ACWA Emirates has reported results from a portable membrane bioreactor (MBR) sewage treatment plant that is purifying wastewater for a $9 billion gas megaproject at Habshan, near Abu Dhabi.
The plant was installed on behalf of CCC Contractors at the Habshan 5 gas complex, and has been undertaking operations and maintenance since start-up.
Habshan 5 is a gas processing and sulphur production facility, around 150km south west of Abu Dhabi, which will process 1000 million cubic feet per day of gas from the offshore Umm Shaif facility and a further equivalent amount of onshore gas. When completed, the site will provide 270MW of much-needed power to meet UAE’s fast-growing demand.
The portable MBR plant supplied to the Abu Dhabi Gas Industries (GASCO) consists of two containerised Memtreat® units, which treat roughly half of the flow each (with an average flow of 501 m3 through MBR1 and 480 m3 through MBR 2. On some days the treatment plant has capably surpassed its 1000 m3 design flow, according to the supplier.
Final effluent from the membranes is said to be suitable for direct discharge without further treatment, or for reuse in irrigation, cooling, or industrial processes. The portable format was selected for Habshan 5 as a permanent facility was not possible but non-mains wastewater treatment was required.
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. Solutions were implemented as part of the installation, including 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/day. 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. Around 10,000 gallons of sludge are removed every three days to maintain a healthy level of Mixed Liquor Suspended Solids (MLSS).
ACWA Emirates said cost savings achieved using the portable MBR solution are estimated at AED 10 million ($2.7 million, £1.7 million). Removing the wastewater by tanker from such a remote site to the nearest treatment facility, 100 km away, and bringing in water for wastewater treatment, would have cost an estimated AED 42 million ($11.4 million, £7.1 million), equivalent to AED2700 ($735, £500) for each round of delivery and removal by tanker.
Gary Jackson, director and general manager of ACWA Emirates, said: “The Habshan 5 site is already being hailed as an incredible success for its high environmental and safety standards as well as its remarkable speed of construction, and we are delighted that ACWA Emirates’ portable MBR solution has played its part in making these goals possible.”