The basic knowledge of environmental protection water treatment is all here!

1. Noun explanation

1, raw water: refers to the natural water without any treatment or urban tap water, also called raw water.

2, clarified water: remove the suspended impurities in the raw water water.

3, demineralized water: refers to the Yang, anion in the water basically removed or reduced to a certain degree of water called demineralized water. The methods of salt removal include distillation, electrodialysis, reverse osmosis, ion exchange and so on.

4, turbidity: refers to the turbidity of the water, it is because the water contains a certain amount of suspended substances (including colloidal substances) caused by the optical effect. Units are expressed in NTU. Turbidity is one of the main characteristics to determine whether water is polluted in appearance. The standard unit of turbidity is specified as 1 degree turbidity composed of 1mgSi02.

5, flocculant: can cause colloidal condensation bridge and flocculation of the agent.

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

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

8, hardness: refers to some metal ions that are easy to form precipitates in water, usually referring to calcium and magnesium ion content.

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

10, resistivity: is also an indicator that reflects the electrical conductivity of water, the greater the resistivity of water, the worse the electrical conductivity of water, the less ions contained in water. Its common unit is mω.cm. It has an reciprocal relationship with the conductivity. For example, if the conductivity of water is 0.2μs/cm, its resistivity is 1/0.2=5(mω.cm).

11, TDS(total dissolved solids) : is the remaining inorganic after filtering out suspended solids (SS) and colloids and evaporating to see all the water. The unit is ppm or mg/l and can be measured with a TDS meter. It also reflects the amount of ions in the water. There is a rough correspondence between it and the conductivity: for a sodium chloride reference solution, a TDS value of 1ppm corresponds to a conductivity of 2μs/cm.

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

13, alkalinity: alkalinity refers to the content of substances in water that can accept the neutralization reaction of [H+] ions with strong acids. The substances that produce alkalinity in water are mainly carbonate alkalinity from carbonate and bicarbonate alkalinity from bicarbonate, and hydroxide alkalinity from the presence of hydroxide.

14, SDI: Pollution index - used to measure the amount of suspended solids in the raw water used in the reverse osmosis system.

15, ozone: an unstable, highly active form of oxygen, it is produced by natural lightning or high voltage charge through the air, is an excellent oxidizing agent and disinfectant.

16, residual chlorine: water after chlorination disinfection, contact for a certain time, the effective chlorine left in the water.

17, Total Escherichia coli: Total Coliform group refers to a group of aerobic and facultative anaerobic, at 37℃ growth can make lactose fermentation, within 24 hours to produce acid and gas gram-negative bacillus. Total Coliform is the number of total coliform bacteria per liter of water sample.

18, recovery rate: refers to the ratio of the flow of product water produced by the system to the flow of water.

19, desalting rate: reflects the performance of the membrane parameters, usually a primary RO membrane system desalting rate of more than 97%. It can be simply calculated: (raw water conductivity - electrical conductivity of product water)/ raw water conductivity.

20, salt content: The salt content of water, also known as salinity, is the number of salts contained in the water. Since various salts in water generally exist in the form of ions, the salt content can also be expressed as the sum of the amount of various cations and the amount of anions in water.

21, precipitation: one of the technical methods of wastewater treatment. It can be divided into two kinds of physical precipitation and chemical precipitation. The precipitation usually referred to is physical precipitation, that is, the method of gravity separation.

22, water: a variety of explanations, sewage engineering is called recycled water, the factory is called reuse water, generally differentiated by water quality. Mainly refers to urban sewage or domestic sewage after treatment to reach a certain water quality standards, can be reused in a certain range of non-drinking water.

The quality of reclaimed water is between the upper water (drinking water) and the water (domestic sewage), which is also the origin of the name of the water, and people will supply the water system is called the water system.

23, organic pollution: refers to natural organic matter in the form of carbohydrates, proteins, amino acids and fats and other forms of some other biodegradable synthetic organic matter. It mainly comes from domestic sewage and industrial wastewater.

24, concentration polarization: Under the operating condition of reverse osmosis, the salt on the surface of the film is concentrated, and there is a concentration difference between the salt in the water, if the flow rate of concentrated water is small, the flow rate is low, the water with high content of salt can not be taken away in time, and a high concentration difference will be formed on the surface of the film, which hinders the diffusion of salt, this phenomenon is called concentration polarization.

25, suspended matter (SS) : refers to the solid substances suspended in water, including insoluble in water inorganic matter, organic matter and mud sand, clay, microorganisms, etc. The content of suspended matter in water is one of the indicators to measure the degree of water pollution. It is the amount of solid obtained by drying the intercepts on the filter paper at 103-105 degrees after the water sample is filtered. The unit is mg/l.

