Breakthrough in prefiltration that protects RO membranes
Dr. Ibrahim El-Azizi, of the University of Sheffield, recently presented a paper at a desalination conference in Amman Jordan, focusing on the causes of fouling of reverse osmosis (RO) membranes. In a pilot test of filters at a desalination plant in Libya, he studied the causes and extent of fouling. He concluded that filters using “Disruptor™ media is the best solution for reducing the fouling of RO in seawater desalination plants. It can remove the majority of foulants including colloids, bacteria, polysaccharides and natural organic matter at high flow with low cost. Using Disruptor™ prior to SWRO membranes will reduce energy consumption, chemical cleaning frequency, prolong membrane life and consequently will reduce operational costs.”
Disruptor™ is an electropositive nano alumina media invented by Argonide Corporation and whose manufacture and sales are exclusively licensed to Ahlstrom. Argonide purchases the media and fabricates a full line of standard-sized pleated filter cartridges under the NanoCeram® trademark. NanoCeram® cartridges are being used in diverse applications including purifying fresh drinking water, removing colloidal iron, bacteria and virus contaminants for industrial and pharmaceutical processing and in virus sampling of water.
Dr. El-Azizi’s work complements data previously reported by Argonide in collaboration with Toyota, where NanoCeram® cartridges are being used for protection of RO membranes in recovering and recycling contaminated fresh water in automobile manufacture. In one Toyota plant, contaminated fresh water was passed through a 5 micron prefilter intended to protect an RO unit. The RO membranes became so heavily contaminated that they needed to be replaced every 2nd or 3rd month. When the 5 micron prefilters were replaced by a combination of a 1 micron depth filter, followed by the NanoCeram® polishing filter, the RO membranes remained unfouled for at least one year (and still running), without requiring any cleaning. The payback through six months of operation exceeded 5:1 as compared to costly membrane replacements, exclusive of savings in improved water yield, elimination of cleaning chemicals and their disposal.
“The highest payback is achieved with a NanoCeram® cartridge that has its own prefilter such as a 1 micron depth filter or a back-flushable 2 micron filter produced by Amiad” says Fred Tepper, co-inventor of NanoCeram®/Disruptor™ and President of Argonide.