Reverse Osmosis (RO) is a separation method that is appropriate for a variety of purposes, especially when salt and/or dissolved solids have to be removed from a solution. It is probably one of the commonest kinds of water treatment.
According to Anelia Hough, water therapy advisor at Allmech, leading South African manufacturer of boilers and provider of water treatment parts, there are a quantity of elements to be considered when selecting an RO system: the customer’s capacity requirement (i.e. water usage), the every day manufacturing capacity of the system, and the % rejection for particular contaminants within the source water.
“Beyond this, RO plants require correct maintenance and care to make sure they perform optimally and to increase their lifespan,” she says. “Aside from common maintenance, the easiest way to guard a RO plant is by pre-treating water, which reduces the strain on the RO membrane – a pricey element. It also helps to avoid issues like scaling and bio-fouling.”
Common Issues with RO Plants
“Factors that may have an result on a RO system’s efficiency embody temperature, working strain, back stress, the equilibrium effect/TDS creep, percent recovery, and, of course, the RO membrane’s permeate manufacturing and percent rejection ratings,” says Hough.
The most typical issues in RO plants include:
• Fouling: occurs when contaminants accumulate on the membrane surface, effectively plugging the membrane. There are many contaminants in municipal feed water which are harmless for human consumption, however giant enough to quickly foul (or plug) an RO system.
• Scaling: when particles are deposited on a membrane, causing it to plug. As sure dissolved compounds turn into extra concentrated, scaling can happen if these compounds exceed their solubility limits and precipitate on the membrane floor as scale. Scaling calculations are normally only based mostly on the silicate concentration in the feed water.
• Biofouling: reduces precise membrane performance by way of microbial technology in a biofilm that varieties on the membrane floor.
• Chemical injury: on a RO membrane, this implies the next permeate move and poorer quality permeate water. Dosing of oxidant agents, such as chlorine or hypochlorite, can scale back performance and ultimately end result in the failure of the RO membranes. Use of aggressive cleaners can also cause chemical injury.
• Mechanical injury: can occur when a system is pressurised too quickly, damaging the RO membrane components. One of the most clears indicators of damages on a RO membrane is the dearth of salt rejection capabilities. There can also be fairly often an increase of permeate flow rate.
Pre-treatment may help to avoid these issues, and Hough says there are various choices available.
Pre-treatment Options
“When deciding on a pre-filter, customers should all the time look for a verified effectivity rating next to the micron measurement 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 type of sediment filtration is right for a pre-treatment process to any reverse osmosis system serving to to ensure lengthy life of the RO membrane components. A well operated multimedia filter can remove particulates down to twenty microns. A multimedia filter that makes use of a coagulant addition can remove particulates right 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 component that might be removed via microfiltration.
• Antiscalants and scale inhibitors: There are many chemical substances that can be utilized as antiscalants and dispersants to enhance the operation of RO. Antiscalants are a household of chemicals designed to inhibit the formation and precipitation of crystallized mineral salts that kind scale.
• Softening by ion change: A water softener is a filtration system that removes hardness-causing calcium and magnesium minerals from water through a course of called ion exchange. Standard water softeners are cation exchange devices. เครื่องมือวัดความดัน involves the substitute 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 includes 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 essential to wash the RO membrane regularly,” says Hough. “This entails low and high pH cleaners to remove contaminants from the membrane. We address scaling with low pH cleaners and organics, whereas colloidal and biofouling are handled with a excessive pH cleaner.”
Allmech provides the whole vary of pre-treatment and RO membrane maintenance solutions for RO crops, including filtration systems, softeners, antiscalants, chemical substances and other consumables.
“At Allmech, we’re looking forward to growing this a part of our business in 2022 and past, leveraging our experience in all things related to water therapy. We also have a boiler division and we stock a complete range of Runxin valves, so we’re nicely positioned to be a one-stop shop for anybody needing a water therapy or boiler specialist, and we’re anticipating a busy 12 months ahead,” Hough says.

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