【Dry goods】28 knowledge points of sewage treatment

Pay more attention to the public account: environmental protection water treatment

1. Total solids: dry the quantitative water sample to constant weight in a small oven at 105~110 °C, and the resulting weight: .

2. There are four nitrogen-containing compounds in sewage: organic nitrogen, ammonia nitrogen, nitrite nitrogen and nitrate nitrogen.

3. Kjeldahl nitrogen (KN) is the sum of organic nitrogen and ammonia nitrogen: Kjeldahl nitrogen index can be used to judge whether the nitrogen nutrition is sufficient when the sewage is treated by biological methods.

4. There are 5 physical forms of grease in sewage:

(1) Floating oil, when still water, can float to the liquid surface to form an oil film, accounting for about 60%~80% of the total amount of oil;

(2) Mechanically dispersed oil, the diameter of oil particles is greater than 5 μm, which is relatively stably dispersed in sewage, and there is no surfactant between the oil-water interface;

(3) Emulsified oil, the diameter of the oil particles is also 5 μm, but there is a surfactant between the oil and water boundary, so it is more stable;

(4) Attached oil, that is, the oil attached to the surface of the suspended group;

(5) Dissolved oil, including oil beads dissolved in water and oil particles with a diameter of less than 5 μm. (1), (2), (3), (4) types of grease - generally can be removed by physical methods such as oil separation, air flotation or precipitation, and (5) type of oil can mainly be removed by biological method or air flotation method.

5. Coliform count (coliform value): is the number of coliform bacteria contained in each liter of water sample, measured in pcs/L.

6. Water pollution: refers to the amount of pollutants discharged into the water body that exceeds the background content of the substance in the water body and the environmental capacity of the water body, resulting in changes in the physical, chemical and microbial properties of the water, and the destruction of the inherent ecosystem and functions of the water body.

7. Water environment capacity: Under the condition of meeting the water environment quality standards, the maximum allowable pollution load of the water body, also known as the water body's pollution holding capacity.

8. The basic force method of sewage treatment: it is to use various technologies and means to separate, remove, recycle, or convert the pollutants contained in the sewage into harmless substances, so that the water can be purified.

9. Stabilization pond: It is a sewage biological treatment technology that has been artificially properly trimmed on the land, set up a levee and an impermeable layer, and mainly relies on the natural biological purification function to purify the sewage.

10. Sewage land treatment system: It also belongs to the category of natural sewage treatment, which is a sewage treatment process that distributes sewage to the land under the condition of artificial control.

11. Wetland treatment system: It is a land treatment process in which sewage is put into the swamp where the soil is often in a state of water saturation and there are water-tolerant plants such as reeds and cattails, and the sewage flows in a certain direction, and in the process of flowing, under the joint action of water-resistant plants and soil, the sewage is purified.

12. Advanced treatment: When the outflow standard of sewage treatment is some specific pollutants, the treatment process is often called advanced treatment.

13. Activated sludge (two expressions)

Concept 1: Inject air into domestic sewage for aeration, and after a period of time, a yellow-brown floc is formed in the sewage. This floc is mainly composed of a large number of microbial populations, which are easy to precipitate and separate from water, and purify and clarify the wastewater, and this floc is a biological sludge called "activated sludge".

Concept 2: Activated sludge is the main substance in the activated sludge treatment system. Activated sludge inhabits a community of microorganisms with strong vitality. Under the action of the metabolic function of the microbial community, the activated sludge only has the activity to convert organic pollutants into stable inorganic substances, so it is called "activated sludge".

14. Energy content of activated sludge: the ratio of organic matter (F) to microbial mass (M) (F/M).

15. Metabolism of microorganisms: The activated sludge microorganisms living in the aeration tank continuously ingest the organic pollutants in the sewage as nutrients from the surrounding environment for ingestion and absorption.

16. Activated sludge treatment technology is a bioengineering technology that makes the physiological function of activated sludge microorganisms with oxidation and decomposition of organic matter as the main body be fully utilized through a series of artificial strengthening and control technical measures, so as to achieve the purpose of sewage purification.

17. Mixed liquid suspended solids concentration MLSS: also known as mixed liquid sludge concentration, it indicates the total weight of activated sludge solids contained in the mixed liquid per unit volume of aeration tank.

18. Concentration of volatile suspended liquid in mixed liquid MLVSS: This index represents the concentration of organic solid matter in the activated sludge of mixed liquid.

19. Sludge volume index SVI is referred to as "sludge index": the physical meaning of this index is the volume occupied by the sedimented sludge formed by each g of dry sludge after 30min of static sedimentation in the mixed liquid at the outlet of the aeration tank, measured in mL.

20. Sludge sedimentation ratio SV: the volume of the sedimented sludge formed by the mixture after standing in the graduated cylinder for 30min accounts for the percentage of the volume of the original mixture, expressed as %.

21. Sludge age: the ratio of the total amount of activated sludge (VX) in the aeration tank to the daily amount of sludge discharged, that is, the average residence time of activated sludge in the aeration tank, so it is also called "average residence interval of biosolids", that is:

22. BOD - sludge load (Ns): It represents the amount of organic pollutants (BOD) per unit weight (kg) of activated sludge in the aeration tank that can be accepted within the unit time (1d) and degraded to a predetermined degree.

23. Volumetric load (Nv) unit: The volume of the aeration tank (m3), within the unit time (1 day), can accept and degrade to a predetermined degree of organic pollution (BOD) amount.

24. Activated sludge method: It is a sewage biological treatment technology that takes artificial measures to create suitable conditions, strengthens the metabolic function of activated sludge microorganisms, and accelerates the degradation of organic pollutants in sewage.

25. The essence of the biofilm method: it is to make microorganisms such as bacteria and fungi and microscopic animals such as protozoa and metazoan attach to the filter material or some carriers to grow and reproduce, and form a membrane-like biological sludge - biofilm on it.

26. Biofilm: A membranous bioaggregate formed by a variety of microorganisms attached to the surface of a solid material.

27. Biological filter: It is an artificial biological treatment method developed on the basis of the practice of sewage irrigation.

28. The basic principle of the new theory of denitrification: first partially oxidize ammonia nitrogen to nitrite nitrogen, control the ratio of NH4+ to NO2- to 1:1, and then achieve the purpose of denitrification through anaerobic ammonia oxidation as denitrification.