1、 Noun interpretation (this paper summarizes from eight aspects)

1. Raw water   Raw water: refers to the natural water without any treatment or the tap water of the city, etc. is also called raw water

2. Clear water clear water: water that removes suspended impurities from raw water.

3. Desalted water refers to the water that the positive and negative ions in the water are basically removed or reduced to a certain extent, which is called desalted water. The methods of desalination include distillation, electrodialysis, reverse osmosis and ion exchange.

4. Turbidity turbidity: refers to the turbidity of water, which is caused by the optical effect of containing certain suspended substances (including colloidal substances) in water. Units are represented by NTU. Turbidity is one of the main characteristics of judging whether water is polluted or not. The standard unit of turbidity is 1 degree of turbidity composed of 1mgsi02.

5. Flocculant flocculant: a kind of agent that can cause the rubber particles to form a condensation bridge and flocculate.

6. Total alkalinity: refers to the total amount of substances in water that can neutralize with strong acids.

7. Acidity and acidity: refers to the total amount of substances in water that can neutralize with strong alkali.

8. Hardness: refers to some metal ions in water that are easy to form precipitates, usually refers to the content of calcium and magnesium ions.

9. Conductivity conductivity: it is the conductivity of the solution between two parallel electrodes with a cross-sectional area of 1 square centimeter and a distance of 1 cm at a certain temperature. It can indirectly indicate the content of dissolved salt in water.

10. Resistivity: it is also an indicator of water conductivity. The greater the resistivity of water, the worse the conductivity of water, the less ions contained in water. Its common unit is m Ω.Cm. It is reciprocal to conductivity. For example: the conductivity of water is 0.2 μ S/cm, the resistivity is 1 / 0.2 = 5 (m Ω.Cm).

11. TDS (total soluble solid): it is the residual inorganic matter after filtering out suspended matter (SS) and colloid and evaporating to see all water. The unit is ppm or mg/l, which can be measured by TDS. It also reflects the ion content in water. It has a rough correspondence with conductivity: for sodium chloride reference solution, the TDS value of 1ppm corresponds to 2 μ The conductivity of s/cm.

12. PH pH: relative content of acid and alkali in solution. PH is a measure of the negative logarithm (log) of the concentration of hydrogen ions in water. The pH value is divided into 0-14 gears, and the water is neutral when the pH value is 7.0; If the pH value is less than 7.0, the water is acidic; The pH value is greater than 7.0. The water is alkaline.

13. Alkalinity: alkalinity refers to the content of substances in water that can be neutralized by [h+] ions and strong acids. The alkalinity in water is mainly caused by carbonate alkalinity, bicarbonate alkalinity and hydroxide alkalinity.

14. Sdisdi: pollution index - used to measure the number of suspended solids in raw water used in the RO system.

15. Ozone: an unstable and highly active form of oxygen, which is produced by natural lightning or high voltage charges through the air, and is an excellent oxidant and disinfectant.

16. Residual chlorine: the effective chlorine left in the water after chlorination and disinfection and after contacting for a certain time.

17. Total coliform: total coliform group refers to a group of gram negative bacillus that is aerobic and facultative anaerobic, which can ferment lactose when growing at 37 ℃ and produce acid and gas within 24 hours. Total coliform is the number of total coliforms contained in each litre of water sample.

18. Recovery rate: refers to the ratio of the flow of product water produced by the system to the inflow flow.

19. Desalination rate: desalination rate: the parameter reflecting the performance of the membrane, usually the desalination rate of the first RO membrane system is over 97%. It can be calculated simply: (raw water conductivity - conductivity of product water) / raw water conductivity.

20. Salt content: the salt content of water is also known as salinity, which means the amount of salt in water. Since all kinds of salts in water generally exist in the form of ions, the salt content can also be expressed as the sum of the amount of cations and anions in water.

21. Precipitation: one of the technical methods for wastewater treatment. It can be divided into physical precipitation and chemical precipitation. The precipitation is usually referred to as physical precipitation, that is, gravity separation method. It is separated from water by gravity sedimentation or upfloating by using the different proportion of suspended matter and water in wastewater. Chemical precipitation is to add some chemical agent to the wastewater to react with the dissolved substances in the wastewater, and produce the compounds which are difficult to dissolve in water and precipitate and precipitate.

