Sewage treatment and calcium removal combined tank and process

Abstract

The invention discloses a sewage treatment and calcium removal combined tank and process, belongs to the field of sewage treatment, and solves the problem of adverse effects caused by untreated calcium ions in sewage. The system comprises a water inlet tank, a NaOH dosing tank, a NaCO3 dosing tank, a PAC dosing tank, a PAM dosing tank, a horizontal flow sedimentation tank, an inclined tube sedimentation tank and a neutralization tank which are connected in sequence, the water inlet tank is connected with a water inlet pipe, and the neutralization tank is connected with a water outlet pipe. A calcium removal process: the sewage enters a NaOH dosing tank, and the pH value of the sewage is controlled to be greater than or equal to 12; mixing with NaCO3 to generate calcium carbonate precipitate; mixing with PAC, and enabling calcium carbonate precipitates to be mutually bonded; mixing with PAM, and further bonding the calcium carbonate precipitate; and after precipitation, the sewage enters a neutralization tank to adjust the pH value of the sewage to 7.0-8.5. According to the method, dosing mixing, precipitation and sludge discharging and slag scraping are integrated, sodium carbonate, PAC and PAM are sequentially added after alkalinity is adjusted, it is ensured that calcium precipitates are changed from small to large, and finally particle precipitates are removed.

Description

Technical Field

[0001] The invention belongs to the field of sewage treatment, and in particular relates to a sewage treatment decalcification combined pool and process. Background Art

[0002] The currently implemented "Water Quality Standard for Sewage Discharge into Urban Sewers" (GB / T31962-2015) does not clearly stipulate the concentration of calcium ions discharged. Papermaking wastewater, leather wastewater and non-ferrous metal smelting wastewater contain a large amount of calcium ions in the wastewater discharged by these industries because calcium chloride, calcium hydroxide and other calcium-containing chemicals are added during the production process. Most companies do not carry out calcium removal treatment on the discharged wastewater, resulting in a lot of calcium ions entering urban domestic sewage. In the influent of the sewage treatment plant, if the concentration of calcium ions in the sewage is high, there will be the following adverse effects. First, it is easy to cause scaling of the related equipment and inner wall of the pipeline of the sewage treatment plant, resulting in a gradual decrease in the sewage treatment capacity; second, it will also cause calcification of the aerobic aeration system of activated sludge and scaling on the surface of the aerator, making the aeration effect of the aerobic tank worse and the dissolved oxygen content lower; third, excessive calcium ion concentration will also destroy the bacterial floc structure of the activated sludge in the aerobic tank, reduce the biological activity of microorganisms, and cause a decrease in biochemical treatment capacity. Therefore, when treating calcium-containing wastewater, it is imperative to increase pretreatment and reduce the calcium ion concentration in the wastewater. Summary of the invention

[0003] The purpose of the present invention is to provide a combined sewage treatment and decalcification pool to solve the problem of adverse effects caused by untreated calcium ions in sewage.

[0004] Another object of the present invention is to provide a wastewater treatment and decalcification process.

[0005] The technical solution of the present invention is: a combined sewage treatment and decalcification tank, comprising an inlet tank, a NaOH dosing tank, a NaCO3 dosing tank, a PAC dosing tank, a PAM dosing tank, a horizontal flow sedimentation tank, an inclined tube sedimentation tank and a neutralization tank connected in sequence, the inlet tank is connected to an inlet pipe, and the neutralization tank is connected to an outlet pipe.

[0006] As a further improvement of the present invention, the NaOH dosing tank is connected to the NaOH dosing pipe, and the NaOH dosing tank is provided with a first stirrer; the NaCO3 dosing tank is connected to the NaCO3 dosing pipe, and the NaCO3 dosing tank is provided with a second stirrer; the PAC dosing tank is connected to the PAC dosing pipe, and the PAC dosing tank is provided with a third stirrer; the PAM dosing tank is connected to the PAM dosing pipe, and the PAM dosing tank is provided with a fourth stirrer; the neutralization tank is connected to the acid dosing pipe, and the neutralization tank is provided with a fifth stirrer.

