I. Chemical Water Treatment

1. Surface water; refers to water existing on the earth's surface and exposed to the atmosphere. It is the general term for rivers, glaciers, lakes, and swamps, also known as "land water."

2. Groundwater; is water stored in the voids of strata below the vadose zone (the vadose zone refers to the geological medium below the earth's surface and above the water table), including rock pores, fissures, and caves. Groundwater exists in the cracks of the earth's crust or soil voids.

3. Raw water; refers to water collected from nature, including but not limited to groundwater and reservoir water, which is visible in nature and has not undergone any artificial purification treatment.

4. PH; represents the numerical value of the acidity and alkalinity of a solution, pH = -lg[H+], which is the negative value of the common logarithm of the hydrogen ion concentration.

5. Total alkalinity; the total amount of substances in water that can neutralize strong acids. These substances include strong bases, weak bases, and strong base weak acid salts.

6. Phenolphthalein alkalinity; is the alkalinity measured using phenolphthalein as an indicator (titration endpoint pH = 8.2～8.4).

7. Methyl orange alkalinity; is the alkalinity measured using methyl orange as an indicator (titration endpoint pH = 3.1～4.4).

8. Total acidity; acidity refers to the total amount of substances in water that can neutralize strong bases, including inorganic acids, organic acids, and strong acid weak base salts.

9. Total hardness; in general natural water, it is mainly Ca2+ and Mg2+, the content of other ions is very small, usually the total content of Ca2+ and Mg2+ in water is called the total hardness of water.

10. Temporary hardness; hardness formed due to the presence of Ca(HCO3)2 and Mg(HCO3)2 in water, which can be removed after boiling. This hardness is called carbonate hardness, also known as temporary hardness.

11. Permanent hardness; hardness formed due to the presence of salts such as CaSO4 (CaCl2) and MgSO4 (MgCl2) in water, which cannot be removed after boiling. This hardness is called non-carbonate hardness, also known as permanent hardness.

12. Dissolved substances; exist in the form of simple molecules or ions in water (or other solvents), the particle size is usually only a few tenths to several nanometers, invisible to the naked eye, and there is no Tyndall phenomenon. It cannot be seen with an optical microscope.

13. Colloids; particle groups formed by the combination of several molecules or ions, the size is usually tens of nanometers to tens of micrometers, invisible to the naked eye, but the Tyndall phenomenon will occur. Small colloidal particles cannot be seen with an optical microscope, while large ones can be seen.

14. Suspended solids; are small particles visible to the naked eye formed by the combination of a large number of molecules or ions, with a size usually above tens of micrometers. They can be clearly seen with an optical microscope. Suspended solids can settle after a long time of standing.

15. Total dissolved solids; the total amount of ions in water is called total dissolved solids. It is obtained by adding up the amounts of all cations and anions obtained from water quality analysis, and the unit is expressed in mg/L (formerly also in PPM).

16. Turbidity; also known as turbidity. In a technical sense, turbidity is a water quality surrogate parameter used to reflect the content of suspended solids in water. The main suspended solids in water are generally soil. 1 mg of silicon dioxide in 1 L of distilled water is used as the unit of standard turbidity, expressed as 1 PPM.

17. Total dissolved solids; TDS, also known as total dissolved solids, is measured in milligrams per liter (mg/L), indicating how many milligrams of dissolved solids are dissolved in 1 liter of water.

18. Resistance; according to Ohm's law, under a certain water temperature, the size of the water resistance value R is inversely proportional to the vertical cross-sectional area F of the electrode and directly proportional to the distance L between the electrodes.

19. Conductivity; the strength of the water's ability to conduct electricity is called conductivity S (or conductance).

20. Conductivity; the conductivity of water, which is the reciprocal of the resistance of water, is usually used to indicate the purity of water.

21. Resistivity; the resistivity of water refers to the resistance between the opposite sides of a 1 cm cube of water at a certain temperature, with the unit being ohm*centimeter (Ω*CM). It is generally a parameter indicating the quality of high-purity water.

22. Softened water; refers to water in which the hardness (mainly referring to calcium and magnesium ions in water) has been removed or reduced to a certain extent. During the softening process of water, only the hardness is reduced, while the total dissolved solids remain unchanged.

