1. Domestic sewage; Mainly the discharge water produced by 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.
2. Municipal sewage; A general term for sewage discharged into the urban sewage system. In a combined sewer system, it also includes industrial wastewater and intercepted rainwater. Municipal sewage mainly includes domestic sewage and industrial wastewater, which is collected by the city drainage network and transported to the sewage treatment plant for treatment.
3. Industrial wastewater; Refers to wastewater, sewage, and waste liquid produced during industrial production, which contains industrial production materials, intermediate products, and products lost with the water flow, as well as pollutants generated during the production process.
4. COD; Chemical Oxygen Demand, the amount of oxidant consumed in the chemical oxidation process of substances that can be oxidized in water under specified conditions, expressed as the number of milligrams of oxygen consumed per liter of water sample, usually denoted as COD. BOD; The amount of dissolved oxygen in the surface water consumed by the process of microbial decomposition of organic matter is called Biochemical Oxygen Demand, usually denoted as BOD, with common units of mg/L.
5. BC ratio; Indicates the biodegradability of pollutants in water. 0.1-0.25 is difficult to biodegrade, 0.25-0.5 is biodegradable, >0.5 is easily biodegradable. 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.
6. Ammonia nitrogen; Refers to nitrogen in water that exists in the form of free ammonia (NH3) and ammonium ions (NH4+).
7. Organic nitrogen; A general term for nitrogen-containing substances combined with carbon, such as proteins, amino acids, amides, and urea.
8. 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.
9. Nitrate nitrogen; NOxˉ, refers to the nitrogen element contained in nitrates. Nitrate and nitrite only.
10. Total nitrogen; TN, is the total amount of various forms of inorganic and organic nitrogen in water.
11. Total phosphorus; TP, the result measured after various forms of phosphorus in the water sample are converted into orthophosphate after digestion, measured in milligrams of phosphorus per liter of water sample.
12. Hypophosphite; Phosphate existing in the form of H2PO2ˉ, which cannot be removed by normal chemical phosphorus removal and needs to be converted into sulfate before it can be removed.
13. Color; Refers to the degree of yellowish to yellowish-brown color presented by the dissolved or colloidal substances contained in the water.
14. Screen; Used to remove floating matter in water.
15. Primary sedimentation tank; Also known as the primary sedimentation tank, a structure used in wastewater treatment to remove settleable and floating matter.
16. 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 and temperature of wastewater, and has a pre-aeration regulation function. It can also be used for accident drainage.
17. Accident tank; Accident water collection tank, a type of structure required in wastewater treatment. When treating high-concentration wastewater discharged from some factories such as chemical and petrochemical plants, an accident tank is generally set up.
18. Oil-water separator; It achieves separation by utilizing the difference in specific gravity between suspended matter and water in wastewater.
19. Flotation; A large number of fine bubbles are generated in the water, causing air to adhere to the 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 of the water, thereby achieving solid-liquid separation.
20. Bioreactor; The pool where bacteria metabolize in biochemical treatment.
21. Secondary sedimentation tank; Also known as the secondary sedimentation tank, the secondary sedimentation tank is an important component of the activated sludge system. Its main function is to separate sludge, clarify, concentrate, and return activated sludge.
22. Horizontal flow sedimentation tank; The plane of the pool is rectangular, and the inlet and outlet are located at both ends of the pool length.
23. Vertical flow sedimentation tank; Also known as a vertical sedimentation tank, it is a sedimentation tank in which wastewater flows vertically in the tank. The plane of the tank is circular or square, and the water enters the tank from top to bottom through the inlet pipe in the center of the tank. Sedimentation is achieved through the self-weight of the sludge.
24. Radial flow sedimentation tank; Wastewater enters the tank from the central inlet pipe and flows slowly along the radial direction to the periphery of the tank. Suspended matter settles during the flow and enters the sludge hopper along the bottom slope of the tank, and the clarified water overflows from the peripheral overflow channel of the tank.
