The reverse osmosis device in operation management of some problems are discussed
Abstract: in recent years, along with pure water in microelectronics, electric power, biological engineering, basic particle research and so on the wide application of sophisticated industries, to make a long-term stable operation of pure water system, the key lies in the reverse osmosis device operation management. This paper discusses several aspects in detail with the reverse osmosis device manufacturing industry pure water, the problem that should notice.
Key words: the reverse osmosis device ultra-pure water reverse osmosis membrane dehydration rate water production rate

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Pure water and pure water is the microelectronics, power (including nuclear power), biological engineering, basic particle research, sophisticated industries and scientific research of one of the indispensable basic materials. At present the industrialization of the typical process manufacturing ultra pure water is reverse osmosis and ion exchange technology combined. Because not only to reverse osmosis engineering ion of Yin and Yang has more than 90% of the desulphurization rate, and with 99% of aseptic and heat capacity, at the same time for the neutral silica and molecular weight more than 300 trace organic matter has the high removal rate. So that ion exchange bed about 10 times extended regeneration cycle, wastewater emissions are about 1/10 of all the ion method, especially the important thing is that the mixed bed out of the water resistivity long-term stability in the 17-18 M Ω-cm (25 ℃). Therefore, in recent years, the technology matures, our country has many professional production ro device manufacturers, but for electric power, metallurgy, light industry, automobile, semiconductor, chemical, pharmaceutical, food, medical and health industry with high quality pure water. Pure water system to run the long-term stability of the key is the reverse osmosis device operation management. In this paper, a comprehensive discussion, providing reference for the related personnel.

To make the reverse osmosis device for the long-term stability of performance, in addition to choose component and system process design beyond reasonable, good operation management is a very important factor, operation management, strict carefully earnestly, can prolong the reverse osmosis membrane element of the service life, and to make the reverse osmosis device to design index is difficult, therefore, in long-term operating management in the following problems should be paid attention to.

1 to strictly control the operation conditions

According to user raw water analysis report, in order to meet the desalination rate, water production rate, recovery, life requirement, choose the right components to design, assembly reverse osmosis device. Operating pressure, recovery (or thick water emissions), water SDI (pollution index), PH and residual chlorine and temperature is the reverse osmosis device's main operation control parameters; Desalination rate, produce a water yield and device drop of pressure are the three main monitoring performance parameters. Operation management must be strictly comply with, can never change operating conditions. Special to prevent improve recovery to increase produce a water yield, lead to reverse osmosis membrane fouling surfaces; To prevent SDI value exceeds bid in the running to continue, leading to the reverse osmosis membrane blocked; To prevent the allowed maximum differential pressure continue to work and cause more destructive damage of membrane element.

2 calcium carbonate, prevent and silica precipitation

In pure water manufacturing systems, raw water is often md or city tap water, and CaCO3, CaSO4, SIO2 is reverse osmosis membrane surface form scale the three main material. In engineering, often in the security filter into acid before, lower pH value to prevent CaCO3 precipitation, vinegar fiber membrane to speak, adjust the water pH value of another important role is to reduce the membrane hydrolysis speed; Injection SHMP or FLOCON-100 complexing agent to prevent CaSO4 precipitation; Or in the pretreatment system set up the softener to simultaneously prevent CaCO3 and CaSO4 precipitation; The sediment of SiO2 general through improve inlet water temperature or reduce the recovery to prevent; But because the raw water in various ion is along with the season changes, especially in the factory after water change, change is more big, therefore, already put into operation reverse osmosis system, water and water discharge of each quarter for a comprehensive analysis, through the calculation LSI index, calcium concentration product to predict the ro membrane surface whether to produce calcium carbonate, calcium sulfate precipitation is very necessary. When ro strong water LSI < 0, concentration product < 10 x 10-5, will not produce calcium carbonate, calcium sulfate precipitation. For SiO2 precipitation, reverse osmosis device with the inlet water temperature closely related, strong water concentration of silica, 25 ℃ can't more than 100 mg/l, 5 ℃, no more than 25 mg/l. Therefore, when pretreatment system in no heating equipment, in the winter we must pay great attention to membrane element of silica sediment pollution problem, strictly control the water content of silicon dioxide thick, and the value can't more than in the solubility of temperature. It is in four hours later will SHMP failure, therefore, such as the reverse osmosis device running more than 4 hours, should be low voltage run 10 min, will reverse osmosis device of concentrated water displacement off.

3 prevent colloid on the reverse osmosis membrane pollution

Reverse osmosis membrane for the colloid because it has a very high removal efficiency. So that the reverse osmosis device of the colloid film concentration, along the flow direction constantly improve, when the recovery is 75%, the device last level of the colloid membrane element water concentration is about the first level of four times. Colloid in the membrane surface precipitation mainly depends on two factors, namely the concentration of the colloid and condensing rate constant. The concentration of the colloid with pollution index (SDI) values measured, and the rate constant and 2 ETA potential relevant. People in the long-term practice, has been found to prevent the pollution of film is colloid and need to control SDI value, he rolled type device, it is to control in SDI below 4 or MF value is less than the 150 S. Hollow device, SDI value should be controlled in 3 or 4 below, so that can make the colloid pollution extent the reverse osmosis device can run normally point. It is when the water potential negative 30 more than 2 ETA millivolt, reverse osmosis into SDI value of can be improved. If hollow fiber from components can SDI < 3 to improve SDI > 5. Tell commonly, colloid pollution exist in most from surface water is water system, because the type and concentration of the colloid really with the season