Landfill leachate is a problematic wastewater to treat. High salt concentrations, toxic metals and very high ammonia concentrations make landfill leachate difficult to degrade biologically. Disposal of leachate either to receiving bodies or to municipal wastewater treatment plants can create process disruptions and a significant increase in aeration demand. Therefore, in many cases, the leachate is either fully treated or at least pre-treated on site before passing it to a further wastewater treatment installation situated off site.
Arthurstown Landfill, located in Kill Co. Kildare, Ireland, owned and operated by South Dublin County Council (SDCC) received municipal waste between years 1997 and 2010 and its leachate treatment will continue for another 20 years.
The treated leachate on the site is pumped from the base of each waste storage cell to a storage tank before being sent to a Sequencing batch reactor (SBR) for nitrification and reed beds for denitrification. Treatment using the SBR is expensive due to the high energy required for aeration. It typically accounts of 45-75% of the leachate treatment plants total energy requirements, This presents a significant energy-related operating cost of the leachate treatment alone.
Following on an initial laboratory study, which demonstrated the high ammonia removal rates achievable in an MABR, in 2015 OxyMem in collaboration with SDCC installed a demonstration MABR in Arthurstown Landfill. The installation was employed to show how the OxyMem’s MABR can allow for a significantly reduced OPEX when treating landfill leachate. The initial trial set-up consisted of Anammox system consisting of a partial nitrification stage, followed by an autotrophic ammonia oxidation stage with a final OxyMem MABR stage for achieving low ammonia concentrations of less than 5mg/l in the MABR dis-charge stream.