Why do we need water pre-treatment and how does it happen?

 Why do we need water pre-treatment and how does it happen?

The quality of pre-treatment of water before feeding it to the industrial Ro plant membrane is of great importance, since the life of the membrane element depends on it. It must be remembered that the domestic reverse osmosis system is intended for the post-treatment of tap water previously purified at centralized stations, or water that has been purified at local water treatment plants. Household reverse osmosis systems are not intended for direct purification of water from a well or well, since in most cases such water contains significant amounts of various impurities – iron and manganese, hardness salts, natural organic substances and others. All these impurities are effectively removed by reverse osmosis, but very quickly disable the most expensive element of the system – the reverse osmosis membrane .Therefore, the purification of unprepared water using household reverse osmosis is primarily impractical from an economic point of view. Pollution of the membrane of domestic osmosis due to water treatment of inadequate quality

At the pre-preparation stage in household systems, mainly three cartridge filters (prefilters) are used :

1. Polypropylene mechanical filtration cartridge with a filtration rating of 5-10 microns, designed to remove all kinds of mechanical impurities found in tap water – grains of sand, rust and scale particles and other particles. Removing such impurities extends the life of subsequent cartridges and the system as a whole. The service life of a mechanical filtration cartridge depends on the turbidity of the treated water and averages 3–6 months. Untimely replacement of a cartridge clogged by accumulated mechanical impurities can lead to a decrease in water pressure at the inlet to the membrane element and, as a result, to a decrease in system performance.

Types of filtration cartridges: a) polypropylene cartridge for mechanical filtration; b) a granular activated carbon cartridge; c) cartridge type “carbon block”

2. A cartridge with granular activated carbon to remove natural organic substances and active chlorine from tap water that adversely affect the reverse osmosis membrane. In this case, both coconut and bituminous activated carbon can be used as a filler cartridge. The first refers to microporous coals and effectively removes impurities of active chlorine and organochlorine compounds from water, the second is mesoporous and is very effective for removing natural organic compounds contained in surface waters and tap water obtained from them. The life of a granular activated carbon cartridge is also an average of 3–6 months. The actual resource of this cartridge depends on such indicators of quality of the treated water as oxidizability and color. Untimely replacement of the cartridge at this stage can lead to clogging of the membrane element, the development of microorganisms on the membrane surface due to the breakthrough of nutritious natural organics through an exhausted layer of activated carbon. In turn, this will shorten the life of the membrane element and can degrade the quality of water treatment.

3. In the third stage, various cartridges can be used, depending on the type of reverse osmosis system. In the case of low-cost systems, a polypropylene cartridge with a filter rating of 1 or 5 microns is used at this stage to remove particles of coal that can be washed out of the previous cartridge, as well as possible residual mechanical impurities. In higher-class systems, a cartridge is installed using briquetted activated carbon (carbon block), which provides not only mechanical filtration, but also additional purification from chlorine and organ chlorine. The service life of the cartridge of the third stage of pre filtration is 3-6 months. Thus, all three cartridges are replaced at the same time, which simplifies the use of a household reverse osmosis system.

For further information click here: Ro plant price in Pakistan