1Inlet water pressure 
　  The feed water pressure itself does not affect the salt permeation rate. However, an increase in feed water pressure raises the net pressure driving reverse osmosis, thereby increasing the water production. At the same time, the salt permeation rate remains almost unchanged. The increased water production dilutes the salt passing through the membrane, reduces the salt permeation rate, and enhances the desalination rate. When the influent pressure exceeds a certain value, due to the excessively high recovery rate, the concentration polarization is intensified, which in turn leads to an increase in salt permeation, offsetting the increased water production and causing the desalination rate to no longer increase.  
2.Inlet water temperature 
       Temperature has a significant impact on the operating pressure, desalination rate and pressure drop of reverse osmosis. As the temperature rises, the permeability increases, and the net driving force required at a certain water flux decreases, thus the actual operating pressure drops. At the same time, the solute permeation rate also increases with the rise in temperature, and the salt permeation increases, which is directly manifested as an increase in the electrical conductivity of the product water. 
Temperature also has a certain impact on the pressure drop of each section of reverse osmosis. As the temperature rises, the viscosity of water decreases, and the pressure drop reduces. For Reverse osmosis In devices where the turbulence in the membrane channels is enhanced due to fouling, the influence of viscosity on pressure drop is more pronounced. 
       The conductivity of the water produced by reverse osmosis membranes is highly sensitive to changes in the feed water temperature. As the water temperature increases, the water flux also increases linearly. Every time the feed water temperature rises1℃The water production flux will increase2.5％～3.0％; The reason lies in the fact that the viscosity of water molecules passing through the membrane decreases and their diffusion performance enhances. The increase in the influent water temperature will also lead to an increase in the salt permeation rate and a decrease in the desalination rate. This is mainly because the diffusion rate of salt through the membrane will accelerate with the rise in temperature. 
3Water ingresspHvalue 
      All kinds of membrane modules have an allowable onepHValue range, water ingresspHThe value has almost no impact on the water production volume. But even within the allowable range, PHvalue Regarding the desalination rate also It has a considerable influence, on the one handpHThe value also has a certain impact on the conductivity of the product water. This is because most reverse osmosis membranes themselves contain some active groups.pHThe value can affect the electric field on the membrane surface and thereby influence the migration of ions.pHThe value has a direct impact on the form of impurities in the influent water. For example, for dissociable organic matter, its retention rate variespHIt decreases as the value drops. On the other hand, it is due to the dissolution in waterCO2bypHThe value has a significant impact.pHWhen the value is low, it is in gaseous formCO 2 The form exists and is easy to pass through the reverse osmosis membrane, sopHThe desalination rate is also relatively low at low timespHElevated, gaseous stateCO 2 Transform intoHCO 3 － andCO 3 2－ Ions, and the desalination rate also gradually increasespHin7.5～8.5 the between when The desalination rate reaches a high level. 

4,Influent salt concentration 
      Osmotic pressure is a function of the concentration of salt or organic matter in water. The higher the salt content, the greater the osmotic pressure. Under the condition that the inlet water pressure remains unchanged, the net pressure will decrease and the water production will decline. The salt penetration rate is directly proportional to The salt concentration difference between the front and back sides of the reverse osmosis membrane is that the higher the salt content of the feed water, the greater the concentration difference. The salt permeation rate increases, which in turn leads to a decrease in the desalination rate. For the same system, different salt content in the feed water leads to differences in its operating pressure and the conductivity of the product water. Every increase in the salt content of the feed waterl00ppmThe inlet water pressure requires "Increase about 0 .007MPaAt the same time, due to the increase in concentration, the conductivity of the product water also increases accordingly. 
5Suspended matter  
      Suspended solids in water refer to the substances remaining on the surface of the filter material while water is being filtered, mainly composed of particles. High suspended solids content can cause severe blockage in reverse osmosis and nanofiltration systems very quickly, affecting the water production and water quality of the systems. 

6,Recovery rate 
      The recovery rate has a significant impact on the pressure drop in each section. Under the condition that the total influent flow rate remains constant, an increase in the recovery rate leads to a reduction in the concentrated water flow rate passing through the high-pressure side of reverse osmosis, resulting in a decrease in the total pressure drop and an increase in the recovery rate. Actual operation shows that even if the recovery rate changes very little, such as1%It will also cause a total pressure difference to occur0.02MPaThe changes on the left and right. The influence of recovery rate on the conductivity of product water depends on the salt permeation rate and the amount of product water. Generally speaking, an increase in the system recovery rate will increase the salt content in the concentrated water and accordingly increase the conductivity of the product water.