28 Aug 2024
Analysis of common faults in reverse osmosis system operation
How to protect the environment?
Stark will introduce you to a professional knowledge of environmental protection - routine fault analysis in the operation of reverse osmosis systems.
1.Reverse osmosis failure caused by poor influent quality
In the initial design, the system operation was relatively stable due to the good quality of the influent water. However, as the subsequent influent water quality deteriorated, the reverse osmosis device had serious operating failures when the system could not be optimized and improved through pretreatment.
Specifically, the water production rate decayed rapidly, and the operating pressure and pressure difference increased rapidly.
2.Failure caused by performance degradation in preprocessing
Due to the deterioration of the performance of the pretreatment equipment, the turbidity, SDI value, COD value and other values of the effluent seriously exceed the inlet water quality requirements.
Specific manifestations:
CMF or UF membrane filament breakage;
The bacteria and microorganisms in the buffer water tank are seriously multiplying;
The filter media of the multi-media filter is disordered or biased; the filter media in the activated carbon filter is pulverized or the microorganisms are seriously multiplying.
3. Failure of security filter caused by using inferior filter element
When the output of the security filter increases, the filter element is easy to deform or the filtering accuracy does not meet the requirements, allowing pollutants to directly enter the reverse osmosis device.
Specific manifestations:
The diameter of the filter element of the security filter is too small;
The quality of the filter element is poor, and the filtering accuracy does not meet the requirements;
The filter element is not pressed tightly and is easy to deform.
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4.Failures caused by improper selection and addition of cathodic agents
As the "guardian" of the safe and stable operation of reverse osmosis, antiscalants have become the mainstream of current antiscaling due to their good effects and low operating costs. However, many problems have arisen in the selection, addition and mixing of antiscalants.
The performance of the antiscalant does not match the water quality;
the performance of the antiscalant metering pump is unreliable;
excessive dilution of the antiscalant;
serious pollution of the antiscalant metering box.
Reverse osmosis scale inhibitor PO-100 is a mature composite formula reverse osmosis scale inhibitor. It has good scale inhibition effect and a wide range of applications. It can play a good scale inhibition and dispersion effect on conventional water quality; it is particularly suitable for scaling caused by carbonate, sulfate, calcium oxide, magnesium oxide and iron oxide precipitation. It has high scale inhibition efficiency and does not coagulate with residual coagulants or aluminum-rich and iron-rich compounds, and does not form coagulants. It prevents scaling in reverse osmosis (RO) nanofiltration (NF) or ultrafiltration (UF) systems without ion exchange pretreatment and improves water production and quality.
5.Failures caused by improper addition of other chemicals
According to different water qualities, a certain amount and type of chemicals need to be added to increase the treatment effect of raw water. However, due to various reasons, the improper use and addition of these chemicals may have serious consequences.
Specifically:
Inappropriate flocculants cause serious membrane pollution;
Excessive addition of oxidants causes membrane oxidation;
Excessive addition of reducing agents causes serious fouling of the membrane.
6.Reverse osmosis failure caused by instrument failure
At present, most reverse osmosis devices use imported digital instruments. Under the premise of correct installation, some instruments can display flow very accurately and the readings are stable, such as GF's 9010 flow controller; but other types of digital instruments have large fluctuations in values during operation, especially some instruments have parameter setting functions, and the displayed water production is controlled by human factors. In this way, the instrument that acts as the eyes of the reverse osmosis will affect the technicians' judgment on the reverse osmosis.
Specifically, the concentrated water flow rate is displayed too large (actually smaller), causing the reverse osmosis recovery rate to be too high and causing scaling; The concentrated water flow rate is displayed too small (actually larger), causing the reverse osmosis recovery rate to be too low and causing a pressure difference; The flow meter reading fluctuates too much and cannot be correctly judged according to the ratio of 10-15%.
7.The system is flawed in design
There are many problems with reverse osmosis devices. Some systems have defects in design, and some have partial deviations in daily operation and maintenance, causing serious operational risks.
