Reverse osmosis, also known as reverse osmosis, is a kind of membrane separation operation with pressure difference as driving force to separate solvent from solution. Because it is opposite to the direction of natural infiltration, it is called reverse osmosis.

Failure caused by poor quality of influent water

In the initial design, because the influent water quality is good, the operation of the system is relatively stable, but with the subsequent deterioration of the influent water quality, when the system can not be optimized and improved, the reverse osmosis device has a serious operation failure.

Specific performance in

The decline rate of water yield is faster, and the increase of operating pressure and pressure difference is faster.

Failure caused by performance degradation in preprocessing

Due to the poor performance of the pretreatment equipment, the turbidity, SDI value and COD value of the effluent seriously exceed the requirements of the influent water quality.

The specific performance is as follows

CMF or UF filaments were broken; The bacteria and microorganism in the buffer tank multiply seriously; Multi media filter filter material layer or bias; In the activated carbon filter, the filter material is powdered or the microorganism propagates seriously.

Failure caused by inferior filter element used in security filter

When the output of the security filter increases, the filter element is easy to deform or the filtration accuracy can not meet the requirements, which makes the pollutants directly enter the reverse osmosis device.

The specific performance is as follows

The diameter of security filter element is small; The quality of the filter element is poor, and the filtering accuracy can not meet the requirements; The filter element is not pressed tightly and is easy to deform.

Failure caused by improper selection and dosing of scale inhibitor

As the "protection god" for the safe and stable operation of reverse osmosis, scale inhibitor has become the mainstream of the current scale inhibition form because of its excellent effect and low operation cost. However, there are many problems in the selection, dosing and mixing of scale inhibitor.

The specific performance is as follows

The performance of scale inhibitor does not match the water quality; The performance of scale inhibitor metering pump is not reliable; Excessive dilution of scale inhibitor; The scale inhibitor metering box is seriously polluted.

Failure caused by improper dosing of other chemicals

For different water quality, it is necessary to add a certain amount and category of chemicals 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.

The specific performance is as follows

Unsuitable flocculant brings serious membrane pollution; The excessive addition of oxidant causes membrane oxidation; The excessive addition of reducing agent causes serious fouling of membrane.

Failure caused by instrument failure

At present, imported digital display instruments are used in general reverse osmosis devices. Under the premise of correct installation, some instruments have very accurate flow display and stable reading; However, other types of digital display instruments have large fluctuation range in operation, especially some instruments have the function of parameter setting, and the water yield displayed is controlled by human factors, so the instruments acting as the eyes of reverse osmosis will affect the judgment of technical personnel on reverse osmosis.

The specific performance is as follows

one   The high concentrated water flow rate (actually small) caused the high reverse osmosis recovery rate and scaling;

two   When the concentrated water flow rate is too small (actually large), the reverse osmosis recovery rate is too low, resulting in pressure difference;

three   The reading fluctuation of the flowmeter is too large to judge correctly according to the proportion of 10-15%.

Failure caused by device design defects and improper operation and maintenance

There are many problems in the reverse osmosis device, some systems have defects in design, and some have some deviations in the daily operation and maintenance process, which cause more serious operational risks.

The specific performance is as follows

one   In the initial design, the selection of high pressure pump head is low, and the water yield can not meet the design requirements when the temperature or water quality changes;

two   The oxidation of membrane elements leads to the increase of water flux and the decrease of water quality;

three   The inversion or damage of brine seal ring causes the actual recovery rate to be too high, resulting in scaling and water quality decline;

four   The damage of O-ring causes the decline of water quality;

five   The mixed use of new and old membrane elements and different types of membrane elements leads to the degradation of system performance;

six   The pressure vessel concentrated water thrust ring overlaps or partially overlaps with the concentrated water outlet, which results in high recovery rate and scaling;

seven   The length of the pressure vessel is too long, which causes the concentrated water to leak to the produced water side and causes the quality of the produced water to decline;

eight   The operation of reverse osmosis can not be analyzed and judged reliably without interval pressure gauge;

nine   The larger pressure difference causes the damage of membrane element due to telescope effect;

ten   The increase of backpressure of water production causes the decrease of water production;

eleven   The unreasonable arrangement of reverse osmosis leads to the increase of water flux of local membrane elements and the acceleration of pollution rate;

twelve   The design of reverse osmosis recovery rate is unreasonable and the number of membrane elements is small;

thirteen   The results show that the particulate pollution causes serious mechanical fouling and plugging of membrane components, the pressure difference in the first section is too large, and the water yield and quality become worse;

fourteen   Pollutant deposition and bacterial and microbial pollution caused by system shutdown.