WATER and Environment Technologies Company (Wetico) is putting the finishing touches to a huge sewage treatment plant (STP) in Saudi Arabia’s Najran area.

The plant, which uses a membrane biological reactor (MBR) treatment system, is being constructed over a total area of 102,300 sq m for the Ministry of Water and Electricity’s Directorate of Water in Najran.

The project is being implemented under a SR87.36-million ($23.3 million) contract, involving civil works worth SR30.67 million ($8.18 million) and electromechanical works valued at SR56.69 million ($15.12 million).

GTC is the consultant on the project.

According to the project manager Amer Barsbai, the project was first envisaged four years ago and a contract was signed in September 2008 with mobilisation work having starting a month later.

“The project has included construction, installation and operation of a sewage treatment plant with a capacity of 60,000 cu m per day, and the MBR system. All aspects are executed and we are now at the closing stage,” says Barsbai.

He adds that no date has been set for the final handover of the project, with the go-ahead awaited from the client.

As the main contractor on the project, Wetico’s scope involved both civil and electromechanical works. The civil works aspect called for four valve chambers, one receiving channel, one inlet structure, two equalisation tanks, two anoxic tanks, two aeration tanks, eight MBR tanks, two treated water tanks, four air blower buildings, a dewatering building, a control building, a workshop and store, and a guard room.

The electromechanical works comprised inlet structure equipment (coarse and fine screens and a grit removal system); 12 submersible mixers; an air diffusing system with eight blowers; 640 MBR modules with air scouring system comprising eight blowers; three dewatering units; 40 pumps; and a supervisory control and data acquisition (Scada) system; remote monitoring units (RMU); motor control centres (MCCs); fire alarm system; telephone system; medium and low-voltage (MV and LV) cables; and control cables.

Highlighting the outstanding features of the STP, Barsbai says: “The 640 MBR modules are very sensitive to high temperatures and sunshine. So the installation procedure took a long time, requiring high accuracy from our staff. After installation, there was a need to cover the tanks with sheets and fill them with water until the start of the operation.”

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