1 What kind of pre-processing equipment do you know?

Answer: Pretreatment equipment includes: mechanical filter, high-efficiency fiber filter, activated carbon filter, precision filter, ultrafiltration, microfiltration, sodium ion softener, iron and manganese removal filter, dosing device, raw water tank, exposure gas pool.

2 What pre-desalting equipment do you know?

Answer: Pre-desalting equipment includes electrodialysis device and reverse osmosis device.

3 What are the deep desalination equipment you know?

Answer: The deep desalination equipment includes anion exchanger, cation exchanger, mixed ion exchanger, distillation unit, EDI unit

4 How is the mechanical filter selected? What is its working principle?

Answer: The selection of the mechanical filter is based on the total water inflow to the system to select the size and combination of the filter (one mechanical filter is not enough to choose multiple parallel use and the number of spares), such as water recovery according to the reverse osmosis system The ratio of the ratio of the rate and the water output of the system to the total water inflow of the system.

The packing in the mechanical filter is composed of many refined quartz sands of different particle sizes in strict order from large to small, thus forming a good quartz sand gradation. When the filter is just put into use, the filtering effect is often not very good, because the filter does not form a "bridge" at the beginning. The suspended solids with the same particle size will then intercept the suspended solids with smaller particle sizes, forming an inverse particle size filtration process that intercepts large particles first and then intercepts small particles.

Once the filter forms a "bridge", the filtering effect is very good. As the operation time is prolonged, the filtering accuracy is getting higher and higher, the intercepting net is getting thicker, and the pressure difference between the inlet and outlet is getting larger and larger. When the pressure difference reaches 1kg /cm2 The filter should be backwashed. It is best to use compressed air to scrub the quartz sand during the backwashing process. The general engineering experience is that the mechanical filter with a diameter of less than 2500mm does not need compressed air; The filter must be scrubbed with compressed air to achieve a satisfactory cleaning effect; the backwash flow is generally 3-4 times the design capacity of the filter.

Most of the old-fashioned mechanical filters use large pebbles as the basic cushion, and the bottom is evenly punched with permeable holes with convex steel plates, so that the water distribution is uneven, and it is easy to produce a large central filtration rate and a small edge filtration rate; after the filter is backwashed When the quartz sand is mixed, the filter material will inevitably leak into the lower pipeline and precision filter, which will pose a serious threat to the precision filter and reverse osmosis device.

After continuous practice and experiments, many manufacturers have improved the mechanical filter. The water distribution device adopts a porous plate to install a special form of ABS water cap. This kind of ABS water cap has different functions of bidirectional output, that is, the output is small during operation. , The backwash output force can be increased several times, so that the water distribution of the filter is more uniform when the filter is being washed, and the backwash is more thorough, and the quality of the water is greatly improved.

In order to prevent fine sand from permeating the filter during operation or backwashing, the permeation gap of this ABS water cap is very small, generally around 0.1-0.2mm. It is worth noting that in the process of filling the filter filler, a certain amount of water must be injected into the filter to prevent the large quartz sand from breaking the ABS water cap; in the process of installing the water cap, hard shoes cannot be worn To prevent stepping on the ABS water cap.

The mechanical filter is equipped with a backwash water inlet limit butterfly valve to control and adjust the backwash water flow. The backwash strength should make the filter layer expand by 15-25%, and the backwash compressed air strength is generally 10-18L/S.m2. If there is no compressed air, consider using a Roots blower.

5 How is the precision filter selected? How many ways are there for the filter element?

Answer: The selection of the precision filter is matched with the total water inflow, and the diameter of the precision filter is selected according to the total water inflow. For a filter element with a filtration accuracy of 40"5um, the water yield per root is roughly 2m3/h. The types of filter elements include polypropylene filter elements, honeycomb filter elements, spray-melt filter elements, and pleated filter elements.