23. Desalted water; refers to water in which salts (mainly strong electrolytes dissolved in water) have been removed or reduced to a certain extent. Its conductivity is generally 1.0-10.0μs/cm, resistivity (25℃) 0.1-1000000Ω.cm, and salt content is 1.5mg/L.

24. Pure water; refers to water in which strong electrolytes and weak electrolytes (such as SiO2, CO2, etc.) have been removed or reduced to a certain extent. Its conductivity is generally 1.0-0.1μs/cm, resistivity 1.0-1000000Ω.cm. Salt content <1mg/l.

25. Ultrapure water; refers to water in which conductive media have been almost completely removed, and non-dissociated gases, colloids, and organic substances (including bacteria, etc.) have also been removed to a very low extent. Its conductivity is generally 0.1-0.055μs/cm, resistivity (25℃) >10×1000000Ω.cm, and salt content <0.1mg/l. Ideal pure water (theoretically) has a conductivity of 0.05μs/cm and a resistivity (25℃) of 18.3×1000000μs/cm.

26. Deoxygenated water; also called deoxygenated water, removes dissolved oxygen from water, generally used for boiler water.

27. Ion exchange; a method of separation using the different ion exchange capacities between the exchangeable groups in the ion exchanger and various ions in the solution.

28. Cation resin; possesses acidic groups. In aqueous solution, the acidic groups can ionize to generate H+, which can undergo ion exchange with cations in water.

29. Anion resin; contains alkaline groups that ionize in aqueous solution and undergo ion exchange with anions.

30. Inert resin; without active groups, there is no ion exchange effect. The relative density is generally controlled between anion and cation resins to separate the anion and cation resins, avoiding cross-contamination during regeneration and making regeneration more complete.

31. Microfiltration; MF, also known as microporous filtration, belongs to precision filtration. Microfiltration can filter out micrometer or nanometer-level particles and bacteria in the solution.

32. Ultrafiltration; UF, one of the membrane separation technologies driven by pressure. It aims to separate macromolecules from small molecules, with a membrane pore size between 20-1000 Å.

33. Nanofiltration; NF, a pressure-driven membrane separation process between reverse osmosis and ultrafiltration. The pore size of the nanofiltration membrane is around several nanometers.

34. Osmosis; Osmosis is the phenomenon of water molecules diffusing through a semipermeable membrane. It permeates from a high water molecule area (i.e., low concentration solution) into a low water molecule area (i.e., high concentration solution).

35. Osmotic pressure; For a semipermeable membrane with different concentrations of aqueous solutions on both sides, the minimum additional pressure applied to the high-concentration side to prevent water from permeating from the low-concentration side to the high-concentration side is called osmotic pressure.

36. Reverse osmosis; RO, reverse osmosis is to press water from a concentrated solution to a low-concentration solution by artificial pressurization. The RO reverse osmosis membrane has a pore size as small as the nanometer level. Under certain pressure, water molecules can pass through the RO membrane, while inorganic salts, heavy metal ions, organic matter, colloids, bacteria, viruses and other impurities in the source water cannot pass through the RO membrane.

36. Dialysis; Also known as dialysis. A membrane separation operation driven by concentration difference, using the selective permeability of the membrane to different substances to achieve the separation of substances with different properties.

37. Electrodialysis; ED, when dialysis is carried out under the action of an electric field, the phenomenon that charged solute particles (such as ions) in the solution migrate through the membrane is called electrodialysis.

38. EDI; Also known as continuous electro-deionization technology, it is a pure water production technology that combines ion exchange technology, ion exchange membrane technology, and ion electromigration technology.

39. Recovery rate; refers to the percentage of feed water converted into product water or permeate in the membrane system.

40. Desalination rate; the percentage of the total soluble impurities concentration removed from the system feed water through the reverse osmosis membrane, or the percentage of specific components such as divalent ions or organic matter removed through the nanofiltration membrane.

41. Salt passage rate; the opposite of the desalination rate, it is the percentage of soluble impurities in the feed water that pass through the membrane. Permeate: purified product water produced by the membrane system.

42. Flux; the flow rate of permeate per unit membrane area, usually expressed in liters per square meter per hour (l/m2h) or gallons per square foot per day (gfd).

43. Product water; purified aqueous solution, the product water of reverse osmosis or nanofiltration system.

44. Concentrate; the part of the solution that passes through the membrane, such as the concentrated water of the reverse osmosis or nanofiltration system.

