it is anticipated that the introduction of recycling of cooling water will reduce water consumption at the power plant by 9.5 times. Recycling the treated cooling water for other purposes at the plant should increase reuse by up to 25 times. Specifically, the use of water for industrial purposes prior to reconstruction of the plant consumed 30 x 106m³/year. This volume is expected to be reduced to 3.1 x 106m³/year, or about 10% of the previously consumed volume. Use of recycled water is expected to increase from about 43 x 106m³/year to almost 71 x 106m³/year, or a 1 650% increase.
This reuse technology is suitable for use at thermoelectric power plants.
All of the cooling water, process water, and wash water used in the power plant is treated and reused. The greatest benefit of this technology is the prevention of thermal pollution in the lake.
No disadvantages have been identified. Some modification of the wastewater collection and circulation systems must be undertaken, which has a cost impact.
This technology is accepted as a profitable and efficient environmental technology.
Further Development of the Technology
The technologies used in the Riga Project were designed by the Latvian State Enterprise "Siltumprojekts", which is main design authority for power production and supply in Latvia and the Baltic States.
Rolands Bebris, Ministry of Environmental Protection and Regional Development, 25 Peldu Str., 1494 Riga, Latvia, Tel. (371-7) 227145, fax: (371-7) 820442, e-mail: BEBRI@VARAM.GOV.LV.
Anna Egle, V/U "Meliorprojects", 11 Novembra Bulvaris 31, LV-1494 Riga, Latvia, Tel. (371-7) 228734.