Characterisation of foulants in membrane filtration of biorefinery effluents

Effluents from biorefineries are highly coloured and carry a large organic load. Traditional treatment options, such as anaerobic and aerobic digestions are capable of reducing the biological oxygen demand, but cannot remove the residual chemical oxygen demand (COD) nor decolourise the effluent. Membrane filtration has been increasingly used for water recovery from industrial effluents, such as from these biorefineries. Different grades of membranes can be used to remove particular contaminants, such as suspended solids, organic macromolecules and salts from these effluents. Effluents were filtered by ultrafiltration (UF) and nano- filtration (NF) membranes and samples were analysed for traditional parameters, such as COD, dissolved organic carbon (DOC) and colour. While UF was capable of only partial removal of colour, COD and DOC, NF was shown to be capable of removing close to 100% of the organic content of the molasses and lignocellulosic effluents. Use of advanced analytical techniques, such as fluorescence excitation emission matrix analysis and liquid chromatography, helped to illustrate the difference between organic compounds found within molasses and lignocellulosic effluents. This was also useful in explaining the difference in membrane separation performance between the two effluents.