[0007] As a further improvement of the present invention, a mud discharge bucket is provided at the bottom of the horizontal flow sedimentation tank, a mud discharge scraper is provided in the horizontal flow sedimentation tank, and the first output end of the mud discharge scraper is connected to the mud discharge bucket; a slag discharge pipe is provided at the top of the horizontal flow sedimentation tank, and the second output end of the mud discharge scraper is connected to the slag discharge pipe.

[0008] As a further improvement of the present invention, the inclined tube sedimentation tank is located above the horizontal flow sedimentation tank, and the mud discharge end of the inclined tube sedimentation tank is connected to the horizontal flow sedimentation tank.

[0009] As a further improvement of the present invention, it also includes a mud storage tank, a mud discharge bucket is connected to the mud storage tank through a mud discharge pipe, and the mud discharge pipe is provided with a mud discharge valve and a mud discharge pump; a mud collecting pit is provided at the bottom of the mud storage tank, the mud collecting pit is connected to an output pipe, and the output pipe is provided with an output valve and an output pump.

[0010] As a further improvement of the present invention, a water outlet channel is provided at the rear end of the PAM dosing tank, and a water inlet channel is provided at the front end of the advection sedimentation tank, and the water outlet channel is connected to the water inlet channel.

[0011] As a further improvement of the present invention, a plurality of water collecting tanks are provided on the upper part of the inclined tube sedimentation tank, each of which is connected to a water collecting channel, and the water collecting channel is connected to the neutralization tank.

[0012] As a further improvement of the present invention, the water inlet tank and the NaOH dosing tank are connected through a first water hole, the NaOH dosing tank and the NaCO3 dosing tank are connected through a second water hole, the NaCO3 dosing tank and the PAC dosing tank are connected through a third water hole, the AC dosing tank and the PAM dosing tank are connected through a fourth water hole, the PAM dosing tank and the outlet channel are connected through a fifth water hole, the outlet channel and the inlet channel are connected through a sixth water hole, the inlet channel and the horizontal flow sedimentation tank are connected through a seventh water hole, and the water collection channel and the neutralization tank are connected through an eighth water hole; the flow areas of the first water hole, the second water hole, the third water hole, the fourth water hole, the fifth water hole, the sixth water hole, and the seventh water hole increase in sequence.

[0013] A sewage treatment and decalcification process comprises the following steps: A. Put the sewage into the water inlet tank through the water inlet pipe, and the sewage enters the NaOH dosing tank and mixes with NaOH to control the sewage pH ≥ 12; B. Alkaline sewage enters the NaCO3 dosing tank and mixes with NaCO3 to form calcium carbonate precipitation; C. The sewage from the NaCO3 dosing tank enters the PAC dosing tank and mixes with PAC. PAC helps the calcium carbonate precipitation to bond with each other; D. The effluent from the PAC dosing tank enters the PAM dosing tank, where it mixes with PAM and further bonds the calcium carbonate precipitate; E. The sewage from the PAM dosing tank enters the advection sedimentation tank, which precipitates calcium carbonate and other inorganic precipitates in the sewage to the lower part; F. The sewage after sedimentation in the horizontal flow sedimentation tank enters the inclined tube sedimentation tank to further precipitate calcium carbonate. The water in the upper part of the inclined tube sedimentation tank enters the neutralization tank, mixes with hydrochloric acid, neutralizes and adjusts the pH of the sewage to 7.0-8.5, and is discharged through the outlet pipe.

[0014] Furthermore, from the first water hole to the seventh water hole, the water flow velocity is adjusted to gradually decrease from 0.3 m / s to 0.1 m / s.

[0015] The beneficial effects of the present invention are: 1. The present invention provides a combined decalcification pool for sewage treatment, which has the function of decalcification, integrates dosing and mixing, sedimentation and sludge removal and scraping, has a compact structure and clear divisions, saves the floor space and pipe connection length of the decalcification process, is convenient for operation and management, and saves construction costs. By designing a series of dosing pools, the decalcification efficiency is improved.

