Czajka Wastewater Treatment Works, Poland

Completed at the end of 2010, the project to upgrade and expand Warsaw’s Czajka WWTP is the city’s first wastewater treatment works and Poland's largest.

Designed around a population of around 2.1m, the project will more than double the plant’s present 200,000m³/day inflow to routinely deal with a daily 435,000m³, rising to a potential 515,000m³/day at peak times. As a result, sludge production will double to 160,000t per annum, calling for a new thermal treatment process to be installed at the plant to reduce the volume produced to facilitate disposal.

The work also included extensive associated earthworks, civil engineering, automation and electrical elements and were undertaken in three phases to enable the plant to remain operational throughout.

The project cost was €500m, with funding from the EU cohesion fund and the local municipality.

Czajka WWTP background

Situated in 56ha of the Bialolęka borough in north-east Warsaw, Czajka WWTP was completed in 1991, after a building programme that took 17 years to come to a close. This lengthy construction meant that much of the technology and equipment was outdated by the time the plant came online, forcing the almost immediate start of a series of modernisations.

Although the works relied on relatively old mechanical and biological systems to produce the necessary BOD and suspended solids removal, it managed to produce respectable quality effluent by the standards of the time and represented a big advance on the previous arrangements – the discharge of untreated wastewater into the Vistula.

The main driver on the extensive modernisation project was the need to meet EU wastewater standards – including limits on nitrogen of 10mg/l and 1mg/l for phosphorus, effective from January 2007 – and to provide adequate treatment for all urban effluent flows.

Czajka programme of works

The Czajka upgrade and extension project forms part of the Warsaw water supply and wastewater treatment scheme, which consists of three phases. Phase 1 involved the construction of new sewers and collectors for the city’s new Poludnie WWTP, funded by an EU grant awarded in 2001.

Due to the large size of the project, the construction of the collector system has further been divided into three segments. The first segment includes installation of 5.7km of jacking pipes along the right side of the river Vistula. In the second segment, 1.4km of OD 3000 (DN 2800) jacking pipes will be installed along the left side of the river.

In the third segment jacking pipes from both the sides will meet and two parallel 63in diameter lines will be inserted in a concrete tunnel of 4.5m diameter that will be built at the crossing beneath the river. The pipes used will be the largest centrifugally cast fiberglass reinforced polymer mortar (CCFRPM) pipes.

Phase 2 extended and improved aspects of the city’s potable water supply, including upgrading the treatment process at the Zaklad Wodociągu Centralnego and Zaklad Wodociągu Pólnocnego plants, the construction of a new water distribution network and implementing modern computer control for both the water supply and wastewater systems.

The Czajka project – comprising the plant upgrade, the construction of a thermal drying facility for the sludge, new transmission sewers and the modernisation of the wastewater system in Bialolęka, Mlociny, Bielany and Rembertów – stands as the largest element of Phase 3.

To date, the plant has been responsible for processing sewage only from right-bank Warsaw and Legionowo, the flow from areas on the left bank of the city being discharged directly into the Vistula at a rate of more than 300,000m³ /day. By the end of the programme of work, Czajka will also accept and treat this wastewater, which will be transported to the plant beneath the river.

This will have obvious benefits to water quality in the Vistula, improve the environment of communities south of the city and ultimately reduce the contaminant loadings entering the Baltic Sea.

Czajka plant improvements

One of the most significant plant improvements centres on sludge management. The plant’s existing disposal arrangements rely on land-spread, which is no longer an acceptable route.

To reduce the volume of material and facilitate its landfilling, the project includes the provision of a new thermal sludge treatment and ash condensation facility, with an average output of about 24t of sludge an hour.

A second key aspect of the facility’s modernisation programme involves a completely new automation installation, providing a comprehensive visualization, control and monitoring system. The design includes nine process stations, more than 60 controllers, two redundant servers, five operators’ workstations, more than 1,000 analogue measurements and in excess of 2,000 drives.

Once installed, the SCADA automation and monitoring will ensure optimal flow through the plant processes, providing full control and operational visualisation, with real-time data measurement, equipment status, alarm notification and system failure alerts.

Treatment at the plant is also to be upgraded to meet required EU standards using a range of technologies developed by OTV and Kruger, including the implementation of a chemical scrubbing system to reduce any perceived odour nuisance.

The Czajka project's key players

The client is the Miejskie Przedsiębiorstwo Wodociągów i Kanalizacji w Warszawie (Warsaw Water and Wastewater Company). The consortium responsible for project delivery comprises Veolia, Warbud, OTV, Kruger and WTE Wassertechnik, with plant automation being provided by Siemens.

EnviroSim conducted the calibration study to characterise the wastewater and establish the nitrification rate as well as developing pre-design options for the project and the sludge treatment design studies were carried out by WS Atkins-Polska. The project is funded by the EU and from local funds.

Regulatory oversight at the national level is the responsibility of the National Fund for Environmental Protection and Water Management, together with the Ministries of Environment and Regional Development.

The CCFRPM pipes for the collector system are being supplied by HOBAS. BUTTING is responsible for the supply of aeration panels to complete the plant. The company has already installed six of the ten aeration basins with panels by December 2009. The remaining four basins will be installed by the end of 2010.