Chemical, Membrane, Biological : Which is the best for Water treatment?
All water treatment systems aim to remove impurities from water so the water can be released (discharged) or reused in other processes.
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Different industries require different qualities of water, producing wastewater and liquid effluent containing various concentrations of impurities.
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The types of impurities and the saturation (amount) of impurities in the liquid define the best treatment technology and approach.
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Thus, the question of whether chemical, membrane, biological, or all treatment approaches are best for water treatment is a matter of application.
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In some cases, a single treatment is all that is needed to treat water to the specified quality. Still, multi-stage treatment is necessary when the impurities in the water are diverse, and no single treatment achieves the quality of water you need.
Chemical water treatmentÂ
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Chemical water treatment is an old-fashioned approach, with chemical precipitation, chemical disinfection (usually with chlorine, chlorine dioxide or ozone depending on the application), and ion exchange the most common.
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At Membracon, we have moved away from chemical treatment in favour of Reverse Osmosis (RO), bioreactors (MBRs) and membranes.
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Chloramine and chlorine are most commonly used to disinfect water – an alternative to this is Ultraviolet Disinfection (UV).
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Chemicals contaminate water in low concentrations, but nether-the-less, this presents environmental and safety concerns. Chemicals have a high carbon footprint, and inorganic chemicals do not biodegrade under normal conditions.
Membrane water treatmentÂ
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Membranes are clean, green and safe, capable of treating water to a precise specification through a series of filters. More traditional treatments include the use of harsh chemicals; membranes are physical filters that use no chemicals.
Reverse Osmosis
RO systems are the most common. They work by jetting water at pressure through semi-permeable membranes, removing impurities as the water passes through.
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The membranes used include:
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- Microfiltration (blocks bacteria and suspended solids for fuel refinement, wastewater treatment and separating oil/chemical emulsions)
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- Ultrafiltration (also blocks viruses)
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- Nanofiltration (blocks 50-90% of monovalent ions and organic molecules and salts, making it ideal for treating hard water)
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Reverse Osmosis is widely used to treat water to precise specifications, like the finishing water used in the automotive and aerospace sectors.
Biological water treatmentÂ
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Biological treatments remove organic impurities from water. In a biological system, organic matter, nitrogen, phosphorus, and other impurities are eliminated by microorganisms, carefully selected and cultivated with precise microbiology.
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The most rudimentary biological treatment is activated sludge. A cleaner, greener and more modern system is a Membrane Bio-Reactor (MBR).
MBR – Membrane Bio-Reactor
Compared to activated sludge, a Membrane Bio-Reactor has lower waste, higher-quality effluent and no need for secondary clarifiers. The system is self-contained, requiring little intervention and supporting flow rates up to 2,000m3/day.
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The living biomass in the membrane biodegrades contaminants, assimilating them into the culture (in other words, converting them to food).
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The biological wastewater treatment process is coupled to a membrane filtration system, with the membrane system polishing the water. The result is high-quality treated water, suitable for reuse in industrial applications.
Summing upÂ
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Chemical water treatment is old-fashioned, easily replaceable with Ultraviolet Disinfection (UV) for disinfection and membranes for purification.
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Reverse osmosis and membrane bioreactors offer a green, clean, low-maintenance water treatment solution for large-scale filtration and purification.
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Find out more
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To find out more about the biological, membrane and chemical wastewater treatment processes discussed in this article, feel free to contact us.