Specifically:
The high-pressure pump head is selected too low in the initial design, which causes the water output to fail to meet the design requirements when the temperature or water quality of the inlet water changes;
The membrane element is oxidized, causing the water flux to increase and the water quality of the produced water to decrease;
The inversion or damage of the brine sealing ring causes the actual recovery rate to be too high, resulting in scaling and water quality degradation;
The damage of the O-ring causes the water quality of the produced water to decrease;
The mixed use of new and old membrane elements and different types of membrane elements causes the system performance to decrease;
8.Failures in reverse osmosis membranes
Conditions for long-term stable operation of a reverse osmosis system:
Attention must be paid to pretreatment, and the pretreated water should meet the reverse osmosis water inlet requirements;
Pay attention to the inherent quality of the reverse osmosis device, such as the reasonable selection of membrane components (components) and their quantity, the reasonable arrangement and combination of membrane components, etc.;
Pay attention to the operation, maintenance and management of the reverse osmosis system.
3. Determination of membrane cleaning cycle
When the reverse osmosis membrane surface is blocked by inorganic salt scale, metal oxides, microorganisms, colloidal particles and insoluble organic matter, the standardized water production and desalination rate will decrease, and the pressure difference between sections will increase. When the above phenomenon is caused by chemical pollution, the reverse osmosis system needs to be chemically cleaned.
For the determination of the membrane chemical cleaning time, the operation data standardization calculation of the reverse osmosis system should be carried out regularly. After the operation data is standardized, if the system water production decreases by more than 15% compared with the initial value or the desalination rate decreases by more than 10% compared with the initial value or the pressure difference between sections increases by more than 15% compared with the initial value, the online cleaning of the reverse osmosis membrane should be carried out in time.
PO-511 reverse osmosis cleaning agent is an alkaline composite liquid agent suitable for chemical cleaning of CA and TFC series reverse osmosis membrane elements. It has no damage to the reverse osmosis membrane, has strong permeability and solubility to sludge, organic matter, grease, microorganisms and sticky substances and non-acid solubility, and does not produce secondary precipitation pollution during the cleaning process.
Stark will introduce you to a professional knowledge of environmental protection - routine fault analysis in the operation of reverse osmosis systems.
1.Reverse osmosis failure caused by poor influent quality
In the initial design, the system operation was relatively stable due to the good quality of the influent water. However, as the subsequent influent water quality deteriorated, the reverse osmosis device had serious operating failures when the system could not be optimized and improved through pretreatment.
Specifically, the water production rate decayed rapidly, and the operating pressure and pressure difference increased rapidly.
2.Failure caused by performance degradation in preprocessing
Due to the deterioration of the performance of the pretreatment equipment, the turbidity, SDI value, COD value and other values of the effluent seriously exceed the inlet water quality requirements.
Specific manifestations:
CMF or UF membrane filament breakage;
The bacteria and microorganisms in the buffer water tank are seriously multiplying;
The filter media of the multi-media filter is disordered or biased; the filter media in the activated carbon filter is pulverized or the microorganisms are seriously multiplying.
3. Failure of security filter caused by using inferior filter element
When the output of the security filter increases, the filter element is easy to deform or the filtering accuracy does not meet the requirements, allowing pollutants to directly enter the reverse osmosis device.
Specific manifestations:
The diameter of the filter element of the security filter is too small;
The quality of the filter element is poor, and the filtering accuracy does not meet the requirements;
The filter element is not pressed tightly and is easy to deform.
.jpg?imageView2/1/format/webp)
4.Failures caused by improper selection and addition of cathodic agents
As the "guardian" of the safe and stable operation of reverse osmosis, antiscalants have become the mainstream of current antiscaling due to their good effects and low operating costs. However, many problems have arisen in the selection, addition and mixing of antiscalants.
The performance of the antiscalant does not match the water quality;
the performance of the antiscalant metering pump is unreliable;
excessive dilution of the antiscalant;
serious pollution of the antiscalant metering box.
