Membrane distillation treatment of landfill leachate: Characteristics and mechanism of membrane fouling

Landfill leachate (LFL), which contains organic and inorganic contaminants in high concentration, poses a detrimental hazard to the ambient environment. Although membrane distillation (MD) shows great potential in wastewater treatment, the membrane fouling in LFL treatment is still a rarely reported. In this study, the membrane fouling was systematically investigated in a real LFL treatment by a direct contact MD system. Various characterization methods, such as scanning electron microscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and attenuated total reflection Fourier transform infrared spectroscopy were adopted in membrane fouling identification. Increasing membrane fouling was observed with the increasing feed pH. The analysis of membrane autopsy and differential log-transformed absorbance spectroscopy revealed that the increase of feed pH strengthened the deprotonation of carboxyl groups in organic matter, contributing to the formation of organo-inorganic complexation. The interaction between magnesium-related substances and humic-like matter might be the culprit of organo-inorganic membrane fouling in alkaline feed condition based on correlation analysis (R-2 = 0.996). The results enhance the understanding of the mechanisms by which pH affects membrane fouling and lay the foundation for controlling membrane fouling in the LFL treatment.

Automated summary

In this study, the membrane fouling in landfill leachate treatment by membrane distillation was systematically investigated. It was found that the increase of feed pH enhanced the deprotonation of carboxyl groups in organic matter, contributing to the formation of organo-inorganic complexation, which might be the main cause of membrane fouling in alkaline feed condition.