[0016] 2. The decalcification process of sewage treatment of the present invention adjusts the pH value of sewage at the water inlet to ensure that only carbonate ions exist in the water, which facilitates accurate control of the dosage of sodium carbonate. After adjusting the alkalinity, sodium carbonate, PAC and PAM are added in sequence to ensure that the calcium precipitates formed are from small to large, and finally enter the horizontal flow sedimentation tank and the inclined tube sedimentation tank in sequence to remove the granular precipitates. After the calcium ions are removed, the water is then neutralized by acid addition and enters the subsequent biochemical stage, which fully considers the adaptability to the subsequent treatment process. It is suitable for decalcification of domestic sewage. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is an upper plan view of a sewage treatment and decalcification combined pool of the present invention; Figure 2 It is a lower floor plan of a sewage treatment and decalcification combined pool of the present invention; Figure 3 for Figure 1 AA section view in; Figure 4 for Figure 1 BB section diagram in; Figure 5 for Figure 1 CC cross-section diagram in .

[0018] In the figure: 1 is the water inlet tank; 2 is the NaOH dosing tank; 3 is the NaCO3 dosing tank; 4 is the PAC dosing tank; 5 is the PAM dosing tank; 6 is the horizontal flow sedimentation tank; 7 is the inclined tube sedimentation tank; 8 is the neutralization tank; 9 is the mud bucket; 10 is the mud storage tank; 11 is the outlet channel; 12 is the scum well; 13 is the equipment transportation corridor; 14 is the first mixer; 15 is the mud scraper; 16 is the inclined tube; 17 is the water inlet pipe; 18-1 is the first water hole; 18-2 is the second water hole; 18-3 is the third water hole; 18-4 is the fourth water hole; 18-5 is the fifth water hole; 18-6 is the sixth water hole; 18-7 is the seventh water hole; 18-8 is the eighth water hole; 19 is Outlet pipe; 20-1 is the first gate; 20-2 is the second gate; 20-3 is the third gate; 21 is the mud discharge valve; 22 is the output pump; 23 is the mud collection pit; 24 is the submersible mixer; 26 is the output valve; 27 is the slag discharge pipe; 28 is the water collection tank; 29 is the water collection channel; 30 is the inclined pipe support beam; 31 is the air pipe; 32 is the NaOH dosing pipe; 33 is the NaCO3 dosing pipe; 34 is the PAC dosing pipe; 35 is the PAM dosing pipe; 36 is the acid dosing pipe; 37 is the stairs; 38 is the second mixer; 39 is the third mixer; 40 is the fourth mixer; 41 is the fifth mixer; 42 is the mud discharge pipe; 43 is the mud discharge pump; 44 is the output pipe; 45 is the water inlet channel. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0020] like Figure 1-5 As shown, a combined sewage treatment and decalcification tank comprises an inlet tank 1, a NaOH dosing tank 2, a NaCO3 dosing tank 3, a PAC dosing tank 4, a PAM dosing tank 5, a horizontal flow sedimentation tank 6, an inclined tube sedimentation tank 7 and a neutralization tank 8 which are connected in sequence. The lower part of the inlet tank 1 is connected to an inlet pipe 17, and the neutralization tank 8 is connected to an outlet pipe 19.

[0021] The NaOH dosing tank 2 is connected to a NaOH dosing pipe 32, and a first stirrer 14 is provided in the NaOH dosing tank 2; the NaCO3 dosing tank 3 is connected to a NaCO3 dosing pipe 33, and a second stirrer 38 is provided in the NaCO3 dosing tank 3; the PAC dosing tank 4 is connected to a PAC dosing pipe 34, and a third stirrer 39 is provided in the PAC dosing tank 4; the PAM dosing tank 5 is connected to a PAM dosing pipe 35, and a fourth stirrer 40 is provided in the PAM dosing tank 5; the neutralization tank 8 is connected to an acid dosing pipe 36, and a fifth stirrer 41 is provided in the neutralization tank 8.