6 How to remove iron in water?

Answer: The iron in groundwater is generally ferrous ferrous, so ferrous ferrous must be oxidized to ferric iron. The oxidation process is completed by aeration. The aeration device fully contacts the water with oxygen to produce natural oxidation ;The aerated water goes through the iron and manganese removal filter to remove iron. If most of the iron in the water is trivalent iron, it does not need to be aerated and directly enters the iron and manganese removal filter for removal.

7 Why do some water types have to add a carbon dioxide remover after passing through the cation exchanger?

Answer: As a result of the exchange of metal ions in water and H+ ions on the cation resin, H+ ions enter the water, so the effluent of the cation exchanger is acidic, so that most of the HCO3- in the water is converted into H2CO3 and further converted into CO2 gas, Due to the low solubility of CO2 gas, one is to provide good conditions for degassing, and the other is that if degassing is not carried out, H2CO3 will be exchanged with the anion exchange resin, which increases the burden on the anion exchanger and shortens the anion exchanger. water production cycle.

Usually the carbon dioxide remover is placed after the cation exchanger, in front of the anion exchanger, and before some pre-demineralization systems such as reverse osmosis, but in some places, there is no need to add a carbon dioxide remover, all of which depend on the water quality of the user. Certainly.

8 How many ways are there to prevent corrosion?

A: There are various anti-corrosion methods such as rubber lining, epoxy, plastic lining, and enamel.

9 What equipment is the reverse osmosis device mainly composed of?

Answer: The reverse osmosis device is mainly composed of high pressure pump, high pressure pump outlet gate valve (manual or electric), high and low pressure protection switch, inlet water flowmeter (or not), produced water flowmeter, concentrated water flowmeter, produced water conductivity meter, Membrane module (pressure vessel, reverse osmosis membrane element), concentrated water electric valve, concentrated water shut-off valve, inlet water pressure gauge, interstage pressure gauge, concentrated water pressure gauge, produced water pressure gauge, reverse osmosis bracket, reverse osmosis control panel , reverse osmosis sampling plate, bursting membrane and corresponding pipes, clamps, elbows, etc.

10 What are the advantages and disadvantages of electrodialysis?

Answer: The advantages of electrodialysis are:

1 Low energy consumption and small footprint.

2 Simple operation and low noise.

3 The water quality of the effluent is stable, and there is no phase change during the desalination process.

4 The pollution of the environment is small.

5 The applicable range is 200-40000mg/h.

The disadvantages of electrodialysis are:

1 Installation is more complicated.

2 The desalination effect is not very complete, generally 75%.

3 The low water recovery rate is generally 50%.

11 What are the brands of yin and yang heterophase ion exchange membranes? What characteristics do they have?

Answer: The yin and yang heterogeneous ion exchange membranes mainly include Shanghai Chemical Factory Shuanghua brand heterogeneous ion exchange membrane, Lin'an heterogeneous ion exchange membrane, Beijing Shunyi heterogeneous ion exchange membrane, etc. A good quality heterogeneous ion exchange membrane must have the following Features:

1 Select strong permeability. Selective permeability is the main index to measure membrane performance, which directly affects the current efficiency and desalination effect of electrodialyzers, and its selective permeability is greater than 85%.

2 The film resistance is small. The electrodialyzer consists of hundreds of pairs of ion exchange membranes, so the membrane resistance accounts for a large proportion of the total resistance. If the resistance is small, the operating voltage will be low and the current efficiency will be high.

3 Strong chemical stability. In the process of the migration of anions and cations, a concentrated ion solution will be formed in the concentrated water chamber; when polarization occurs, the PH value of the retention layer on both sides of the membrane will also change, especially when polar water participates in chemical reactions, it will produce oxidative polar Strong oxygen and chlorine, so the membrane must have strong chemical stability to prolong the life of the electrodialyzer.

4 Strong mechanical strength and dimensional stability.

5 Lower diffusivity.

6 has a high removal effect on strong electrolytes.

12 What material is the electrode of electrodialysis made of? What are the specifications? What are the advantages and disadvantages of each?

