Characteristics of Reverse Osmosis Membrane Heavy Contamination and Offline Cleaning？

RO reverse osmosis membrane product introduction

Reverse osmosis membrane can retain substances larger than 0.0001 microns, is the most delicate kind of membrane separation products, which can effectively retain all dissolved salts and molecular weight greater than 100 organic matter, while allowing water molecules to pass through. Reverse osmosis membrane material: polyamide, unique composite membrane.

Reverse osmosis system design will have a certain degree of surplus, to ensure that in the emergency time is not because of the reverse osmosis system of water production or desalination rate drop, reverse osmosis system differential pressure rise and make the water supply is not enough to cause a threat to the safety of the production, but in fact it is also because of the existence of these surplus makes the hidden faults are sometimes not able to show in time, so that ultimately may be evolved into reverse osmosis membrane Heavy contamination of reverse osmosis membrane elements.

1, the concept of reverse osmosis membrane element heavy pollution

　　Reverse osmosis system into the water contained in the suspended solids, colloids, organic matter, microorganisms and other particles on the RO membrane surface adhesion, deposition of pollution or chemical ionic components in the water on the membrane surface due to the concentration of polarisation and other factors leading to the ionic product is greater than the solubility product after the generation of chemical scale and other phenomena. Heavy contamination refers to the contamination of a single section of the differential pressure is greater than the system put into operation at the beginning of a single section of the differential pressure value of more than 2 times, reverse osmosis system water production decreased by more than 30% or a single reverse osmosis membrane element weight more than the normal value of more than 3 kg of the situation.
Heavy pollution is often heavy physical pollution and heavy chemical pollution superposition, in some cases, both concomitant, and to a certain extent is in many times after cleaning pollution also occurs repeatedly.

 2, heavy contamination of RO membrane off-line cleaning requirements

　　When the following conditions occur, the need for heavy contamination of RO membrane elements for off-line cleaning: (1) reverse osmosis membrane element contamination in line with the ‘heavy contamination’ standard;

　　(2) reverse osmosis system through the online cleaning can not reach the system rated standard;

　　(3) reverse osmosis water treatment system due to water supply constraints and can not be online cleaning or no online cleaning equipment;

　　(4) reverse osmosis pollution type is more complex, through the online cleaning is easy to cause cross-contamination; (reverse osmosis system before the section of the pollutants may be brought into the system through the online cleaning of the back section of the membrane element after the section of the membrane suffered from contamination is called cross-contamination);

　　(5) reverse osmosis system in a number of cleaning pollution also occurs repeatedly.

3, reverse osmosis membrane element offline cleaning and steps

　　1) Firstly, replace the membrane element to be cleaned on the reverse osmosis system with the spare membrane element with good performance to ensure that the reverse osmosis system does not stop running and to ensure the continuous stability of the whole production process.　　

       2) Reverse osmosis membrane element performance test (this step is particularly important): Each membrane element is individually tested for various performance indicators, including: desalination rate, water production, differential pressure, weight, etc., and make a good record before the test.　　Desalination rate, water production and differential pressure test conditions: in line with the standards provided by different types of membrane manufacturers.　　
       3) Understand the current operating conditions of the system before system cleaning;　　
       4) Collect the indicators of each parameter of the operating reverse osmosis system and make original records;　　
       5) According to the user raw water analysis report, performance test results and understanding of the system information to determine the cleaning process;
　    6) Identification of contaminants. First of all, according to 5) the analysis results of the initial determination, and then through special equipment, apparatus for further verification to determine the specific type of contaminants.　　
        7) Determination of the required cleaning formula based on the analysis results of 5) and 6). When the contaminants on the RO membrane to determine, we can choose the membrane manufacturer to provide a series of formulations, choose a more appropriate one or two formulations; or choose a special formula (when the RO membrane is contaminated by special pollutants, the use of ordinary formulations are not good, or from the economic point of view when comparing the special formula is more economical). At present, there are many domestic and foreign reverse osmosis membrane element cleaning special agents, such as Kaiyuan Hengye's KY series of cleaning agents and biocides, according to the author's experience, the use of good results, and compared with the traditional agents, the economy is also good.　　
        8) In reverse osmosis special cleaning equipment with the above cleaning agent combined with physical processing cleaning means for experimental cleaning, in order to select the appropriate cleaning formula and cleaning procedures;　　
        9) Determine the cleaning method for all the above membrane elements;　　
      10) After cleaning the membrane element into the test platform for testing and recording, does not meet the requirements
       11) Organise the cleaning data and write a cleaning summary report.

Importance of off-line cleaning process of membrane elements in reverse osmosis water purification equipment

　In the current reverse osmosis membrane element cleaning, offline cleaning as an effective means of completely eliminating reverse osmosis membrane element pollution has been accepted by the majority of reverse osmosis users, and is becoming more and more important means of reverse osmosis membrane element cleaning.
　　But there are more and more owners unit added certain confusion:
　　1, reverse osmosis membrane elements in the offline cleaning period, the water treatment system must stop running or intermittent operation, which is often very difficult for industrial enterprises to do things, and even if they do is also made in the case of affecting normal production, to the enterprise profit and safe production with a considerable hidden danger;
　　2, due to the lack of spare membrane elements, only to speed up the cleaning schedule, the result is that the membrane element cleaning effect can not fully meet the requirements, the pollution hazard is still there;
　　3, after offline cleaning of the system in the installation of the initial operating parameters are not bad, but in the cleaning process found in the cause of pollution and the solutions adopted have not been fully verified, pollution often followed. Even in the signing of the warranty period on the relevant content, but reverse osmosis system in the near future into the pollution - cleaning - pollution of the circle makes the service life of the membrane element is also getting shorter and shorter, but also due to a variety of other reasons the interests of the owners are not necessarily to be guaranteed.

Reverse osmosis water purification equipment with membrane elements in the early offline cleaning came into being, the good performance of the spare membrane element also has a lot of ability is not inferior to the new membrane. During the use of spare membrane:
　　1, effectively on the cleaning process found in the measures taken to deal with the problem and verify one by one;
　　2, may be used in the RO pre-treatment of certain measures are not appropriate, there may be damage to the membrane element, but because of the standby membrane element (old membrane), so may suffer less damage, both for Party A and Party B are beneficial;
3, take effective measures to solve the problem, it takes a period of time to observe the operating parameters to prove that catalysing the problems identified by the measures taken to ensure that the system is sound and appropriate, and whether it can ensure the long-term stability of the system operation, with first-hand data, after cleaning the contamination problem is not a problem, and is no longer that flow on paper a paragraph of the text of the comparisons.
　　In reverse osmosis pollution control, the most fundamental measures lie in the reverse osmosis as the core of the water treatment system design and manufacturing and installation process, reverse osmosis system of various consumables selection, operation and management level of control. Good grasp of these aspects of the reverse osmosis system plays a vital role in the safe and healthy operation.
　　Of course, when the reverse osmosis system occurs serious pollution, the first measures taken must be to analyse the causes of pollution, find ways to solve the pollution, and through the appropriate way in the shortest possible time to reverse osmosis system cleaning, because with the extension of time, means that the difficulty of cleaning rises.