II. Circulating Water Treatment

45. Circulating water; a system that uses water to cool process media is called a cooling water system.

46. Once-through cooling water system; cooling water only passes through the heat exchange equipment once, and the water is discharged after use.

47. Open circulating water; using water to cool and remove the heat dissipated by the process media or heat exchange equipment, then evaporating part of the hot water by direct contact between hot water and air, and cooling most of the hot water before recycling.

48. Closed circulating water system; also known as a closed circulating cooling water system. In this system, the cooling water is not immediately discharged after use, but is recycled.

49. Cooling tower; a device that uses water as a circulating coolant to absorb heat from a system and discharge it into the atmosphere to reduce the water temperature. It is divided into natural ventilation and mechanical ventilation cooling methods.

50. Water distributor; the return water is evenly distributed to the packing through the water distributor.

51. Packing; the return water passes through the packing to form a water film, increasing the contact area with the air.

52. Water collector; recovers liquid water carried in part of the evaporated water vapor.

53. Circulating water volume; refers to the total circulating water volume of the cooling towers in the circulating water system. n50 retained water volume: the total volume of all water in the circulating water system, equal to the sum of the water pool volume and the volume of water in the pipelines and water-cooled equipment.

54. Makeup water volume; the water needed to make up for the loss of water in the circulating water system due to evaporation/blowdown/splashing.

55. Side filtration water volume; the amount of water diverted from the circulating cooling water system, treated as required, and then returned to the system.

56. Evaporation water volume; the amount of water lost due to evaporation in the circulating cooling water system during operation.

57. Blowdown water volume; the amount of water that needs to be discharged from the circulating cooling water system under the condition of a determined concentration factor.

58. Wind and leakage loss water volume; the amount of water lost due to wind and leakage in the circulating cooling water system during operation.

59. Makeup water volume; the amount of water supplemented to the circulating cooling water system during operation to compensate for the loss of water.

60. Concentration factor; the ratio of the salt concentration of the circulating cooling water to the salt concentration of the makeup water.

61. Heat exchange; the exchange of heat between objects is called heat exchange. There are three basic forms of circulating water heat exchange: heat exchange, convection heat exchange, radiation heat exchange, and evaporation heat exchange.

62. Heat conduction; the phenomenon of heat transfer between parts of objects in direct contact is called heat conduction.

63. Convective heat transfer; in a fluid, heat transfer between fluids is mainly due to the movement of the fluid, causing part of the heat in the hot flow to be transferred to the cold fluid. This method of heat transfer is called convective heat transfer.

64. Radiative heat transfer; part of the thermal energy of a high-temperature object is converted into radiant energy and emitted outward in the form of electromagnetic waves. After reaching the receiving object, the radiant energy is converted back into thermal energy and absorbed. This method of heat transfer by electromagnetic waves is called radiative heat transfer.

65. Evaporative heat transfer; a form of heat transfer through the evaporation of water molecules, which takes away the latent heat of vaporization.

66. Cooling water inlet and outlet temperature difference; the temperature difference between the cooling tower inlet and the water pool outlet.

67. Wet-bulb temperature; refers to the air temperature at which water vapor in the air reaches saturation under the same enthalpy air state.

68. Dry-bulb temperature; the temperature measured by a thermometer in ordinary air, which is the air temperature often mentioned in general weather forecasts.

69. Physical cleaning; cleaning debris out of pipes using water flow.

70. Chemical cleaning; using chemicals to keep the surface of metal heat exchangers clean and activated, preparing for pre-filming.

71. Pre-filming; also known as chemical conversion film, is a type of protective layer on the surface of metal equipment and pipes, especially pipes that have passed acid washing and passivation, which can be protected using pre-filming.

72. Corrosion inhibitor; the process of inhibiting or slowing down the corrosion of metals.

73. Scale inhibitor; the process of preventing the formation of deposits on the heating surface of heat exchange equipment using chemical or physical methods.

74. Oxidizing biocide; a biocide with strong oxidizing properties, usually a strong oxidizing agent, with a strong bactericidal effect on microorganisms in water.

75. Non-oxidizing biocide; it does not kill microorganisms through oxidation, but by poisoning specific parts of microorganisms, therefore, it is not affected by reducing substances in water.

76. Available chlorine; refers to the amount of chlorine with equivalent oxidizing capacity in chlorine-containing compounds (especially as disinfectants), which can quantitatively represent the disinfection effect.

