1、 Introduction to Reverse Osmosis Pure Water Equipment

The application of membrane separation technology in reverse osmosis equipment can effectively remove charged ions, inorganic substances, colloidal particles, bacteria, and organic substances from water, making it the best equipment for high-purity water preparation, desalination of brackish water, and wastewater treatment processes.

1. Equipment system composition

The reverse osmosis purified water treatment system generally includes pre-treatment system, reverse osmosis device, post-treatment system, cleaning system, and electrical control system. 

The pretreatment system generally includes raw water pumps, dosing devices, quartz sand filters, activated carbon filters, precision filters, etc. Its main function is to reduce the pollution index of raw water and other impurities such as residual chlorine, in order to meet the inlet requirements of reverse osmosis. 

The reverse osmosis device mainly consists of multi-stage high-pressure pumps, reverse osmosis membrane elements, membrane shells (pressure vessels), brackets, etc. Its main function is to remove impurities from water and make the effluent meet the requirements for use.

The post-treatment system is a configuration added when reverse osmosis cannot meet the effluent requirements. It mainly includes one or more equipment such as anion bed, cation bed, mixed bed, sterilization, ultrafiltration, etc.

The cleaning system mainly consists of a cleaning water tank, a cleaning water pump, and a precision filter. When the reverse osmosis system is contaminated and the effluent indicators cannot meet the requirements, it is necessary to clean the reverse osmosis system to restore its effectiveness.

The electrical control system is used to control the normal operation of the entire reverse osmosis system. Including instrument panel, control panel, various electrical protections, electrical control cabinet, etc.

2. Design Features

(1) By increasing the pressure on water, deep filtration of water can be achieved. In addition to general filters, reverse osmosis purified water equipment also includes fine filters, granular activated carbon filters, and compressed activated carbon filters. Fine filters have finer filtering functions than regular filters and can better filter impurities in water. As we know, activated carbon has good adsorption and filtration functions for odors and impurities. The reverse osmosis purified water equipment uses dual activated carbon filters to achieve deep filtration processing of raw water, improving the filtration efficiency of the equipment. Meanwhile, enhancing filtration capacity by increasing water pressure is also an innovation.

(2) The core of reverse osmosis purified water equipment is the application of reverse osmosis membrane. Reverse osmosis membrane is a type of filtration membrane with extremely small pore size, which can achieve ultrafine filtration of raw water and separate water into high and low concentrations. Higher concentration water can be recycled and reused, while low concentration water is pure water that can be used by humans.

3. Main process flow

(1) Raw water tank

Store raw water for settling large sediment particles and other precipitable substances in water. Simultaneously buffering the impact of unstable water pressure in the original water pipe on the water treatment system. (such as pressure sensing reactions caused by low or high water pressure).

(2) Raw water pump

Constant system water supply pressure, stable water supply volume.

(3) Multi media filter

The main purpose of using a filter with multiple filtration layers is to remove substances such as sediment, rust, colloidal substances, suspended solids, and other particles with a particle size of more than 20um in the raw water. Manual valve control or fully automatic controller can be used for a series of operations such as backwashing and forward flushing. Ensure the quality of water produced by the equipment and extend its service life.

(4) Activated carbon filter

The system adopts a fruit shell activated carbon filter, which can not only adsorb electrolyte ions but also perform ion exchange adsorption. Activated carbon adsorption can also reduce the oxygen demand (COD) of potassium permanganate from 15mg/L (O2) to 2-7mg/L (O2). In addition, due to the adsorption effect, the concentration of adsorbed and replicated on the surface increases, thus playing a catalytic role, removing pigments, odors, a large amount of biochemical organic compounds, reducing the residual chlorine value and pesticide pollutants in water, and removing trihalides (THM) and other pollutants from water. At the same time, the equipment has a self maintenance system and low operating costs.

(5) Ion softening system

In order to dissolve solid substances in concentrated discharge and utilize fresh water, R/O devices should use ion softening devices or appropriate scale inhibitors to prevent the crystallization and precipitation of concentrated water, especially on the concentrated water side of the membrane component after the RO device, from exceeding its equilibrium solubility constant and damaging the proper characteristics of the membrane components. Before entering the reverse osmosis membrane component, an ion softening device or an appropriate amount of scale inhibitor should be added to prevent carbonate from forming, SiO2, Crystallization of sulfates.

(6) Precision filter

By using precision filters to remove suspended solids, non straight particles, colloids, and other substances remaining in the influent, the subsequent equipment such as the RO system can operate more safely and reliably. The filter element is a 5um melt blown filter element, designed to prevent impurities larger than 5um from being missed by the higher-level filtration unit. Prevent entering the reverse osmosis device and damaging the surface of the membrane, thereby damaging the desalination performance of the membrane.

(7) Reverse osmosis system

Reverse osmosis device is a process that uses sufficient pressure to separate the solvent (usually water) in a solution through a reverse osmosis membrane (or semi permeable membrane), which is called reverse osmosis because this process is opposite to the direction of natural permeation.

The reverse osmosis method can adapt to various types of raw water with high salt content, especially in water treatment projects with high salt content, and can achieve good technical and economic benefits. The desalination rate of reverse osmosis is improved, the recovery rate is high, the operation is stable, the footprint is small, and the operation is simple. The reverse osmosis equipment not only removes salt, but also removes most bacteria, colloids, and high molecular weight organic matter.

2、 Maintenance skills for reverse osmosis purified water equipment

1. Strictly control the incoming water quality to ensure that the device operates under water quality conditions that meet the requirements of the incoming water indicators. The incoming water quality does not meet the requirements, which can easily cause fouling and blockage of the reverse osmosis membrane, leading to the rapid failure of consumables and seriously affecting the effluent quality.

2. The total inlet water volume of reverse osmosis is controlled by the RO inlet control valve. If the inlet water volume of reverse osmosis does not change, do not adjust the RO inlet control valve, and it is strictly prohibited to fully open or close it. The RO drainage control valve is used to adjust the system recovery rate. If there is no change in the recovery rate, do not tamper with the concentration control valve. It is absolutely forbidden to fully open or close it.

3. The device cannot be shut down for a long time and should run for at least 2 hours per day. If it is prepared to shut down for more than 72 hours, a chemical cleaning device should be used to fill the components with 1% sodium hydrogen sulfate and 18% glycerol for protection.

4. After each shutdown, the reverse osmosis device should be flushed for 10 minutes under the condition of a water inlet pressure of 0.4 Mpa.

5. Operating pressure control should take the lowest possible pressure value while meeting the requirements of water production and quality, which is beneficial for reducing membrane water flux attenuation and decreasing membrane replacement rate.

6. The operator should record the operating parameters every hour, check the usage of the pure water equipment and the quality of the effluent.

The main recorded content is as follows:

(1) Inlet water:

PH value, conductivity, pressure, SDI， Water temperature.

(2) Water production:

Conductivity, flow rate, pH value;

(3) Concentrated water:

Flow rate, pressure, and inlet pressure of each section.

7. When a high and low pressure alarm occurs in the reverse osmosis device, first check if the manual valve opening between the security filter and the high pressure pump is too small, then check if the RO inlet control valve and concentration discharge valve are normal, and then press the high and low pressure alarm reset button to restart the purified water production equipment.

8. The inlet water temperature control should be based on the actual water consumption, taking the critical pressure (the pressure value below which the desalination rate decreases significantly) that cannot meet the requirements of water production and quality as the inlet water temperature during this time period. This can reduce the attenuation of membrane water volume.