26, aeration: The process of transferring O2 in the air to the mixed liquid and being used by microorganisms. The purpose is to provide dissolved oxygen required by activated sludge and other microorganisms to ensure the oxygen demand of microbial metabolic processes.

27, biochemical oxygen demand (BOD) : refers to the dissolved oxygen consumed by microorganisms in the process of decomposition and oxidation of organic matter in water under the specified time, temperature 20 ° C, usually for 5 days, abbreviated BOD5, unit mg/L.

28, chemical oxygen demand (COD) : refers to the oxygen consumed by the oxidation of organic substances in wastewater with strong oxidants under certain conditions. The standard of wastewater inspection generally uses potassium dichromate as an oxidant, the unit mg/L.

29, water hammer: also known as water hammer. In the process of water (or other liquids) transportation, due to the sudden opening or closing of the valve, the sudden stop of the pump, and the sudden opening and closing of the guide vane, the flow rate changes suddenly, and the pressure fluctuates greatly.

30, adsorption: refers to the use of porous solid adsorption of some or several pollutants in the wastewater to recover or remove some pollutants, so that the wastewater can be purified method.

31, enzyme: is a catalyst made by the biological cells themselves (biocatalyst). Its basic component is protein, which is a substance that promotes the speed of biochemical reactions.

32, sewage: sewage is a general term for water discharged in production and living activities. In human life and production activities, to use a large amount of water, these waters are often polluted to different degrees, the polluted water is called sewage.

33, sewage treatment: is the use of various technologies and means, the sewage contained in the separation of pollutants removal, recycling or conversion into harmless substances, so that the water is purified.

34, sewage reuse: sewage or waste water after secondary treatment and in-depth treatment back for production systems or domestic utility is called sewage reuse. When the treated water meets the specific reuse requirements and is reused, it can also be called reclaimed water.

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

36, water slag: refers to the solid matter suspended in the furnace water and deposited in the drum, the bottom of the lower header and other slow flow of sediment. The difference from scale: the water slag is relatively loose, in suspension or sediment state, and some of it is easy to discharge with the boiler blowdown; The scale can be firmly bonded to the pipe wall and is not easy to discharge.

37, iron, manganese, aluminum: trace amounts of iron and manganese will create staining, scaling and taste problems, iron in the reduced state of the environment is in the form of water-soluble bivalent iron, when and air contact will gradually oxidize into yellow brown colloidal trivalent iron, and finally precipitated into brown iron hydroxide. The characteristics of manganese and iron are similar, because the oxides of iron, manganese and aluminum are also one of the reasons for scaling of RO film, it is necessary to analyze its content.

38, pure water: refers to the removal of the strong dielectric that is easy to remove in water, and the weak electrolyte such as silica acid and carbon dioxide that is difficult to remove to a certain degree of water. The salt content of pure water is less than 1.0mg/L, and the conductivity is less than 3μs/cm.

39, ultra-pure water: also known as high pure water, refers to the water conductive medium is almost all removed, and the water does not dissociate colloidal substances, gases and organic matter are removed to a very low degree of water. The salt content of ultra-pure water is less than 0.1mg/L, and the conductivity is less than 0.1μs/cm.

In addition to the salt content or conductivity of pure water and ultra-pure water have strict requirements, the content of various metal ions in water, the content of organic matter, the size and number of particles and the number of microorganisms also have strict indicators

40, distilled water: the raw water is heated and vaporized, and then the water condensed into steam is called distilled water. Generally, the conductivity of distilled water is about 10μs/cm, and the distilled water is distilled again to obtain secondary distilled water, and the distilled water is distilled multiple times, and the conductivity can be reduced to a very low of about 1.0μs/cm.

41, scale inhibitor: It is a kind of agent that can disperse insoluble inorganic salts in water, prevent or interfere with the precipitation and scaling of insoluble inorganic salts on the metal surface, and maintain the good heat transfer effect of metal equipment.

42, ion exchange resin: It is a polymer compound with a functional group (an active group of exchange ions), with a network structure and insolubility. Usually spherical particles.

43, ion: refers to the atom due to its own or external action to lose or get one or several electrons so that it reaches the outermost electron number of 8 or 2 (helium atom) or no electron (four neutrons) stable structure. This process is called ionization.

44, water production (water flux) : refers to the capacity of the reverse osmosis system, that is, the amount of water per unit time through the membrane, usually expressed in tons/hour (t/h) or gallons/day (g/d).

45, EDI: referred to as continuous electric desalting, is a new ultra-pure water preparation technology. It cleverly combines electrodialysis technology and ion exchange technology.

Second, pure water treatment basic process explanation

1, coarse filtration: refers to mechanical filtration, removal of suspended matter in water, colloids, turbidity, color, odor and so on. The main filtration methods are clarification tank, fast filter, sand filter, sand filter, multi-media filter, active carbon filter, disc filter, high efficiency fiber filter and so on.

