Kevan Brian (Watercare Services Ltd), Jeff Peeters & Matt Reeve(SUEZ Water Treatment Solutions, Canada), Nadine Oschmann(SUEZ Water Treatment Solutions, Australia)
Membrane Aerated Bio Reactors or MABR’s are a new technology for the treatment of wastewater. The process is reported as being very energy efficient, having lower nitrous oxide emissions than alternative processes such as activated sludge. It is also ideal for process intensification where additional total nitrogen removal or nitrification (conversion of ammonia into nitrate and nitrite) is required.
Most MABR installations and pilot scale plants around the world have been operated in hybrid mode where the MABR membranes are used within an activated sludge reactor (typically the anoxic zone). In this application the MABR augments the activated sludge process by providing an aerated carrier onto which a nitrifying and denitrifying biofilm can develop. This means that nitrogen removal via nitrification and denitrification can occur in the same reactor and in the same space.
This pilot study looked at the application of MABR in a biofilm only mode. In this mode the process could be used to either nitrify or denitrify without the need for mixed liquor in the liquid phase. This application of MABR is potentially very well suited to process upgrades in New Zealand where oxidation pond systems are required to meet tighter nitrogen consents year-round, often resulting in these being replaced with activated sludge plants such as SBR or MBR, that are energy intensive. In addition, MABR processes may have lower N2O emissions per unit of nitrogen treated and are therefore of particular interest to Watercare in our goals to meet net zero emissions by 2050.
This paper presents the results of piloting undertaken by Watercare Services Limited with a SUEZ ZeeLung MABR in biofilm only operation mode. The goal of the trail being to understand the efficacy of the process in terms of nitrogen removal from raw or primary wastewater without mixed liquor, to quantify N2O emissions and to better understand how a full-scale system could be configured and commissioned.