Our Research High-efficiency chemical-free backwash strategy for reverse osmosis membrane antifouling

Schematic illustrating osmotically-induced cleaning (OIC) for a fouled RO membrane. Image credit: Zhao, Lienhard Research team

Cartoon flow chart of procedure for biofilm experiments

Procedure for real biofilm experiments. Image credit: Zhao, Lienhard Research team

Five confocal microscopy images with bright green signaling depicting biofilm.

Confocal microscopy images of the membrane surfaces with biofilms after exposure to OIC. Photo credit: Zhao, Lienhard Research team

Four video stills of membranes being cleaned of purple biofilm.

Video stills of the OIC process. Photo credit: Zhao, Lienhard Research team

Schematic illustrating osmotically-induced cleaning (OIC) for a fouled RO membrane. Image credit: Zhao, Lienhard Research team

Procedure for real biofilm experiments. Image credit: Zhao, Lienhard Research team

Confocal microscopy images of the membrane surfaces with biofilms after exposure to OIC. Photo credit: Zhao, Lienhard Research team

Video stills of the OIC process. Photo credit: Zhao, Lienhard Research team

Principal Investigators

Xuanhe Zhao

Noyce Career Development Professor
Associate Professor
Department of Mechanical Engineering

John H. Lienhard V

Abdul Latif Jameel Professor of Water and Mechanical Engineering, Department of Mechanical Engineering
Director, J-WAFS
Director, Rohsenow Kendall Heat Transfer Laboratory

Challenge:

Membrane fouling in reverse osmosis (RO) desalination leads to high energy consumption and cost and requires chemical additives for cleaning. Is there a cost efficient, chemical-free answer?

Research Strategy

Study the fouling process of RO membranes to understand how contaminants adhere
Engineer a physical membrane fouling mitigation process such as vibration that is targeted, chemical-free, and energy efficient

Project description

Reverse osmosis (RO) technology has attracted great academic and industrial interest due to the increasing demand for clean water in various aspects of our life and society. However, membrane fouling, or the accumulation of foulants on the RO membrane, inevitably leads to a decrease in membrane permeability, higher energy consumption and cost. The conventional method of mitigating fouling is to add chemicals such as chloramine to the feed solution, which is costly, time- and energy-inefficient, and environmentally undesirable.

In this project, the research team is developing new chemical-free fouling mitigation strategies with low cost and a reduced energy consumption to achieve high-efficiency RO membrane antifouling. The research objectives include: i) studying the fouling process during RO membrane operation and characterizing the adhesion between fouling film and RO membrane; ii) understanding new foulant-detaching mechanisms based on mechanical methods.

The significance and impact of the proposed project is two-fold: i) it will provide fundamental understanding of foulant detaching mechanisms; and ii) based on this understanding, it will result in the development of a high-efficiency, chemical-free antifouling strategy for RO systems. Whereas existing studies on membrane fouling and antifouling have not incorporated a deep understanding of solid mechanics; the proposed work is creating a new collaboration between experts in soft material mechanics (Zhao lab) and experts in RO membrane fouling (Lienhard lab) to develop targeted, efficient, chemical-free membrane fouling mitigation protocols.

Outcomes

Designed and constructed flow setups to deploy physical cleaning methods as alternatives to chemicals in mitigating fouling in RO membranes
Investigated the effectiveness of osmotically-induced cleaning (OIC) and applicability in the presence of spacers for brackish water desalination
Evaluated the potential of OIC on biofilms for desalination applications