77. Residual chlorine; residual chlorine refers to the available chlorine remaining in the water after chlorination disinfection and a certain contact time.

78. Combined chlorine; refers to the compounds of chlorine and ammonia in water, including NH2Cl, NHCl2, and NHCl3. NHCl2 is more stable and has a good bactericidal effect, also called combined residual chlorine.

79. Free available chlorine; refers to ClO-, HClO, Cl2, etc., in water. It has a fast bactericidal speed and strong bactericidal power, but disappears quickly, also called free residual chlorine.

80. Orthophosphate; phosphorus in the +5 valence state in phosphates.

81. Organic phosphorus; a compound containing a carbon-phosphorus bond or a phosphoric acid derivative containing an organic group.

82. Total iron; iron in various states of existence, including all iron elements.

83. Total zinc; zinc in various states of existence, including all zinc elements.

84. Chemical retention time; the effective time of chemicals in the circulating cooling water system.

85. Scaling; the dissolved calcium and magnesium bicarbonates in water decompose upon heating, precipitating white sediment, which gradually accumulates and adheres to the container, called scaling.

86. Corrosion; refers to the process of loss and destruction (including metals and non-metals) under the action of surrounding media (water, air, acids, alkalis, salts, solvents, etc.).

87. Biological slime; a viscous substance adhering to the surface of objects, composed of microorganisms and their produced mucus, mixed with other organic and inorganic impurities.

III. Wastewater Treatment

88. Domestic sewage; mainly the discharge water produced from various kitchen water, washing water, and toilet water used in human life. It is mostly non-toxic inorganic salts. Domestic sewage contains a lot of nitrogen, phosphorus, and sulfur, and many pathogenic bacteria.

89. Municipal wastewater; a general term for wastewater discharged into the urban wastewater system. In combined sewer systems, it also includes industrial wastewater and intercepted rainwater. Municipal wastewater mainly includes domestic sewage and industrial wastewater, which is collected by the city drainage network and transported to the wastewater treatment plant for treatment.

90. Industrial wastewater; refers to wastewater, sewage, and waste liquid produced during industrial production, which contains industrial raw materials, intermediate products, and products lost with water flow, as well as pollutants generated during production.

91. COD; Chemical Oxygen Demand, the amount of oxidant consumed in the chemical oxidation process of oxidizable substances in water under specified conditions, expressed as the number of milligrams of oxygen consumed per liter of water sample, usually denoted as COD.

92. BOD; Biochemical Oxygen Demand, the amount of dissolved oxygen in surface water consumed by the process of microbial decomposition of organic matter, usually denoted as BOD, with common units of mg/L.

93. BC ratio; indicates the biodegradability of pollutants in water. 0.1-0.25 is difficult to biodegrade, 0.25-0.5 is biodegradable, and >0.5 is easily biodegradable.

94. TOC; refers to the total amount of carbon in dissolved and suspended organic matter in water, reflecting the content of oxidized organic compounds in water, with units of ppm or ppb.

95. Ammonia nitrogen; refers to nitrogen in water that exists in the form of free ammonia (NH3) and ammonium ions (NH4+).

96. Organic nitrogen; a general term for nitrogen-containing substances combined with carbon, such as proteins, amino acids, amides, and urea.

97. Kjeldahl nitrogen (TKN) refers to the nitrogen content measured by the Kjeldahl method. It includes ammonia nitrogen and organic nitrogen compounds that can be converted into ammonium salts under these conditions and measured.

98. Nitrate nitrogen (NOxˉ) refers to the nitrogen element contained in nitrates. Nitrates and nitrites only.

99. Total nitrogen (TN) is the total amount of various forms of inorganic and organic nitrogen in water.

100. Total phosphorus (TP) is the result of measuring various forms of phosphorus converted into orthophosphate after digestion of the water sample, measured in milligrams of phosphorus per liter of water sample.

101. Hypophosphite: Phosphate existing in the form of H2PO2ˉ, which cannot be removed by normal chemical phosphorus removal and needs to be converted into sulfate for removal.

102. Color: Refers to the degree of yellowish to yellowish-brown color presented by soluble or colloidal substances in water.

103. Screen: Used to remove floating matter from water.

104. Primary sedimentation tank: Also known as a primary clarifier, a structure used in wastewater treatment to remove settleable and floating matter.

