Reverse Osmosis Filtration

REVERSE OSMOSIS

The process of reverse osmosis through semi permeable membranes or a reverse osmosis membrane was first observed in 1748 by Jean Antoine Nollet. For the following 200 years, osmosis was only a phenomenon observed in the laboratory. In 1949, the University of California at Los Angeles (UCLA) first investigated desalination of seawater using semi permeable membranes. Researchers from both UCLA and the University of Florida successfully produced freshwater from seawater in the mid-1950s, but the flux was too low to be commercially viable. By the end of 2001, about 15,200 desalination plants using s reverse osmosis membrane were in operation or in the planning stages worldwide.

Reverse osmosis (RO) is a reverse filtration method that removes many types of large molecules and ions from solutions by applying pressure to the solution when it is on one side of a selective membrane. The result is that the solute is retained on the pressurized side of the membrane and the pure solvent can pass to the other side. To be 'selective', this membrane should not allow large molecules or ions through the pores (holes) but should allow smaller components of the solution (such as the solvent) to pass freely.

Reverse osmosis is most known for its use in drinking water purification from seawater, removing the salt and other substances around the H2O molecules. This is the reverse of the normal osmosis process, in which the solvent naturally moves from an area of low solute concentration, through a membrane, to an area of high solute concentration. The movement of a pure solvent to equalize solute concentrations on each side of a membrane generates a pressure and this is the "osmotic pressure." Applying an external reverse pressure to reverse the natural flow of pure solvent, thus, is reverse osmosis.

The process is like membrane filtration. However, there are key differences between reverse osmosis and filtration. The predominant removal mechanism in membrane filtration is straining, or size exclusion, so the process can theoretically achieve perfect exclusion of particles regardless of operational parameters such as influent pressure and concentration. Reverse Osmosis however involves a diffusive mechanism so that separation efficiency is dependent on solute concentration pressure, and flux rate.

Formally, reverse osmosis is the process of forcing a solvent from a region of high solute concentration through a semi permeable membrane to a region of low solute concentration by applying a pressure more than the osmotic pressure.

The membranes used for reverse osmosis have a dense barrier layer in the polymer matrix where most separation occurs. In most cases the membrane is designed to allow only H2O to pass through this dense layer while preventing the passage of solutes (such as salt ions). This process requires that a high pressure be exerted on the high concentration side of the membrane, usually 30-250 psi for fresh and brackish water, and 600-1000 psi for seawater. This process is best known for its use in desalination (removing the salt from sea water to get fresh water), but since the early 1970s it has also been used to purify fresh and brackish water for medical, industrial, and domestic applications.

Osmosis describes how solvent moves between two solutions separated by semi permeable membranes to reduce concentration differences between the solutions. 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. Instead of mixing the two solutions together, they can be put in two compartments where they are separated from each other by a semi permeable membrane. The semi permeable 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. Osmosis is an example of diffusion.

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 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.

Domestic Reverse Osmosis Uses

Around the world, household drinking water purification systems, including a reverse osmosis step, are commonly used for improving water for drinking and human consumption.

Such systems typically include a number of steps:

• a sediment filter to trap particles including rust and calcium carbonate
• optionally a second sediment filter with smaller pores
• an activated carbon filter to trap organic chemicals and chlorine, which will attack and degrade TFC reverse osmosis membranes
• a reverse osmosis (RO) filter which is a thin film composite membrane
• optionally a second carbon filter to capture those chemicals not removed by the RO membrane
• optionally an ultra-violet lamp for disinfecting any microbes that may escape filtering by the reverse osmosis membrane

In some systems, the carbon pre-filter is omitted, and cellulose triacetate membrane (CTA) is used. The CTA membrane is prone to rotting unless protected by chlorinated water, while the TFC membrane is prone to breaking down under the influence of chlorine. In CTA systems, a carbon post-filter is needed to remove chlorine from the final product water.

