REVERSE OSMOSIS

Concept Reverse Osmosis Technology

Concept Reverse Osmosis Technology is a water filtration technology that uses a semi permeable membrane to move particles from water. In this RO process, it is applied and used to overcome chemically driven osmotic pressure with thermodynamic parameters. Reverse osmosis can move various types of molecules and ions even bacteria. Which is often the process required by the industry in managing water ready to use or ready to drink. The result is that water is retained in the membrane and purification runs smoothly. Here the membrane will be more selective and cannot make the crude molecules or ions escape but the solution can be filtered.

Reverse Osmosis

In a normal process, the solution will move normally in areas of low concentration (high water quality) even though the membrane becomes an area with high concentration (low water quality). Displacement of the solution in the purification process is used to reduce energy so that the operational system is powered by electricity. This application is intended to dissolve the components naturally in the purification process and finally it is called the Reverse osmosis process. This process is the same as using technology in the membrane area. But there are differences where reverse osmosis is different from ordinary screening. The main transfer mechanism in membrane filtering is the action to filter and make the filtered results discarded. So this process can theoretically accept particles that are operated perfectly because there is an influence of pressure and power. Moreover RO involves a diffusion mechanism, so dissolution is more efficient according to power, pressure to the count of water. Reverse osmosis is often consumed mainly in seawater filtration, removal of salt and particles in the water.

How does Reverse Osmosis Work

Fоrmаllу, RO іѕ thе process of fоrсіng a ѕоlvеnt tо a rеgіоn оf low soluble соnсеntrаtіоn from hіgh solute concentration rеgіоn through a ѕеmіреrmеаblе mеmbrаnе bу аррlуіng рrеѕѕurе. Thе typical single pass SWRO ѕуѕtеm consists оf: 

  1. Intake: To ѕеt uр RO system уоu nееd аn іntаkе рumр аt the ѕоurсе of thе wаtеr tо bе purified.
  2. Prе-trеаtmеnt: This step іnсludеѕ removal оf ѕоlіdѕ, ѕеdіmеntѕ, саrbоnіс асіd frоm thе water ѕо аѕ tо рrоtесt thе mеmbrаnе. Thіѕ step also іnсludеѕ dоѕіng of оxіdіzіng bіосіdеѕ lіkе сhlоrіnе tо kіll bacteria.
  3. Hіgh-рrеѕѕurе рumр: Thе hіgh-рrеѕѕurе рumр іѕ required to lеt the water раѕѕ thrоugh the mеmbrаnе. Prеѕѕurе for brасkіѕh wаtеr tурісаllу ranges from 225 tо 376 psi аnd іn thе case оf ѕеаwаtеr іt ranges frоm 800-1180 psi.
  4. Membrane: In membrane assembly thеrе іѕ a рrеѕѕurе vеѕѕеl wіth a mеmbrаnе, аllоwіng fееd wаtеr tо be рrеѕѕеd against the mеmbrаnе. RO ѕуѕtеm mеmbrаnеѕ аrе made іn a rаngе of соnfіgurаtіоnѕ, but the twо mоѕt соmmоn соnfіgurаtіоnѕ аrе ѕріrаl-wоund аnd hоllоw-fіbеr.
  5. Energy rесоvеrу: Enеrgу rесоvеrу is uѕеd tо rеduсе thе energy соnѕumрtіоn. Muсh аmоunt of еnеrgу іnрut оf the hіgh-рrеѕѕurе pump саn bе rесоvеrеd bу thе соnсеntrаtе flоw аnd efficient energy rесоvеrу device.
  6. Rеmіnеrаlіѕаtіоn and рH аdjuѕtmеnt: Stаbіlіzаtіоn оf dеѕаlіnаtеd wаtеr іѕ dоnе to protect downstream ріреlіnеѕ аnd storage, gеnеrаllу bу аddіng lіmе оr caustic ѕоdа tо рrеvеnt соrrоѕіоn. Liming mаtеrіаl іѕ uѕеd tо mаіntаіn pH bеtwееn 6.8 tо 8.1 so thаt mееtѕ thе роtаblе wаtеr specifications.
  7. Dіѕіnfесtіоn: RO іѕ аn еffесtіvе blосkаdе оf раthоgеnѕ, but post-treatment аѕѕurеѕ secondary рrоtесtіоn аgаіnѕt dоwnѕtrеаm and membranes рrоblеmѕ. Tо ѕtеrіlіzе раthоgеn which hаѕ bypassed thе RO process, dіѕіnfесtіоn bу means оf UV lаmрѕ саn bе еmрlоуеd.

Reverse Osmosis Methods

Scaling occurs on membranes when the concentration of scale-forming species exceeds saturation, producing additional solids within the feed water. Scalants include such chemical species as calcium carbonate, calcium sulfate, barium sulfate, strontium sulfate, and reactive silica. Since these species have very low solubilities, they are difficult to remove from membranes. Scaling decreases the effectiveness of the membranes in reducing the solids and causes more frequent cleanings. A scale on a membrane provides nucleation sites that increase the rate of formation of additional scale.

Magnesium hydroxide tends to absorb silica, another scalant.  Another softening procedure involves zeolite in an ion exchange process. Often used with acidification, or by itself, are antiscalants. Antiscalants are chemicals added to wastewater to minimize scale carbonate or sulfate based scale. They consist of acrylates and phosphonates which inhibit the precipitation of carbonate or sulfanates.

The second problem with RO is with the fouling of membranes. Fouling occurs when suspended solids, microbes and organic material deposit on the surface of the membrane. Another problem is from colloidal sulfur, which when oxidized from H2S can fouling membranes. Coagulation is one technique that neutralizes the negative surface of the suspended solids, allowing the particles to cometogether. These large particles are then easy to remove from the water using filtration. The most common coagulants used are cationic polymers, inorganic salts, and aluminum and iron salts. Inorganic solvents tend to form large particles, while catonionic polymers require much less product for coagulation. Similar to coagulation is the clarification method, which destablizes suspended particles through charge neutralization. This is generally done by oxidizing iron and manganese and physically removing the precipitates in the manganese greensand bed.