105. Equalization tank: A structure used to regulate the inflow and outflow. It mainly plays a role in regulating water volume and quality, as well as the pH value, water temperature, and pre-aeration of wastewater, and can also be used for emergency drainage.

106. Emergency tank: An emergency water collection tank, a type of structure required in wastewater treatment. Emergency tanks are generally set up when processing high-concentration wastewater discharged from chemical, petrochemical, and other factories.

107. Oil and grease separator: Achieves separation by utilizing the difference in specific gravity between suspended matter and water in wastewater.

108. Flotation: A large number of fine bubbles are generated in the water, causing air to adhere to suspended matter particles in the form of highly dispersed fine bubbles, resulting in a density less than water. The principle of buoyancy is used to make it float on the surface, thereby achieving solid-liquid separation.

109. Bioreactor: The tank where bacterial metabolism occurs in biological treatment.

110. Secondary sedimentation tank: Also known as a secondary clarifier, an important component of the activated sludge system. Its main function is to separate sludge, clarify the mixed liquor, concentrate and return activated sludge.

111. Horizontal flow sedimentation tank: The plan view of the tank is rectangular, and the inlet and outlet are located at both ends of the tank length.

112. Vertical flow sedimentation tank: Also known as a vertical sedimentation tank, it is a sedimentation tank in which wastewater flows vertically. The plan view of the tank is circular or square, and water enters the tank from top to bottom through an inlet pipe located in the center of the tank. Sedimentation is achieved through the self-weight of the sludge.

113. Radial flow sedimentation tank: Wastewater enters the tank from the central inlet pipe and flows slowly along the radial direction towards the periphery of the tank. Suspended matter settles during flow and enters the sludge hopper along the bottom slope of the tank, and clarified water overflows from the peripheral overflow channel.

114. Sludge tank: Generally used to hold return sludge and excess sludge.

115. Monitoring tank: Also known as a clear water tank, used to hold treated wastewater.

116. Coagulation: The process by which colloids lose their stability. Commonly known as colloid destabilization.

117. Flocculation: The process by which destabilized colloids aggregate into large flocs.

118. Coagulation: The entire process of the two stages of forming large flocs through destabilization and flocculation. The general term for coagulation and flocculation.

119. Metabolism: The exchange of matter and energy between an organism and its external environment, as well as the self-renewal process of matter and energy within the organism, is called metabolism. Metabolism includes anabolism (assimilation) and catabolism (dissimilation).

120. Bacterial floc: Due to their genetic characteristics, some bacteria adhere to each other in a certain arrangement, surrounded by a common capsule to form a bacterial group of a certain shape, which is called a bacterial floc.

121. Filamentous bacteria: A type of bacteria with a filamentous structure. The framework of bacterial flocs.

122. Autotrophic bacteria: Bacteria that use inorganic carbon sources as carbon sources.

123. Heterotrophic bacteria: Bacteria that use organic carbon sources as carbon sources.

124. Anaerobic environment: Theoretically, anaerobic refers to the absence of molecular oxygen and nitrate nitrogen. However, this is impossible in practice. In engineering, DO < 0.2 is considered anaerobic.

125. Aerobic environment: Both dissolved oxygen and nitrate nitrogen are present. In engineering, DO > 0.5 is considered aerobic.

126. Anoxic environment: Refers to the absence of molecular oxygen but the presence of nitrate nitrogen. In engineering, DO between 0.2 and 0.5 is considered anoxic.

127. Activated sludge process: A wastewater treatment method achieved through the adsorption, metabolism, and solid-liquid separation of bacterial flocs.

128. Biofilm process: A method of treating organic wastewater using microorganisms (i.e., biofilms) that grow attached to the surfaces of certain solids.

129. Hydraulic retention time (HRT): A term in water treatment technology, the hydraulic retention time refers to the average residence time of wastewater to be treated in the reactor, which is the average reaction time of wastewater interacting with microorganisms in the bioreactor.

130. Sludge age: Refers to the average residence time of microbial cells in the aeration tank. For activated sludge processes with return flow, the sludge age is the time (in days) required for the average renewal of the entire aeration tank sludge.