22. There are many explanations for the definition of "reclaimed water" in water, which is called "reclaimed water" in sewage engineering, and "reuse water" in factory. Generally, water quality is regarded as the distinguishing mark. It mainly refers to the non drinking water which can be reused within a certain range after being treated to meet certain water quality standards. The reclaimed water quality is between the upper water (drinking water) and the sewage (domestic sewage), which is also the origin of the name of water. People also call the system of water supply as the reclaimed water system.

23. Organic pollution

Organic pollution: refers to the artificial synthesis of organic substances, such as natural organic substances, such as carbohydrate, protein, amino acids and fat, etc. It mainly comes from domestic sewage and industrial wastewater.

24. Concentration polarization concentration polarization: under the operation condition of reverse osmosis, the salt on the membrane surface is concentrated, and there is a concentration difference between the salts entering the water. If the concentrated water flow is small and the flow rate is low, the water of high content salt cannot be taken away in time, and a high concentration difference will be formed on the membrane surface, which hinders the diffusion of salt. This phenomenon is called concentration polarization.

25. Suspended substance (SS) suspension (SS): refers to the solid substance suspended in water, including inorganic matter, organic matter and mud sand, clay, microorganism, etc. which are insoluble in water. The content of suspended matter in water is one of the indicators to measure the degree of water pollution. It is the solid amount obtained by drying the interceptor on the filter paper at 103-105 ℃ after water sample filtration. Unit mg / L.

26. Aeration: the process of transferring O2 in the air to the mixture and being used by microorganisms. The purpose is to provide dissolved oxygen needed by activated sludge and other microorganisms, and to ensure the aerobic demand of microbial metabolism.

27. BOD: refers to the dissolved oxygen consumed by microorganisms in the process of decomposition and oxidation of organic matter in water under specified time, specified temperature and specified conditions. Generally, the time used is 5 days, the temperature is 20 ℃, and BOD5 is briefly recorded, unit mg / L.

28. Chemical oxygen demand (COD): refers to the oxygen consumption of organic substances in wastewater oxidation with strong oxidant under certain conditions. The standard for wastewater inspection is generally potassium dichromate as oxidant, unit: mg / L.

29. Water hammer is also called water hammer. During the process of water (or other liquid) transportation, the flow rate changes suddenly and the pressure fluctuates greatly due to the sudden opening or closing of the valve, the sudden stop of the water pump and the sudden opening and closing of the guide vane.

30. Adsorption and adsorption: it refers to the method of using porous solid to absorb some or several pollutants in wastewater to recover or remove some pollutants, so as to make the wastewater purified.

31. Enzyme: it is a catalyst (biocatalyst) made by itself in biological cells. Its basic component is protein, which is a material to promote the speed of biochemical reaction.

32. Sewage: sewage refers to the general name of water discharged in production and living activities. In human life and production activities, we need to use a lot of water, which is often polluted to varying degrees. The polluted water is called sewage.

33. Sewage treatment: it is to separate, remove, recycle or convert the pollutants contained in the sewage into harmless substances by various technologies and means, so as to purify the water.

34. Sewage reuse: sewage or wastewater is reused for production system or domestic miscellaneous use after secondary treatment and deep treatment. When the treated water meets the specific reuse requirements and is reused, it can also be called reclaimed water.

35. Scale and scale: that is, solid-state attachment generated on the pipe wall where the heating surface contacts water after a period of operation due to the poor water quality of boiler.

36. Water slag

Water slag: refers to the solid substance in suspended state in the boiler water and the sediment deposited in the slow water flow places such as the bottom of the steam drum and the lower header. Different from scale: the slag is loose, in suspended or sediment state, and some of them are easily discharged with boiler blowdown; The scale can be firmly adhered to the pipe wall and is not easy to be discharged.

37. Iron, manganese, aluminum    Trace amount of iron and manganese will cause dyeing, scaling and taste problems. Iron exists in the form of water soluble iron in the reduced state. When contacted with air, it will gradually oxidize into yellow brown colloidal trivalent iron, and finally precipitate into brown iron hydroxide. The characteristic of manganese is similar to that of iron. Because the oxide of iron, manganese and aluminum is also one of the causes of RO membrane fouling, it is necessary to analyze its content.

