1 What are the pretreatment equipment you know?

A: 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, aeration tank.

2 What do you know about the pre-desalting equipment?

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

3 What do you know about deep desalting equipment?

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

4 How is the mechanical filter selected? How does it work?

Answer: The selection of mechanical filter is based on the total water inflow of the system to select the size of the filter and the combination mode (if one mechanical filter is not enough, you can select multiple filters for parallel use and standby). For example, the total water inflow of the system can be calculated according to the ratio of the water recovery rate of the reverse osmosis system and the water yield of the system. The filler in the mechanical filter is made of many fine quartz sand with different particle sizes in strict order from large to small, thus forming a good quartz sand grading. When the filter is just put into use, the filtering effect is often not very good, because the filter does not form a "bridging" at the beginning. The so-called "bridging" refers to an intercepting net composed of suspended solids in the water, which intercepts suspended solids with the same particle size, and then intercepts suspended solids with smaller particle size, forming a reverse particle filtering process that intercepts large particles first, and then intercepts small particles. Once the filter is "bridged", the filtering effect is very good. With the extension of the time of putting into operation, the filtering accuracy becomes higher and higher, the intercepting screen becomes thicker and thicker, and the pressure difference between the inlet and outlet becomes larger and larger. When the pressure difference reaches 1kg/cm2, the filter should be backwashed. During the backwashing process, it is better to use compressed air to scrub the quartz sand. The general engineering experience is that mechanical filters with diameter less than 2500mm do not need compressed air; The mechanical filter with diameter greater than 2500mm must be scrubbed with compressed air to achieve satisfactory cleaning effect; The backwash flow is generally 3-4 times the design capacity of the filter. Most of the old mechanical filters use large pebbles as the foundation cushion, and the bottom is evenly perforated with convex steel plates to make the water distribution uneven, which is easy to produce high central filtration rate and low edge filtration rate; When the filter is backwashed, the phenomenon of quartz sand mixed layer will occur, which will inevitably lead to the leakage of filter material into the lower pipeline and precision filter, which will pose a serious threat to the precision filter and reverse osmosis device. Through continuous practice and experiment, many manufacturers have improved the mechanical filter. The water distribution device adopts perforated plate and special ABS water cap. This kind of ABS water cap has different functions of two-way output, that is, the output is small during operation, and the backwashing output can be increased several times, so that the water distribution of the filter is more uniform during washing, and the backwashing is more thorough, and the water quality is greatly improved. In order to prevent fine sand from penetrating the filter during operation or backwashing, the penetration clearance of the ABS water cap is very small, generally about 0.1-0.2mm. It is worth noting that during the filling process of filter filler, a certain amount of water must be injected into the filter to prevent large quartz sand from breaking the ABS water cap; In the process of installing the water cap, you should not wear hard shoes to prevent crushing the ABS water cap. The mechanical filter is equipped with a backwash water inlet limit butterfly valve to control and regulate the backwash water flow. The backwash strength should make the filter layer expand by 15-25%, and the backwash compressed air strength is generally 10-18 L/S.m2. Roots blower can be considered if there is no compressed air.

5 How is the precision filter selected? How many kinds of filter elements are there?

Answer: The selection of precision filter is matched with the total water inflow. The diameter of precision filter is selected according to the total water inflow. For the filter element with 40 "5um filtering accuracy, the water yield of a single filter element is about 2m3/h. The types of filter elements include polypropylene filter element, honeycomb filter element, spray fusion filter element, folding filter element, etc.

6 How to remove iron from water?

Answer: The iron in groundwater is usually ferrous iron, so ferrous iron must be oxidized to ferric iron. The oxidation process is completed by aeration. The aeration device fully contacts water with oxygen to produce natural oxidation; The aerated water passes through the iron and manganese removal filter for iron removal. If most of the iron in the water is trivalent iron, it will directly enter the iron and manganese removal filter for removal without aeration.

7 Why do some water types need to be equipped with carbon dioxide remover after passing through the cation exchanger?

Answer: The result of the exchange of metal ions in water and H+ions on the cation resin causes H+ions to enter the water. Therefore, the effluent of the cation exchanger is slightly acidic, making most of the HCO3 - in the water 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 anion exchange resin, It increases the burden of the anion exchanger and shortens the water production cycle of the anion exchanger. Usually, the CO2 remover is placed behind the cation exchanger, before the anion exchanger, and also before some pre-desalting systems such as reverse osmosis, while some places do not need to add the CO2 remover, all of which depend on the water quality and water type of the user.