Answer: Electrodialysis electrodes are divided into several types: titanium-plating electrodes, titanium-coated ruthenium electrodes, graphite electrodes, and stainless steel electrodes; the electrodes vary according to the size of the electrodialysis body. Common engineering electrode specifications are: 800× 1600mm, 400×1600mm, 400×800mm, 340×640mm, etc.

Different electrode materials have different characteristics:

Titanium platinized electrode: The corrosion resistance is quite good, and it can be used under very harsh conditions, but the price of platinum is expensive and the resources are few, which limits its promotion in China.

Titanium-coated ruthenium electrode: It is a compound of ruthenium (Ru), iridium (Ir), and titanium (Ti) coated on a titanium substrate, and its mixed oxide is formed after high temperature treatment; due to ruthenium (Ru), iridium (Ir), The ionic radius of titanium (Ti) is very close, and the lattice structure and space group belong to the same type, so it can form a solid solution of RuO2-IrO2-TiO2 in the co-oxidation of heat treatment, which has excellent corrosion resistance and is very suitable as an electrode material.

Graphite electrode: Graphite electrode is easily corroded, mainly due to chemical corrosion and mechanical wear; when graphite is used as an anode, due to anodic oxidation, graphite is oxidized to CO2 or CO, and its crystal structure is destroyed and damaged; in the electrodialysis device The loss of medium graphite electrode is mainly caused by mechanical action. The high flow rate of polar water has a strong scouring effect on graphite. On the other hand, the gas generated by the electrode reaction has an impact on graphite. Coupled with electrochemical corrosion, it often causes graphite Particle exfoliation pollutes water quality and even blocks polar water channels; with the advent of titanium-coated ruthenium electrodes, graphite electrodes have been gradually eliminated.

Stainless steel electrode: Generally speaking, stainless steel is only used as a cathode and cannot be used as an anode. Otherwise, because the natural water contains more chloride ions, the anode of stainless steel will dissolve to generate divalent iron, nickel and chromium ions.

The correct selection of electrode materials is of great significance to prolong the service life of electrodes, reduce system investment and operating costs, and choose electrodes of different materials for different water quality:

1 For natural water with chloride as the main component, titanium-coated ruthenium electrodes can be preferred.

2 For natural water with sulfate as the main component, lead plate, stainless steel and titanium-coated ruthenium electrodes can be preferred.

3 For natural water with calcium bicarbonate as the main component, stainless steel and titanium-coated ruthenium electrodes can be preferred.

4 For natural water with mixed ions, titanium-coated ruthenium, graphite and titanium-coated platinum electrodes can be preferred.

13 How are fresh water chambers, concentrated water chambers, and extreme water chambers distinguished?

Answer: A cationic membrane, a separator, and an anion membrane form a membrane pair, and a water chamber is formed between the cationic membrane and anion membrane. Under the action of the electric field, the ions in the water chamber move in a direction. When the ions in the water chamber When the water chamber leaves the water chamber through traction and the selective permeability of the membrane, the water chamber is called a fresh water chamber; on the contrary, when ions enter the water chamber through the traction and the selective permeability of the membrane, the water chamber becomes a concentrated water chamber ; The water chamber generated between the anodic film, the negative film or the separator and the electrode becomes the polar water chamber.

14 What are the parts of the electrodialysis device? What are the characteristics and functions of each part?

A: The electrodialysis device is composed of several parts, anion membrane, anode membrane, separator, electrode, clamping device, leak-proof rubber plate, pickling system, flow meter, pressure gauge, ABS pipe fittings, valves, controllable Silicon rectifier cabinet.

The selective permeability of the anion membrane and the anode membrane to the ions in the water makes the system divided into concentrated water, fresh water and extreme water, which is the desalination part of the device.

The main material of the separator is polypropylene, which plays the role of supporting the pudendal membrane and forming a concentrated fresh water chamber with it.

The electrodes mainly form the electric field required for the ion exchange membrane. The electrode consists of a water distribution head, a porous plate, and a PVC frame.

The clamping device is mainly to fix the anion and cation exchange membranes, electrodes, separators, etc. to make them a whole.