38. Pure water refers to the water that not only removes the strong electric medium which is easy to remove in water, but also removes weak electrolytes such as silicic acid and carbon dioxide which are difficult to remove in water to a certain extent. The salt content of pure water is below 1.0mg/l, and the conductivity is less than 3 μ s/cm。

39. Super pure water

Ultra pure water, also known as high-purity water, refers to the removal of almost all conductive media in water, and the removal of non dissociated colloidal substances, gases and organic substances to a very low level of water,. The salt content of ultrapure water is below 0.1mg/l, and the conductivity is less than 0.1 μ s/cm。  

In addition to strict requirements on salt content or conductivity, pure water and ultra pure water also have strict limits on the contents of various metal ions, organic matter, particle size and quantity, and microbial quantity

40. Distilled water distilled water is the water that will be heated and vaporized, and then condensed into steam is called distilled water. The conductivity of distilled water is 10 μ About s/cm, the primary distilled water is distilled again to obtain the secondary distilled water, and the repeated distillation water is obtained by multiple distillation. The conductivity can be reduced to 1.0 μ About s/cm.

41. Scale inhibitor: it is a kind of agent which can disperse the insoluble inorganic salt in water, prevent or interfere the precipitation and scaling of insoluble inorganic salt on the metal surface, and maintain the good heat transfer effect of metal equipment.

42. Ion exchange resin ion exchange resin is a kind of polymer compound with functional group (active group with exchange ion), network structure and insoluble property. It is usually spherical particles.

43. Ion ion refers to the stable structure of an atom that loses or obtains one or more electrons due to its own or external effects, which makes it reach the stable structure with the outermost electron number of 8 or 2 (helium atom) or no electron (four neutron). This process is called ionization. The energy needed or released in the ionization process is called ionization energy. In chemical reactions, the metal element atoms lose the outermost electrons, and the nonmetallic atoms get electrons, which makes the atoms or clusters participating in the reaction have charge. Charged atoms are called ions, positive charged atoms are called cations, and negatively charged atoms are called anions. Anion and cation form non charged compounds due to electrostatic action. Like molecules and atoms, ions are also the basic particles that make up matter. For example, sodium chloride is made up of chloride and sodium ions.

43. Ion ion refers to the stable structure of an atom that loses or obtains one or more electrons due to its own or external effects, which makes it reach the stable structure with the outermost electron number of 8 or 2 (helium atom) or no electron (four neutron). This process is called ionization. The energy needed or released in the ionization process is called ionization energy. In chemical reactions, the metal element atoms lose the outermost electrons, and the nonmetallic atoms get electrons, which makes the atoms or clusters participating in the reaction have charge. Charged atoms are called ions, positive charged atoms are called cations, and negatively charged atoms are called anions. Anion and cation form non charged compounds due to electrostatic action. Like molecules and atoms, ions are also the basic particles that make up matter. For example, sodium chloride is made up of chloride and sodium ions.

44. Water yield   Water yield (water flux) refers to the capacity of the reverse osmosis system, that is, the amount of water passing through the membrane in unit time, usually expressed in tons / hour (T / h) or gallon / day (g/d).

45. EDI (electrodeionization) is a new type of ultra pure water preparation technology which has been developed gradually in the 1990s. It combines electrodialysis technology and ion exchange technology skillfully, and selects and passes through the anion exchange membrane to anion and anion ions and the exchange effect of ion exchange resin on ions, The ion transfer to the concentrated water chamber is realized under the action of DC electric field, so as to achieve the deep desalting of water and obtain super pure water. At the same time, the water molecules are electrolyzed as hydrogen ion and hydrogen hydroxide ion to regenerate the resin, and the traditional acid-base chemical regeneration is avoided

2、 Basic process interpretation of pure water

1. Primary filter

Coarse filtration: refers to mechanical filtration, removing suspended substances in water, colloid, turbidity, chroma, peculiar smell, etc. The main filtration methods include clarifier, fast filter, sand filter, sand filter, multi-media filter, active carbon filter, disc filter, high efficiency fiber filter, etc.

2. Fine filtration

Fine filtration: the filter film made of special materials has high filtration precision. The common ones are microfiltration membrane and filter element filtration.