131. SV30: 30-minute settling ratio. It refers to the ratio of the volume of settled sludge to the volume of the mixed liquor taken after allowing a well-mixed aeration tank activated sludge mixed liquor to settle for 30 minutes in a 1000 ml graduated cylinder filled to the full mark. It is also known as sludge settling volume (SV30), expressed as mL/L. Because the sludge generally reaches or approaches its maximum density after 30 minutes of settling, this time is generally used as the standard time for determining this indicator.

132. MLSS; Sludge concentration, the weight of dry sludge contained in 1 liter of aeration tank sludge mixed liquor

133. MLVSS; Mixed liquor volatile suspended solids concentration, indicating the concentration of organic solid matter in the mixed liquor activated sludge.

134. RSS; Sludge concentration of return sludge.

135. SVI; Sludge volume index, an indicator for measuring the settling performance of activated sludge. It refers to the volume (in mL) occupied by 1 g of dry sludge after 30 min of sedimentation of the aeration tank mixed liquor, i.e., SVI = Sludge volume after 30 min sedimentation (mL) / Dry sludge weight (g), i.e., SVI = SV30/MLSS.

136. Internal recirculation ratio; The ratio of the flow rate of nitrified liquid recirculation to the influent flow rate, generally expressed as a percentage, with the symbol r.

137. External recirculation ratio; Also known as sludge recirculation ratio, the ratio of the return sludge flow rate to the influent flow rate. Generally expressed as a percentage, with the symbol R.

138. Inoculation; The process of adding activated sludge or granular sludge to a biochemical treatment system.

139. Acclimation; The conversion process by which mature fecal sewage activated sludge gradually develops the ability to treat specific industrial wastewater.

140. Organic load; Refers to the amount of pollutants removed per unit mass of activated sludge per unit time.

141. Volumetric load; The weight of pollutants that can be removed per unit volume of aeration tank per unit time.

142. Shock load; During wastewater treatment operation, the amount of sludge generally remains at a certain level, and the volume of the reactor (aeration tank, anaerobic reactor, etc.) will not change. However, if the influent water quality changes significantly (COD surges or drops sharply), it will cause significant changes in sludge load and volumetric load, affecting the sludge microorganisms, which is the so-called shock load.

143. ORP; Oxidation-reduction potential, a measure of the oxidation-reduction capacity of an aqueous solution, with units of mV.

144. DO; Molecular oxygen dissolved in water is called dissolved oxygen, usually denoted as DO, expressed in milligrams of oxygen per liter of water.

145. Aeration; A means of bringing air into strong contact with water, with the aim of dissolving oxygen from the air into the water, or expelling unwanted gases and volatile substances from the water into the air.

146. Oxygenation rate; In wastewater treatment, the ability of an aerator to supply oxygen to a liquid is called oxygenation capacity, measured in kg/(m3˙h) [10℃ or 20℃, 101.3kPa). The oxygenation capacity of a liquid per kilowatt-hour is called oxygenation efficiency.

147. Plug flow activated sludge process; Wastewater is uniformly propelled to flow, wastewater enters from the head end of the tank and flows out from the tail end, with no mixing between the front and rear liquid flows.

148. Sequencing batch reactor (SBR) activated sludge process; An activated sludge wastewater treatment technology that operates in an intermittent aeration mode. Its main characteristics are orderly and intermittent operation.

149. Microscopic examination; Abbreviation for microscopic examination. It involves sampling, slide preparation, observation, analysis, and judgment of the sample under a microscope.

150. Protozoa; Protozoa are the lowest class of eukaryotic unicellular animals in the animal kingdom, with individuals composed of a single cell.

151. Metazoa; The collective term for all animals other than protozoa (Metazoa subkingdom).

152. Non-filamentous bulking; Bulking caused by the accumulation of a large amount of highly viscous substances (such as various sugars formed by glucose, mannose, arabinose, rhamnose, and deoxyribose) in the bacterial cells of the floc bacteria.

153. Filamentous bulking; Sludge bulking caused by the proliferation of a large number of filamentous bacteria in the activated sludge.

154. Endogenous respiration; Microorganisms continue oxidation reactions when oxygen is sufficient but nutrients are insufficient, i.e., when carbon sources in wastewater are insufficient.

155. Exogenous respiration; Under normal circumstances, the respiration metabolism of microorganisms using externally supplied energy is called exogenous respiration.

156. Endogenous respiration; If no external energy is supplied, but the internal stored energy substances are used for respiratory metabolism, it is called endogenous respiration.

