FAQ

1. What is sewage treatment?

Wastewater treatment refers to the process of treating domestic sewage, industrial wastewater and other water containing harmful substances to remove or reduce pollutants so that they meet environmental emission standards or reusable water quality requirements.

2. What are the steps of sewage treatment?

Sewage treatment generally includes four steps: pretreatment, primary treatment, intermediate treatment and advanced treatment. Pretreatment mainly removes large particles and sediments; primary treatment removes floating matter, organic matter and some inorganic matter through physical and chemical methods; intermediate treatment mainly uses biological treatment technology to use microorganisms to degrade organic pollutants; advanced treatment removes difficult-to-degrade organic matter and trace pollutants through further physical, chemical and biological methods.

3. What are the methods of sewage treatment?

Common sewage treatment methods include physical treatment, chemical treatment and biological treatment. Physical treatment includes screen grit chamber and sedimentation tank, etc. Chemical treatment mainly uses coagulation, flocculation and oxidation, etc. Biological treatment uses microorganisms to degrade organic matter.

4. What are the sewage treatment equipment?

Common sewage treatment equipment includes screen machines, grit chambers, gas chambers, activated sludge tanks, coagulation sedimentation tanks, filter tanks, ultraviolet disinfectors, etc. These equipment are used to remove different pollutants in sewage according to different treatment steps and methods.

5. What can the treated sewage water be used for?

The water after sewage treatment can meet the environmental discharge standards and can also be used for agricultural irrigation, industrial circulating cooling water, urban greening, etc. Some areas also use the treated water for drinking water replenishment, and through further advanced treatment, its water quality meets the drinking water standards.

6. What are the impacts of sewage treatment on the environment?

Wastewater treatment has many positive effects on the environment. First, it can effectively remove harmful substances in sewage, reduce water pollution, and protect water resources. Second, the treated water can meet environmental emission standards and reduce the load on the natural water environment. In addition, sewage treatment can also reduce eutrophication of water bodies and the death of aquatic organisms, maintaining ecological balance.

7. What are the challenges of wastewater treatment?

The challenges faced by sewage treatment mainly include treatment scale, treatment process and operation management. With the increase of urban population and industrial development, the scale of sewage treatment needs to be continuously expanded. At the same time, different types of sewage pollutants are complex and diverse, and appropriate treatment processes need to be selected. In terms of operation management, it is necessary to ensure the normal operation of equipment and timely maintenance and repair.

8. What is the future development trend of sewage treatment?

The future development trend of sewage treatment is mainly reflected in technological innovation and resource utilization. With the advancement of science and technology, new treatment technologies such as membrane separation and biofilm reactors will be widely used. At the same time, organic matter and energy resources in sewage will be more effectively recycled and utilized to achieve resource utilization.

9. Does sewage treatment need government support?

Yes, sewage treatment needs government support. While formulating relevant laws, regulations and standards, the government should strengthen supervision over the construction and operation of sewage treatment facilities to ensure their normal operation. The government can also provide financial support and technical guidance to promote the innovation and promotion of sewage treatment technology.

10. What is the significance of sewage treatment?

The significance of sewage treatment is to protect water resources, improve the quality of water environment, reduce the impact of water pollution on the ecosystem, and improve people’s quality of life. Through effective sewage treatment, sustainable development can be achieved and the earth’s home can be protected.

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

(1) Ensure the quality of incoming water;

(2) Ensure the quality of regeneration and extend the water production cycle.

(3) Ensure the quality and purity of the regeneration fluid and strictly control the regeneration operating procedures

(4) Ensure that the equipment operates safely, reliably and normally.

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

(1) The colloid surface is charged;

(2) There is a water layer on the surface of the colloid

(3) The surface of the colloid adsorbs certain substances that stabilize the colloid.

13. What is the purpose of using coagulant?

1) Improve the floc structure, make the particles bigger, stronger and heavier

2) Adjust the pH value and alkalinity of the treated water to achieve the best coagulation conditions and improve the coagulation effect; the coagulant itself does not have a coagulation effect, but can promote the coagulation process of impurities in the water.

14. What is the basic concept of coagulation?

Since the colloidal particles in the water are negatively charged, they repel each other and at the same time they are constantly doing “Brownian motion” in the water, which makes them extremely stable and not easy to sink. When an appropriate amount of coagulant is added, the tiny colloidal particles in the water can be destabilized, producing an adsorption and bridging effect, flocculating into flocs and rapidly sinking. This process is called coagulation.