3. Ultrafiltration

Ultrafiltration: it is a membrane filtration, which can remove macromolecules, colloids, bacteria, etc. The filtration precision is high, and the common one is ultrafiltration membrane. The ultrafiltration membrane can not remove the ions in water, that is, it has no desalination function. It can be used for RO pretreatment or after ro finishing, and can also be used separately. Ultrafiltration is a kind of filtration process driven by tangential flow and pressure, and particles are separated according to molecular weight. The pore size of the ultrafiltration membrane is about 0.002-0.1 μ M. The dissolved substances and the substances with smaller pore diameter can be used as the permeation liquid to pass through the filter membrane, and the substances that cannot pass through the membrane can be concentrated in the discharge liquid. Therefore, the water produced contains water, dissolved solids and small molecular weight substances, while colloids, suspended particles, high molecular weight organic matter, bacteria, viruses and protozoa will be filtered out.

4. Reverse osmosis

Reverse osmosis: RO is a membrane separation technology developed in 1960s. Its principle is that raw water passes through RO membrane under high pressure. The solvent in water diffuses from high concentration to low concentration to achieve the purpose of separation, purification and concentration. Because it is opposite to the natural direction of infiltration, it is called reverse osmosis. Reverse osmosis can remove bacteria, viruses, colloids, organic substances and more than 98% of soluble salts in water. The method has the characteristics of low operating cost, simple operation, high automation and stable effluent quality. Compared with other traditional water treatment methods, it has obvious advantages, and is widely used in all walks of life related to water treatment. The reverse osmosis water treatment technology is basically a physical desalination method, which has the outstanding characteristics that the traditional water treatment method has not

a. Reverse osmosis is to remove salt and purify salt water supply by physical method without phase change at room temperature. At present, the desalination rate of ultra thin composite membrane element can reach 99.5%, and the colloid, organic matter, bacteria and virus in water can be removed at the same time.

b. Water treatment only depends on the pressure of water as the driving force, and its energy consumption is the lowest in many treatment methods.

c. No large amount of chemical agents and acid and alkali regeneration treatment are needed, no chemical waste is discharged and no environmental pollution is required.

d. The reverse osmosis device can run continuously to make water, which is simple in system, convenient in operation and stable in water quality.

e. The reverse osmosis device has high automation and little work in operation and maintenance.

f. The equipment covers a small area and requires a small space.

g. It is suitable for the large range of raw water quality, not only for the treatment of bitter salty water, sea water and sewage, but also for the fresh water treatment with low salt content. Our company has accumulated many years of experience in process design, equipment manufacturing, system complete set and membrane application technology of industrial water treatment system, and selected reasonable process setting and design parameters to ensure long-term stable operation of the equipment.

5. Ion exchange

The cation in water is replaced by hydrogen ion when it passes through the layer of hydrogen ion exchange agent, which is the principle of salt removal in the cation bed.

The anions in water are replaced by OH ions when they pass through the OH-type ion exchange agent layer, which is the principle of desalination in anion bed.

The mixed bed is an ion exchange device which is mixed with cation and anion exchange resin in the same exchange column in a certain proportion. The resin layer of uniform mixing is arranged in close staggered arrangement between the cation resin and anion resin. Each pair of cation resin and anion resin particles are similar to a group of compound beds, so the mixed bed can be regarded as numerous groups of compound beds for series operation. Because the hydrogen ions entering the water after mixed ion exchange and the hydrogen oxygen ions immediately generate water molecules with low ionization degree, and it is very unlikely to form the cation or anion exchange counter ions, which can make the exchange reaction be carried out thoroughly, so the effluent quality of the mixed bed is better than that of the complex bed composed of cation and anion exchange series, It can produce the finished water with high purity

6、EDI

Edi:edi technology is a new desalination process combining electrodialysis and ion exchange. The equipment takes the advantages of electrodialysis and mixed bed ion exchange, which makes up for the short of each other. The ion exchange can be used for deep treatment, and no reagent is used for regeneration. The purpose of regeneration resin is achieved by using h+ and oh-, which are produced by ionization. EDI has high requirements for water inflow, which must be the water quality of RO production or equivalent to that of RO production water. It has the following characteristics:

It can continuously produce qualified super pure water which meets the requirements of users, and the water production is stable

      No chemical products are needed for regeneration, no chemical emission, and they are green and environmental protection products

      Compact structure, small floor area and low water production cost

      Before leaving the factory, the device commissioning is completed, and the field installation and commissioning is simple

      Simple operation, low labor intensity and easy training

3、 The producers of ultrafiltration membrane, reverse osmosis membrane and EDI commonly used in Engineering

