SWANSEA, Wales – A self-cleaning water treatment membrane made of electrically conductive nanofibers could change the economics of desalination plant operation and maintenance, according to researchers.
The microfiltration membrane was originally developed in 2014 by Professor Nidal Hilal (pictured above), director of the centre for advanced technologies and environmental research (CWATER) at Swansea University’s College of Engineering and Professor Raed Hashaikeh from the Masdar Institute in Abu Dhabi.
Next the researchers developed a self-cleaning nanofiltration membrane, mixing carbon nanostructures with networked cellulose gel and as the mixture dried, the networked cellulose shrank.
The shrinking of the network cellulose in turn pressurized the nanostructures in the membrane, resulting in much smaller pore sizes.
A latest development has seen further research, applied for the first time, the electrolysis concept at the spacer component of the membrane module where the conductive spacers work as an electrode (cathode) in electrochemical set-up.
The membrane system was subjected to fouling and then exposed to periodic electrolysis, wherein in-situ cleaning of membrane surface by hydrogen bubbles generation at the spacer is applied.
This project has already yielded a patent filing.
Self-cleaning membranes offer a critically needed solution to the problem of the unwanted build-up of organic and inorganic deposits on a membrane’s surface that reduces the membrane’s ability to filter impurities, the researchers said.
Water treatment and purification membranes that can easily clean themselves when fouled could make pressure-driven membrane filtration systems used to treat and desalinate water more energy-efficient.
Keeping membranes clean, permeable and functional is a great challenge to membrane desalination technologies. When a membrane becomes fouled much less water can pass through the membrane at a constant pressure.
Conventional methods for cleaning fouled membranes involve chemical treatments.
In the UAE, annual spending on desalination is already estimated to cost US$3.5 billion, indicating a pressing need for solutions that avoid costly shut-downs and treatments.
In addition to posing a heavy financial burden, fouled membranes are also a sustainability issue, as once a membrane becomes fouled, the higher pressure needed to push water through clogged pores significantly increases the plant’s energy consumption.