8 What are the methods of corrosion prevention?

Answer: There are many anti-corrosion methods, such as rubber lining, epoxy, plastic lining, enamel, etc.

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

Answer: The reverse osmosis device mainly consists of high pressure pump, high pressure pump outlet gate valve (manual or electric), high and low pressure protection switch, inlet flow meter (optional), permeate flow meter, concentrated water flow meter, permeate conductivity meter, membrane module (pressure vessel, reverse osmosis membrane element), concentrated water electric valve, concentrated water stop valve, inlet pressure gauge, inter-segment pressure gauge, concentrated water pressure gauge, permeate pressure gauge, reverse osmosis support, reverse osmosis control panel Reverse osmosis sampling plate, bursting disc and corresponding pipes, clamps, elbows, etc.

What are the advantages and disadvantages of electrodialysis?

A:

The advantages of electrodialysis are:

1. Low energy consumption and small floor area.

2 Simple operation and low noise.

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

4. Little pollution to the environment.

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

The disadvantages of electrodialysis are:

1 The installation is complex.

2 The desalting effect is generally 75%.

3 The water recovery rate is generally 50%.

What are the brands of anion and cation heterogeneous ion exchange membranes? What are their characteristics?

Answer: The anion and cation heterogeneous ion exchange membranes mainly include Shanghai Chemical Plant 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 characteristics:

1. Strong selection permeability. The selective permeability is the main index to measure the performance of the membrane, which directly affects the current efficiency and desalting effect of the electrodialyzer, 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 is low and the current efficiency is high.

3 Strong chemical stability. In the process of anion and cation migration, the concentrated water chamber will form ionic solution with high concentration; When polarization occurs, the PH value of the retention layer on both sides of the membrane will also change, especially when the polar water participates in the chemical reaction, it will produce highly oxidizing oxygen and chlorine. Therefore, the membrane must have strong chemical stability to extend the service life of the electrodialyzer.

4 Strong mechanical strength and dimensional stability.

5 Low diffusivity.

6 has high removal effect for strong electrolyte.

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

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

Different electrode materials have different characteristics:

Platinum-plated titanium electrode: it has good corrosion resistance and can be used under very harsh conditions, but the high price of platinum and less resources limit its promotion in China.

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

Graphite electrode: graphite electrode is easy to be corroded, mainly due to chemical corrosion and mechanical wear; When graphite is used as anode, due to anodic oxidation, graphite is oxidized to CO2 or CO, and its crystal structure is damaged; In the electrodialysis device, the graphite electrode loss is mainly caused by mechanical action. The high flow rate of polar water has a strong scouring effect on the graphite. On the other hand, the gas generated by the electrode reaction has an impact on the graphite. In addition, electrochemical corrosion often causes the graphite particles to peel off and pollute the water quality and even block the polar water channel; With the appearance of titanium coated ruthenium electrode, graphite electrode has been gradually eliminated.

Stainless steel electrode: generally speaking, stainless steel can only be used as cathode instead of anode. Otherwise, because natural water contains more chloride ions, it will lead to the anodic dissolution of stainless steel to generate bivalent iron, nickel and chromium ions.

The correct selection of electrode materials is of great significance for prolonging the service life of the electrode, reducing the system investment and operating costs. For different water quality, electrodes of different materials can be selected:

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

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

3 For natural water with calcium bicarbonate as the main component, stainless steel and titanium coated ruthenium electrode 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 rooms, concentrated water rooms and extreme water rooms distinguished?

A: A positive membrane, a diaphragm and a negative membrane form a membrane pair. The positive membrane and the negative membrane form a water chamber in the middle. Under the action of the electric field, the ions in the water chamber move in a direction. When the ions in the water chamber leave the water chamber through traction and selective permeability of the membrane, the water chamber is called the fresh water chamber; On the contrary, when the ions enter the water chamber through traction and selective permeability of the membrane, the water chamber becomes a concentrated water chamber; The water chamber between the positive membrane, negative membrane or separator and the electrode becomes the polar water chamber.

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

Answer: The electrodialysis device is composed of several parts: negative membrane, positive membrane, diaphragm, electrode, clamping device, leak-proof rubber plate, acid cleaning system, flowmeter, pressure gauge, ABS pipe fittings, valve, silicon controlled rectifier cabinet.

