Waste water

Ostrava’s waste water treatment plants (WWTPs) are run by the Ostrava Water and Sewerage Company (OVAK). All WWTP operations are fully compliant with the legislation stipulating quality requirements for treated water and sludge. There are also 35 waste water pumping stations and two retention reservoirs.

Central Waste Water Treatment Plant

98.7% of waste water treatment in Ostrava takes place at the mechanical-biological Central Waste Water Treatment Plant (CWWTP) in Ostrava-Privoz, which receives waste water from the majority of the city. The CWWTP was opened in 1996, and it gradually replaced most of the city’s existing WWTPs, which were technically obsolete and no longer had the required capacity. The CWWTP uses mechanical/biological methods to treat domestic and industrial waste water applying the principle of low-loaded activation with nitrification and upfront denitrification. The anaerobically stabilized sludge is dewatered in centrifuges featuring an automated technological process management system and sanitized using lime. This complex process ensures that waste water treatment is conducted to the highest standards, and the high capacity of the CWWTP (638 850 PE) enables it to cope with the city’s future development needs. The high capacity is also necessary because the CWWTP treats waste water not only from domestic sources (the majority of Ostrava’s inhabitants), but also:

• from the food industry;
• from other industries (after prior pre-treatment);
• from coking plants in Ostrava (concentrated phenol-ammonia water).

All the other WWTPs use at least second-degree mechanical-biological treatment. One of the WWTPs (Michalkovice) uses long-term activation technology which is highly effective in removing organic impurities and nitrogen pollution.

In 2016, Ostrava’s WWTPs treated a total 31.9 million m3 of waste water. The Central WWTP in Ostrava-Privoz also treated over 533 000 m3 of concentrated waste water from the coking and heating industries and 189 000 m3 of other concentrated waste water. A total 27 090 t of dewatered sludge was produced. The dried and hygienically cleaned sludge is used to produce substrate for the recultivation of landfill sites and areas suffering from mining-related ground subsidence.