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

1) Water pH: If PAC is added and hydrolyzed to produce AI(OH)3 colloid, the dissolution is minimal when the pH is between 6.5 and 7.5, and the coagulation effect is also good:

2) Water alkalinity: When the alkalinity is insufficient, the coagulant will continuously produce H+ during the hydrolysis process, causing the pH value to drop and the coagulation effect to decrease;

3) Water temperature: When the temperature is low, the viscosity of water is high, the hydrolysis rate is slow, the floccules are formed slowly and the structure is loose, the particles are small and not easy to precipitate.

4) Composition of impurities in water: properties and concentration have a great influence on the coagulation effect

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

1) When the pH value is <4.3, there is only C02 (free) in the water

2) When the pH value is 8.3-3.4, more than 98% is HCO3-

3) When the pH value is >8.4, there is no C02 in the water

17.What is the purpose of water treatment in boiler?

1) Prevent the water and steam in the boiler body and its auxiliary systems from accumulating sediment and corrosion during operation. Improve the heat transfer efficiency of the boiler

2) Ensure steam quality, prevent scaling and corrosion of turbine components, reduce boiler blowdown losses and improve economic benefits while ensuring water quality

18. What is the working principle of a centrifugal pump?

The centrifugal pump works by using the rotation of the impeller to generate centrifugal force in water. Before starting the pump, the pump casing and the suction pipe must be filled with water, and then the motor is started so that the pump shaft drives the impeller and water to rotate at high speed. Under the action of centrifugal force, the water is thrown to the outer edge of the impeller and collected in the pump casing, and flows into the water pressure pipeline of the water pump through the flow channel of the vortex pump casing. At the same time, a vacuum is formed at the center of the water pump impeller due to the water being thrown out, and the water in the suction pool is sucked into the impeller through the suction pipe under the action of atmospheric pressure. The impeller keeps rotating, and the water is constantly thrown out and replenished. This forms the continuous water supply of the centrifugal pump.

19. What is resin regeneration?

After a period of softening or desalting, the resin loses its ability to exchange ions. At this time, it can be reduced and regenerated with acid, alkali or salt to restore its exchange capacity. This process of restoring the resin’s ability is called resin regeneration.

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

(1) The quality of the influent water;

(2) Control indicators for the exchange endpoint;

(3) Height of the resin layer;

(4) Water temperature and water flow rate;

(5) The effect of exchange agent regeneration and the performance of the resin itself

21. What are the chemical properties of resin?

1) Reversibility of ion exchange reactions, such as: RH + Na+ RNa + H+

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

3) Selectivity: Ion exchange resins adsorb different ions differently.

4) Resin exchange capacity

Cationic resin:Fe 3+ >Al3+ >Ca 2+ >Mg 2+ >K + NH 4+ >Na+

Anion resin: S042->N03->CI->HC03->HSi

22. What are the pollutions of mixed bed resin?

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

2) Organic pollution: mainly occurs in strong alkaline cationic resin. Main recovery method: Soak the resin in a mixed solution of NaOH (1-4%) and NaCl (5-12%) for 24 hours.

3) Heavy metal ion iron pollution: mostly formed in the anion resin, which increases the corrosion of pipes and equipment, reduces the Fe content of the incoming water, and increases iron removal measures.

23. What are the main reasons for the decline in RO membrane performance?
24. Chemical changes in the membrane itself: hydrolysis of the membrane, oxidation interference of free chlorine and active chlorine
25. Physical changes of the membrane itself: compaction of the membrane reduces the water permeability and increases the salt removal rate; membrane pollution: scaling, microorganisms, and solid particles on the membrane surface or inside the membrane cause pollution and blockage.

24.How to prevent scaling of RO membrane?

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

2) During RO operation, an appropriate working pressure must be maintained. Generally, as the working pressure increases, the water output also increases, but too high a pressure will compact the membrane.

3) During RO operation, the concentrated water should be kept in a flocculent state to reduce the concentration polarization of the solution on the membrane surface and avoid the precipitation of insoluble salts on the membrane surface;

4) When RO is shut down, it should be flushed with chemicals in the short term and protected with CH20 protective solution in the long term.

5) When the RO water output is significantly reduced or the salt content increases, the surface is scaled or contaminated and chemical cleaning should be performed.

25. What is the role of adding NaHCO3 in the desalination process of RO device?

Eliminate or reduce the residual chlorine content in water to ensure the stability of RO elements. Our company’s residual is less than 0.1mg/L.

26. What is the function of setting an electric slow-opening automatic valve in front of the RO membrane assembly?

Prevent the high-pressure pump from suddenly starting and stopping during RO operation to increase pressure, which will cause high-pressure impact on the RO membrane element and form water hammer to damage the RO membrane.

