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PROTECTING REVERSE OSMOSIS PLANTS THROUGH WATER PRE-TREATMENT

Reverse Osmosis (RO) is a separation approach that is suitable for a extensive range of functions, especially when salt and/or dissolved solids have to be removed from a solution. It is amongst the most common kinds of water therapy.
According to Anelia Hough, water therapy advisor at Allmech, leading South African producer of boilers and provider of water treatment parts, there are several elements to be thought of when selecting an RO system: the customer’s capacity requirement (i.e. water usage), the day by day manufacturing capacity of the system, and the p.c rejection for specific contaminants within the supply water.
“Beyond this, RO plants require proper upkeep and care to ensure they perform optimally and to extend their lifespan,” she says. “Aside from regular upkeep, the best way to protect a RO plant is by pre-treating water, which reduces the pressure on the RO membrane – a expensive part. It also helps to keep away from issues like scaling and bio-fouling.”

Common Issues with RO Plants

“Factors that may affect a RO system’s performance include temperature, working stress, back strain, the equilibrium effect/TDS creep, % restoration, and, of course, the RO membrane’s permeate manufacturing and p.c rejection rankings,” says Hough.
The most common points in RO vegetation include:
• Fouling: occurs when contaminants accumulate on the membrane floor, successfully plugging the membrane. There are many contaminants in municipal feed water which might be innocent for human consumption, however large enough to shortly foul (or plug) an RO system.
• Scaling: when particles are deposited on a membrane, causing it to plug. As sure dissolved compounds turn into more concentrated, scaling can happen if these compounds exceed their solubility limits and precipitate on the membrane surface as scale. Scaling calculations are often solely based mostly on the silicate concentration in the feed water.
• Biofouling: reduces pressure gauge via microbial era in a biofilm that varieties on the membrane floor.
• Chemical harm: on a RO membrane, this implies the next permeate flow and poorer quality permeate water. Dosing of oxidant agents, similar to chlorine or hypochlorite, can reduce performance and finally outcome in the failure of the RO membranes. Use of aggressive cleaners can also trigger chemical harm.
• Mechanical harm: can happen when a system is pressurised too rapidly, damaging the RO membrane elements. One of probably the most clears signs of damages on a RO membrane is the lack of salt rejection capabilities. There can be very often an increase of permeate move rate.
Pre-treatment might help to avoid these problems, and Hough says there are various choices obtainable.
Pre-treatment Options

“When selecting a pre-filter, customers should all the time search for a verified efficiency score subsequent to the micron size on the filter’s technical knowledge sheet,” says Hough.
• Multi Media Filtration: A multi-media filter is used to assist forestall fouling of a RO system. This sort of sediment filtration is right for a pre-treatment process to any reverse osmosis system helping to make sure long life of the RO membrane parts. A nicely operated multimedia filter can take away particulates down to 20 microns. A multimedia filter that uses a coagulant addition can remove particulates all the way down to 10 microns.
• Micro Filtration: The filters utilized in microfiltration have a pore measurement of roughly 0.1 micron. Bacteria and suspended solids are the one factor that could be eliminated via microfiltration.
• Antiscalants and scale inhibitors: There are many chemical substances that can be used as antiscalants and dispersants to enhance the operation of RO. Antiscalants are a household of chemical compounds designed to inhibit the formation and precipitation of crystallized mineral salts that form scale.
• Softening by ion exchange: A water softener is a filtration system that removes hardness-causing calcium and magnesium minerals from water through a process referred to as ion change. Standard water softeners are cation trade gadgets. Cation trade includes the replacement of the hardness ions with non-hardness ions.
• Granular Activated Carbon (GAC) Filtration: Activated carbon removes residual chlorine and chloramines by a chemical reaction that entails a switch of electrons from the surface of the GAC to the residual chlorine or chloramines. The chlorine or chloramines end up as a chloride ion that’s no longer an oxidizer.
“It’s additionally necessary to scrub the RO membrane frequently,” says Hough. “This includes low and high pH cleaners to remove contaminants from the membrane. We handle scaling with low pH cleaners and organics, while colloidal and biofouling are handled with a high pH cleaner.”

Allmech presents the whole range of pre-treatment and RO membrane maintenance options for RO plants, together with filtration methods, softeners, antiscalants, chemicals and different consumables.
“At Allmech, we’re trying ahead to rising this a part of our enterprise in 2022 and beyond, leveraging our experience in all issues associated to water remedy. We also have a boiler division and we inventory a comprehensive vary of Runxin valves, so we’re properly positioned to be a one-stop shop for anybody needing a water remedy or boiler specialist, and we’re expecting a busy yr ahead,” Hough says.
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