At the end of the second week in June the site was handed over to the contractor and an important modernization project started. Investment will reach five million Czech crowns and it will be completed in September.

Ostrava 15. 6. 2017 – The goal of the project is to make use of a part of the third corridor of aero-tank, which is currently used as a reserve and it is not equipped with process equipment, for further reduction of nitrogen contents in treated water. The very removal of this element and its compounds from water is the most tracked parameter from the point of view of the whole process quality.

 “The wastewater treatment plant in Karviná was sized for higher volume of treated wastewater than current reality. The aero-tank, which forms an imaginary heart of the wastewater treatment plant and where most of the organic water pollution is removed by means of forced oxygen, can up to an extent decompose also nitrogen and phosphorus compounds. The aero-tank in Karviná has three corridors. We are currently using only two and this capacity is sufficient for us. The third one is not equipped and we actually use it as a reserve. Therefore we decided to use the part,” says the sewer system director, SmVaK Ostrava, Jan Tlolka.

Part of the third corridor will be used for so-called postdenitrification. It is a process where undesirable nitrates in water are converted to nitrogen oxides and nitrogen gas. Feces and also fertilizers used in agriculture are well-known sources of nitrogen. Presence of this element in water creates suitable environment for the growth of algae.

The project includes structural partitioning of the last part of the third corridor of aero-tank and creation of a tank to be used for postdenitrification, connection of all necessary parts of the wastewater treatment plant with the newly equipped tank, and also for example installation of pumps, electrical installation, measuring and regulation.

The original wastewater treatment plant in Karviná was built in 1961. It was gradually modernized and extended. The new modern facility for over 400 million Czech crowns was built in 1998-2001. The current wastewater treatment plant capacity is 88 thousand population equivalent and it can treat up to 30 thousand cubic meters of wastewater a day.

Remarks

Screen – process equipment used to remove floating impurities from wastewater. The trapped impurities are called screenings.

Mechanical part of the wastewater treatment plant – first part of the plant at the inflow of wastewater from the sewer system. Gravel trap, screen and sand trap, sedimentation tank where coarse floating impurities and undissolved substances are removed

Biological part of the wastewater treatment plant – follows after the mechanical part. Bacteria are used to remove pollution, it includes also the aero-tank and settling tank.

Agitator – mixes the activation mixture (wastewater, activated sludge) in order for the organic impurities in mechanically pre-treated wastewater to be efficiently broken down.

Aeration elements – are used to mix and aerate wastewater in aero-tanks in the biological part of the wastewater treatment plant.

Aero-tank – heart of the wastewater treatment plant; aerobic bacteria with air, which is constantly forced into the tank, with its metabolism remove 99% of organic water pollution.

Settling tank – treated water is separated from the activated sludge that sediments. Treated water runs back to nature.