Improving the water quality of the Mar Menor
The poor condition of the Mar Menor in Murcia has been making headlines for several years. The vast lagoon is linked to the Mediterranean Sea via several channels but in recent years the depth of these ducts has been dramatically reduced, leading to a marked drop in the amount of water flowing in and out of the Mar Menor. This has exacerbated the problems of pollution. After reading about the situation, a Finnish professor who has been living on the Mar Menor since retirement in 2015 has written to Costa Blanca News to propose a solution
LAST autumn I read in Costa Blanca News about the water quality problems of Mar Menor, and methods to treat farming chemicals spillages in order to help the Mar Menor to recover again to perfect condition.
Inspired by this article I would like to introduce a safe method to improve water quality of big lakes, used in Finland with very good results.
Saimaa is the biggest lake in Finland. The centre part of the lake is very clean, but in the side bays of the lake there are some problems, mainly because of the use of the fertilizers in farming.
Because there are more than 10,000 summer houses, many holiday resorts and a lot of fishing on the coast of Lake Saimaa, the Lappeenranta Region’s Environmental Office wanted the water quality to be perfect everywhere in this lake. Therefore many years ago a cooperative project with LUT University was started to develop a special pump to increase water exchange in the side bays. The university developed a huge pump with advanced hydrodynamic design.
This pump is transferring 300 million cubic metres of water per year, but its power demand is only 15 kW of electricity. The pump was installed four years ago, and the result has been a significant improvement of water quality.
The principle is simply – when clean water is pumped to polluted areas, it replaces the polluted water and helps the natural, biological processes of lake or sea water to promote the recovery. This same technology could be used also to increase water exchange of Mar Menor – there is probably a suitable place for the pump in the canal connecting the Mediterranean Sea and Mar Menor in the base part of La Manga. The only problem may be, that if very much Mediterranean Sea water is pumped to Mar Menor, the salt content of Mar Menor may decrease.
There is also another alternative to using this technology. Last spring another vertical pump type was installed into Lake Saimaa in order to improve the water quality of deep parts of the lake.
This pump is also developed by LUT University, and it is powered with solar panels. It is pumping the oxygen-rich surface water to the deep parts (15 to 20 metres deep) of the lake. This pump type has also improved greatly the water quality of basins of the lake.
Obviously this technology would be very easy to use in Mar Menor, because in Spain there is much more sunshine available to run the solar panels than in Finland, and vertical pumping is not causing any change in salt content of water. A vertical, solar panel powered pump unit could be installed to each basin of the Mar Menor, where pollution and low oxygen content is suspected.
It is a very safe method to use huge pumps to improve water quality, because no chemicals are required. The city of Lappeenranta and LUT University would be pleased to present the pumping stations of Lake Saimaa and the results obtained, if the representatives of the environmental office of San Javier or Murcia are interested in this method.