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RO water filtration is considered the best water purification solution today, because it can remove up to 99% of dissolved impurities. In the article below, some information related to RO system will be less or more usefull. Do not miss it!

1. Overview of RO water filtration system

The topic of RO water purification system has many documents and images related to the structure, operating principle, and maintenance, so following is only mention a few key points that customers wonder, without fully clear answers in the past. At the same time, expand some more related information about clean water, RO water, purified water, ultrapure water as verall understanding of pure water to detail dicuss in near future.

1. Clean water is also called domestic water or city water, be understood as the water that used in each household or company, which has met QCVN 01-1:2018/BYT on physicochemical and microbiological criteria. This water can be supplied from a public water network station or self-treated on-site from different sources such as well water, river water, spring water, seawater or saline water.

2. Pure water is understood to be free of any impurities or ions and has killed all microorganisms – that is, only water molecules remain. To achieve this, a machanical filtration such as an RO membrane is required and can be combined with chemical filtration by ion exchange and sterilization. In practice this pure concept is more technical than reality. To indicate the degree of absolute purity, technical term “ultra-pure water” is also used.

3. RO water is water that has been filtered through the RO membrane (Reverse Osmosis) which is simply understood as mechanical filtration with an extremely small size (<0.001 micrometer) so it can filter 98 – 99.8% of conductivity in the water, including microorganisms. However, after the membrane, there are still 0.2 – 2.0% of ions with small size (almost monovalence) or microbiological detection even frequency is very low.

4. Deionized water or DI water is water that has no Ions left, but still has many non-ionic impurities, because of its charge; it needs to be removed to avoid affecting production in some industries

5. Canned or bottled water for direct drinking according to QCVN 6-1:2010/BYT can be water that has been through RO water purification system or natural mineral water and sterilized by UV, Ozone.In fact, there is confusion between RO, pure and bottled water

Alkaline ionized drinking water, also known as electrolyte water – is clean water that had been sterilized then through the electrolysis unit to increase the alkaline with pH (8.5 – 9.5) to be good for the body. This pH increased by electrolysis, is quite different from the increasing pH with chemical. The amount of hydrogen ion in the electrolyte water is introduced to have a good effect on the body, but there is no clear conclusion


Theoretical description of impurities and ions filtered through RO membrane


RO membrane is the highest filtration among membranes

2. Installation procedure of RO water filtration system

RO water filtration systems as well as other water treatment systems should be performed by a highly qualified and experienced contractor, in order to bring the best value to customer. Because high investment and maintenance cost, and treated quality needs to be stable, so should keep in mind the following steps.

1- Requirement of RO water capacity and quality.

2- Understanding water source and re-analyze if uncertain.

3- Preliminary plan, investment and operation costs.

4- Discuss again to have the best option and sign the contract.

5- Carry out detailed design, installation and test run of RO water purification system.

6- Test run for quality and capacity according to design.

7- Operating and handing instructions includes hand-over.

8- Check and report the system periodically.

3. Things to know when designing an RO water purification system

Below is the information related to RO water purification systems that many customers have concerned and often ask us questions or needed to received the support so far

3.1 Things to know when designing an RO water purification system

For high capacity industrial water filtration systems, it is advisable to mention the “optimal” cost between investment and operation. When investing, if skip a certain stage, the cost of operation, replacement and maintenance maybe increase or the quality after treatment maybe not stable. It is recommended that should consider the long-term and sustainable investing to avoid any possible effects in the production process.

Therefore, RO water purification systems or other technologies such as DI water system, Mixed Bed water treatment should not be designed according to experience from other water source or guesswork, but should really understand the nature of the water source, the change in years to provide an appropriate redundancy factor or safely pre-treatment steps so that the water before and after the RO filter has the least impact.

The consumption of RO water for a plant also needs to consider the overall, the purpose of use, including quantity and quality.

Example: A food factory has 4 points that need water, which are:

  • For boiler: Need to remove hardness with a water softener to limit the use of boiler chemicals.
  • For cooling tower: Make up water quality must meet LEED standards, require hardness a partial reduction to ensure cycle of operating water , as well as a reduction in chemical for cooling tower in the future.
  • Water for food production must pass through an RO water purification system.
  • Drinking water for all employees needs to be sterilized with RO water by UV lamp.