1. Ultrafiltration membrane

Ultrafiltration membrane: Koch, norite, Netherlands, Shanghai China membrane

2. Reverse osmosis membrane

Reverse osmosis membrane: hyderability, US Dow, world Korea, Runmei, TfU, Huitong

4、 Common water treatment process

01

Raw water is groundwater

Raw water is groundwater: sand filter + precision filter + reverse osmosis + mixed bed or EDI

02

Raw water is tap water

Raw water is tap water: sand filter + active carbon filter + precision filter +ro+ mixed bed or EDI

03

Raw water is surface water

① Multi media filter + active carbon filter + precision filter +ro+ mixed bed or EDI

② Multi media filter (or other type filter) + ultrafiltration + precision filter +ro+ mixed bed or EDI

③ Disc filter + ultrafiltration + precision filter +ro+ mixed bed or EDI

5、 Common pipe materials in water treatment engineering

Main materials

Carbon steel pipe

Carbon steel pipe: used for raw water inlet pipeline.

UPVC pipe

UPVC pipe: it is better for the occasion with pipe diameter less than DN150 and convenient installation.

Stainless steel pipe

Stainless steel pipe: used in special occasions, mostly used in small medical systems.

Steel lining rubber or plastic pipe

Steel lining rubber or plastic pipe: used in large projects, reliable use, construction is more difficult.

6、 Various uses of pure water

Pure water and ultra pure water are widely used in power plants, electronics, medicine and chemical industries. Through filtration or ion exchange of various membranes, harmful ions in water are removed.

Power plant: the main indicators of desalted water quality of the multi-purpose desalted water in the power plant are: hardness is about zero, conductivity is ≤ 0.2 μ s.cm，SiO2≤20ppb。

Chemical plant: chemical water is diverse, and the water quality will not be higher than that of power plant, but some ions may be required. Therefore, primary or secondary reverse osmosis process is commonly used. The conductivity of effluent water is 5-10 μ s. Cm or more. If higher requirements are required, mixed bed or EDI is added behind.

Medicine: the water for medicine requires more conductivity and bacteria, and the material and material used in the system. Stainless steel products are more used. Usually, after pure water, sterilization device should be added.

Electronic industry: the electronic industry has the highest requirement for water, and most of the electronic water requirements reach 18 trillion. The requirement of resistivity is only a small part of electronic water, it has higher requirements for many ions, so it has special requirements for installation materials and pipes. The selection process is also the most complex. Usually, polishing mixed bed, ultrafiltration, sterilization, nitrogen sealing water tank and other devices are added after EDI, and the cost is also very high.

7、 The process usually used according to the water quality requirements

one

The conductivity of water production is required to be 10-20 μ s/cm

The conductivity of water production is required to be 10-20 μ S/cm, RO pretreatment + primary reverse osmosis (chemical industry)

two

Water conductivity 2-9 μ s/cm

Water conductivity 2-9 μ S/cm, RO pretreatment + secondary reverse osmosis (medicine, chemical industry) or ro pretreatment + softening + primary reverse osmosis +edi (medicine and chemical industry)

three

The conductivity of water production is less than 0.2-2 μ s/cm

The conductivity of water production is less than 0.2-2 μ S/cm, RO pretreatment + primary reverse osmosis + mixed bed

four

Water production resistance 5-13 m Ω.Cm

The water production resistance is 5-13 m Ω.Cm, and R0 pretreatment + softening + primary reverse osmosis +edi is adopted

Or ro pretreatment + secondary reverse osmosis +edi (medicine, chemical, electronic, power generation)

five

Water production resistance 13-17 m Ω.Cm

The water production resistance is 13-17 m Ω.Cm, and R0 pretreatment + softening + primary reverse osmosis + EDI + mixed bed is adopted

Or ro pretreatment + secondary reverse osmosis +edi+ mixed bed (medicine, chemical industry, electronics, power generation)

six

Water production resistance 18 m Ω.Cm

The water production resistance was 18 m Ω.Cm, and RO pretreatment + secondary reverse osmosis +edi+ mixed bed + sterilization + nitrogen seal were used.

