Water Treatment

Galway Water specialise in water treatment systems for water quality correction which can be located at certain points in the plumbing system, hopefully having a predicted influence at other points in the plumbing system ...

water quality or treatment entering premises (point of entry - POE) primary

water quality or treatment leaving pipework (end of pipe - EOP) secondary

small scale superior filtration at drinking points (point of use - POU) secondary

To master the idea of "point of entry" and "point of use" and the differing types of "source water" and the types of "treated water" for the particular desires of different end users, is to understand a little "water quality".

Water treatment systems are used to "engineer" water acceptable for a "desired end use" for entry to, use within, or exit from a premises.

So what is good water ?  Lets say it is water that offers the end user a solution to their needs ...

It could be soft water for bathing and washing. It could be hard water for gardening. It could be deionised, sterile water for kidney dialysis or silicon chip production.

It could be a combination of things, soft + de-chlorinated + full of bacteria, very much like rain tank water ... dogs and cats and horses love it !  Or it could be say, hard + chlorinated + no bacteria, very much like mains tap water, ideal for gardening ... Grand Da's love it ! What about yer Grand Mammy, sure she like a good aul' cuppa, so that's - soft + dechlorinated + no bacteria, ooh that's a cracking cuppa is that.  Back to serious ...

Primary or point of entry water treatment systems are generally designed for improving water quality entering a premises to a high standard for high volume general domestic use for purposes such as bathing, showers, washing clothes and dishes and flushing toilets.

Secondary or point of use drinking water filter systems such as reverse osmosis filter units can be used in combination with primary water treatment systems to polish water up to an extremely high quality for potable (drinking) water quality within premises.

Water purification is the removal of contaminants from untreated water to produce for example drinking water that is pure enough for its intended use. Substances that are removed include suspended solids, bacteria, viruses, water hardness minerals and minerals such as iron, manganese and sulphur along with man made chemical pollutants including fertilisers.

Because of the wide complexity of contaminant combinations and varying concentrations of contaminants in different water sources with a wide range of flow demands, no single solution or universal standardised selection of processes can be used as a one stop panacea, nor is there a unique solution or selection of processes for any given type of water.

Many combinations of processes can be used to correct water quality issues that fall under the scope of water treatment, some using filtration and separation methods, some aiding filtration and others types that do not employ filtration methods:

Backwash media bed filtration using precipitation, absorbtion or adsorption, coagulation, flocculation, mechanical barrier filtration, cross flow membrane filtration or hyper-filtration, nano-filtration, ultra-filtration, sub-micron filtration, microfiltration, ultraviolet disinfection, aeration, chlorination, ozonation, distillation, pH dosing, ion exchange, mixed bed de-ionisation, de-alkalising, acidic dosing and lesser used methods such as pre-coat filtration, centrifugal separation, settling and sedimentation.

The definitions of water treatment from Wiki are as follows ...

Water treatment describes those processes used to make water more acceptable for a "desired end-use" or for a particular function or job.

These can include water use as drinking water, industrial processes, medical and many other uses (these can also include water just used for domestic and bathing functions within the household or gardening outside the household).

The goal of all water treatment process is to remove existing contaminants in the water, or reduce the concentration of such contaminants so the water becomes fit for its desired end-use. One such use is returning water that has been used back into the natural environment without adverse ecological impact.

The processes involved in treating water for drinking purpose may be solids separation using physical such as settling and filtration, chemical such as disinfection and coagulation.

Biological processes are also employed in the treatment of wastewater and these processes may include, for example, aerated lagoons, activated sludge or slow sand filters.

Potable water purification - Water purification is the removal of contaminants from untreated water to produce drinking water that is pure enough for its intended use, most commonly human consumption. Substances that are removed during the process of drinking water treatment include suspended solids, bacteria, algae, viruses, fungi, minerals such as iron, manganese and sulphur, and man-made chemical pollutants including fertilisers.

It is important to take measures to make available water of desirable quality at the consumer end. That leads to protection of the treated water during conveyance and distribution after treatment. It is common practice to have residual disinfectants in the treated water in order to kill any bacteriological contamination after water treatment.

World Health Organisation (WHO) guidelines are generally followed throughout the world for drinking water quality requirements. In addition of the WHO guidelines, each country or territory or water supply body can have their own guidelines in order for consumers to have access to safe drinking water.

Processes for drinking water :

The combination of following processes is used for municipal drinking water treatment worldwide:

* Pre-chlorination - for algae control and arresting any biological growth

* Aeration - along with pre-chlorination for removal of dissolved iron, manganese, sulphide

* Coagulation - for flocculation

* Coagulant aids also known as polyelectrolytes - to improve coagulation and for thicker floc formation

* Sedimentation - for solids separation, that is, removal of suspended solids trapped in the floc

* Filtration - removing particles from water

* Desalination - process of removing salt from the water

* Disinfection - for killing bacteria

There is no unique solution (selection of processes) for any type of water. Also, it is difficult to standardise the solution in the form of processes for water from different sources. Treatability studies for each source of water in different seasons need to be carried out to arrive at most appropriate processes.

The above mentioned technologies are well developed and generalised designs are available which are used by many water utilities (public or private). In addition to the generalised solutions, a number of private companies provide solutions by patenting their technologies.