防止反渗透膜表面上污染，即防止悬浮杂质、微生物、胶体物质等附着在膜表面上或污堵膜元件水流通道。

　　1 to prevent the pollution on the surface of the membrane,which prevent suspended impurities,microorganisms,colloidadhesion blocking membrane element flow channel on the membrane surface or dirt.

　　2.防止膜表面上结垢。反渗透装置运行中，由于水的浓缩，有一些难溶盐如CaCO3、CaSO4、BaSO4、SrSO4、CaF2等沉积在膜表面上，因此要防止这些难溶盐生成。

　　2 keep on the surface of the membrane fouling.Operation of the reverse osmosis device,because the water concentration,there are some insoluble salts such as CaCO3,CaSO4,BaSO4,SrSO4,CaF2 deposition on the membrane surface,so to prevent these insoluble salt formation.

　　3.确保反渗透膜免受机械和化学损伤，以使膜有良好的性能和足够长的使用寿命

　　3 to ensure that the film from mechanical and chemical damage,so that the film has a good performance and long service life

　　预处理方案应考虑的因素：

　　Factors to be considered in preprocessing scheme:

　　1、原水水源类型、进水水温及水质情况

　　1,the raw water source type,inlet water temperature and water quality

　　①反渗透预处理必须能够去除原水中的绝大多数杂质，达到进水要求;

　　The reverse osmosis pretreatment must be removed by the vast majority of impurities,meet water requirements;

　　②反渗透预处理必须考虑水质的变化，防止原水水质波动时影响整个系统的稳定运行；

　　The reverse osmosis pretreatment must consider the change of water quality,stable operation of the whole system to prevent the fluctuation of raw water at;

　　③不同膜的进水水质要求不同。

　　The different water quality requirements of different membrane.

　　2、预处理设备类型的选择

　　2,pretreatment equipment type selection

　　预处理设备必须能够高效、稳定地运行，同时尽量简化流程，降低投资和运行成本。

　　Pretreatment equipment must be capable of high efficiency,stable operation,at the same time try to simplify the process,reduce the investment and operation cost.

　　3、药剂类型的选择与用量的确定

　　To determine the selection and dosage 3,agents of the

　　4、设备的控制水平。

　　The control level 4,equipment.