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

The main material of the diaphragm is polypropylene, which supports the amniotic membrane and forms a concentrated fresh water chamber with it.

The electrode mainly forms the electric field required by the ion exchange membrane. The electrode is composed of cloth head, perforated plate and PVC frame.

The clamping device is mainly used to fix the anion and cation exchange membrane, electrode, separator, etc. into a whole.

The leak-proof rubber plate is between the electrode and the partition, which plays a role in preventing the system from leaking water at the edge of the electrode.

The pickling system is an indispensable part of the whole plant. When the desalting rate, water yield and operating pressure rise of the electrodialysis device are abnormal, it is necessary to judge the reason why the system is formed, such as scaling, inorganic fouling, organic fouling, etc., and take corresponding chemical agents for chemical cleaning.

The thyristor rectifier cabinet is the energy feed part of the device, which is used to rectify the power frequency alternating current into the DC voltage with adjustable voltage through the thyristor rectifier device, and add it on the electrode to form the DC electric field in the membrane stack to draw the anion and cation in the solution to produce directional movement. The main parameters of thyristor rectifier cabinet are: rectifier voltage, working current and rectifier power. Flowmeter, pressure gauge, ABS pipe fittings and valves are accessory parts of electrodialysis, which play a role in displaying various operating parameters of electrodialysis device, connection of water chamber and switching of water flow direction.

15 What is the desalting principle of 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, concentrated water or fresh water is formed in different water chambers by using the selective permeability of the anion and cation exchange membrane to penetrate or not penetrate the corresponding exchange membrane.

What is the distribution ratio of concentrated, dilute and polar water in electrodialysis?

Answer: The distribution ratio of concentrated water, fresh water and polar water in the electrodialysis device is about 4:4:2, so it is very meaningful to take measures to save polar water in the electrodialysis desalination system; Commonly used measures to save extreme water include discharging some concentrated water as extreme water or adopting extreme water circulation; The specific way of polar water circulation system is to use demineralized water or desalted water+NaCL solution as polar water circulation.

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

Answer: In the current water treatment industry, the automatic polarity reversal system for frequent concentrated water circulation is based on the programmable controller as the control core, and the operation time of the system's water production process as the control function. The electric or pneumatic straight-through valve and three-way valve are used to regularly switch the flow direction of concentrated fresh water, so that the fresh water always flows into the water production tank, while the concentrated water is discharged into the concentrated water circulation tank. In today's increasingly scarce water resources, the frequent automatic reversal system of concentrated water circulation has far-reaching significance. First, the water recovery rate of the system is high, which can reach 80% (depending on the quality of influent water). The water-saving effect is very obvious in some large water treatment systems. Second, the cost of the system is relatively low, and the requirements for the quality of the incoming water of the system are relatively low, which is easy to promote (it is more competitive in the water treatment projects of some enterprises or factories and mines that require high recovery rate and cannot invest more funds).

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

Answer: In water treatment system engineering, general pumps, booster pumps and anti-corrosion pumps are generally required. IS type cast iron pump is generally selected for common pump; Booster type water pump generally adopts stainless steel water pump, such as the high-pressure pump imported from Granf, Denmark (depending on the specific situation); IH chemical pump or engineering plastic pump is generally selected as the anti-corrosion pump.

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

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

A:

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 SDI requirement of the reverse osmosis device is SDI<5.

LSI: Langelier Saturation Index, Langelier index is used to measure the scaling tendency of reverse osmosis device, LSI=0, and the system has no scaling and corrosion tendency; LSI>0, the system tends to scale; LSI<0, the system is prone to corrosion. For the reverse osmosis system, the LSI value is required to be no more 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 penetrates the solvent and solute in the raw water. The concentration is generated due to the reduction of solvent at the concentrated water side. When the concentration of dissolved solids at the concentrated water side is greater than the solubility equilibrium constant, it will crystallize and precipitate, which will harm the reverse osmosis device. Adding scale inhibitor can increase the solubility equilibrium constant of the system, which can increase the solubility of dissolved solids.

How can the LSI index be effectively controlled?

Answer: To effectively control the LSI index of the system, we can do the following:

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

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

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

4. Easily structured ions in the water can be reduced or pre-removed, such as softening the system inlet water through the softening column.

