Excellent results have been obtained from a portable membrane bioreactor (MBR) sewage treatment plant from ACWA Emirates that is installed at the US$ 9 billion Habshan 5 gas project in Abu Dhabi, UAE.
The company, part of ACWA Services, set up the state-of-the-art plant on behalf of CCC Contractors to treat wastewater from the 5,000-worker construction camp and has been undertaking operations and maintenance since start-up.
The portable MBR plant consists of two containerised Memtreat units, which treat roughly half of the flow each (with an average flow of 501 m³/d through one and 480 m³/d through the other). On some days the treatment plant has capably surpassed its 1,000 m³ design flow thanks to its ability to cope well with widely varying flows.
Challenging issues on the Habshan 5 site included low wastewater flows and oil, grease and chemicals entering the system from the kitchen, shower and toilet facilities. Working in close collaboration with CCC Habshan, ACWA Emirates returned to the source of each challenge for an optimal solution, installing oil and grease traps in the kitchens and ensuring plant operators checked the surface of the balance tanks for oil and grease buildups.
To date, the plant has treated over 585,000 m³ of wastewater, at an average of 685 m³/d. The highly-treated effluent from the portable MBR is stored in a holding tank and transferred by tanker for use in toilet flushing, dust dampening, concrete batches and trench backfilling.
The cost savings achieved using the portable MBR solution are considerable. Removing the wastewater by tanker from the remote desert site to the nearest treatment facility, 100 km away, and bringing in water for wastewater treatment, would have cost an estimated AED 42 million (US$ 11.43 million.
Factoring in the investment costs of the plant, tank, pipelines, pumping stations, operation and maintenance, chemicals and labour, the net financial savings are estimated at AED 10 million (US$ 2.7 million). The ability to avoid moving water and wastewater by tanker also has significant environmental benefits in terms of reduced fuel consumption and environmental damage.
ACWA Emirates director and general manager, Gary Jackson said: “The site management is committed to making every effort to eliminate or minimise any environmentally adverse effects of the operation, so the multiple benefits and low impact of the portable MBR solution have made it an ideal solution.”