Aghagallon is a small village in Northern Ireland with a population of 1,600. The established treatment works consists of 2 main Membrane Bio-Reactors (MBR). The client, Northern Ireland Water (NIW) have found that operation of the plant for the past 12 years has led to the following issues:
If maintenance such as membrane cleaning was not carried out frequently it became impossible to pass Full Flow to Treatment (FFT) flows through the MBR. This could lead to excessive spills to storm tanks, potentially affecting the receiving water.
The best solution was to modify the existing treatment works to a Moving Bed Bio-Reactor, with tertiary treatment provided by reed beds. Changing to a MBBR plant would not only achieve the final effluent discharge consent of BOD:SS:NH3-N of 5:10:3 mg/l, but also be more robust and reliable, with a lower energy requirement.
To date, the performance has been extremely encouraging with respect to the consent standard. Effluent from the MBBR routinely falls below the 5:10:3 consent standard, and will only improve when the second MBBR is installed on site. Alongside these impressive results, energy usage is around 50% lower than the previous MBR requirements.