Answers
We design, manufacture and supply wide range of water treatment plant which find applications in almost all the industries where ever water ...
Why are engineers still using such huge primary clarifiers and trickling filter and ... instead of reverse osmosis technology?
Clarifiers are used as secondary treatment for sewage after flocculation and sedimentation prior to final disposal, and for potable water before it enters filters and chlorination.
Reverse Osmosis can be used only for potable water and when some compounds in solution must be removed like ClNa that can't be accomplished by normal treatment.
The construction and operation of conventional clarifiers are much cheaper than Reverse Osmosis.
http://www.wetterwater.com/reverse-osmos is-education/reverse-osmosis-technology. html
are you an infomercial audience member?
hi-tech
The term reverse osmosis comes from the process of osmosis, the natural movement of solvent from an area of low solute concentration, through a membrane, to an area of high solute concentration if no external pressure is applied.
In simple terms, reverse osmosis is the process of pushing a solution through a filter that traps the solute on one side and allows the pure solvent to be obtained from the other side. More formally, it is the process of forcing a solvent from a region of high solute concentration through a membrane to a region of low solute concentration by applying a pressure in excess of the osmotic pressure. The membrane here is semipermeable, meaning it allows the passage of solvent but not of solute.
The membranes used for reverse osmosis have no pores, the separation takes place in a dense polymer layer of only microscopic thickness. In most cases the membrane is designed to only allow water to pass through. The water goes into solution in the polymer of which the membrane is manufactured, and crosses it by diffusion. This process requires that a high pressure be exerted on the high concentration side of the membrane, usually 2 - 14 bar (30 - 200 pounds per square inch) for fresh and brackish water, and 40 - 70 bar [(600 - 1000 psig)] for seawater, which has around 24 Bar (350 psi) natural osmotic pressure which must be overcome.
This process is best known for its use in desalination (removing the salt from sea water to get fresh water) and has been used in this way since the early 1970s. Its first demonstration was done by Sidney Loeb and Srinivasa Sourirajan from UCLA in the California town of Coalinga.
When two solutions with different concentrations of a solute are mixed , the total amount of solutes in the two solutions will be equally distributed in the total amount of solvent from the two solutions. This is achieved by diffusion, in which solutes will move from areas of higher concentration to areas of lower concentrations until the concentration in all the different areas of the resulting mixture are the same, a state called equilibrium.
Instead of mixing the two solutions together, they can be put in two compartments where they are separated from each other by a semipermeable membrane. The semipermeable membrane does not allow the solutes to move from one compartment to the other, but allows the solvent to move. Since equilibrium cannot be achieved by the movement of solutes from the compartment with high solute concentration to the one with low solute concentration, it is instead, achieved by the movement of the solvent from areas of low solute concentration to areas of high solute concentration. When the solvent moves away from low concentration areas, it causes these areas to become more concentrated. On the other side, when the solvent moves into areas of high concentration, solute concentration will decrease. This process is termed osmosis. The tendency for solvent to flow through the membrane can be expressed as "osmotic pressure", since it is analogous to flow caused by a pressure differential.
In reverse osmosis, in a similar setup as that in osmosis, pressure is applied to the compartment with high concentration. In this case, there are two forces to consider influencing the movement of water: the pressure caused by the difference in solute concentration between the two compartments (the osmotic pressure) and the externally applied pressure. In the same way as in conventional osmosis, the solute cannot move from areas of high pressure to areas of low pressure because the membrane is not permeable to it, only the solvent can pass through the membrane. When the effect of the externally applied pressure is greater than that of the concentration difference, net solvent movement will be from areas of high solute concentration to low solute concentration, and reverse osmosis occurs.
Israeli researchers scale up reverse osmosis model for ...
Researchers at the Ben-Gurion University of the Negev are using grants from the NATO Science for Peace program and the Middle East Desalination Research Center (MEDRC) to scale up a method to achieve high recoveries in desalination by reverse osmosis (RO). Jack Gilron, senior scientist and adjunct professor in the environmental engineering unit of the Zuckerberg Institute for Water Research (ZIWR), and Eli Korin, professor in the department of chemical engineering, have developed a method to exploit the finite kinetics of membrane fouling processes by periodically changing the conditions leading to membrane fouling before it can occur. In collaboration with colleagues from the University of Colorado and the Hashemite University of Jordan, the group will develop the technology and set up pilot facilities to produce approximately 120 m3/day each at desalination sites in Israel and in Jordan. “The process will be tuned to reduce brine volumes to 50% to 33% of those generated in conventional RO,” Gilron explains. “This greatly reduces the environmental burden and improves the economics of the inland desalination process.” BGN Technologies, Ben-Gurion University’s tech transfer company, and the Ashkelon Technology Incubator (ATI) Cleantech Group have formed a start-up company, Reverse Osmosis Technologies, to commercialize the technology, which has already attracted an initial investor.
...What Does Reverse Osmosis Do
With the modern technology replacing the old ones, it has been noticed that the diseases have also increased. Nowadays no one is there without a threat of some or the other diseases. The most common ones are related to stomach. For a healthy stomach it is advisable to take pure water so that you get less prone to bacteria which can make you sick. Reverse Osmosis is a process of filtration by which we make water fit for drinking. Previously it was used in industries but now its use in many household as well. We can find water filters in market which works on the reverse osmosis theory. It works by forcing the water by pressure through a membrane by which water can pass by but not the contaminants. The reason is that the size of the contaminants is larger than that of water molecules.