[0022] A mud bucket 9 is provided at the bottom of the horizontal flow sedimentation tank 6, and a mud scraper 15 is provided in the horizontal flow sedimentation tank 6. The first output end of the mud scraper 15 is connected to the mud bucket 9; a slag discharge pipe 27 is provided at the upper part of the horizontal flow sedimentation tank 6, and the second output end of the mud scraper 15 is connected to the slag discharge pipe 27, and the slag discharge pipe 27 is connected to the slag well 12.

[0023] The inclined tube sedimentation tank 7 is located above the horizontal flow sedimentation tank 6 , and the mud discharge end of the inclined tube sedimentation tank 7 is connected to the horizontal flow sedimentation tank 6 .

[0024] It also includes a mud storage tank 10, a mud discharge bucket 9 is connected to the mud storage tank 10 through a mud discharge pipe 42, and a mud discharge valve 21 and a mud discharge pump 43 are provided on the mud discharge pipe 42; a mud collection pit 23 is provided at the bottom of the mud storage tank 10, and the bottom of the mud storage tank 10 slopes toward the mud collection pit 23 with a slope of 0.01, and the mud collection pit 23 is connected to an output pipe 44, and an output valve 26 and an output pump 22 are provided on the output pipe 44. A submersible agitator 24 is provided in the mud storage tank 10.

[0025] An outlet channel 11 is disposed at the rear end of the PAM dosing tank 5 , and an inlet channel 45 is disposed at the front end of the horizontal flow sedimentation tank 6 . The outlet channel 11 is connected to the inlet channel 45 .

[0026] A plurality of inclined tubes 16 are arranged in the inclined tube sedimentation tank 7 , and the inclined tubes 16 are supported by inclined tube support beams 30 . A plurality of water collecting troughs 28 are arranged on the upper part of the inclined tube sedimentation tank 7 , and each water collecting trough 28 is connected to a water collecting channel 29 , and the water collecting channel 29 is connected to the neutralization tank 8 .

[0027] The inlet tank 1 and the NaOH dosing tank 2 are connected via the first water hole 18-1, the NaOH dosing tank 2 and the NaCO3 dosing tank 3 are connected via the second water hole 18-2, the NaCO3 dosing tank 3 and the PAC dosing tank 4 are connected via the third water hole 18-3, the AC dosing tank 4 and the PAM dosing tank 5 are connected via the fourth water hole 18-4, the PAM dosing tank 5 and the outlet channel 11 are connected via the fifth water hole 18-5, the outlet channel 11 and the inlet channel 45 are connected via the sixth water hole 18-6, and the inlet channel 45 and the advection sedimentation tank 6 are connected via the sixth water hole 18-7. The water collection channel 29 and the neutralization tank 8 are connected through the seventh water hole 18-7, and the eighth water hole 18-8 is connected between the water collection channel 29 and the neutralization tank 8; the first water hole 18-1, the third water hole 18-3, and the fifth water hole 18-5 are opened on the upper part of the wall, the second water hole 18-2 and the fourth water hole are opened on the lower end of the wall, and the seventh water hole 18-7 adopts a perforated flower wall form; the flow areas of the first water hole 18-1, the second water hole 18-2, the third water hole 18-3, the fourth water hole 18-4, the fifth water hole 18-5, the sixth water hole 18-6, and the seventh water hole 18-7 increase in sequence. The first water hole 18-1 is provided with a first gate 20-1, the sixth water hole 18-6 is provided with a second gate 20-2, and the eighth water hole 18-8 is provided with a third gate 20-3 for customs inspection.