Portable reverse osmosis water processors are sold for personal water purification in various locations. To work effectively, the water feeding to these units should best be under some pressure (40 psi or greater is the norm). Portable RO purifiers can be used by people who live in rural areas without clean water, far away from the city's water pipes. Rural people filter river or ocean water themselves, as the device is easy to use (Saline water may need special membranes). Some travellers on long boating trips, fishing, island camping, or in countries where the local water supply is polluted or substandard, use reverse osmosis water filters coupled with one or more UV sterilizers. RO systems are also now extensively used by marine aquarium enthusiasts. In the production of bottled mineral water, the water passes through an RO water processor to remove pollutants and microorganisms. In European countries, though, such processing of Natural Mineral Water (as defined by a European Directive) is not allowed under European law. (In practice, a fraction of the living bacteria can and do pass through RO membranes through minor imperfections or bypass the membrane entirely through tiny leaks in surrounding seals. Thus, complete RO systems may include additional water treatment stages that use ultraviolet light or ozone to prevent microbiological contamination).

Membrane pore sizes can vary from .1 to 5,000 nanometres (nm) depending on filter type. "Particle filtration" removes particles of 1,000 nm or larger. Microfiltration removes particles of 50 nm or larger. "Ultrafiltration" removes particles of roughly 3 nm or larger. "Nano filtration" removes particles of 1 nm or larger. Reverse osmosis is in the final category of membrane filtration, "Hyper filtration", and removes particles larger than .1 nm.

Used in: Under-the-sink units; often in combination with a carbon filter or UV disinfection unit or more recently portable reverse osmosis membrane purifiers.

Gets rid of: Most contaminants, including certain parasites such as Cryptosporidium and Giardia; heavy metals such as cadmium, copper, lead and mercury; and other pollutants, including arsenic, barium, nitrate/nitrite, perchlorate and selenium.

Sources on reverse osmosis membrane purification

Reference: http://en.wikipedia.org/wiki/Reverse_Osmosis

RO DI Aquarium Filtration

MARINE AQUARIUMS AND REEF TANKS

When maintaining your marine aquarium, it is essential that you use only the highest quality water to protect the overall condition of your tank and the health of your fish. A RODI system which combines reverse osmosis technology and mixed bed DI resin is best suited to producing clean, contaminant free water for your tank.
 
Purity is Essential

There are few applications that demand the level of purity that is required of a marine aquarium.

One of the greatest concerns that owners of marine aquariums have when topping off their tanks are impurities from the source water contaminating the aquarium and adding further complication to the maintenance of the tank. Excess impurities in source water can cause all sorts of problems in a tank including algae blooms, mineral/salinity creep due to evaporation, and even fish or coral death. Some of the most significant impurities include nitrates, phosphates, heavy metals, hardness, salinity and the TDS (total dissolved solids) present in the feed water.

An RO/DI unit will effectively reduce or remove all contaminants found in your source water and leave you with only the purest water for your tank.

Will this type of system work with my source water?

These systems are very effective when used on mains water, many of our systems are designed to operate passively on the pressure supplied from the mains and will not require booster pump systems to operate properly and produce water of a good quality.

These units may even be adapted for use on low pressure applications such as rain or bore water through the use of specialised low-pressure membranes or in the worst of cases by integrating a booster pump into the system.

As with any system there is a maximum amount of contaminant in the source water that the membrane will be able to deal with. The membranes that are supplied as standard with our units will be suitable for use with most if not all mains water sources and most rainwater sources. Often bore water will have exceedingly high levels of contaminant which may hinder the performance of a membrane, often this can be compensated for with the use of specialised membranes or additional filtration.

If you have special circumstances such as a low-pressure feed, or you suspect that your source water is of an unknown or poorer quality, give us a call or send us a message and we can assist in designing a customised system to suit your specific needs.

Which system would suit my needs best?

Reverse Osmosis systems are rated based on their flow rate, that is, the amount of water that the membrane will produce in 24 hours of constant operation with good feed pressure. Selecting a system that best suits your needs is finding a balance between how much water that you will need each day and how fast you want the unit to produce it.

On our smaller domestic units, the standard membrane ratings are 50gpd (190 litres per day/8 litres per hour), 100gpd (380 litres per day/16 litres per hour) and 180gpd (680 litres per day/28 litres per hour). When required we can also build units capable of producing greater volumes, up to many thousands of litres per day.

Other factors to consider are the size of the pre-membrane filters and the DI resin cartridge, larger filters will generally last longer and not need to be serviced as often, however may not be worth the cost if you are only producing very small volumes.