27. What is the filtration cycle? How many steps does it include? What is the role of each step? The filtration cycle is the actual running time between two backwashes, including: filtration, backwashing, and normal washing.

Backwashing is to remove the dirt accumulated during the filtration process and restore the filter medium’s ability to intercept dirt.

Positive washing is a necessary step to ensure the filtering operation and the water is qualified. Only after the positive washing is qualified can the water production enter the cycle operation.

28. Principle of activated carbon dechlorination

The activated carbon does not remove residual chlorine by physical adsorption, but by chemical reaction. When the free residual chlorine passes through the activated carbon, a catalytic effect occurs on its surface. The free residual chlorine quickly hydrolyzes to produce oxygen atoms [0] and reacts chemically with carbon atoms to produce carbon dioxide. At the same time, the HCLO in the raw water is also quickly converted into C02 gas.

Comprehensive reaction: C+2C12+2H20→4HcI+C021

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

29. Principle of reverse osmosis process

RO uses the property of semi-permeable membrane that is water-permeable but not salt-permeable to remove most of the salt in the water. Pressurize the raw water side of R0 so that part of the pure water in the raw water passes through the membrane in a direction perpendicular to the membrane. The salts and colloids in the water are concentrated on the membrane surface, and the remaining raw water takes away the concentrated substances in a direction parallel to the membrane. There is only a small amount of salt in the permeated water, and the permeated water is collected to achieve the purpose of desalination.

30. What is industrial wastewater?

Industrial wastewater refers to wastewater, sewage and waste liquid generated in the industrial production process, which contains industrial production materials, intermediates and products lost with the water, as well as pollutants generated in the production process.

31. What is domestic sewage?

Domestic sewage mainly refers to the discharge water generated by various kitchen water, washing water and toilet water used in human life. It is generally non-toxic inorganic salts. The sewage contains a lot of nitrogen, phosphorus, sulfur and pathogenic bacteria.

32. What is municipal sewage?

Municipal sewage mainly includes domestic sewage and industrial sewage, which is collected by the urban drainage network and transported to the sewage treatment plant for treatment.

33. What is the role of screens in sewage treatment?

Screens in sewage treatment are mainly used to remove floating objects in the water.

34. What is the role of a grease trap in sewage treatment?

The function of the grease trap is to separate the suspended matter and water in the wastewater by utilizing the different specific gravities.

35. What is the role of the primary sedimentation tank in sewage treatment?

The primary sedimentation tank is also called the first sedimentation tank. It is mainly used to remove settleable matter and floating matter in sewage treatment.

36. What is the role of flotation tanks in sewage treatment?

Flotation can achieve solid-liquid separation by producing a large number of tiny bubbles in the water, allowing the air to attach to the suspended particles in the form of highly dispersed tiny bubbles, resulting in a state with a density lower than that of water. The buoyancy principle is used to make the particles float on the water surface.

37. What is the role of the equalization tank in sewage treatment?

The regulating tank mainly regulates the water quantity and quality, as well as the pH value and water temperature of sewage, and has a pre-aeration regulating function.

38. What is the role of the accident pool in sewage treatment?

When dealing with high-concentration wastewater discharged by chemical and petrochemical plants, accident pools are usually set up to store accident water. The reason is that when these plants have production accidents, they will discharge a large amount of high-concentration organic wastewater with large pH fluctuations in a short period of time. If it directly enters the sewage treatment system, it will bring a high impact load to the operating biological treatment system.

39. What is the role of the biochemical pool in sewage treatment?

The biochemical pool is a technology that uses the metabolism of microorganisms to treat wastewater. Its principle is to use the metabolism of microorganisms to decompose organic matter into inorganic matter, thereby achieving the effect of purifying sewage.

40. What is the role of the secondary sedimentation tank in sewage treatment?

The secondary sedimentation tank is an important component of the activated sludge system. Its main function is to separate the sludge, clarify, concentrate the mixed liquor and return the activated sludge.

41. What factors are related to microorganisms?

In addition to nutrients, microorganisms also require suitable environmental factors such as temperature, pH, dissolved oxygen, osmotic pressure, etc. to survive.

42. What is the ratio between the various nutrient elements required by microorganisms in wastewater?

Like plants and animals, microorganisms also need necessary nutrients to grow and reproduce. The nutrients required by microorganisms mainly refer to carbon, nitrogen and phosphorus. There are certain requirements for the composition ratio of the main nutrients in wastewater. For aerobic biochemistry, it is generally C:N:P=100:5:1 (weight ratio).

43. What is Chemical Oxygen Demand (COD)?

Chemical oxygen demand (COD) refers to the amount of oxygen required by oxidizable substances in wastewater when they are oxidized by chemical oxidants, measured in milligrams of oxygen per liter. It is currently the most commonly used method to determine the content of organic matter in wastewater.