[0028] A sewage treatment and decalcification process comprises the following steps: A. Put the sewage into the water inlet tank 1 through the water inlet pipe 17, and the sewage enters the NaOH dosing tank 2 through the first water hole 18-1, and mixes with the NaOH added through the NaOH dosing pipe 32. After being stirred by the first stirrer 14, the pH value of the sewage is controlled to be ≥ 12 to ensure that only carbonate ions exist in the water; B. Alkaline sewage enters the NaCO3 dosing tank 3 through the second water hole 18-2, mixes with the NaCO3 added through the NaCO3 dosing pipe 33, and generates tiny calcium carbonate precipitation under the stirring of the second mixer 38; since there is no bicarbonate and carbon dioxide in the sewage when the pH is 12, but only carbonate, the added sodium carbonate reacts with the calcium in the sewage completely, and the amount of sodium carbonate added is easy to control, which saves the sodium carbonate dosing and reduces the decalcification operation cost; C. The sewage from the NaCO3 dosing tank 3 enters the PAC dosing tank 4 through the third water hole 18-3, is mixed with the PAC added through the PAC dosing pipe 34 and is evenly stirred by the third mixer 39. The PAC helps the tiny calcium carbonate precipitates to bond to each other to form larger particles of calcium carbonate precipitates; D. The effluent from the PAC dosing tank 4 enters the PAM dosing tank 5 through the fourth water hole 18-4, is mixed with the PAM added through the PAM dosing pipe 35, and is stirred evenly by the fourth mixer 40, so that the calcium carbonate precipitate is further bonded into larger particles of calcium carbonate precipitate; E. The sewage from the PAM dosing tank 5 flows out to the outlet channel 11 through the fifth water hole 18-5, then enters the inlet channel 45 through the sixth water hole 18-6, and then enters the horizontal flow sedimentation tank 6 through the seventh water hole 18-7. The horizontal flow sedimentation tank 6 precipitates the large and easily precipitated calcium carbonate and other large inorganic precipitates in the sewage to the lower part; F. The sewage after sedimentation in the horizontal flow sedimentation tank 6 enters the inclined tube sedimentation tank 7 to further precipitate the fine calcium carbonate that is not easy to precipitate. The water in the upper part of the inclined tube sedimentation tank 7 flows into the water collection tank 28 and then collects in the water collection channel 29. It enters the neutralization tank 8 through the eighth water hole 18-8 and is mixed with the hydrochloric acid added through the acid dosing pipe 36. After being stirred by the fifth mixer 41, the pH value of the sewage is neutralized and adjusted to 7.0-8.5 to meet the subsequent biological treatment requirements, and then it is discharged through the outlet pipe 19 to enter the next treatment structure.

[0029] By controlling the water flow areas from the first water flow hole 18-1 to the seventh water flow hole 18-7, the water flow velocity is adjusted to gradually decrease from 0.3 m / s to 0.1 m / s from the first water flow hole 18-1 to the seventh water flow hole 18-7.

[0030] An equipment transport corridor 13 and stairs 37 are also provided on the side of the combined pool of the present invention.

[0031] An air pipe 31 is provided at the lower end of the inclined tube 16. If the sediment in the inclined tube 16 is seriously silted up and the sedimentation efficiency is reduced, the air pipe 31 is opened to perform air flushing on the inclined tube 16 to restore the sedimentation performance of the inclined tube 16 and ensure the effective removal of calcium carbonate.

[0032] In the horizontal flow sedimentation tank 6, the precipitated calcium carbonate and other inorganic precipitates are scraped into the sludge bucket 9 by the sludge scraper 15, the sludge valve 21 and the sludge pump 43 are opened, and the sludge in the sludge bucket 9 is discharged into the sludge storage tank 10 through the sludge discharge pipe 42, and is evenly mixed by the submersible mixer 24 in the sludge storage tank 10 and concentrated into the sludge collecting pit 23, the output valve 26 and the output pump 22 are opened, and the sludge in the sludge collecting pit 23 is output through the output pipe 44.

[0033] In the horizontal flow sedimentation tank 6, the scum in the sewage is scraped into the scum discharge pipe 27 by the sludge scraper 15, and then discharged into the scum well 12, and finally discharged into the sewage plant drainage system.

[0034] Embodiment 1, The working conditions are as follows: the sewage volume is 2.5×104m³ / d, Ca 2+ The concentration is 800 mg / L and the pH is 7.