If you are unsure of what to select based on your needs, give us a call or send us a message and we will point you in the right direction. 

Water Filter Cartridges

WATER FILTER CARTRIDGES 

Pure water filtration systems allow you to produce great quality drinking water in your home or office. Systems covered in this page are water filtration systems excluding reverse osmosis systems. An advantage of filtration as oppose to reverse osmosis is that water filtration does not strip everything from water, does not create a wastewater stream and can produce water at far higher flow rates for less cost. The advantages of reverse osmosis are that it produces purer water than normal filtration which can be conditioned for specific drinking, aquaria and laboratory use.

Sediment Water Filters

Sediment filtration is an effective method of reducing the turbidity of water caused by the presence of suspended solids such as sand, rust, silt, or clay.

Sediment water filters act as a sieve to remove these particles. The important thing to keep in mind is that sediment filters only reduce sediment by filtration. They do not remove chemicals, heavy metals or make the water taste or smell better.

Water sediment filters will usually be in a filtration system before the specialty filters as this helps to prolong the life of the more expensive speciality filters.

Sediment Melt Blown Water Filters

These water filters are manufactured from 100% polypropylene from melt-blown processed filtration fibre. Formed by thermal bond without the use of any binders and adhesives. These filters are designed to have a high contaminant holding capacity and to last longer.

Nominal Rating Industrial Depth Water Filters

Depth filters are manufactured by using four different pore size diameter spray nozzles. The four-layered structure PP depth cartridge is produced with fine fibres in the inner layer and coarser fibres in outer layer which constitutes four layers of different pore density from the least dense in the outer layers to the densest in the inner layers in order to filtrate the larger particles first and as you move further into the filter the finer particles are removed.

This design has a high contaminant holding capacity and stops the surface from getting clogged. Therefore, the filters have a longer service life and lower aqua pressure drop. Made from 100% polypropylene these water filters are compatible with a wide range of process fluids and are also formed by thermal bond without the use of any binders and adhesives.

Polypropylene depth filtration cartridges are constructed of thermally bonded polypropylene microfibers to ensure high efficiency. The filters incorporate a rigid polypropylene centre core for increased strength and durability. This thermal bonded micro-fibre construction has minimal fibre release, consistent flow rate and superior filtration performance. It also is not brittle or prone to breakage problems like resin-bonded cartridges.

Pleated Water Filters

These are thin, pleated filters that trap contaminants on their surface. Once the surface is filled, the filter is replaced. (Some high-quality pleated filters can be cleaned and reused.) Surface filters are best if you are filtering sediment of similar-sized particles. If all particles are five microns, a pleated 5-micron filter works best because it has more surface area than other filters.

Ceramic Water Filters

Specially designed for royal use in England, this England-made filter with a 0.2 - 0.4-micron hole diameter efficiently filters out any matter with the diameter lager than its hole diameter including bacteria, silt, suspension, Cyanobacteria, pathogen, and viruses in water.

Carbon Water Filter Cartridges

The simple yet effective carbon water filters. These systems are easy to install, relatively inexpensive, and cover the basic functions of filtration. These water filters carbon medium carbon is derived from coconut husk. This absorbs impurities as the water passes through. This form of filter comprises possibly 95% of those in use domestically. They are simple to install, relatively economical, and depending on micron level, will filter out the deadliest of contaminants, Cryptosporidium and Guardia.

Average carbon filters will last a family 6-9 months. Some carbon filters are enhanced by the use of activated nano-silver, which provides extra antibacterial protection, killing around 650 known types of organisms. The minerals in aqua solution can still permeate a carbon filter; these minerals are beneficial to health.

In situations where sediment is a problem it is worthwhile to add a second separate in-line sediment pre-filter. Otherwise the more expensive carbon filter will become clogged up long before its normal lifespan.

A carbon block is a solidified form of honeycombed carbon. It is the best form of water filter, but flow rate is significantly slower than with loose carbon charcoal.

Micron Rating: A 1-micron rating or below will inhibit Cryptosporidium and Guardia as the cysts are larger than this in size. Viruses cannot be inhibited by a filter with a micron rating of more than 0.01 microns.

Carbon filters cannot change the pH balance of the water. If you have acidic water, you will still have acidic water, as the minerals causing the acidity will be dissolved and therefore will pass through the carbon filter.

