Hydrophobic Gas Transfer Membranes for Wastewater Treatment and Resource Recovery

Abstract

Gaseous compounds, such as CH 4 , H 2 , and O 2 , are commonly produced or consumed during wastewater treatment. Traditionally, these gases need to be removed or delivered using gas sparging or liquid heating, which can be energy intensive with low efficiency. Hydrophobic membranes are being increasingly investigated in wastewater treatment and resource recovery. This is because these semipermeable barriers repel water and create a three-phase interface that enhances mass transfer and chemical conversions. This Critical Review provides a first comprehensive analysis of different hydrophobic membranes and processes, and identifies the challenges and potential for future system development. The discussions and analyses were grouped based on mechanisms and applications, including membrane gas extraction, membrane gas delivery, and hybrid processes. Major challenges, such as membrane fouling, wetting, and limited selectivity and functionality, are identified, and potential solutions articulated. New opportunities, such as electrochemical coating, integrated membrane electrodes, and membrane functionalization, are also discussed to provide insights for further development of more efficient and low-cost membranes and processes.

Delignified Wood from Understanding the Hierarchically Aligned Cellulosic Structures to Creating Novel Functional Materials: A Review

“…[213] According to the literature, an ideal MD membrane should have a large pore size, low pore tortuosity, low thermal conductivity, high porosity, good mechanical strength, low cost, and low environmental impacts. [209,[213][214][215][216][217] DW could be an ideal material for MD membranes as it has an inbuilt porous structure and suitable properties. Hou et al [218] explored the potential of DW as a MD membrane.…”

Recent progress using membrane aerated biofilm reactors for wastewater treatment

“…Placement of the MABR in the anoxic tank is an established practice for biological nitrogen removal (Houweling et al 2017; Underwood Packing density is a critical parameter to size the MABR zone in the hybrid process. While a high packing densities can provide a larger specific surface area to support biofilm attachment and consequently promote the pollutant removal rates, biofilm bridging can occur at high packing densities, resulting in a decrease in the effective surface area (Hou et al 2019). Research and practice experiences are in need to investigate solutions to increase packing density while retaining efficient external mass transfer characteristics and avoiding solids build-up.…”

Advanced Nanowood Materials for the Water–Energy Nexus

“…For example, polymer‐based membranes have been widely used in water and wastewater treatment, water reuse, and desalination to remove particles, pathogens, metals, salts, and other constituents and produce clean water with desired qualities. [ 6–9 ] Plastic materials are commonly used as supporting media and reactors in filtration and biological systems for wastewater treatment and energy recovery. [ 10,11 ] Graphite carbon, ceramics, and metal materials are also broadly used in different aspects of water engineering.…”

“…Natural American basswood was first tested along with modified nanowood that was chemically treated to remove lignin and hemicellulose. [ 6 ] The wood membrane surface was treated to become hydrophobic, so vapor could pass through but the liquid will be retained ( Figure a,b). Results showed the nanowood membrane had high porosity (89 ± 3%), low thermal conductivity (<0.05 W m −1 K −1 ), and high hydrophobicity.…”