[0035] The treatment method is as follows: the sewage enters the water inlet tank 1 through the water inlet pipe 17, and then enters the NaOH dosing tank 2. The NaOH dosing tank 2 adds a 10% mass concentration NaOH solution (the theoretical dosage of sodium hydroxide is 0.0036L / L, and the actual addition is 0.0045L / L) to adjust the pH value of the sewage to ≥12. The alkaline sewage then enters the NaCO3 dosing tank 3, and the NaCO3 dosing tank 3 adds a 10% mass concentration NaCO3 solution (the theoretical dosage is 1.06g / L, and the actual addition is 1.38g / L). After adding NaCO3 and mixing evenly, the sewage enters the PAC dosing tank 3 and the PAM dosing tank 4 in turn. The PAC drug dosing concentration is 10% (PAC dosing is calculated based on the pure amount of 7mg / L), and the PAM drug dosing concentration is 0.1% (PAM dosing is calculated based on the pure amount of 1mg / L). Then the sewage is precipitated in the horizontal flow sedimentation tank 6 and the inclined tube sedimentation tank 7 in turn and then enters the neutralization tank 8, in which a hydrochloric acid solution with a mass concentration of 10% is added (the theoretical dosage of hydrochloric acid is 0.0035L / L, and the actual addition is 0.0049L / L) to adjust the pH value of the sewage to 8.0. The neutralized sewage is discharged from the outlet pipe 19 to the subsequent biochemical tank.

[0036] Note: The actual dosage of the above-mentioned reagents is the average value after one year of operation.

[0037] The Ca content in treated sewage 2+The concentration is 400 mg / L, the removal rate is 50%, there is no scaling in the subsequent equipment and pipelines during operation, the subsequent microbial activity is good, and the calcium removal effect is significant. It should be noted that this embodiment only removes 50% of calcium ions due to the consideration of the dosing cost of the sewage treatment plant. This removal rate has met the normal operation of the sewage treatment plant. By adjusting the dosage, the calcium ion concentration can be further removed.

[0038] The moisture content of the sludge entering the sludge storage tank 10 after sedimentation is 97%, and it is pumped to the integrated deep dehydration equipment in the factory area through the output pump 22.

Claims

1. A combined sewage treatment and decalcification pool, characterized in that: The invention comprises a water inlet tank (1), a NaOH dosing tank (2), a NaCO3 dosing tank (3), a PAC dosing tank (4), a PAM dosing tank (5), a horizontal flow sedimentation tank (6), an inclined tube sedimentation tank (7) and a neutralization tank (8) which are connected in sequence. The water inlet tank (1) is connected to a water inlet pipe (17), and the neutralization tank (8) is connected to a water outlet pipe (19).

2. A combined sewage treatment and decalcification pool according to claim 1, characterized in that: The NaOH dosing tank (2) is connected to a NaOH dosing pipe (32), and a first stirrer (14) is provided in the NaOH dosing tank (2); The NaCO3 dosing tank (3) is connected to a NaCO3 dosing pipe (33), and a second mixer (38) is provided in the NaCO3 dosing tank (3); The PAC dosing tank (4) is connected to a PAC dosing pipe (34), and a third mixer (39) is provided in the PAC dosing tank (4); The PAM dosing tank (5) is connected to a PAM dosing pipe (35), and a fourth mixer (40) is provided in the PAM dosing tank (5); The neutralization tank (8) is connected to an acid dosing pipe (36), and a fifth stirrer (41) is provided in the neutralization tank (8).

3. A combined sewage treatment and decalcification pool according to claim 1 or 2, characterized in that: A mud discharge bucket (9) is provided at the bottom of the horizontal flow sedimentation tank (6), a mud discharge scraper (15) is provided in the horizontal flow sedimentation tank (6), and a first output end of the mud discharge scraper (15) is connected to the mud discharge bucket (9); a slag discharge pipe (27) is provided at the top of the horizontal flow sedimentation tank (6), and a second output end of the mud discharge scraper (15) is connected to the slag discharge pipe (27).