What kinds of instruments and meters must be used in the reverse osmosis system?

Answer: Several necessary instruments and meters in the reverse osmosis system include:

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

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

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

4 Pressure gauge: measure the system inlet pressure, inter-section pressure, concentrated water pressure, and produced water pressure.

5 Inlet flow meter: used to measure the total inlet flow of the system.

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

7 Inlet water PH meter: used to measure the change of inlet water PH value of the system.

8 Inlet conductivity meter: used to measure the inlet conductivity of the system and determine the desalting rate of the system in combination with the conductivity of the produced water.

9 Oxidation-reduction instrument: used to measure the amount of oxidizing substances in the system inlet water to determine the degree of threat to the system safety.

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

A reverse osmosis system is relatively complex, and the instruments and meters used depend on the process requirements and user investment. The normal reverse osmosis system only needs the permeate flow meter, concentrated water flow meter, permeate conductivity meter, pressure gauge and high and low pressure protection.

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

Answer: "Water hammer" is because the pressure vessel is mixed with air, and the necessary means are not used to remove the air in the vessel when the device is started, so that the high-pressure water flow mixed with air will cause severe vibration when moving into the vessel, and in serious cases, the membrane elements will be smashed, resulting in irreparable losses. "Prevention first, prevention first", how to prevent "water hammer" phenomenon is very important. The measures generally taken include:

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

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

3 Use control to prevent avoidance. For example, use PLC to control an electric slow door opening and open the valve in tens of seconds.

4. Use the installation process to prevent, for example, setting a return pipe at the concentrated water discharge port, so that the highest point of the pipe exceeds the highest pressure vessel in the reverse osmosis device, so that the pressure vessel will be full of water when the device stops running. The above points are measures commonly used in engineering applications, which can be adopted either or according to the actual situation. It is worth noting that the fourth point of any project is necessary.

23 Why must the RO concentrated water discharge pipe be higher than the device?

Answer: The concentrated water discharge valve is always open during the reverse osmosis operation, so when the reverse osmosis device is stopped, if the highest point of the discharge pipe is lower than the highest point of the pressure vessel, "siphoning" will occur. The water in the pressure vessel 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, The second is that the oxygen in the air will produce more or less oxidation on the reverse osmosis membrane elements during shutdown operation, affecting the service life of the membrane elements.

24 Water inflow index of electrodialysis and reverse osmosis?

Answer: Water inflow indicators of electrodialysis include:

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 diaphragm) SDI is about equal to 0

Free chlorine: CL ≤ 0.3mg-0.5mg/l

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

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

25 Water inlet and outlet indicators of mechanical filter, iron and manganese removal filter and carbon dioxide removal device?

Answer: The influent suspended solids of the mechanical filter are ≤ 20mg/l, and the effluent suspended solids are ≤ 5mg/l. The iron content in the inlet water of the iron and manganese removal filter is ≤ 30mg/l, and the iron content in the outlet water is ≤ 0.3mg/l. The carbon dioxide content in the inlet water of the CO2 remover is ≤ 330mg/l, and the carbon dioxide content in the outlet water is ≤ 5mg/l.

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

Answer: When the working current of electrodialysis exceeds the limit current, water electrolysis is generated at the interface between the anion exchange membrane and fresh water, and H+and OH - ions are generated. When these ions participate in the charge transfer, polarization occurs. In short, the harm of polarization is to consume a kind of electric energy on the electrolytic water irrelevant to desalting, resulting in the waste of electric energy. In addition, after the OH - ion enters the concentrated water chamber and the CO32 - and CaCO3 scale, the performance of membrane and electrodialysis will be reduced. During polarization, the concentration of electrolyte ions on the membrane surface of the desalting chamber is much lower than the concentration of the main solution, resulting in a high polarization potential, while the concentration of the membrane surface of the concentrated water chamber is much higher than the concentration of the main solution, which makes the ions easy to form precipitation in the water precipitate on the membrane surface. The result is that the apparent resistance of the membrane pair increases significantly, the current density decreases, and the desalting rate decreases. The current efficiency decreases because a large part of the current is consumed in the electrolysis of water to generate H+and OH - ions instead of the consumed counter ions to transfer charges. If the negative membrane is polarized first, the H+ions generated by the water dissociation in the desalting chamber enter the concentrated water chamber through the positive membrane, making the membrane surface of the desalting chamber alkaline, which is easy to make Ca2+, Mg2+ions and CO32 - form CaCO3 precipitation. If the positive membrane is polarized first, the OH - ions generated by the hydrolysis of the desalting chamber enter the concentration chamber through the negative membrane, making the Ca2+and Mg2+ions blocked by the negative membrane easy to form scaling. The precipitation formed on the membrane surface is not only the increase of membrane resistance, the obvious increase of water and electricity consumption per unit, and the increase of water flow resistance, but also the corrosion of ion exchange membrane caused by the change of solution PH value, which shortens the service life.

