Behaviour of Bulk and Trace Organics in a Full Scale Membrane Bioreactor for Landfill Leachate Treatment

Abstract

Landfill leachates are generally highly pollutant wastewaters which have percolated through a deposit of solid waste. In many states it is now required to collect and treat landfill leachates to avoid contamination of surface and groundwater bodies. A state of the art technology for landfill leachate treatment uses membrane bioreactor technology prior to potential polishing with dense membrane processes, activated carbon adsorption or chemical oxidation to make the effluent suitable either for discharge. Landfill leachate contains a wide range of potentially hazardous chemical contaminants. This paper investigates contaminant removal mechanisms in the membrane bioreactor, particularly the impact of ultrafiltration on the retention of bulk organics, which are characterized by size exclusion chromatography, and endocrine disrupting trace organics. The xenoestrogenic chemical bisphenol A deals as an indicator substance and is analysed in raw leachate, activated sludge and final effluent. Bisphenol A removal rates of up to 99% were found. Some retention of the low-molecular bisphenol A compound in ultrafiltration of activated sludge biomass has been observed and attributed to an association with macromolecules and colloids, which are retained by the porous membrane.