8、 Key and difficult questions and answers of pure water treatment

ask

1. What are the main measures to reduce acid and alkali consumption?

answer

(1) Ensure the water quality of the water inlet;

(2) Ensure the regeneration quality and prolong the cycle of water production;  

(3) Ensure the quality and purity of the regeneration liquid, and strictly control the regeneration operation rules;

(4) Ensure the equipment is safe, reliable and normal.

ask

2. What are the reasons for the stability of colloids in water?

answer

(1) The colloid surface is charged;

(2) There is water level layer on the colloidal surface;

(3) The surface of the colloid adsorbs some substances that promote the stability of the colloid.

ask

3. What is the purpose of using coagulant aids?

answer

1) The structure of floc is improved to make the particles grow, strong and heavy;

2) Adjust the pH value and alkalinity of treated water to achieve the best coagulation conditions and improve the coagulation effect; Coagulant aid does not act as coagulation, but it can promote the coagulation process of impurities in water.

ask

4. What is the basic concept of coagulation?

answer

Because the colloidal particles in the water are negatively charged, they repel each other in the same sex, and at the same time, they constantly do "Brownian motion" in the water, which is extremely stable and not easy to sink. When an appropriate amount of coagulant is added, the micro colloidal particles in the water can destabilize, produce adsorption bridging effect, flocculate into flocs, and sink rapidly. This process is called coagulation.

ask

5. What are the main factors that affect the coagulation effect?

answer

1) PH of water: if the hydrolysis of PAC is added to produce Al (OH) 3 colloid, the solution is the smallest when pH is 6.5-7.5, and the coagulation effect is good;

2) Alkalinity of water: when alkalinity is insufficient, h+ is produced continuously during hydrolysis of coagulant, which reduces pH value and coagulation effect;

3) Water temperature: when the temperature is low, the viscosity of water is large, the hydrolysis speed is slow, the floc particles form slowly, and the structure is loose, and the particles are small and not easy to precipitate;

4) The composition of impurities in water: the properties and concentrations have a great influence on the coagulation effect.

ask

6. What is the relationship between the form of carbonate in water and pH value?

answer

1) When pH value is less than 4.3, only CO2 (free) is in water;

2) When pH = 8.3-3.4, more than 98% of them were hco3-;

3) When pH value is > 8.4, there is no CO2 in the water

ask

7. Purpose of water treatment in boiler?

answer

1)   Prevent the accumulation of sediment and corrosion in operation of water and steam of boiler body and auxiliary system. The efficiency of heat transfer and conduction of boiler is improved.

2)   Ensure the steam quality, prevent the fouling and corrosion of steam turbine components, reduce the boiler blowdown loss and improve economic benefits under the condition of ensuring water quality

ask

8. How does the centrifugal pump work?

answer

Centrifugal pump is to use impeller rotation to make water produce centrifugal force to work. Before starting, the pump shell and suction pipe must be filled with water, then start the motor to make the pump shaft drive the impeller and water to rotate at high speed. Water is thrown to the outer edge of impeller under centrifugal force, and then collected into the pump shell, and then flows into the water pressure pipeline of the pump through the passage of the scroll pump shell. At the same time, the center of the impeller of the pump is vacuum formed by the water being dumped. The water in the suction tank is sucked into the impeller through the suction pipe under the action of atmospheric pressure. The impeller is constantly rotating, and the water is constantly dumped and replenished. This forms a continuous water delivery of centrifugal pumps.

ask

9. What are the ways of boiler blowdown? What is the role of each?

answer

The boiler blowdown mode is as follows:

(1) Continuous discharge;

Continuous blowdown: it is continuously discharging boiler water from the drum. The main purpose is to prevent the excessive discharge of some small or suspended water slag from the salt content and silicon content in boiler water.

(2) Discharge water regularly.

Regular discharge: it is to discharge water slag, and the general discharge point is set at the bottom of water circulation system; It is better to discharge the water when the boiler is under load.

ask

10. What is resin regeneration?

answer

After a period of softening or desalination, the resin loses the ability of exchange ion; At this time, it can be reduced and regenerated by acid, alkali or salt, and its exchange capacity can be restored. This process of resin recovery is called resin regeneration.

ask

11. What are the main factors that affect the resin working exchange capacity?

answer

(1) The quality of water in the influent;

(2) The control index of exchange terminal;

(3) Height of resin layer;

(4) Water temperature and flow velocity;

(5) The regeneration effect of exchanger depends on the performance of resin itself.

ask

12. What are the chemical properties of the resin?

answer

1) Reversibility of ion exchange reaction, such as RH + Na + RNA + H+

2) Acidity and alkalinity: Roh R + O H-   ;   RH R + H+

3) Selectivity: the adsorption of different ions on ion exchange resin is different.

