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Constructed Wetland for Oily Produced Water Treatment

The treatment wetlands represent a new habitat and ecosystem in the middle of the desert

The largest plant in the world

Nimr Water Treatment Plant (NWTP) in the Sultanate of Oman is the largest treatment wetland of its kind in the world. The constructed wetlands cover 5 million m^2 and 8 million m^2 evaporation ponds. The site treats oil-contaminated wastewater created during oil exploration and production. This is done by different chemical and biological actions occurring in the wetlands plants and soil, including plant uptake, biodegradation, and volatilization. A mix of species including Typha, Cyperus, and Juncus species are planted in the wetlands.

Sultanate Oman


Natural regeneration




Baur Nimr


The Project

The wetland began operation in 2010 and has had three expansions since last completed in 2019. The contract between Bauer Nimr and the Sultanate of Oman also includes operation of the site for 25 years. The current contract ends in 2044.

NWTP has a treatment capacity of 175,000 m^3/day (Stefanakis 2019). The treatment conducted on-site meets an effluent limit of 0.5 ppm for oil in water set by the National Standards of the Sultanate of Oman.

Treatment of the effluent on site is extremely efficient, with a 99% reduction in energy consumption when compared to conventional treatment facilities (Stefanakis et al 2018).

This project contributes more than 6% to Oman’s overall goal of 2% of greenhouse gas emissions by 2030. An agreement that was made as part of the Paris Accord. Projects such as NWTP are an example of how oil producers can take part in the reduction of greenhouse gases and reduce the ecological impact of oil and natural gas.

The treatment wetlands represent a new habitat and ecosystem in the middle of the desert. This can become a crucial habitat patch for migratory birds at a time when their habitat is greatly reduced. More than 100 species have been sighted, including herons, ibis, terns, and cormorants.

Treated effluent from the wetlands is used for irrigation of local crops, including corn and cotton. Plant waste from the wetlands is also gathered and converted to biofuel.

This project was brought to us by Dr. Alexandros Stefanakis, who works for Bauer Nimr Technical University of Crete / Bauer Resources GmbH who worked on the NWTP. Dr. Stefanakis is responsible for both the design and technical operation of the site, as well as the commercial proposal and tender management. This is a great example of a progressive project in one of the most ecological impactful industries in the world.

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