Water reservoir Mšeno

Date of intervention: 17.-18.7. 2008 and 23 - 25 July 2008

Assignment:

Accelerated acquisition of knowledge about the physical methods potential.

Conclusions:

Press release 06th 08th 2008 by the town of Jablonec nad Nisou

The city reservoir in Jablonec nad Nisou has been rapidly disposed of dangerous cyanobacteria incidence. The amount of blue-green algae decreased from 35 000 units of cyanobacteria / ml to several units of cyanobacteria / ml. Electrocoagulation method is not only more economical than the chemical approach, but also especially friendly to other animals.

" In mid- July, we decided to apply the electrocoagulation method on the other water reservoir of the dam Mšeno ," said the council member Sonia Paukrtová , who takes responsibility for solving the problems of cyanobacteria in Jablonec reservoir for the city government.

The reason why the city Jablonec decided in cooperation with the regional health authority , regional authority, the Labe River sp , Czech Fishing Union and the Regional Development Agency , s.r.o. for the application of these methods on one of the water bodies , was the growing presence of cyanobacteria . There were, according to the latest measurements, thirty-five thousand cyanobacterial cells per milliliter of water present. All three water tanks of the Mšeno dam are also interconnected. Studio Silfor has been chosen by the city for the task of destruction of the cyanobacterial bloom .

" We feared that the hot weather could cause the cyanobacteria to travel from the second dam in to the first and then cause a rapid development of cyanobacteria in the first one . Here the values ​​are around five thousand cells per milliliter of water. The regional health authority declares  bathing prohibition when a there is a content of hundred thousand units of cyanobacteria per milliliter , " said  Paukrtová .

Press Release 06th 08th 2008, town of Jablonec nad Nisou

Electrocoagulation technology is based on the principle of water electrolysis in the reactor cell composed of an assembly of aluminum , iron or composite blades , which are under low-voltage direct current .

The optimum concentration of electrolyte , which involves a reduction of dispersed particles potential  and reaching coagulation threshold causes a reaction , which leads to formation of hydrogen, oxygen and ozone microbubbles, with simultaneous formation of positive aluminum ions Al3 + . In solution with water molecules, these ions react with negatively charged colloidal particle ions. The subsequent formation of flakes separates the water not only from mechanical colloidal particles , but also dispersed organic impurities and particulates.

The advantage is the ability to control current density in dependence on the detected amount of impurities in the treated water . Another significant advantage is the absence of previously used coagulant chemicals. A significant reduction of the occurrence of cyanobacteria and simultaneously partial disinfection of the water occurs during the electrolysis, due to the biocidal effect of the released medium of the electrolysis process. Also, this method has no adverse effects on fish and other higher organisms in the aquatic ecosystem.

"The first application of the method described above was done on the dam Mšeno on 16 and 17 July . After visually evaluating the first application, we decided for a second application , because the transparency of the water column was not what we had expected from it . The second application was carried out on 23 and 24 July . During the following weekend, there was a gradual reduction in the occurrence of cyanobacteria and an improvement in the transparency of water . The water was completely clear by Monday, July 28. Laboratory results were performed a week after and a success has been proved , "said Paukrtová .

The results were a very pleasant surprise for all involved. Transparency has increased by tens of centimeters. By Monday, July 28, chlorophyll content decreased from the original 43 micrograms per liter ( before the second application ) to 6 micrograms per liter. But what is most important - the amount of algae in the water was almost zero . Invited experts found nothing but remains of a few isolated cyanobacterial cells per milliliter of water , where it was previously tens of thousands. Analyzes were carried out by accredited laboratories in Vodňany and České Budejovice.

"Intervention is believed to be very successful , even if it´s only a short-term effect for this season. Plans for the next years involve systemic measures such as dredging of the reservoir with the participation of specialists from the state enterprise Elbe River Basin , "added Jablonec city councilor Soňa Paukrtová .