Molecular weight distribution of a full-scale landfill leachate treatment by membrane bioreactor and nanofiltration membrane

In this study, Molecular weight (MW) distributions of a full-scale landfill leachate treatment plant consisting of membrane bioreactor (MBR) and nanofiltration (NF) membrane were investigated. The leachate was sampled from the equalization tank, and effluents of MBR and NF membrane in the landfill leachate treatment plant. Parameters of COD, TOC, TKN, NH4+-N and UV254, 280 and 320 absorbance were analyzed to evaluate both the removal performance of the plant and MW distributions. MW distribution of samples were determined by ultrafiltration (UF) (100 kDa, 10 kDa, 5 kDa, 1 kDa and 500 Da) membranes. The results indicated that organic matter of one third percent is particulate or colloidal form and almost half of the organic fraction has a lower MW than 500 Da. In addition, organic matter had hydrophilic character. Most part of TKN was >500 Da with the corresponding rate of 92%. Further, UV absorbance of raw leachate (RW) decreased 85% after 500 Da.

► Landfill leachate treatment by MBR and NF is evaluated.
► MWs of pollutants for RW and effluents of MBR and NF are determined.
► Significant parts of organic matter in landfill leachate have very low MW.
► UV320 may be used as an indicator of COD in the landfill leachate.
► Membrane with <500 Da MWCO will be better at removing the major part of TKN.