Reverse Osmosis

Reverse osmosis is a water purification process used in industrial, medical, and domestic applications. Pressure is used to force water through a semi permeable membrane during reverse osmosis, filtering out impurities and producing clean water. The pure water can be transferred to its desired application, or it can be re-filtered to reach an even higher purity standard.

The Process

The Reverse Osmosis Industrial RO process begins with pre-filtration of the source water. Pre-filtration allows large particulates and contaminants in the water to be easily removed before reaching the membrane used in the RO process. By removing these objects, the membranes in the RO process are spared unnecessary wear and tear, resulting in a much more efficient process. The filters to be used are determined by the source water employed in the RO process. A carbon filter, a green sand filter, and a 5-micron filter are commonly employed.

Chlorine is particularly damaging to the membranes in the RO machine, so it is important to ensure water is properly de-chlorinated before entering the process. The source water is also heated before filtration. The more the water is heated prior to filtration, the higher the output of the RO Unit. Increases of 20degrees in the water temperature can double the RO production.

Once the source water has been filtered, it is ready to move into the RO process. The water is passed through a semi-permeable filter, commonly constructed of polyimide. Polyimide is highly permeable to water, but relatively impermeable to various dissolved impurities, including salt ions and other un-filterable molecules. These properties make it ideal for use in the RO process. The source water moves through the filter due to the high pressure employed by the RO unit. Depending on the size of the unit, the PSI used to transfer water through the filter can range from 30 PSI all the way to 1000 PSI. The extreme high PSI units are often employed in large desalination plants, while the lower range is more suited for small applications and personal units.

After the filtration, pure water is collected and often stored. If the source water is particularly contaminated, or the purified water needs to reach a very exacting standard, it can be re-filtered through the machine an unlimited number of times. While re-filtration will result in increasingly pure water production from the RO unit, it is not always necessary or desirable. Re-filtering the water slows the down the production of the unit, as smaller and smaller contaminants are filtered. If the water is re-filtered too much, efficiency decreases.

When deciding if re-filtration will be necessary, it is important to closely examine the specifications for the filtered water to determine if one pass through the unit will meet the needs of the water, or if multiple filtrations are necessary. Filtering water past specification levels leads to decreasing returns on time and energy necessary to run the unit.

The RO Unit and Maintenance

The RO Unit is a relatively low maintenance piece of equipment. The unit is automated, and does not require an attendant to be near the machine in order to run. Maintenance of the unit is simple. Filters need to be inspected and cleaned regularly, in order to maintain highest levels of production. The machine will continue to run with dirty or clogged filters, but it will not run at maximum efficiency. Filters should be checked on a regular schedule, and often are able to last 2 to 3 months before needing to be cleaned or replaced. A drop in pressure at any point in the RO process is often a sign of a clogged filter.

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If you have a home aquarium, chances are you already have several filtration units taking care of the water. A UV sterilizers is a good addition to an aquarium, although it should be the last stage of the filtration process. It's important that aquarium water passes through the mechanical filter before moving through the UV unit. The mechanical or canister filter removes solids so that any water that passes through the UV unit afterwards is cleaned with optimal results.

UV sterilizers continue to work well as long as the bulb wattage is sufficient and the bulb isn't too old. The efficiency of the device also depends on the cleanliness of the quartz sleeve and the flow rate of the unit.

The Bulb

As time goes by UV the bulb will start to lose its effectiveness, which is why you should replace it every 6 months. You can purchase bulbs between 8 watts and 130 watts - a higher wattage does a better job at cleaning the water. Devices with a lower wattage bulb require a lower flow rate to work well.

Flow Rate

The flow rate is also an important factor to consider - a slower flow rate is more effective at killing parasites, in addition to algae and bacteria. The flow rate is measured in either gallons per hour or liters per hour. A device with a 15-watt bulb has no problem controlling algae and bacteria at a 120 gph flow, but it won't kill parasites unless the flow rate drops to 75 gph.