44. What is biochemical oxygen demand (BOD5)?

Biochemical oxygen demand can also characterize the degree of organic pollution in wastewater. The most commonly used is the 5-day biochemical oxygen demand, expressed as BOD5, which indicates the amount of oxygen required for wastewater to undergo biochemical degradation in the presence of microorganisms within 5 days. In the future, we will often use the 5-day biochemical oxygen demand.

45. What is ammonia nitrogen?

Ammonia nitrogen refers to combined nitrogen in the form of ammonia or ammonium ions, that is, nitrogen in the form of free ammonia (NH3) and ammonium ions (NH4+) in water. Combined nitrogen in the form of free ammonia (NH3) and ammonium ions (NH4+) is called ammonia nitrogen. Ammonia nitrogen is a nutrient in water bodies, which can cause eutrophication of water. It is the main oxygen-consuming pollutant in water bodies and is toxic to fish and some aquatic organisms.

46. What is Total Phosphorus?

Total phosphorus is referred to as TP. It is the result of the determination of various forms of phosphorus in water samples after digestion, and is measured in milligrams of phosphorus per liter of water sample. Phosphorus in water can exist in the form of elemental phosphorus, orthophosphate, condensed phosphate, pyrophosphate, metaphosphate and phosphate combined with organic groups.

47. What is heavy metal wastewater?

Heavy metal wastewater refers to wastewater containing heavy metals discharged from industrial production processes such as mining, machinery manufacturing, chemical industry, electronics, and instrumentation. Heavy metal wastewater (such as cadmium, nickel, mercury, zinc, etc.) is one of the most serious industrial wastewaters that pollute the environment and cause the greatest harm to humans.

48. What are the common sewage treatment chemicals?

Common sewage treatment agents include: polyaluminium chloride PAC, polyacrylamide PAM, phosphorus remover, ammonia nitrogen remover, heavy metal capture agent…

49. Polyaluminium chloride

Polyaluminium chloride is an inorganic polymer coagulant, abbreviated as PAC. It is an inorganic polymer compound and a hydrolysis product between aluminium chloride and aluminium hydroxide. Due to the bridging effect of hydroxide ions and the polymerization of multivalent anions, it generates an inorganic polymer water treatment agent with a large molecular weight and a high charge.

50. Polyacrylamide

Polyacrylamide is a linear organic macromolecular polymer, abbreviated as PAM. It is a macromolecular water treatment flocculant product that can specifically adsorb suspended particles in water, act as a link and bridge between particles, make fine particles form relatively large flocs, and accelerate the precipitation rate. With good flocculation effect, PAM is used as a flocculant for water treatment and is widely used in sewage treatment.

51. Antiscalant

Also known as antiscalant, it refers to a class of chemicals that can inhibit the formation of scale by scale-forming salts such as calcium and magnesium in water. There are natural antiscalants such as tannins and lignin derivatives; inorganic antiscalants such as sodium hexametaphosphate and sodium tripolyphosphate; organic and polymer antiscalants, among which polymer antiscalants have the best effect and have a promising future.

52. Phosphorus removal agent

Phosphorus removers mainly use flocculation and sedimentation to remove phosphorus. After adding phosphorus removers to wastewater, they quickly neutralize the negative charge on the surface of colloidal particles in the water, and easily combine with phosphorus ions in the water to produce precipitates. Then, through sedimentation tanks or filtration processes, phosphorus in wastewater can be guaranteed to meet discharge standards. It is commonly used for phosphorus removal in domestic sewage treatment plants, pharmaceuticals, papermaking, pesticides, fertilizer plants and other wastewater treatment.

53. Ammonia nitrogen remover

Ammonia nitrogen remover is mainly used to remove ammonia nitrogen in wastewater. After addition, the ammonia nitrogen in the wastewater will generate water-insoluble nitrogen, carbon dioxide and water, and it can assist in removing COD and decolorizing. It has a fast reaction, no residue, no pollution, and a high removal rate. It is suitable for the treatment of pharmaceutical factories, circuit board factories, coking plants and domestic sewage.

54. Heavy metal capture agent

It is a chemical agent that strongly chelates heavy metal ions. Using the grafting synthesis process, the chelating groups on its branch chains can chelate heavy metals to form stable insoluble substances and precipitate. The reaction can not only be carried out at room temperature and a wide range of pH conditions, but also is not affected by the concentration of heavy metal ions. Even if the treated wastewater contains complex components, it can better precipitate various heavy metal ions in the wastewater, so that the wastewater meets the discharge standards.