The leak-proof rubber sheet is between the electrode and the separator, which prevents the system from leaking water near the electrode.

The pickling system is an indispensable part of the whole device. When the electrodialysis unit produces abnormal phenomena such as a decrease in desalination rate, a decrease in water production, and an increase in operating pressure, it should be determined what the system is due to, such as scaling, inorganic fouling, organic fouling, etc., and take corresponding chemicals. Perform chemical cleaning.

The thyristor rectifier cabinet is the energy feeding part of the device. It rectifies the power frequency alternating current through the thyristor rectifier to a DC voltage with adjustable voltage, and adds it to the electrode to form a DC electric field in the membrane stack to draw the yin and yang in the solution. The ions produce directional movement.

The main parameters of the thyristor rectifier cabinet are: rectified voltage, working current and rectified power. Flow meters, pressure gauges, ABS pipes and fittings, and valves are the accessories of electrodialysis, which play the roles of displaying various operating parameters of the electrodialysis device, connecting the water chamber and switching the direction of water flow.

15 What is the principle of desalination by electrodialysis?

Answer: The anion and cation exchange membrane in the electrodialysis device has selective permeability. When the ions in the solution move directionally under the action of the electric field, the selective permeability of the anion and cation exchange membrane is used to pass through or not through the corresponding The exchange membrane forms concentrated or fresh water in different water compartments.

16 What is the approximate distribution ratio of concentrated, light and polar water in electrodialysis?

Answer: The distribution ratio of concentrated water, fresh water and extreme water in the electrodialysis device is roughly 4:4:2, so it is very meaningful to save extreme water in the electrodialysis desalination system; measures to save extreme water are commonly used. Some of the concentrated water is discharged as the polar water or adopts the polar water circulation; the specific method of the polar water circulation system is softened water or demineralized water + NaCL solution as the polar water circulation.

17 How is the frequent automatic reverse pole system of concentrated water circulation realized? What is its significance?

Answer: In the current water treatment industry, the automatic pole-reversing system with frequent concentrated water circulation takes the programmable controller as the control core, takes the running time of the water production process of the system as the control function, and uses electric or pneumatic straight-through valves and three-way valves for timing Switch the flow direction of the concentrated fresh water, so that the fresh water always flows into the production water tank, and the concentrated water is fixedly discharged into the concentrated water circulation tank.

In today's increasingly scarce water resources, the automatic reverse pole system with frequent concentrated water circulation has far-reaching significance. First, the water recovery rate of this system can reach 80% (depending on the quality of the influent water). In some large-scale water treatment systems The effect of water saving is very obvious.

Second, the cost of the system is relatively low, the requirements for the water quality of the system are relatively low, and it is easy to popularize (competitive in some water treatment projects of enterprises or factories and mines that have high requirements for recovery rates but cannot invest more funds) force).

18 What types of pumps are needed in water treatment system engineering? How to select the types of pumps from different manufacturers?

Answer: Generally, ordinary pumps, booster pumps and anti-corrosion pumps are needed in water treatment system engineering. Ordinary pumps generally use IS type cast iron pumps; pressurized pumps generally use stainless steel pumps such as high-pressure pumps imported from Denmark's Granf (depending on the specific situation); anti-corrosion pumps generally use IH type chemical pumps or engineering plastic pumps.

The pump models of different manufacturers are different. First, select the flow rate of the pump according to the process requirements of the system; secondly, select the lift of the pump according to the process requirements (1 kg is about 10 meters of lift, 1MPa is about 10 kg); again according to the process requirements. Select the material of the water pump (mainly refers to the material of the pump head); finally, according to the power consumption of various pumps, select the water pump that can meet the process requirements and save the energy consumption of the system.

19 Several basic concepts in water treatment system: TDS, SDI, LSI, KSP

answer:

TDS: total dissolved solids (generally similar to salinity)

SDI: The pollution index is an index to measure the pretreatment effect of the system. SDI<6.7. For deep well water, the reverse osmosis device requires SDI<5 for the influent SDI.

