In the industrial production process, often have separation, concentration, classification and purification of a water solution needs. Conventional methods are precipitation, filtration, heating, freezing, distillation, extraction and crystallization processes. These methods show the shortcomings of long process, energy consumption, material loss, large equipment, low efficiency, cumbersome operation and other shortcomings to ultrafiltration membrane technology to replace some of the traditional technology can obtain significant economic benefits.
The reverse osmosis system ultimately needs to be cleaned. It is recommended that you clean the RO system before your RO system shows a tendency to contaminate, long outage, or scheduled routine maintenance. When the following pollution characteristics are present (10 to 15% reduction in normalized production, 10 to 15% reduction in normalized product water quality, or 10 to 15% increase in pressure drop between feed and concentrate), your RO system needs Clean up.
RO system due to dirt and the need to clean the frequency varies with the location, the general customary acceptable cleaning frequency is 3 to 12 months. If you have to clean more than once a month, you should improve the RO pretreatment system, adjust the RO system operating parameters, if every 1 to 3 months need to be cleaned once, you need to improve the current level of equipment operation Work, but it is difficult to determine whether the need to improve the pretreatment system.
In the RO design usually ignore the use of RO products in the system of water rinse dirt, the use of this method can reduce the number of RO cleaning. Immersion of the RO membrane module with product water during device outage helps to dissolve scale and loose deposits, thereby reducing the frequency of chemical cleaning.
Dirt sites need to be cleaned out of different dirt, but there are often more than one pollutant, so the problem is complicated, the common types of pollutants are:
• Calcium carbonate scale
• Calcium sulfate, barium sulfate, strontium sulfate scale
• Metal oxides such as iron, manganese and aluminum
• Silica
• Colloidal deposits (inorganic or inorganic / organic mixtures)
• Natural or synthetic organic matter
• Biomass (biological sludge, mold or fungi)
There are many factors associated with choosing the right cleaning chemistry and the right cleaning method. It is advisable to contact the manufacturer of the equipment, the manufacturer of the RO membrane module, or the RO system supplier for the first time you perform the cleaning. Once the type of contamination has been identified, one or more cleaning products are recommended. These may be conventional, available from many suppliers, or special cleaning solutions, which may be more expensive, but easier to use, and which have the added benefit of providing technical support. Other companies may provide more valuable services; they take the membrane modules taken from your system back to the test, and choose the right cleaning drugs and methods.
Usually in a specific order using a variety of different cleaning drugs for cleaning, in order to obtain the best cleaning results. For example, first remove the scale with a low pH wash, and then remove the organics using a high pH cleaning solution. However, sometimes the first use of high pH cleaning fluid to remove oil dirt, and then use a low pH value of the cleaning solution. Some detergents are also added to the cleaning solution, which will help remove contaminating biological and organic impurities. Other cleaners are added with chelating agents such as EDTA, which help to remove colloids, organics, biological impurities and sulfate scale. It must be remembered that improper cleaning of the product or improper cleaning steps may make the fouling more serious.