In 2008, ADSSC, the sewage and sanitary authority in Adu Dhabi, decided to convert two of the existing concrete emergency storage tanks at Mafraq WWTP into sequencing batch reactors, increasing the secondary treatment capacity of the plant by 50,000 m3 per day. Napier-Reid’s BIO-BATCH™ SBR was selected to meet the stringent effluent discharge limits.  As part of the design, the equipment included four duplex decanters with a total weir length of 36 meters. The decanter travel speed is controlled by VFD to maintain a constant decant rate from the top water level to the bottom water level. Each SBR basin is 30 m wide by 109 m long, which makes the Mafraq SBR plant the world’s largest two-basin SBR in terms of treatment capacity and tank size.

Napier-Reid also provided detailed process design and supplied most process equipment including one influent magnetic flowmeter and motorized plug valve, one fine bubble aeration system complete with membrane fine-bubble diffusers, four submersible mixers, two submersible waste sludge pumps, one magnetic flowmeter for monitoring waste activated sludge, and two dissolved oxygen analyzers., as well as all instrumentation and programmable logic control systems.