157. Aging; Sludge disintegration caused by excessive sludge age, prolonged low load, or endogenous respiration.

158. Excess sludge; Refers to the activated sludge discharged from the secondary sedimentation tank (or sedimentation zone) out of the activated sludge system.

159. Ammonification; Refers to the process by which nitrogen-containing organic matter such as proteins and urea is decomposed by microorganisms into ammonia.

160. Nitrification; Refers to the process by which ammonia is oxidized to nitrate under the action of microorganisms.

161. Denitrification; Refers to the biochemical process by which bacteria reduce nitrate (NO3−) nitrogen (N) to nitrogen gas (N2) through a series of intermediate products (NO2−, NO, N2O).

162. Short-cut nitrification and denitrification; Short-cut nitrification refers to the generation of nitrite from NH3 without the production of nitrate; while the direct generation of N2 from nitrite is called short-cut denitrification.

163. Simultaneous nitrification and denitrification; Nitrification and denitrification reactions often occur under the same treatment conditions and in the same treatment space, therefore, these phenomena are called simultaneous nitrification/denitrification (SND).

164. Anammox; The biological reaction process in which anaerobic ammonium oxidizing bacteria use nitrite as an electron acceptor to oxidize ammonium nitrogen to nitrogen gas under anoxic conditions.

165.Breakpoint chlorination; In wastewater, NH3-N can be oxidized to chloramine (NH2Cl, NHCl2, NCl3) using chlorine-based oxidants (such as Cl2, NaOCl) at an appropriate pH value, and then further oxidized and decomposed into N2 gas to achieve the purpose of removal.

166.Struvite crystallization; A method to remove ammonia nitrogen and total phosphorus by forming struvite (magnesium ammonium phosphate) precipitate using magnesium ions, ammonium ions, and phosphate in water.

167.Biological phosphorus removal; The process of removing phosphorus using the excessive phosphorus uptake characteristics of polyphosphate-accumulating organisms.

168.Chemical phosphorus removal; The process of removing phosphorus based on the principle that phosphate forms precipitates with certain metal ions.

169.Gasification phosphorus removal; The process in which phosphate forms phosphine under the action of microorganisms.

170.Sludge drying; The process of removing most of the water content from sludge through filtration or evaporation.

171.Anaerobic reactor; A specialized reactor designed for anaerobic treatment technology.

172.Anaerobic granular sludge; Granular sludge produced by upflow anaerobic sludge bed and similar reactors, which is nearly spherical and hollow, mainly composed of inorganic precipitates and extracellular polysaccharides. Various microorganisms live together to effectively remove pollutants from wastewater.

173.Aerobic granular sludge; Granular activated sludge formed by the self-aggregation of microorganisms in an aerobic environment.

174.MBR; Also known as membrane bioreactor, it is a new type of water treatment technology that combines a membrane separation unit and a biological treatment unit. The membrane replaces the secondary sedimentation tank.

175.Advanced oxidation; The process of oxidizing and degrading pollutants in wastewater that cannot be oxidized by ordinary oxidants through the generation of hydroxyl radicals.

176.Hydroxyl radical; An important reactive oxygen species, which is formed by the loss of one electron from the hydroxide ion (OH-). Hydroxyl radicals have a very strong electron-accepting ability, i.e., oxidizing ability, with an oxidation potential of 2.8V. It is the second strongest oxidant in nature after fluorine.

177.Evaporation crystallization; Heating and evaporating the solvent to change the solution from unsaturated to saturated. Continued evaporation will cause the excess solute to crystallize out, which is called evaporation crystallization.

178.Halophilic bacteria; Refers to a type of bacteria and microorganisms with specific physiological structures that can only survive in saline environments.

179.Reclaimed water reuse; This refers to the process of treating domestic sewage (or urban sewage) or industrial wastewater through advanced technologies to remove various impurities, toxic and harmful substances, and certain heavy metal ions from the polluted water body, and then disinfecting and sterilizing it. The water is colorless, odorless, and clear, and meets or exceeds the national standards for reclaimed water (or relevant regulations), widely used in industrial production or residents' lives.

180.Zero discharge; Refers to the fact that after industrial water is repeatedly used, the high-concentration wastewater containing salt and pollutants is completely (more than 99%) recovered and reused, or the substances insoluble in water are filtered out using a filter press and then recycled, with no wastewater discharged from the factory.