Reverse osmosis scale inhibitor PO-100 is a mature composite formula reverse osmosis scale inhibitor. It has good scale inhibition effect and a wide range of applications. It can play a good scale inhibition and dispersion effect on conventional water quality; it is particularly suitable for scaling caused by carbonate, sulfate, calcium oxide, magnesium oxide and iron oxide precipitation. It has high scale inhibition efficiency and does not coagulate with residual coagulants or aluminum-rich and iron-rich compounds, and does not form coagulants. It prevents scaling in reverse osmosis (RO) nanofiltration (NF) or ultrafiltration (UF) systems without ion exchange pretreatment and improves water production and quality.
5.Failures caused by improper addition of other chemicals
According to different water qualities, a certain amount and type of chemicals need to be added to increase the treatment effect of raw water. However, due to various reasons, the improper use and addition of these chemicals may have serious consequences.
Specifically:
Inappropriate flocculants cause serious membrane pollution;
Excessive addition of oxidants causes membrane oxidation;
Excessive addition of reducing agents causes serious fouling of the membrane.
6.Reverse osmosis failure caused by instrument failure
At present, most reverse osmosis devices use imported digital instruments. Under the premise of correct installation, some instruments can display flow very accurately and the readings are stable, such as GF's 9010 flow controller; but other types of digital instruments have large fluctuations in values during operation, especially some instruments have parameter setting functions, and the displayed water production is controlled by human factors. In this way, the instrument that acts as the eyes of the reverse osmosis will affect the technicians' judgment on the reverse osmosis.
Specifically, the concentrated water flow rate is displayed too large (actually smaller), causing the reverse osmosis recovery rate to be too high and causing scaling; The concentrated water flow rate is displayed too small (actually larger), causing the reverse osmosis recovery rate to be too low and causing a pressure difference; The flow meter reading fluctuates too much and cannot be correctly judged according to the ratio of 10-15%.
7.The system is flawed in design
There are many problems with reverse osmosis devices. Some systems have defects in design, and some have partial deviations in daily operation and maintenance, causing serious operational risks.
Specifically:
The high-pressure pump head is selected too low in the initial design, which causes the water output to fail to meet the design requirements when the temperature or water quality of the inlet water changes;
The membrane element is oxidized, causing the water flux to increase and the water quality of the produced water to decrease;
The inversion or damage of the brine sealing ring causes the actual recovery rate to be too high, resulting in scaling and water quality degradation;
The damage of the O-ring causes the water quality of the produced water to decrease;
The mixed use of new and old membrane elements and different types of membrane elements causes the system performance to decrease;
8.Failures in reverse osmosis membranes
Conditions for long-term stable operation of a reverse osmosis system:
Attention must be paid to pretreatment, and the pretreated water should meet the reverse osmosis water inlet requirements;
Pay attention to the inherent quality of the reverse osmosis device, such as the reasonable selection of membrane components (components) and their quantity, the reasonable arrangement and combination of membrane components, etc.;
Pay attention to the operation, maintenance and management of the reverse osmosis system.
- Insufficient attention to the operation and management of the pretreatment system
- The pretreatment system does not sterilize or kill algae or the effect is not good;
- The dosage of the clarifier is not adjusted in time according to the water quality, and the sludge discharge of the clarifier is not timely;
- Decline rate of desalination rate
3. Determination of membrane cleaning cycle
When the reverse osmosis membrane surface is blocked by inorganic salt scale, metal oxides, microorganisms, colloidal particles and insoluble organic matter, the standardized water production and desalination rate will decrease, and the pressure difference between sections will increase. When the above phenomenon is caused by chemical pollution, the reverse osmosis system needs to be chemically cleaned.
For the determination of the membrane chemical cleaning time, the operation data standardization calculation of the reverse osmosis system should be carried out regularly. After the operation data is standardized, if the system water production decreases by more than 15% compared with the initial value or the desalination rate decreases by more than 10% compared with the initial value or the pressure difference between sections increases by more than 15% compared with the initial value, the online cleaning of the reverse osmosis membrane should be carried out in time.
PO-511 reverse osmosis cleaning agent is an alkaline composite liquid agent suitable for chemical cleaning of CA and TFC series reverse osmosis membrane elements. It has no damage to the reverse osmosis membrane, has strong permeability and solubility to sludge, organic matter, grease, microorganisms and sticky substances and non-acid solubility, and does not produce secondary precipitation pollution during the cleaning process.