25. Sludge tank; Generally used to hold return sludge and excess sludge.
26. Monitoring pool; Also known as a clear water pool, used to store treated wastewater.
27. Coagulation; The process by which colloids lose their stability. Commonly known as colloid destabilization.
28. Flocculation; The process by which destabilized colloids aggregate into larger flocs.
29. Coagulation; The entire process of two stages: destabilization and flocculation to form large flocs. The general term for coagulation and flocculation.
30. 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).
31. 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 bacterial floc.
32. Filamentous bacteria; A type of bacteria with a filamentous structure. The skeleton of bacterial flocs.
33. Autotrophic bacteria; Bacteria that use inorganic carbon sources as carbon sources.
34. Heterotrophic bacteria; Bacteria that use organic carbon sources as carbon sources.
35. 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.
36. Aerobic environment ; both dissolved oxygen and nitrate nitrogen are present. In engineering, DO > 0.5 is considered aerobic.
37. 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.
38. Activated sludge process; A wastewater treatment method achieved through the adsorption, metabolism, and solid-liquid separation of bacterial flocs.
39. Biofilm process; A method of treating organic wastewater using microorganisms (i.e., biofilm) that adhere to the surface of certain solid materials.
40. Hydraulic retention time; Abbreviated as HRT, a term in water treatment technology, 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.
41. 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.
42. SV; 30-minute settling ratio, refers to the ratio of the volume of settled sludge to the volume of the mixed liquid sample after settling for 30 minutes in a 1000ml graduated cylinder. It is also known as sludge settling volume (SV30), expressed in 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.
43. MLSS; Sludge concentration, the weight of dry sludge contained in 1 liter of aeration tank sludge mixture.
44. MLVSS; Mixed liquor volatile suspended solids concentration, representing the concentration of organic solid matter in the mixed liquor activated sludge.
45. RSS; Return sludge concentration.
46. SVI; Sludge volume index, an indicator for measuring the settling performance of activated sludge. It refers to the volume (in mL) occupied by 1g of dry sludge after 30min of settling of the aeration tank mixed liquor, i.e., SVI = volume of sludge after 30min settling (mL) / dry sludge weight (g), i.e., SVI = SV30 / MLSS.
47. 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.
48. 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.
49. Inoculation; The process of adding activated sludge or granular sludge to a biochemical treatment system.
50. Acclimation; The conversion process by which mature fecal wastewater activated sludge gradually develops the ability to treat specific industrial wastewater.
51. Organic loading; Refers to the amount of pollutants removed per unit mass of activated sludge per unit time.
52. Volumetric loading; The weight of pollutants that can be removed per unit volume of aeration tank per unit time.
53. Shock loading; During wastewater treatment operation, the sludge volume 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.
54, ORP; Oxidation-reduction potential is a measure of the oxidation-reduction capacity of an aqueous solution, and its unit is mV.
55, DO; Molecular oxygen dissolved in water is called dissolved oxygen, usually denoted as DO, expressed as the number of milligrams of oxygen per liter of water.
56, Aeration; A method of bringing air into intense 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.
57, Oxygen transfer rate; In wastewater treatment, the ability of an aerator to supply oxygen to a liquid is called oxygen transfer capacity, measured in kg/(m3˙h) [10℃ or 20℃, 101.3kPa). The oxygen transfer capacity of the liquid per kilowatt-hour is called oxygen transfer efficiency.
58, Plug flow activated sludge process; Wastewater is uniformly propelled forward, entering the tank from the head end and exiting from the tail end, with no mixing between the front and rear liquid flows.
59, 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.
60, Microscopic examination; Short for microscopic examination. It involves sampling and preparing a slide of the specimen to be tested, and then observing, analyzing, and judging it under a microscope.
61, Protozoa; Protozoa are the lowest class of eukaryotic single-celled animals in the animal kingdom, with individuals composed of a single cell.
62, Metazoa; The collective term for all animals other than protozoa (Metazoa subkingdom).
63, Non-filamentous bulking; Non-filamentous 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.
64, Filamentous bulking; Sludge filamentous bulking caused by the proliferation of a large number of filamentous bacteria in the activated sludge.
65, Endogenous respiration; Microorganisms continue to undergo oxidation reactions when there is sufficient oxygen but insufficient nutrients, i.e., insufficient carbon sources in the wastewater.
