Adana Wastewater Treatment Plants, Turkey


The two new wastewater treatment plants at Adana - Turkey's fourth largest city - which became operational in 2004, represent part of a major national programme to enhance the country's infrastructure and improve environmental management.

A Turkish / International consortium led by Va Tech Wabag (formerly Austrian Energy) constructed the plants on a build-operate-transfer (BOT) contract with a three-year operational phase after which the plant reverted to the Adana Metropolitan Municipality. The project included the design, construction and commissioning of the new plants themselves, together with the installation of the mechanical, electrical and process-control systems, along with the provision of wastewater and storm water collection and all associated pipe-works. An associated smaller contract worth €2m to supervise the construction of a storm water canal network was awarded to a consortium of Montgomery Watson and Sigmatek.

Designed to meet the needs of the city's predicted population to the year 2025, when the plants' combined daily flow is expected to be 516,000m³, the project cost €45m and was one of a number of similar schemes partially funded by the European Investment Bank.

BACKGROUND

Prior to the 1990s, progress on addressing many of the country's pressing environmental problems had been slow. In 1991, the establishment of the Turkish Ministry of Environment marked a significant step in changing this situation and dramatic improvements were made, particularly in respect of air pollution in the nations two largest cities, Istanbul and Ankara.

However, as the decade closed, other areas, most notably water and wastewater treatment facilities together with solid waste management continued to pose significant challenges, particularly in the light of the country's ambitions to join the EU. This led to a major programme of infrastructure investment and the extensive updating and modernisation of environmental legislation, largely intended to facilitate an eventual full harmonisation with European law. Ultimately these factors were to prove significant drivers of projects such as the Adana treatment plants.

CONTRACTS

In January 2000, the ASKY Consortium was awarded the Adana contract and construction start-up began the following month. The construction phase lasted for three years and the plants finally became operational in 2004. Under the three-year terms of the original BOT contract, transfer was scheduled for June 2007. The final acceptance certificate (FAC) for Adana West was granted along with a further one-year contract for operational management to WABAG until June 2008.

In addition, the provisional acceptance certificate (PAC) was issued for Adana East. The Adana East plant was modified in June 2006 by an additional biological treatment stage which increased its capacity and effectiveness. Adana East was also placed under the operations management of WABAG for a further twelve months until June 2008.

PLANT DESIGN

The two plants, located on opposing sides of the city and known respectively as Adana West and Adana East, both accept domestic and partially treated industrial effluents, with an average BOD of around 230mg/L. The process train employs a conservative approach, using screening, primary settlement, trickling filters and conventional activated sludge methods. Subsequent treatment of the raw and excess activated sludges is by anaerobic digestion, with biogas energy recovery which contributes around 50% of the operating requirement. After dewatering and thickening, the resultant sludge-cake is used for beneficial land application.

The treated effluent is discharged into the Seyhan river which is a major source of irrigation water for the Cukurova plain, the fertile heartland of Turkish cotton and citrus growing; the need to protect this important resource was one of the drivers behind the new plants. The effluent currently meets EU standards and the plants have been designed to enable further expansion, in particular to accommodate the higher nitrogen and phosphorus loads anticipated in the future.

Initially, the plants were intended to accept a daily flow of around 250,000m³ (Adana West) and 210,000m³ (Adana East) but this might rise to a combined capacity of 520,000m³/d by 2025, representing a projected equivalent population of 2.6 million.

KEY PLAYERS

Adana Metropolitan Municipality - as the Adana Water and Sewerage Administration - was the project sponsor. The plants were constructed by the ASKY Consortium, which comprises Va Tech Wabag, Serco Group, Yüksel Construction and Ener Construction. Hidrotek was the process system consultant and the Montgomery Watson / Sigmatek consortium supervised the storm-water canal construction. The project was co-financed by the Municipality, ASKY and the European Investment Bank.