LSI: Langelier Saturation Index, Langelier index is a measure of the fouling tendency of the reverse osmosis device. LSI=0, the system has no fouling and corrosion tendency; LSI>0, the system has a fouling tendency; LSI<0, the system has a corrosion tendency. For reverse osmosis systems, the LSI value is required not to be greater than 0. The LSI value of the system can be reduced by adding acid or by reducing the water recovery rate of the system.

Ksp: Solubility equilibrium constant, the reverse osmosis device selectively permeates the solvent and solute in the raw water, and concentration occurs on the concentrated water side due to the reduction of the solvent. When the concentration of the dissolved solids on the concentrated water side occurs because the concentration product is greater than the solubility equilibrium constant. It will crystallize out, which will cause harm to the reverse osmosis device. To increase the solubility equilibrium constant of the system, scale inhibitors can be added, which can increase the solubility of dissolved solids.

20 How can the LSI index be effectively controlled?

Answer: To effectively control the LSI index of the system, the following aspects can be used:

1 The system LSI index can be reduced by reducing the system water recovery rate.

2 The system LSI index can be reduced by adding acid.

3 The solubility of dissolved salts in the system can be increased by adding corresponding agents, such as adding TRISPE1000 scale inhibitor.

4 The water can be softened by reducing or pre-removing the ions that are easy to structure in the water, such as softening the system inlet water through a softening column.

21 Which instruments and meters must be used in a reverse osmosis system?

Answer: Several kinds of instruments and meters are necessary in the reverse osmosis system:

1 Pollution index meter: used to measure the SDI index of system pretreatment.

2 Concentrated water flowmeter: used to measure the flow of concentrated water in the system, and used in conjunction with the produced water flowmeter to determine the system recovery rate.

3 Product water flow meter: used to measure the flow rate of the system product water. Produced water conductivity meter: used to measure the water quality (conductivity) of the water produced by the system

4 Pressure gauge: measure the system inlet water pressure, interstage pressure, concentrated water pressure, and product water pressure.

5 Influent flow meter: used to measure the total influent flow of the system.

6 Thermometer: used to measure the operating temperature of the system.

7 Influent PH meter: It is used to measure the change of the PH value of the influent water of the system.

8 Influent conductivity meter: used to measure the conductivity of the influent water of the system, and used in conjunction with the conductivity of the produced water to determine the desalination rate of the system.

9 Redox meter: It is used to measure the amount of oxidizing substances in the influent water of the system to determine the degree of threat to the security of the system.

10 High and low pressure protection switch: used to protect the system from running under low pressure (insufficient water supply) and high pressure.

A reverse osmosis system is more complicated, and the instrumentation used is determined by the process requirements and user investment. A normal reverse osmosis system only needs a product water flowmeter, a concentrated water flowmeter, a product water conductivity meter, a pressure gauge, and high and low pressure protection.

22 What is water hammer? How to solve this problem?

Answer: "Water hammer" is caused by the fact that there is air mixed in the pressure container, and the necessary means are not used to remove the air in the container when the device is started, so that the high-pressure water flow mixed with the air moves into the container to produce severe vibrations, serious When the membrane element is hit, it will smash and cause irreversible losses. "Prevention first, prevention first", how to prevent the phenomenon of "water hammer" is very important. The measures generally taken are:

1 The high-pressure pump is avoided by soft start, such as step-down start, variable frequency speed control start, and series resistance start with automatic controller.

2 Avoid in the operation mode, such as closing or closing the inlet valve at startup, and then slowly opening the valve until the working pressure of the system is reached.

3 Use control to prevent and avoid, such as using PLC to control an electric slow door, open the valve within tens of seconds.

4. Use the installation process to prevent, such as setting a return pipeline at the concentrated water discharge port, so that the highest point of the pipeline exceeds the highest pressure vessel in the reverse osmosis device, so that when the device stops running, the pressure vessel will be full of water. The above points are the measures that are often used in engineering applications. They can be adopted or adopted according to the actual situation. It is worth noting that the fourth point is required no matter which project.

