1.反渗透纯水机系统应多久清洗一次？

1. how long should the reverse osmosis pure water system be cleaned once?

一般情况下，当标准化通量下降10～15%时，或系统脱盐率下降10～15%，或操作压力及段间压差升高10～15%，应清洗RO系统。清洗频度与系统预处理程度有直接的关系，当SDI15＜3时，清洗频度可能为每年4次；当SDI15在5左右时，清洗频度可能要加倍但清洗频度取决于每一个项目现场的实际情况。

In general, when the standardized flux drops by 10 to 15%, or the desalination rate of the system drops by 10 to 15%, or the operation pressure and the intersegment pressure difference increase by 10 to 15%, the RO system should be cleaned. There is a direct relationship between the frequency of cleaning and the degree of system preprocessing. When SDI15 < 3, the frequency of cleaning may be 4 times a year; when SDI15 is around 5, the frequency of cleaning may be doubled, but the frequency of cleaning depends on the actual situation of each project.

2.什么是SDI？

2. what is SDI?

目前行之有效的评价RO/NF系统进水中胶体污染可能的最好技术是测量进水的淤积密度指数(SDI，又称污堵指数)，这是在RO设计之前必须确定的重要参数，在RO/NF运行过程中，必须定期进行测量(对于地表水每日测定2～3次)，ASTMD4189-82规定了该测试的标准。膜系统的进水规定是SDI15值必须≤5。降低SDI预处理的有效技术有多介质过滤器、超滤、微滤等。在过滤之前添加聚电介质有时能增强上述物理过滤、降低SDI值的能力。

The best technique to evaluate the possibility of colloidal contamination in the influent of RO/NF system is to measure the deposition density index of the influent (SDI, also known as the pollution plugging index). This is an important parameter that must be determined before the design of the RO. During the operation of the RO/NF, it must be measured regularly (2~3 times per day for the surface water), ASTMD4189-8 2 the standard of the test is stipulated. The regulation of the influent of the membrane system is that the SDI15 value must be less than 5. The effective technologies for reducing SDI pretreatment include multi media filters, ultrafiltration and microfiltration. Adding dielectric before filtering can sometimes enhance the above physical filtration and reduce the SDI value.

3.一般进水应该选用反渗透工艺还是离子交换工艺？

3. should general reverse osmosis process or ion exchange process be used?

在许多进水条件下，采用离子交换树脂或反渗透在技术上均可行，工艺的选择则应由经济性比较而定，一般情况下，含盐量越高，反渗透就越经济，含盐量越低，离子交换就越经济。由于反渗透技术的大量普及，采用反渗透＋离子交换工艺或多级反渗透或反渗透＋其它深度除盐技术的组合工艺已经成为公认的技术与经济更为合理的水处理方案，如需深入了解，请咨询水处理工程公司代表。

Under many influent conditions, the use of ion exchange resin or reverse osmosis is technically feasible, and the selection of the process should be determined by economic comparison. In general, the higher the salt content, the more economical the reverse osmosis will be, the lower the salt content, the more economical the ion exchange will be. Because of the widespread popularity of reverse osmosis technology, the combined process of reverse osmosis + ion exchange or multistage reverse osmosis or reverse osmosis + other deep desalination technology has become a more reasonable water treatment scheme for technology and economy. If we need to understand deeply, please consult the representative of the water treatment engineering company.

4.反渗透膜元件一般能用几年?

4. the reverse osmosis membrane elements can usually be used for a few years?

膜的使用寿命取决于膜的化学稳定性、元件的物理稳定性、可清洗性、进水水源、预处理、清洗频率、操作管理水平等。根据经济分析通常为5年以上。

The service life of the membrane depends on the chemical stability of the membrane, the physical stability of the components, the washability, the water source, the pretreatment, the frequency of the cleaning, the management level and so on. According to the economic analysis, it is usually over 5 years.

5.反渗透和纳滤之间有何区别？

5. what is the difference between the reverse osmosis and the nanofiltration?

纳滤是位于反渗透合同超滤之间的膜法液体分离技术，反渗透可以脱除最小的溶质，分子量小于0.0001微米，纳滤可脱除分子量在0.001微米左右的溶质。纳滤本质上是一种低压反渗透，用于处理后产水纯度不特别严格的场合，纳滤适合于处理井水和地表水。纳滤适用于没有必要象反渗透那样的高脱盐率的水处理系统，但对于硬度成份的脱除能力很高，有时被称为“软化膜”，纳滤系统运行压力低，能耗低于相对应的反渗透系统。

Nanofiltration is a membrane process liquid separation technology between the reverse osmosis contract ultrafiltration, the reverse osmosis can remove the smallest solute, the molecular weight is less than 0.0001 microns, and the nanofiltration can remove the solute with a molecular weight of about 0.001 microns. Nanofiltration is essentially a low-pressure reverse osmosis, which is suitable for treating well water and surface water when it is used to treat water with less stringent purity. Nanofiltration is suitable for water treatment systems with high desalination, which is not necessary as reverse osmosis, but the ability to remove the hardness components is very high. Sometimes it is called "softening film", and the operation pressure of nanofiltration system is low and the energy consumption is lower than that of the corresponding reverse osmosis system.

6.膜技术具有怎样的分离能力？

How does the 6. membrane technology have the ability to separate?