2, fine filtration: the filter membrane made of special materials, high filtration accuracy. Common for microfiltration membrane and filter element filtration.

3, ultrafiltration: is a membrane filtration, remove macromolecules and colloids, bacteria and so on. High filtration accuracy, the common is ultrafiltration membrane.

4, reverse osmosis: reverse osmosis referred to as RO, the principle is that raw water under the action of high pressure through the reverse osmosis membrane, the solvent in the water from high concentration to low concentration diffusion so as to achieve the purpose of separation, purification, concentration, because it is the opposite direction of natural penetration.

5, ion exchange: all kinds of inorganic salts in the water ionization to produce positive, anion, through the hydrogen ion exchanger layer, the cation in the water is replaced by hydrogen ions, that is, the salt removal principle of the Yang bed; When passing through the OH-type ion exchanger layer, the anions in the water are replaced by OH- ions, that is, the principle of salt removal in the negative bed.

The mixed bed is an ion exchange device in which positive and anion exchange resins are mixed and filled in the same exchange column in a certain proportion.

6, EDI: is the combination of electrodialysis and ion exchange of the new process of salt removal, take electrodialysis and mixed bed ion exchange, the use of ion exchange for deep treatment, without chemical regeneration, ionization to produce H+ and OH-, to achieve the purpose of regeneration resin.

Third, commonly used water treatment technology

1, the raw water is groundwater: sand filter + precision filter + reverse osmosis + mixed bed or EDI

2, the raw water is tap water: sand filter + activated carbon filter + precision filter +RO+ mixed bed or EDI

3. Surface water:

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

② Multi-media filter (or other forms of filter)+ ultrafiltration + precision filter +RO+ mixed bed or EDI

③ Disk filter + ultrafiltration + precision filter +RO+ mixed bed or EDI

4. Pipe materials commonly used in water treatment projects

1, carbon steel pipe: used for raw water inlet pipe

2, UPVC pipe: for pipe diameter less than DN150 occasions is better, easy to install.

3, stainless steel pipe: for occasions with special requirements, mostly used in small pharmaceutical systems.

4, steel lined rubber or plastic pipe: used in large projects, reliable use, construction is more troublesome.

5. Various uses of pure water

Pure water and ultra-pure water are widely used in power plants, electronics, medicine, chemical industry, through various membrane filtration or ion exchange, the harmful ions in water are removed.

1, power plant: multi-purpose desalted water, the main indicators of the desalted water quality are: hardness is about zero, conductivity ≤0.2μs.cm, SiO2≤20ppb.

2, chemical plants: chemical water is diverse, usually the water quality is not higher than the water quality of the power plant, but it may have requirements for some ions, so it is commonly used a primary or secondary reverse osmosis process. The effluent water conductance is above 5~10μs.cm. Mixed bed or EDI is added to the back if there are higher requirements.

3, medicine: medical water more requirements for conductance and bacteria, the material material used in the system has requirements, more use of stainless steel products. Usually pure water is followed by sterilization devices.

4, the electronics industry: the electronics industry has the highest requirements for water, and most electronic water requirements reach 18 trillion. The requirement for electrical resistivity is only a small part of the electronic water, which has high requirements for many ions, so there are special requirements for installation materials and pipes. The selection process is also the most complex. It is usually necessary to add polishing mixed bed and ultrafiltration, sterilization, nitrogen sealed water tank and other devices after EDI, and the cost is also very high.

6. According to the water quality requirements, the process usually used

1, the conductivity of the production water is required to be 10~20μs/cm: RO pretreatment + primary reverse osmosis (chemical)

2, water conductivity 2~9μs/cm: using RO pretreatment + secondary reverse osmosis (pharmaceutical, chemical) or using RO pretreatment + softening + primary reverse osmosis +EDI(pharmaceutical, chemical)

3, the conductivity of water production is less than 0.2~2μs/cm: The use of RO pretreatment + one stage reverse osmosis + mixed bed

4, water production resistance 5~ 13mω.cm: R0 pretreatment + softening + primary reverse osmosis +EDI or RO pretreatment + secondary reverse osmosis +EDI(medicine, chemical, electronics, power generation)

5, water production resistance 13~ 17mω.cm: R0 pretreatment + softening + primary reverse osmosis +EDI+ mixed bed or RO pretreatment + secondary reverse osmosis +EDI+ mixed bed (medicine, chemical, electronics, power generation)

6, water production resistance 18mω.cm: using RO pretreatment + secondary reverse osmosis +EDI+ mixed bed + sterilization + nitrogen seal.

Seven, the key and difficult questions of pure water treatment

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

(1) Ensure water quality;

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

(3) Ensure the quality of the regenerated liquid,