4) Resin exchange capacity

Cation exchange resin: Fe 3 + > Al 3 + > Ca 2 + > Mg 2 + > K + ≈ NH 4 + > Na+

Anion resin: SO42 - > NO3 - > Cl - > HCO3 - > HSI

ask

13. Working principle of mixed bed

answer

The mixed bed is a multi-stage compound bed with two kinds of resins in one exchange period, which is equivalent to many cation beds and anion beds connected in series. In such an exchanger, cation and anion ion exchange reactions are completed simultaneously, and the exchanged H + and oh - generate water. H + and oh - can not accumulate, eliminating the counter ion effect of ion exchange reaction, making the exchange reaction complete, The effluent quality reaches the water quality index of refined pure water.

ask

14. What is the pollution of mixed bed resin?

answer

1) Suspended pollution: mostly in the form of cation resin. Strengthen the pretreatment of raw water.

2) Organic pollution: mainly occurred in strong alkali cation resin. Main resuscitation method: soak the resin in the mixed solution of NaOH (1-4%) and NaCl (5-12%) for 24 hours.

3) Heavy metal ion iron pollution: mostly formed in anion resin, strengthen the corrosion of pipes and equipment, reduce the Fe content of influent water, and increase iron removal measures.

ask

15. What are the main reasons for the performance degradation of RO membrane?

answer

1) Chemical changes of membrane itself: hydrolysis of membrane, oxidation interference of free chlorine and active chlorine

2) The physical changes of membrane itself: the compaction of membrane makes the permeability rate decrease and the desalination rate increase; Fouling of membrane: fouling, microorganism and solid particles on the surface or inside of membrane.

ask

16. What are the precautions for starting the metering pump?

answer

(1) Check whether there is liquid level in the metering tank;

(2) Whether the outlet valve of the pump is fully open;

(3) Whether the entrance line of the dosing part is fully open;

(4) Check whether the dosing is normal;

(5) The dosing pump can be started only after it is confirmed to be correct.

ask

17. Process principle of security filter?

answer

It is the mechanical filtration with 5um porous PP filter element, so that the residual micro suspended particles and colloidal microorganisms in the water are intercepted or adsorbed on the surface and voids of the filter element. With the increase of water making time, the resistance of the filter element increases due to the solids. When the pressure difference between the inlet and outlet increases to 0.1MPa, the filter element should be replaced; The filter element of the filter is a replaceable cartridge filter rod.

ask

18. How to prevent the scaling of RO membrane?

answer

1)   Do a good job in the pretreatment of raw water, ensure the SOI < 4, and add bactericide to prevent the growth of microorganisms;

2)   In RO operation, the appropriate working pressure should be maintained. Generally, with the increase of working pressure, the water yield will also increase, but if it is too large, the membrane will be compacted.

3)   During ro operation, the flocculent state of concentrated water shall be maintained to reduce the concentration polarization of solution on the membrane surface and avoid the precipitation of insoluble salt on the membrane surface;

4)   When the RO is out of service, it is necessary to add chemicals for flushing in the short term and CH2O protection solution for protection in the long term.

5)   Chemical cleaning should be carried out when the RO produced water is obviously reduced or the salt content is increased, and the surface is scaling or polluted.

ask

19. What is backwashing of mixed bed? What are the conditions for backwashing? What is its purpose?

answer

When the resin in the mixed bed fails, wash the resin with a large flow from bottom to top with a water flow opposite to the water making direction to loosen the resin and remove pollutants. The operation method is called backwashing.

Backwashing conditions:

① After newly installed or newly added resin;

② The mixed bed reaches the operation cycle;

③ The rate of periodic water production decreased significantly;

④ The running resistance increases obviously.

