Written by: Gu Yatian
Translated by: Wang Yumeng
Edited by: William Mosteller
Recently, Professor Ma Jun, School of Environment, Harbin Institute of Technology (HIT), with his research team, has made important progress in the research field of ceramic membrane filtration technology. As a highlight achievement, the work of his team "Interaction Analysis between Gravity-Driven Ceramic Membrane and Smaller Organic Matter: Implications for Retention and Fouling Mechanism in Ultralow Pressure-Driven Filtration System" was published in the well-known international journal Environmental Science & Technology. The State Key Laboratory of Urban Water Resources and Water Environment is the organization of the first authorship and correspondent author of the paper.
Gravity-driven membrane has attracted much attention because of its low energy consumption, stable operation and simple maintenance. It has broad application potential in many fields such as water treatment, sewage treatment, reclaimed water reuse, oil-water separation, rainwater utilization, domestic drinking water treatment and seawater pretreatment. The interception mechanism of pollutants and membrane fouling mechanism in gravity-driven membrane operation are the core issues affecting membrane filtration efficiency.
Professor Ma Jun's team has revealed for the first time physicochemical interaction between ceramic membranes and organic compounds in the process of gravity and low-pressure driving and the mechanism of its influence on interception and fouling behavior of gravity-driven membranes. Flux declined more seriously at lower operation height, probably due to heavier cake fouling caused by the rejected foulant. Interactions of ceramic membrane-SOM were analyzed through extended Derjaguin-Landau-Verwey-Overbeek theory (XDLVO) and hydrodynamic permeation drag (PD). Among van der Waals (LW), acid-base (AB), and electrostatic (EL) forces in XDLVO, EL played a significant role on GDCM filtrating SOM, and altering membrane electrostatic property could greatly influence SOM filtration. Furthermore, the rising PD force largely weakened the EL dominant zone with operation height increasing, while barely influencing the LW and AB dominant zones. Therefore, the weakened EL-dominant repulsive zone caused less rejection of like-charged foulant with operation height increasing. Fe2O3- and MnO2-modified membranes further validated the comprehensive influence of LW, AB, EL, and PD interactions on GDCM filtration. The possible "trade-off" of pore blocking-cake fouling with operation height decreasing demonstrated potential enhancement for both rejection and antifouling performance by electrically modified membrane under ultralow pressure. This study provides insight on membrane selection/preparation/modification and performance control of ultralow pressure-driven filtration.
The first author of this thesis is Zhao Yumeng, a doctoral student of HIT in Grade 2017. Her research work was completed under the joint guidance of Professor Ma Jun and Lecturer Lu Dongwei. This study was supported by the National Key Research and Development Program, the China Post-doctoral Science Fund and the Special Fund for School of Environment and Ecological Innovation of HIT.