23 Why does the reverse osmosis concentrate discharge pipe have to be a little higher than the device?

Answer: The concentrated water discharge valve is always open during reverse osmosis operation, so when the reverse osmosis device stops running, if the highest point of the discharge pipe is lower than the highest point of the pressure vessel, a "siphon" phenomenon will occur, and the pressure vessel will The water will flow out of the reverse osmosis device through the concentrated water discharge pipe due to its own weight, and air will be mixed in the pressure vessel. First, it is easy to cause water hammer phenomenon. More or less oxidation will affect the service life of the membrane element.

24 Influent indicators of electrodialysis and reverse osmosis?

Answer: The influent indicators of electrodialysis are:

Temperature range: 4-40℃ Iron and manganese content: Fe≤0.3mg/l, Mn≤0.1mg/l

Turbidity: less than 0.3mg/l (for 0.9mm thick separators) SDI is approximately equal to 0

Free chlorine: CL≤0.3mg-0.5mg/l

The influent indicators of reverse osmosis are: iron content: Fe≤1mg/l free chlorine: CL≤0.1mg

SDI: less than 4 Temperature range: 5-45℃ Turbidity: less than 1NTU

25 Mechanical filter, iron and manganese removal filter, carbon dioxide remover inlet and outlet water indicators?

Answer: The influent suspended solids of the mechanical filter are ≤20mg/l, and the effluent suspended solids are ≤5mg/l. The iron content of the influent water of the iron and manganese removal filter is less than or equal to 30mg/l, and the iron content of the effluent is less than or equal to 0.3mg/l. The carbon dioxide content of the influent water of the carbon dioxide remover is less than or equal to 330mg/l, and the carbon dioxide content of the effluent is less than or equal to 5mg/l.

26 What is the phenomenon of concentration polarization of electrodialysis? What are the hazards of concentration polarization?

Answer: When the working current of electrodialysis exceeds the limit current, water electrolysis occurs at the interface between the anion exchange membrane and fresh water, and H+ and OH- ions are generated. When these ions participate in the transfer of charges, polarization occurs.

In short, the hazard of polarization is that a kind of electric energy is consumed on the electrolyzed water that is not related to desalination, thus causing a waste of electric energy, and OH- ions enter the concentrated water chamber and scale with CO32- and CaCO3, causing membrane and electrodialysis. performance drops.

During polarization, the concentration of electrolyte ions on the membrane surface of the desalination chamber is much lower than that of the main solution, causing a high polarization potential, while the concentration of the membrane surface of the concentrated water chamber is much higher than that of the main solution, which makes it easy to form precipitates in the water. The ions are precipitated on the membrane surface, and the result is that the apparent resistance of the membrane increases significantly, the current density decreases, and the salt rejection rate decreases.

The current efficiency drops because a large portion of the current is consumed on the electrolysis of water to generate H+ and OH- ions instead of consumed counter ions to transfer charge. If the anion membrane is polarized first, the H+ ions generated by water dissociation in the desalination chamber pass through the cationic membrane and enter the concentrated water chamber, making the membrane surface of the desalting chamber alkaline, and it is easy to cause Ca2+, Mg2+ ions and CO32- to form CaCO3 precipitation.

If the anodic membrane is polarized first, the OH- ions generated by the hydrolysis in the desalination chamber pass through the anion membrane and enter the concentration chamber, so that the Ca2+ and Mg2+ ions blocked by the anion membrane are easy to form scaling. The precipitation formed on the membrane surface is not only due to the increase of membrane resistance, the significant increase of power consumption per unit of water produced, and the increase of water flow resistance, but also due to the change of the pH value of the solution, the ion exchange membrane is corroded and the service life is shortened.

27 How to control the phenomenon of concentration polarization?

answer:

1 The operating current is strictly controlled, and the electrodialysis is operated under the condition that the current density is lower than the limit.

2 Strengthen the transfer process in the electrodialysis compartment, such as using a partition screen with good turbulence effect, high temperature electrodialysis.