The water source can contain many different components that causing trouble to RO membrane, mostly clogging, so the more impurities remove before RO, the less will be clogged. Common as oxidizing and separation for heavy metal ; sand prefiltration, microfilter; UF membrane filter; nano filter for suspended solid; active carbon for organic compound and chlorine removal; softener to reduce hardness; FujiKlean electrolytic and scale collector to collect Silica, hardness, Ion; FujiKlean electromagnetic or anti-scalent chemical to avoid clogging…



20 m3/h RO water filtration system

3.2 What is the next treatment after RO filtration?

Water after the RO membrane, depending on each application, may have further treatment steps, for example in some of the following cases.

No Treatment after RO Application
1 RO → No further treatment For boiler, cooling, chiller…
2 RO → Ozone, UV Food, drinking water…
3 RO → Mineral supplement + Ozone, UV Caned, bottle drinking water
4 RO 1 → RO 2 → EDI Electronics, high pressure boilers, chemical industries
5 RO 1 → Ion exchange resin
6 RO 1 → RO 2 → Activated carbon → Distillation Pharmaceutical, medical…

Thus, not only focusing on RO water system, but also should have an overall plan of demand for the whole project. In the past time, we have supported many customers to check water sources, establish an initial master plan or re-evaluate the existing condition in terms of technical and optimal investment and operating budget. Please contact us to work together to bring good results!

3.3 How many percent recovery rate and membrane life

Basing on salinity (TDS) RO membranes divided into 3 groups, fresh water filter, brackish water filter and seawater filter. The higher TDS, the higher pressure filtered, while the lower recovery rate accordingly.

Fresh water Brackish water Sea water
TDS –Total dissolved solid < 1% 1 – 10% > 10%
< 10,000 ppm 10,000 – 100,000 ppm  > 100,000 ppm
Recovery rate 60 – 85% 50 – 70% 35 – 45%
Operating pressure 7 – 10 bar 10 – 40 bar 50 – 75 bar

Reference parameters only, please contact for detail

How many recovery percent depends on feed water quality , recovery rate can be more than 80% or less than 50%, even can’t use RO membrane to filter or pre-treatment before to RO, or must change to other process, such as cation – anion resin system , DI system and mixed Bed

In addition to depending on quality of feed water , life of membrane also depends on protection with chemical of anti-scalent, biocide, chlorine removal during operation are necessary, periodic cleaning (CIP) and good operating and management. Sensors of instrument need to be calibrated to ensure the correct quality via the actual data as well as promptly handle it before too late, causing damage to the membrane, so some places membrane just for a few weeks, in some places it can be operating a few years.

3.4 How many membranes in 1 vessel and when 1 or 2 passes is needed?

As mentioned above, basing on quality parameters of feed water, capacity and quality after treatment, then design system with software support will provide configurations of membrane quantity of a vessel, and vessel quantity of RO system as well as 1 pass or 2 passes and other related to technical such as flow rate, power of feed pump…. A long with practical experience, will adjust for better design of highest water quality while highest recovery rate, adjust for lowest investment and operating cost…

If the input TDS is high or the post-processing requires a low TDS, the second re-filter option (2 passes) is usually designed to reach.

3.5 What can rejected water be used for?

Normally, TDS and other components of the discharged water will be 2.5 – 5.0 times higher than feed water. Therefore, the quality of discharge depends much on feed water. In the case of fresh water (domestic) with low components, the rejected water from the RO water purification system can be used to supply a part to the cooling system, gardening, house cleaning, car washing, and toilet flushing…

RO membrane configuration and rejected water quality

RO membrane configuration and rejected water quality

3.6 Is there any other option besides RO membrane filtration to achieve the same conductivity?

(Please refer to the section DI Mixed Bed Water Treatment System)

As mentioned above, in theory, RO water filtration is a mechanical filtration and can remove up to monovalent ions – that is, it filters all, while chemical filtration through with ion exchange resin or physical evaporation ofdistillation by boiling or solar energy the conductivity of those treatment methods can be the same, but the non-ionic components present in water will be different.

1 RO membrane Mechanical filtration
2 Cationic, Anionic and Mixed resin Ion exchange as chemical reaction
3 Activated carbon + Distillation 1-2 times physical

The choice of technology depends on the purpose and actual conditions, such as industrial RO water purification systems suitable for high TDS water sources, distillation suitable for pharmaceutical factories producing injectable drugs, while using ion exchange resin for chemical filtration, for large industrial water capacity or high Silica input water sources…

Contact us to discuss the most suitable, lowest cost option!

3.7 Is RO, ultra-pure water beneficial to health?

(Please refer to the article about DI water treatment system, Mixed Bed water treatment system)

Emotionally, thinking that the higher purity of drinking water, the better but this understanding is not true because pure water has been removed almost minerals out while these minerals is good for heath such as Calcium, Magnesium, Potassium, Sodium, etc. Phosphorus, Fluorine, HCO3–… are essential for body.

