By World Water Works
BACKGROUND
Sharjah Municipality of the United Arab Emirates (U.A.E.) was requiring to treat more and more flow despite having very little space for new treatment systems. They were looking at wanting to expand their plants No. 4 & No. 5 plants to meet new total nitrogen limits and try to do so by having to reuse the existing systems.
Sharjah’s engineer, having worked with other large cities around the world, upgrading them to meet new lower effluent permit requirements relating to Total Nitrogen and Ammonia- Nitrogen, showed Sharjah Municipality what could be done using their existing tanks and upgrade them without having to build any new tanks. This type of upgrade would save on cost as well as space at the plant.
SOLUTION
The process used for this type of upgrade is called Integrated Fixed Film Activated Sludge (IFAS). This is the combination of Conventional Activated Sludge (CAS) and Moving Bed Biofilm Reactor (MBBR) System in the same tank. The goal is to retain / grow the slower growing bacteria called nitrifiers on the MBBR media. In the figure, one can see the Activated sludge in the bottom portion of the graduated cylinder and the MBBR media on top which houses the slower growing bacteria.
The system reached full capacity in May 2020 and has treated 115% of its average load since this time. Figures 1 – 5 show operationally the influent loads for COD & TKN with also removal rate of Total Nitrogen and SVI of the MLSS.