27 How to control the concentration polarization phenomenon?

A:

1. Strictly control the operating current, which means that electrodialysis operates under the condition of lower than the limit current density.

2 Strengthen the transfer process in the electrodialysis chamber, such as using the mesh with good turbulence effect and high temperature electrodialysis.

3. Take measures such as regular acid cleaning, adding anti-scaling agent, and changing electrodes to eliminate the precipitation caused by concentration polarization.

4. Proper pretreatment can be adopted to improve the quality of system inlet water.

What are the characteristics of ultraviolet sterilizer?

A: The characteristics of ultraviolet sterilizer are as follows:

1. Ultraviolet sterilization is fast, efficient and effective.

2 Ultraviolet radiation will not change the physical and chemical properties of water, and will not bring pollution to pure water as introduced by additives.

3. It can be used under various water flows. It is simple to operate and convenient to use. It only needs to clean the quartz glass tube sleeve regularly.

4. Small size, portable, low power consumption and long service life.

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

A: The factors that affect the germicidal efficacy of UV are the intensity of UV, the wavelength of UV spectrum and the irradiation time. Precautions when using ultraviolet sterilizer are:

Installation position: The ultraviolet ray installation position should be as close as possible to the use point, but there should also be room for installing or pulling out the quartz tube sleeve from one end and replacing the lamp tube.

Flow rate: in the same sterilizer, when the ultraviolet radiation energy is constant and the bacterial content in the water changes little, the water flow rate through the sterilizer has a significant impact on the sterilization effect.

Physical and chemical properties of water: the color, turbidity and total iron content of water can absorb ultraviolet rays to varying degrees, which results in lower sterilization effect.

Lamp power: the ignition power of the lamp has a great impact on the sterilization efficiency.

Medium temperature 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 applicable tube sleeve are related to the ultraviolet transmittance. The quartz tube sleeve has high purity and efficiency.

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

What are the characteristics of ozone sterilizer?

A: Ozone is one of the most effective fungicides in water treatment. Only free chlorine can compare with ozone's bactericidal ability. The advantage of ozone disinfection is its high sterilization efficiency. It is also the most effective disinfectant so far, even for highly resistant microorganisms such as viruses and cysts. It can reduce the smell, taste and chroma of water supply, and the only remaining substance is dissolved oxygen during decomposition. In addition, the bactericidal ability of ozone is not affected by pH changes and ammonia. There is also a disadvantage of using ozone for disinfection, because electricity must be used to generate ozone and cannot be stored. When water quality and quantity change, it is difficult to adjust the demand for ozone in time. Experience has proved 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 oxidation ability is selective and does not generally produce oxidation. Substances that are easy to be oxidized, such as ethanol, are not easy to react with ozone.

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

Answer: In water quality analysis, the following problems should be paid attention to:

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

The water quality of the water sample should be stable or have no obvious change between adoption and analysis. The sampling quantity shall be 4-5 times of the sample quantity required for the test item to ensure the water sample quantity for repeated analysis and re-inspection. The minimum sampling quantity shall be subject to the requirements for ensuring the accuracy and precision of the analysis.

The contact time between the water sample and the sampling equipment shall be shortened as much as possible. The water sample shall flow through the pipeline at a high linear flow rate. If it is necessary to connect the intermediate flow path such as the pipeline and the valve when it is used, special attention shall be paid to the pollution problem of this intermediate link. Its material and cleaning requirements shall be consistent with those of the container.

For the items tested on site, such as PH value, dissolved oxygen, alkalinity, CO2, ferrous, ammonia nitrogen, residual chlorine, etc., the time interval from sampling to analysis should be shortened as much as possible, and online analysis and detection should be used as much as possible.

There shall be a record of sampling and a label shall be affixed to the sampling container, indicating the name, time, place, temperature, sampling volume, container and sampler of the sampling.