Carbon filters may be susceptible to mould attack if left unused over extended periods. It is important to realize that a filter gathers the 'garbage' in your tap water and the organic component of this garbage is quite capable of rotting. Add a little summer humidity to the already damp internals of a carbon filter and you may have a mould attack. Taste will always be the deciding factor, and if the taste of the water suddenly changes after an extended period of non-use, such as your annual vacation, change the filter.

Note that carbon filters reduce in efficiency the longer they are in use. For this reason, it is best to change the filters regularly. A good quality activated coconut shell carbon filter will filter out most pollutants of concern.

How it works: Positively charged and highly absorbent carbon in the filter attracts and traps many impurities.

Used in: Countertop, faucet filters and under-the-sink units.

Gets rid of: Bad tastes and odours, including chlorine. Standard 53-certified filters also can substantially reduce many hazardous contaminants, including heavy metals such as copper, lead and mercury; disinfection by-products; parasites such as Giardia and Cryptosporidium; pesticides; radon; and volatile organic chemicals such as methyl-tert-butyl ether (MTBE), dichlorobenzene and trichloroethylene (TCE).

KDF Filter Cartridge

This Cartridge uses the patented KDF-55 filtering media which eliminates contaminants from water by utilizing electrochemical oxidation reduction.

Chemical Properties of KDF include its ability to kill algae and fungi, control bacterial growth, remove Chlorine, Pesticides, Organic matter, Rust, Unpleasant taste and odour Hydrogen sulphide, Iron, Lead, Calcium, Aluminium, Mercury, Arsenic and other inorganic compounds.

Combined with an Activated Carbon Cartridge it creates an excellent all-round filtration system with an extremely long-life capacity.

KDF media can remove up to 99% of water-soluble lead, mercury, nickel, chromium, and other dissolved metals. The water passes through a bed of a media made of a special high-purity alloy blend of two dissimilar metals - copper and zinc KDF55. This media is a major advancement in water treatment technology that works on the electro-chemical and spontaneous-oxidation-reduction (redox) principles.

Chlorine is instantaneously and almost inexhaustibly oxidized. Iron and hydrogen sulphide are oxidized into insoluble matter and attach to the surface of the media. Heavy metals such as lead, cadmium, and aluminium are removed from the water by the electrochemical process. They are attracted to the surface of the media, much like a magnet. The media inhibits bacteria growth throughout the entire unit.

Whole House Filtration

BIG BLUE FILTRATION SYSTEMS

Sometimes filtering your water at the point of use can be impractical or insufficient, in these cases a point of entry system may be more suitable as it filters all the water entering the home. These types of systems are most popular with homeowners who rely on tank or bore water, but are becoming ever more popular with home owners on a mains water supply.

Suitable for Various Water Sources

Why use whole of house filters?

Sometimes just treating your drinking water simply is not enough. Many households rely on water that is not of the best quality. Water that is discoloured or has a foul odour can be off-putting when showering or brushing teeth and can stain clothing in the washing machine. Water with high levels of sediment can damage valves and hot water units or constantly block taps and showerheads.

Filtering your water before it enters the house can help to eliminate these issues and improve the aesthetic qualities of the water significantly.

Are these units suitable for use on tank or bore water?

These types of systems are immensely popular for use on tank or bore water as a means of preventing dirt and dust that has settled to the bottom of a tank from being pumped into the house. These units are also extensively used to reduce/remove tannins or colouration from water and any odour that may be present.

These types of systems are also often used with specialty filters or combined with an ultraviolet steriliser to treat the water for any bacteria or viruses that may be present in the tank, protecting the health of your family and preventing any microbiological contamination from causing harm.

When water is sourced from a bore or ground source it may be necessary to treat for hardness or iron content in the water, we have various options available for these applications too.

Are these units suitable for use on mains water?

In recent years, these types of systems have become more popular for use on mains water supplies as a means of removing chlorine and improving the general aesthetic condition of the water. These units are equally as suited to use on a mains source as a tank water source. 

We offer these big blue systems in our own brand as well as the Pentek brand and have them available in single, twin and triple systems in 20"x2.5", 10"x4.5" and 20"x4.5" housings. When filtering non-potable water, it is recommended to have an anti-bacterial filter as one of the stages or an ultraviolet water steriliser after the filtration system.