66, Exogenous respiration; Under normal circumstances, the respiration metabolism of microorganisms using externally supplied energy is called exogenous respiration.
67, Endogenous respiration; If no external energy is supplied, but the respiration metabolism is carried out using the energy substances stored inside the organism, it is called endogenous respiration.
68, Aging; Sludge disintegration caused by excessive sludge age, prolonged low load, or endogenous respiration.
69, Excess sludge ; refers to the activated sludge discharged from the secondary sedimentation tank (or sedimentation zone) out of the system.
70, Ammonification; Refers to the process by which nitrogen-containing organic matter such as proteins and urea is decomposed by microorganisms into ammonia.
71, Nitrification; Refers to the process in which ammonia is oxidized to nitrate under the action of microorganisms.
72, Denitrification; Refers to the biochemical process in which bacteria reduce nitrate (NO3−) nitrogen (N) to nitrogen gas (N2) through a series of intermediate products (NO2−, NO, N2O).
73, Short-cut nitrification and denitrification; Short-cut nitrification refers to the generation of nitrite from NH3, without the production of nitrate; while nitrite is directly converted to N2, which is called short-cut denitrification.
74, 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).
75, Anammox; That is, the biological reaction process in which anaerobic ammonium oxidizing bacteria use nitrite as an electron acceptor to oxidize ammonia nitrogen to nitrogen gas under anoxic conditions.
76, Breakpoint chlorination; NH3-N in wastewater 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.
77, Struvite precipitation; A method of removing ammonia nitrogen and total phosphorus by forming magnesium ammonium phosphate precipitates using magnesium ions, ammonium ions, and phosphates in water.
78, Biological phosphorus removal; The process of removing phosphorus by utilizing the excessive phosphorus uptake characteristics of polyphosphate-accumulating organisms.
79, Chemical phosphorus removal; The process of removing phosphorus by utilizing the principle of phosphate forming precipitates with certain metal ions.
80, Gasification phosphorus removal; The process by which phosphate forms phosphine under the action of microorganisms.
81, Sludge drying; The process of removing most of the water content from sludge through infiltration or evaporation.
82, Anaerobic reactor; A special reactor designed for anaerobic treatment technology.
83, Anaerobic granular sludge; Granular sludge produced by upflow anaerobic sludge bed and similar reactors, hollow and nearly spherical, mainly composed of inorganic precipitates and extracellular polysaccharides, with various microorganisms living together to effectively remove pollutants from wastewater.
84, Aerobic granular sludge; It is granular activated sludge formed by the self-aggregation of microorganisms in an aerobic environment.
85, MBR; Also known as a membrane bioreactor, it is a new type of water treatment technology that combines a membrane separation unit with a biological treatment unit. The membrane replaces the secondary sedimentation tank.
86, Advanced oxidation; The process of oxidizing and degrading pollutants in wastewater that cannot be oxidized by ordinary oxidants through the generation of hydroxyl radicals.
87, Hydroxyl radical; It is an important reactive oxygen species, which, from the molecular formula, is formed by a hydroxide ion (OH-) losing an electron. Hydroxyl radicals have a very strong electron-accepting ability, that is, oxidizing ability, with an oxidation potential of 2.8V. It is the second strongest oxidant in nature after fluorine.
88, Evaporation crystallization; Heating to evaporate the solvent, causing the solution to change from unsaturated to saturated. Continued evaporation causes the excess solute to precipitate as crystals, which is called evaporation crystallization.
89, Halophile; Refers to a type of bacteria and microorganisms with specific physiological structures that can only survive in saline environments.
90, Wastewater reuse; This refers to the process of deeply treating domestic sewage (or urban sewage) or industrial wastewater 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 national standards for miscellaneous water use (or relevant regulations), widely used in industrial production or residential life.
91, Zero discharge; Refers to industrial water being reused repeatedly, with the high concentration of salt content and pollutants in this part of the water being completely (more than 99%) recovered and reused, or using a filter press to filter out insoluble substances before recycling, with no wastewater discharged from the factory.
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