Case description of reverse osmosis water treatment scheme

Application scope of reverse osmosis pure water treatment> Preparation of pure water and ultrapure water in electronics, industry, medicine, food and other industries; purification and preparation of water for textile and chemical industry; purification and preparation of water for food and beverage, and brewing process; industrial The production of useful substances and concentration and recovery of aqueous solutions in production; pre-salting treatment of make-up water for high-pressure boilers in power plants and other enterprises; desalination of brackish and seawater; purified water equipment as a first-level desalination equipment for high-purity water production.
Water quality requirements for reverse osmosis equipment:
◆ The highest SDI in water (15 minutes) <5
◆ The highest turbidity in the water is less than 1.0NTU
◆ The highest free chlorine concentration in the water is less than 0.1ppm
◆ Maximum temperature of water inlet <45 ℃
◆ The highest Fe content in the water is less than 0.05ppm

Role: To overcome the instability of water supply in the pipe network and ensure the stable and continuous water supply of the entire system; at the same time, it provides a guarantee for the long-term reliable performance of various equipment.
Selection: PE or stainless steel water tank.
Control: The water tank is equipped with a high water level float valve and a low water level switch. It has the advantages of high reliability, low price, simple structure and convenient installation. When the water level is high, the float valve is closed and the water supply is stopped. When the water level is low, the high-water float valve opens and starts to fill the water tank. At the same time, the low water level switch is turned off and the booster pump stops working.

Role: To provide necessary working pressure for pretreatment equipment.
Selection: According to the design pressure drop of each pretreatment equipment (the maximum pressure drop of each filter equipment is 0.05Mpa), and the pressure in front of the high-pressure pump cannot be less than 0.5Kg / cm2, determine the working pressure of the booster pump.
Control: Adjust the pressure and water volume with a regulating valve after the pump.

Function: The raw water first passes through a mechanical filter, and 12-24 mesh fine quartz sand is placed in the filter, so that flocculants, rust and other suspended impurities in the raw water are trapped in the process. Because the mechanical filter traps a large amount of suspended impurities during work, in order to ensure the normal work of the filter, the filter must be periodically flushed and backwashed.
Selection: Use FRP (FRP) container.
Control: The manual filter is used for the backwash operation of the mechanical filter. The filter should be cleaned once a day for 10-20 minutes.

Function: This process uses activated carbon filter as pretreatment of reverse osmosis device, which is very important. The reverse osmosis system requires the water intake index SDI≤5 and the residual chlorine <0.1mg / L. In order to meet its water intake requirements, the raw water needs to be further purified to meet the reverse osmosis water intake index. A carbon filter is installed in front of the reverse osmosis device, which mainly has two functions: 1. It adsorbs some organic substances in water, and the adsorption rate is about 60%; 2. It adsorbs residual chlorine in water. Adsorption of inorganic colloids, organic colloids and soluble organic polymer impurities with a particle size of about 10-20 angstroms, and residual chlorine that is difficult to remove in sand filters. The reason why activated carbon can be used to adsorb actives with a particle size of tens of angstroms is because of its structure with a large number of micropores and grain gaps with an average pore diameter of 20-50 angstroms. This structural feature of activated carbon makes its surface adsorb The area can reach 500-2000m2 / g. Because the molecular diameter of general organics is slightly less than 20-50 angstroms, activated carbon has a strong adsorption effect on organics. In addition, activated carbon has a strong dechlorination ability. Due to the strong oxidizing property of residual chlorine, residual chlorine reacts with carbon to generate carbon dioxide and -1 valence chloride ions, so only a small amount of carbon is lost, so activated carbon dechlorination Can be used for quite a long time. Activated carbon not only has the above functions, but also can remove odors and pigments in the water and improve the clarity of the water. After activated carbon has been used for a period of time, its adsorption capacity decreases and it needs to be regenerated or replaced. Therefore, after the raw water passes through the carbon filter, it can greatly improve the water quality and reduce the pollution to the reverse osmosis membrane. The treated water quality can meet the requirements of the inlet water quality of the reverse osmosis device (residual chlorine <0.1mg / L).
Selection: Select glass fiber reinforced plastic container, the expansion rate is 40%.
Control: The activated carbon filter is controlled by a manual controller. Since the activated carbon filter absorbs a large amount of suspended impurities in the work, in order to ensure the normal operation of the system, it must be flushed and backwashed every day. The cleaning process consists of 15- 30 minutes.

Fully automatic water softener or dosing device

Role: The process of removing hardness (Ca2 +, Mg2 +) in water is called softening. This equipment is filled with 001 × 7 strong acid type Na ion exchange resin, and the calcium and magnesium ions in the raw water are replaced with sodium ions, so that the residual hardness in the raw water is lower than 0.03mmol / L. The purpose of softening is to prevent fouling on the surface of the reverse osmosis membrane, so as to extend the service life and treatment efficiency of the reverse osmosis membrane.
Selection: The water softener is a glass fiber reinforced plastic container.
Control: The control system adopts American automatic control valve type. According to the set time / flow rate, the control valve head can automatically regenerate the resin to complete the process of salt absorption, backwash, forward flushing and water injection. The water softener is equipped with a regeneration tank. The salt and water content of the salt tank should be checked daily, and salt should be replenished in time (the use of iodized salt and other salts with additives is prohibited).

Role: Precision filtering is also called security filter. It is a treatment process before the raw water enters the reverse osmosis membrane device. PP filter core has the characteristics of large filtration flow, large dirt holding capacity, and low pressure loss. It can block impurity particles with different particle sizes, and integrates surface filtration and deep filtration. The precision filter also becomes clogged after a certain period of use. Therefore, the PP meltblown filter element must be replaced after a certain period of time. The basis for replacement is: the pressure difference before and after precision filtration is 0.05-0.1Mpa.
Selection: Use stainless steel container.

Role: The high pressure pump is the working pressure that provides the required water flow and water quality for the reverse osmosis system. After the filtered water passes through the pump body, it reaches a pressure of about 10 kg, so as to meet the water inlet pressure of the membrane body and ensure the output of pure water.
Selection: According to the working pressure required by the reverse osmosis membrane, Grundfos multi-stage high-pressure pump is used.
Control: When the pointer of the raw water pressure gauge reaches 2KG, press the water production switch, the high-pressure pump starts, and water production starts. There is a pressure protection switch in front of the high-pressure pump. When the water inlet pressure is lower than 1KG, the pressure protection switch is turned off and the high-pressure pump stops working.

Reverse osmosis device

Reverse osmosis device
Role: The reverse osmosis device is the main part of the purified water production line. This device uses the energy-saving composite membrane ESPA reverse osmosis membrane element produced by Japan’s Nitto Denko Group and the United States Hyde Energy Company. ESPA series are desalination membranes with high salt rejection. High water flux can be obtained at lower operating pressures, with an average desalination rate of 99.5%.

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