Caravan + Mobile Home Filters

PORTABLE DRINKING WATER FILTRATION

Prevention is always better than cure and there is nothing worse than being far away from home on a lovely holiday and ending up crook for the whole trip because you consumed contaminated water. While the water flowing in the streams and rivers of the outback may look pure, it can still be contaminated with bacteria, viruses, parasites, and other contaminants. Camp sites and caravan parks take all precautions available to prevent this from happening but at the end of the day you put a lot of people, and in some cases their pets, in relatively small spaces using the same facilities contamination and cross contamination is bound to happen.

When planning on camping, hiking, or going on a caravan trip, it is of utmost importance to remember your water needs. There are so many approaches you can take to provide yourself and loved ones in your group with safe water for both drinking and sanitation.

WHICH SYSTEM DO YOU CHOOSE?

We have put together a few systems that we feel cover most of the needs of our avid adventurous clients.

With our standard 10 x 2.5" housings, once you have the filtration system, we can help you with the choice and combination of filter cartridges that will best suit the area you are traveling to.

The most common filtration system for caravans are a standard dual filtration system that you can connect directly to a tap or hose to fill a water tank or in some cases filter the water as it enters the caravan water system. These filter systems are very easy to install and maintain. The fact that you can at any time change the filter cartridges to cater for the different source water needs you might encounter is a definite bonus to these systems.

With the dual set up we usually recommend a sedimentary filter for the first housing. As explained under water filters these filters' main job is to eliminate any 'bigger' sedimentary contaminants in the water, like sand and leaves etc., so the second specialty filter does not get clogged up and can perform its job properly. The filters for the second housing would be more specialized as these ranges from the basic Carbon block filter to anti-bacterial Nano silver filters to self-fill filter cartridges that you can fill with the KDF media (please see water filters for a detailed explanation of the KDF media)

We also have smaller compact systems that you can install in your caravan at the point of use. These systems range from standard dual systems that you can install straight into the water line to more complex reverse osmosis systems with their own pressurised water tank and faucet. (please see reverse osmosis for detailed information on RO)

We understand that you do not always have the facilities with water pressure to assist with filtration and for this reason we have a hand pump system with reverse osmosis that you can take anywhere and purify your water.

We have tried to cater for all the variables in camping and caravanning that we could think of but we welcome our clients to contact us with their specific needs and together we are usually able to come to a brilliant workable filtration or purification solution.

Water Cooler Information

Why invest in a water cooler?

Water coolers are a very convenient way of having high quality pure drinking water on tap 100% of the time. These coolers are convenient in that you can place them wherever you have a power point. It is for this reason that they are extremely popular for business use.

But they are not restricted to businesses only. We have found that they are great to have in the home if you do not have a fridge that dispenses cold water or simply do not wish to plumb in a filtration / RO system under sink. What is better than being able to instantly pour a glass of ice-cold water on a hot summer's day?

We offer a wide range of water coolers from several leading Australian suppliers which are high quality electrically approved and use LG compressors.

Water Cooler Options

We offer water coolers that can be permanently connected to the mains supply and dispense either filtered and chilled as well as heated water or reverse osmosis purified chilled and heated water.

For those who prefer not to have their cooler plumbed into the mains supply we can offer bottled water cooler and filter your own bottle top housings that will filter and chill or chill and heat filtered or bottles spring water.

Ultra Violet Sterilisation

UV WATER STERILISERS

The process of sterilisation to eliminate bacteria by ultraviolet [UV] light has been extensively used for almost 150 years in hospitals and medical practices. This process is a proven technology and is remarkably effective at treating water for bacteria, viruses and micro-organisms if used in conjunction with sediment and carbon pre-filters.

UV Applications

The main uses for ultra-violet water sterilisation is in the treatment of non-potable water for drinking purposes i.e. rain-water from tanks, creek and dam water as well as bore water. People with immunodeficiency and those recovering from serious illnesses or operations would use UV sterilisation as a post filter to mains water filtration systems as added protection against possible bacterial infections.

We have a wide range of UV water sterilisers available from low flow domestic under sink to high flow whole of home and commercial systems.