反渗透是目前最精密的液体过滤技术，反渗透膜对溶解性的盐等无机分子和分子量大于100的有机物起截留作用，另一方面，水分子可以自由的透过反渗透膜，典型的可溶性盐的脱除率为>95～99%。操作压力从进水为苦咸水时的7bar(100psi)到海水时的69bar(1,000psi)。纳滤能脱除颗粒在1nm(10埃)的杂质和分子量大于200～400的有机物，溶解性固体的脱除率20～98%，含单价阴离子的盐(如NaCl或CaCl2)脱除率为20～80%，而含二价阴离子的盐(如MgSO4)脱除率较高，为90～98%。超滤对于大于100～1,000埃(0.01～0.1微米)的大分子有分离作用。所有的溶解性盐和小分子能透过超滤膜，可脱除的物质包括胶体、蛋白质、微生物和大分子有机物。多数超滤膜的截留分子量为1,000～100,000。微滤脱除颗粒的范围约0.1～1微米，通常情况下，悬浮物和大颗粒胶体能被截留而大分子和溶解性盐可自由透过微滤膜，微滤膜用于去除细菌、微絮凝物或总悬浮固体TSS，典型的膜两侧的压力为1～3bar.

Reverse osmosis is the most precise liquid filtration technology at present. The reverse osmosis membrane plays an intercepting effect on inorganic molecules such as dissolved salts and organic compounds with molecular weight greater than 100. On the other hand, water molecules can freely permeate the reverse osmosis membrane, and the removal rate of typical soluble salts is >95 to 99%. The operating pressure was 7bar (100psi) from the influent to brackish water to 69bar (1000PSI) in seawater. Nanofiltration can remove the impurities in 1nm (10 Egypt) and the organic matter more than 200~400. The removal rate of dissolved solids is 20 to 98%, and the removal rate of monovalent anion salts (such as NaCl or CaCl2) is 20 to 80%, while the removal rate of salt containing two valence anions (such as MgSO4) is higher, from 90 to 98%. Ultrafiltration has a separation effect on macromolecules larger than 100~1000 (0.01 to 0.1 microns). All soluble salts and small molecules can pass through the ultrafiltration membrane, and the substances that can be removed include colloid, protein, microorganism and macromolecular organic matter. The molecular weight of most ultrafiltration membranes is 1000~100000. The range of micro filtration particles is about 0.1 to 1 microns. In general, suspended particles and large particles can be intercepted while large molecules and dissolved salts can be freely permeable through microfiltration membrane. Microfiltration membrane is used to remove bacteria, microfloc or total suspended solid TSS. The pressure of the typical two sides of the membrane is 1 ~ 3bar.

8.反渗透膜进水最大允许二氧化硅浓度多少？

8. what is the maximum allowable silica concentration in RO membrane influent?

最大允许二氧化硅的浓度取决于温度、pH值以及阻垢剂，通常在不加阻垢剂时浓水端最高允许浓度为100ppm，某些阻垢剂能允许浓水中的二氧化硅浓度最高为240ppm，请咨询阻垢剂供应商。

The maximum permissible silica concentration depends on the temperature, pH value and scale inhibitor. The maximum permissible concentration of the concentrated water is 100ppm when the scale inhibitor is free, and some scale inhibitors can allow the highest concentration of silica in concentrated water to be 240ppm. Please consult the scale inhibitor supplier.

9.铬对RO膜有何影响？

What is the effect of 9. chromium on the RO film?

某些重金属如铬会对氯的氧化起到催化作用，进而引起膜片的不可逆性能衰减。这是因为在水中Cr6+比Cr3+的稳定性差。似乎氧化价位高的金属离子，这种破坏作用就更强。因此，应在预处理部分将铬的浓度降低或至少应将Cr6+还原成Cr3+。

Some heavy metals such as chromium will play a catalytic role in the oxidation of chlorine, which will cause the irreversible degradation of the membrane. This is because the stability of Cr6+ in water is worse than that of Cr3+. It seems that the metal ions with high oxidation price are more destructive. Therefore, the concentration of chromium should be reduced in the pretreatment part or at least Cr6+ should be reduced to Cr3+.

10.RO系统一般需要何种预处理？

What preprocessing does the 10.RO system usually require?

通常的预处理系统组成如下，粗滤(～80微米)以除去大颗粒，加入次氯酸钠等氧化剂，然后经多介质过滤器或澄清池进行精密过滤，再加入亚硫酸氢钠还原余氯等氧化剂，最后在高压泵入口之前安装保安滤器。保安滤器的作用顾名思义，它是作为最终的保险措施，以防止偶然大颗粒对高压泵叶轮和膜元件的破坏作用。含颗粒悬浮物较多的水源，通常需要更高程度的预处理，才能达到规定的进水要求；硬度含量高的水源，建议采用软化或加酸和加阻垢剂等，对于微生物及有机物含量高的水源，还需要使用活性炭或抗污染膜元件。

The usual preprocessing system is composed of the following, coarse filter (~ 80 micron) to remove large particles, add sodium hypochlorite and other oxidants, then through the multi medium filter or the clarifier for precision filtration, and then add the oxidizing agent of the Sodium Bisulfite reduction residual chlorine, and finally install the security filter before the entrance of the high pressure pump. The function of the safety filter is, as the name suggests, as the ultimate insurance measure to prevent accidental particles from damaging the impeller and membrane elements of the high pressure pump. Water sources with more particulate matter usually require a higher degree of pretreatment in order to meet the required intake of water. The water source with high hardness is recommended to soften or add acid and scale inhibitors. For water sources with high microbial and organic content, active carbon or anti pollution membrane elements are also needed.