3 Take measures such as regular pickling, adding anti-scaling agent, and switching electrodes to eliminate the precipitate caused by the phenomenon of concentration polarization.

4 Appropriate pretreatment can be used to improve the quality of the influent water to the system.

28 What are the characteristics of UV sterilizer?

Answer: The characteristics of UV sterilizer are as follows:

1 Ultraviolet sterilization is fast, efficient and effective.

2 Ultraviolet irradiation will not change the physical and chemical properties of water, and will not bring pollution to pure water such as the addition of additives.

3 It can be used under various water flow, simple operation and convenient use, only need to clean the quartz glass tube sleeve regularly.

4 Small size, light weight, low power consumption and long life.

29 What are the factors and precautions that affect the effect of ultraviolet sterilizers?

Answer: The factors that affect the effect of ultraviolet sterilization are the intensity of ultraviolet rays, the wavelength of the ultraviolet spectrum and the irradiation time. Things to pay attention to when using UV sterilizers are:

Installation location: The UV installation location is as close to the point of use as possible, but there should also be room for inserting or extracting the quartz tube sleeve from one end and replacing the lamp tube.

Flow rate: In the same sterilizer, when the radiation energy of ultraviolet rays is constant and the bacterial content in the water does not change much, the flow rate of water passing through the sterilizer has a significant impact on the sterilization effect.

The physical and chemical properties of water: the color, turbidity, and total iron content of water have different degrees of absorption of ultraviolet rays, and as a result, the effect of sterilization is reduced.

Lamp power: The lighting power of the lamp has a great influence on the sterilization efficiency.

The temperature of the medium around the lamp: the radiant spectral energy of the ultraviolet lamp is related to the temperature of the lamp wall.

Quartz tube sleeve: The quality and wall thickness of the tube sleeve are related to the transmittance of ultraviolet rays. The purity of the quartz tube sleeve is high and the efficiency is good.

Thickness of water layer: The thickness of water layer has a great relationship with the bactericidal effect.

30 What are the characteristics of ozone sterilizer?

Answer: Ozone is one of the most effective bactericides in water treatment. Only free chlorine can compare with the bactericidal ability of ozone. The advantage of disinfection with ozone is its high bactericidal efficiency, and it is by far the most effective disinfectant even against highly resistant microorganisms such as viruses and cysts.

It reduces the smell, taste and color of the feedwater, and the only thing left over when it decomposes is dissolved oxygen. In addition, the germicidal ability of ozone is not affected by pH changes and ammonia. Disinfection with ozone also has a downside, because electricity must be used to generate ozone, and it cannot be stored. When encountering changes in water quality and water quantity, it is difficult to adjust the amount of ozone required in time.

Experience has shown that ozone is most suitable for water plants with low water consumption and stable water consumption; in addition, although ozone is a strong oxidant, its oxidizing ability is selective and does not generally produce oxidation. Not easy to interact with ozone.

31 What should be paid attention to in water sample collection in water quality analysis?

Answer: The following questions should be paid attention to when collecting water samples in water quality analysis:

Sampling should be representative, that is, the water samples taken can represent the water quality of the entire water body.

The quality of the water samples should be stable or not significantly changed between use and analysis. The sampling volume should be 4-5 times the required sample volume of the test item to ensure the water sample volume for repeated analysis and re-inspection. The minimum sampling volume should be subject to the requirements of ensuring the accuracy and precision of the analysis.

The contact time between the water sample and the sampling equipment should be shortened as much as possible. The high linear flow rate should be adopted when the water sample flows through the pipeline. If it is necessary to connect intermediate flow paths such as pipelines and valves, special attention should be paid to the pollution of this intermediate link. The requirements for cleaning should be consistent with the container used.

Items tested on site, such as PH value, dissolved oxygen, alkalinity, CO2, ferrous iron, ammonia nitrogen, residual chlorine, etc., should be as short as possible from sampling to analysis, and online analysis should be used as much as possible.

Records of use should be kept and labels should be attached to the sampling container, indicating the name, time, location, temperature, sampling volume, container and person of sampling.