4. A combined sewage treatment and decalcification pool according to claim 3, characterized in that: The inclined tube sedimentation tank (7) is located above the horizontal flow sedimentation tank (6), and the mud discharge end of the inclined tube sedimentation tank (7) is connected to the horizontal flow sedimentation tank (6).

5. A combined sewage treatment and decalcification pool according to claim 4, characterized in that: It also comprises a mud storage tank (10), wherein the mud discharge bucket (9) is connected to the mud storage tank (10) via a mud discharge pipe (42), and the mud discharge pipe (42) is provided with a mud discharge valve (21) and a mud discharge pump (43); a mud collection pit (23) is provided at the bottom of the mud storage tank (10), and the mud collection pit (23) is connected to an output pipe (44), and the output pipe (44) is provided with an output valve (26) and an output pump (22).

6. A combined sewage treatment and decalcification pool according to claim 5, characterized in that: The PAM dosing tank (5) is provided with an outlet channel (11) at the rear end, and the advection sedimentation tank (6) is provided with an inlet channel (45) at the front end, and the outlet channel (11) is connected to the inlet channel (45).

7. A combined sewage treatment and decalcification pool according to claim 6, characterized in that: A plurality of water collecting tanks (28) are provided on the upper part of the inclined tube sedimentation tank (7), each water collecting tank (28) is connected to a water collecting channel (29), and the water collecting channel (29) is connected to the neutralization tank (8).

8. A combined sewage treatment and decalcification pool according to claim 7, characterized in that: The water inlet tank (1) and the NaOH dosing tank (2) are connected via a first water hole (18-1), the NaOH dosing tank (2) and the NaCO3 dosing tank (3) are connected via a second water hole (18-2), the NaCO3 dosing tank (3) and the PAC dosing tank (4) are connected via a third water hole (18-3), the AC dosing tank (4) and the PAM dosing tank (5) are connected via a fourth water hole (18-4), the PAM dosing tank (5) and the outlet channel (11) are connected via a fifth water hole (18-5), and the outlet channel (11) is connected via a fifth water hole (18-6). The first water hole (18-1), the second water hole (18-2), the third water hole (18-3), the fourth water hole (18-4), the fifth water hole (18-5), the sixth water hole (18-6), and the seventh water hole (18-7) are connected to each other.

9. A process for decalcification of sewage treatment, characterized in that: The combined sewage treatment and decalcification pool of claim 1 comprises the following steps: A. Put the sewage into the water inlet tank (1) through the water inlet pipe (17), and the sewage enters the NaOH dosing tank (2) to mix with NaOH to control the pH of the sewage to ≥ 12; B. Alkaline wastewater enters the NaCO3 dosing tank (3) and mixes with NaCO3 to form calcium carbonate precipitation; C. The wastewater from the NaCO3 dosing tank (3) enters the PAC dosing tank (4) and mixes with PAC, which helps the calcium carbonate precipitates to bond with each other; D. The effluent from the PAC dosing tank (4) enters the PAM dosing tank (5), where it is mixed with PAM and further bonded by calcium carbonate precipitation; E. The sewage from the PAM dosing tank (5) enters the horizontal flow sedimentation tank (6), and the horizontal flow sedimentation tank (6) precipitates calcium carbonate and other inorganic precipitates in the sewage to the lower part; F. After being precipitated in the horizontal flow sedimentation tank (6), the sewage enters the inclined tube sedimentation tank (7) to further precipitate calcium carbonate. The water in the upper part of the inclined tube sedimentation tank (7) enters the neutralization tank (8) to mix with hydrochloric acid to neutralize and adjust the pH value of the sewage to 7.0-8.5, and then is discharged through the outlet pipe (19).

10. A wastewater treatment and decalcification process according to claim 9, characterized in that: From the first water hole (18-1) to the seventh water hole (18-7), the water flow velocity is adjusted to gradually decrease from 0.3 m / s to 0.1 m / s.

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