Drinking water quality directly affects to health

Drinking water quality directly affects to health

But, because of its convenience, easy and safety for food management and microbiological control, bottled drinking water was born; most of it has been filtered with RO water purification system, and then sterilized by UV light. Bottled, canned for mobile use or use directly on site.

Thus, RO water, pure, ultra-pure water is not beneficial to health if used daily and continuously. Therefore, some drinking water suppliers have replenished minerals back for its lost when filtered through membrane, but it is difficult to have enough elements as natural water, the supplement must comply with QCVN 6-1:2010/BYT.

For families with have well-off conditions but a bad water source such as alum contamination, salinization while small quantity consumption, the home RO water purification system is a portable package with many combined features such as alum removal, odor removal, then filtered through a low-pressure RO membrane, with re-minerals, sterilization then need periodic inspection and maintenance according to the supplier’s instructions to ensure water quality.

Households as well as small-scale companies should also pay attention to the domestic water quality from water work station, can contact them for quality periodly. However, the quality is only analyzed at the source, and the pipeline may be dirty and contaminated with microorganisms, so it is necessary to filter it again with a filter of about 10 micrometers, absord the smell with activated carbon first and sterilize with UV for domestic daily life; boiled to cool, filtering with a ceramic filter to drink (not left for too long) is safe, healthy, and economical.

4.Prolong lifetime of RO membrane with chemical

Using chemicals to protect RO membrane is very necessary because althought there are pre-treatment steps for the membrane but cannot be eliminated. However, it is necessary to choose suitable chemical with water source to bring high efficiency and limit membrane cleaning.

Refer more at: https://uce.com.vn/chemical-for-boiler-cooling-chiller-ro-fcu-ahu/ro-chemical/


Maintainence and cleaning chemical for RO membrane

Maintenance chemicals include:

Maintenance chemicals to increase membrane life and limit cleaning (CIP)

Continuous dosing:

  • Anti-scale chemicals, avoid causing membrane clogging.
  • Chemicals to reduce Chlorine, avoid causing perforation of membranes.
  • Stable pH control in/out the filter.

Intermittent dosing:

  • Circulating chemicals kill microorganisms; avoid causing odors and damaging membranes.

Cleaning chemical (CIP) to recovery filtration rate and ensure low conductivity

  • Cleaning of organic scale.
  • Cleaning of inorganic scale.

Using too much chemicals also causes clogging or improper cleaning also make will also damage. Therefore, it is best to contact us to ensure that the right quantity is always the right one.

5. Why should you choose UCE Co., Ltd to install RO water purification system?

In order to have an RO system, as well as other water treatment systems with low cost, high quality and stability, it is necessary to have the foundation and performance of the installation unit. UCE Co., Ltd has full facilities to perform, such as:

  • Water laboratory supports to check quality of water source for a good plan as well as periodic testing during operation.
  • Engineers of technology, equipment, electromechanical, programming and maintenance have many years of experience in participating projects.
  • Not only the RO water system, but also help to evaluate whole other parts of factory related to using chemicals, so it is necessary to consider the best plan.
  • Ensure work quality according to ISO-9001 standard.
  • Bring the best solution, the lowest investment and operating costs.
  • The team is determined to have the one goal – Serving customer first.

UCE Co., Ltd can solve the most difficult problem of RO membrane

As mentioned above, every step of process to ensure and reduce the load for RO membrane is very important. If water source changes for the worse or the design does not have enough pre-treatment steps for the membrane, it is difficult to maintain it in time; it is difficult to ensure the water quality as well as the life of the membrane.


The water after the membrane does not reach, is sometimes one membrane is damaged? That is the most difficult problem.

The RO system with membranes continued installation; it is common that the first or last membrane in housing to be more clogged. However, there are cases where only 1 membrane is damaged, resulting in poor output quality and difficult to determine which membrane is. If removing and checking each membrane is time consuming, but replacing all membranes is very expensive. During the maintenance of RO system, we have accumulated many good experiences, when needed, contact us for prompt assistance.

RO system has filtered out most of the impurities, but the investment and operation costs are difficult to think about it

If you have difficulties, you can contact us for free support and analysis of basic criteria or instructions for the most economical handling. UCE Co. Ltd has supported many families to companies, for free during the past time and that is also our professional pleasure.


Wish everyone and family, every company has good water quality to ensure health, good for production!