Clean the Quartz

The quartz sleeve is located where the UV bulb fits into the device. A lot of people forget about this part of the UV sterilizer and fail to give it a good cleaning every once in a while. Cleaning removes buildup and ensures that the UV sterilizer continues to work at top capacity. More expensive sterilizers are designed with a wiper handle positioned outside of the device for fast and easy cleaning of the sleeve, without having to take everything apart.

Luckily, it's easy to find UV sterilizers these days, in local stores and online. These devices make a wonderful addition to any aquarium, but they come with a hefty price tag, especially when you factor in the cost of replacement bulbs.

Saltwater aquarium enthusiasts are more likely to purchase UV sterilizers because they improve the quality of the water and offer another layer of protection for expensive saltwater fish.

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INTRODUCTION

In September 2008, Pure Aqua successfully manufactured and supplied to a major water treatment company in Dubai UAE, more than 15 units of Commercial Brackish Water Reverse Osmosis (BWRO) Units to produce different capacities between 1,500 GPD to 6, 000 GPD at a maximum 2000 ppm feed water TDS. Reverse osmosis occurs when the water is moved across the membrane against the concentration gradient, from lower concentration to higher concentration. To illustrate, imagine a semi-permeable membrane with fresh water on one side and a concentrated aqueous solution on the other side. If normal osmosis takes place, the fresh water will cross the membrane to dilute the concentrated solution. In reverse osmosis, pressure is exerted on the side with the concentrated solution to force the water molecules across the membrane to the fresh water side. Reverse osmosis is often used in commercial and residential water filtration. It is also one of the methods used to desalinate seawater. Sometimes reverse osmosis is used to purify liquids in which water is an undesirable impurity (e.g., reclaimed waste water, ethanol).

SYSTEM AND PROCESS

The Commercial Brackish Water Reverse Osmosis Water Units were selected from our RO-200 Series, model number RO-1500 and RO-6000 The BWRO Unit consists of TFC spiral wound membranes to have a recovery rate of 60% with an advanced microprocessor control panel.

PERFORMANCE

From a feed TDS of 2,000 mg/L at temperature range of 25 ?C, the system produces from 1.2 to 7gpm of high quality water at less than 100 ppm.

INTRODUCTION

In January 2009, Pure Aqua supplied to a major water treatment company in Croatia 6 Commercial Brackish Water Reverse Osmosis (BWRO) Units to produce 7500gpd at max. feed TDS 1000 PPM.

SYSTEM AND PROCESS

Due to the increased exposure of dialysis patients to water used in the manufacture of dialysis fluid, which originates as drinking water, requires additional treatment to ensure that it meets a more stringent contaminant level content than drinking water. The more stringent levels are embodied in national and international standards that have evolved out of the desire to minimize the complications arising from the use of inappropriate water quality. For water used in the preparation of dialysis fluid, chemical contaminant levels are set lower for three groups of chemical contaminants: contaminants to which exposure is associated with clinical sequel such as aluminum and fluoride, compounds present in the dialysis fluid (e.g. sodium), and trace metals. The dialytic process utilizes high volumes of water in the preparation of the dialysis fluid. Improvements in water treatment or reverse osmosis water equipment have resulted in improvements in chemical quality. Awareness that endotoxin and bacterial fragments present in the water distribution loop within the dialysis, are able to cross the dialyser membrane, has resulted in an increased focus on this aspect of water quality. Practically, the age of many water treatment plants, extensions of distribution systems and suboptimal cleaning procedures have prevented the achievement of optimal microbiological quality on a routine basis. When achieved and maintained, clear benefits to the patient have been demonstrated. The BWRO Unit was selected from our RO-200 Series, model number RO-7500. It includes (5) 4"x40" membrane elements from (Filmtec LP-4040), (5) FRP pressure vessels, SS pump, 5 micron prefilter, pressure regulating valve, low pressure switch, pressure gauges, advanced microprocessor control panel, multi media filter, carbon filter, water softener and post UV and 0.2 micron filter to remove dead bacteria (pyrogen).