Backwashing purpose:

① Loosen the resin layer to create good conditions for regeneration;

② Remove suspended solids, organic matter, microorganisms and other pollution during resin layer;

③ Remove debris caused by resin in operation.

ask

20. What are the common methods of water pretreatment? What is its main task?

answer

There are mainly: coagulation, clarification, filtration, adsorption, sterilization and other methods

Main tasks:

(1) Remove suspended matter, colloidal matter and organic matter in water;

(2) Reducing microbial substances;

(3) Remove heavy metal ions;

(4) Reduce the hardness and bicarbonate in water.

ask

21. The role of adding NaHCO3 in the desalination process of RO unit?

answer

Eliminate or reduce the residual chlorine content in water to ensure the stability of RO components. The residual chlorine of our company is less than 0.1mg/l.

ask

22. The function of setting electric slow opening automatic valve in front of RO membrane module?

answer

To prevent the sudden start-up and shut-down of high-pressure pump during ro operation, resulting in high-pressure impact on RO membrane components, forming water hammer and damaging RO membrane.

ask

23. What is filtration cycle? How many links are included? What is the role of each link?

answer

The filtration cycle is the actual running time between two backwashes

Including: filtration, backwashing, and washing three links

The purpose of backwashing is to remove the dirt accumulated in the filtration process and restore the interception capacity of the filtration medium

Is washing to ensure filtration operation? It is a necessary link for water to be qualified. Only after the washing is qualified, can it enter the periodic operation of water production.

ask

24. What is the harm of resin leaking into the thermal system?

answer

After the resin is leaked into the thermal system, it decomposes under the action of high temperature and high pressure and is transformed into acid, salt and gaseous products to reduce the pH value of boiler water.

ask

25. Function of each dosing device of reverse osmosis device

answer

1. Scale inhibitor dosing system:

It is mainly composed of scale inhibitor metering tank and scale inhibitor metering pump. In order to prevent the slightly soluble and insoluble salts dissolved in water from precipitating when the concentration on the concentrated water side of reverse osmosis exceeds the solubility product, the scale inhibitor is added in front of the reverse osmosis unit.

2. Reductant dosing system:

It is mainly composed of reductant dosing box and reductant metering pump. Since the influent of reverse osmosis device has strict requirements on residual chlorine (less than 0.1ppm), oxidant is added at the raw water inlet and ultrafiltration backwashing for sterilization, and reductant is added for reduction to meet the requirements of reverse osmosis influent. The dosing point is at the inlet main pipe of reverse osmosis unit.

3. Oxidant dosing system:

It is mainly composed of oxidant metering tank and oxidant metering pump. As the raw water is circulating sewage, which contains a lot of organic matter and oxides, adding bactericide can oxidize and kill most of the bacteria in the raw water, effectively prevent the biological pollution of the membrane system, and ensure the stable and reliable operation of the system.

4. Alkali dosing system:

It is mainly composed of alkali metering tank and alkali metering pump. It can be used for ultrafiltration or reverse osmosis chemical cleaning to remove organic matters adhered on the surface of ultrafiltration membrane or reverse osmosis membrane.

5. Acid dosing system

It is mainly composed of acid metering tank and acid metering pump. As the raw water is circulating sewage, the pH value is high and there is a trend of carbonate scale formation. Without acid addition, the LSI value of RO concentrated water side is 2.14. Acid addition can not only control the formation of carbonate scale, but also adjust the LSI value to below 1.8 to reduce the dosage of scale inhibitor. The dosing point is at the inlet main pipe of reverse osmosis unit.

ask

26. Principle of chlorine removal by activated carbon

answer

The removal of residual chlorine by activated carbon is not physical adsorption, but chemical reaction. When the free residual chlorine passes through the activated carbon, it will produce catalytic effect on its surface. The free residual chlorine will hydrolyze oxygen atoms quickly and react with carbon atoms to generate carbon dioxide. At the same time, the HClO in raw water is also rapidly converted into CO2 gas.

Comprehensive reaction: C + 2Cl2 + 2H2O → 4hcl + CO2 ↑

According to the above, the activated carbon in the reaction vessel will be gradually reduced according to the residual chlorine content in the raw water, and it should be supplemented appropriately every year.

ask

27. Reverse osmosis process principle

answer

Ro removes most of the salt in water by using the water permeability and salt impermeability of semi permeable membrane. Pressurize the raw water side of RO to make a part of pure water pass through the membrane along the direction perpendicular to the membrane. The salt and colloidal substances in the water are concentrated on the membrane surface, and the rest of raw water is taken away along the direction parallel to the membrane. There is only a small amount of salt in the permeated water. The purpose of desalination is achieved by collecting the permeated water.