CN102515352A - Method for removing ammonia nitrogen from industrial waste water produced in synthetic ammonia industry - Google Patents

Abstract

The invention discloses a method for removing ammonia nitrogen from synthetic ammonia industrial wastewater. The synthetic ammonia industrial wastewater enters anoxic pool, anaerobic pool, microoxic pool, aerobic pool and sedimentation pool in turn, and part of the sewage in the microoxic pool flows back into the anaerobic pool. , part of the sewage in the aerobic tank is returned to the anoxic tank, and part of the sewage in the sedimentation tank is returned to the inlet of the anoxic tank. The invention realizes anoxic denitrification, anaerobic ammonium oxidation and short-range nitrification and denitrification in the same biological treatment system. Realize short-range nitrification and denitrification, save 25% of oxygen supply and 40% of organic carbon source, shorten reaction residence time, reduce volume; realize anaerobic ammonium oxidation, reduce energy consumption, and prevent secondary pollution; high ammonia nitrogen removal rate, reaching More than 99%; the consumption of alkali in the whole process is reduced, and the operating cost is low.

Description

A method for removing ammonia nitrogen from synthetic ammonia industrial wastewater

technical field

The invention relates to a method for removing ammonia nitrogen in waste water, in particular to a method for removing ammonia nitrogen in synthetic ammonia industrial waste water.

Background technique

The synthetic ammonia industry produces a large amount of ammonia-nitrogen-containing industrial wastewater during the production process. The wastewater in this industry has the characteristics of many types of pollutants, poor biodegradability, low carbon-nitrogen ratio, and high ammonia-nitrogen content. At present, the synthetic ammonia industrial wastewater is generally treated by biochemical methods, especially the biological denitrification process represented by A/O denitrification. The principle of this process is that the ammonia nitrogen in the wastewater is nitrified into nitrate nitrogen by nitrifying bacteria under aerobic conditions, and a large amount of nitrate nitrogen flows back to the anoxic section. Under anoxic conditions, through the action of facultative anaerobic denitrifying bacteria, The organic matter in the wastewater is used as the electron donor, and the nitrate nitrogen is used as the electron acceptor, so that the nitrate nitrogen is reduced to nitrogen gas, which escapes into the atmosphere to achieve the purpose of final denitrification. In the process, the aerobic section requires a large amount of blast air, large power consumption, and a large amount of alkali to be supplemented; the anoxic section needs to supplement a large amount of organic carbon sources. Under the condition of low carbon-nitrogen ratio of ammonia industrial wastewater, denitrification The rate is low, the amount of supplementary organic carbon source is large, and the operating cost is high; the denitrification efficiency of this process is low. In order to improve the denitrification rate, the reflux ratio must be increased, but the high reflux ratio will cause rich oxidation in the anoxic section, destroy the denitrification environment, and reduce The denitrification rate is improved, and the kinetic energy consumption is increased at the same time.

Contents of the invention

The purpose of the present invention is to provide a method for removing ammonia nitrogen in synthetic ammonia industrial wastewater with high treatment efficiency, low operating cost and small investment, which can make the wastewater discharge of this industry reach the national standard.

The technical scheme of the present invention includes the following contents: a method for removing ammonia nitrogen in synthetic ammonia industrial wastewater, wherein the synthetic ammonia industrial wastewater enters the anoxic pool, the anaerobic pool, the microoxic pool, the aerobic pool and the sedimentation pool in turn, and a part of the sewage in the microoxic pool flows back To the anaerobic tank, part of the sewage in the aerobic tank is returned to the anoxic tank, and part of the sewage in the sedimentation tank is returned to the inlet end of the anoxic tank.

The synthetic ammonia industrial wastewater first enters the anoxic pool, and is mixed with the reflux mixture containing nitrate nitrogen (NO ₃ ^- -N) for denitrification reaction. The organic matters in the wastewater are used as electron donors, and the nitrate nitrogen (NO ₃ ^- -N) As an electron acceptor, NO ₃ ^- -N is reduced to nitrogen (N ₂ ) and removed; the wastewater after denitrification in the anoxic pool enters the anaerobic pool, and in the anaerobic pool, it contains nitrite The reflux water of nitrogen (NO ₂ ^- -N) is mixed for anaerobic ammonium oxidation reaction, the ammonia nitrogen (NH ₄ ⁺ -N) in the wastewater is used as the electron donor, and the nitrite nitrogen (NO ₂ ^- -N) is used as the electron donor Acceptor, convert NH ₄ ⁺ -N or NO ₂ ^- -N into N ₂ ; the wastewater containing NH ₄ ⁺ -N in the anaerobic tank enters the micro-aerobic tank for nitrosation reaction, and oxidizes NH ₄ ⁺ -N At the same time, part of the sewage containing NO ₂ ^- -N in the micro-aerobic pool is returned to the anaerobic pool; _the ^remaining waste water containing NO ₂ ^- -N in the micro-aerobic pool enters the aerobic pool for nitrification. NO ₂ ^- -N is oxidized to form NO ₃ ^- -N, part of the wastewater containing NO ₃ ^- -N in the aerobic tank is returned to the anoxic tank for denitrification and denitrification, and the rest in the aerobic tank contains NO ₃ ^- - The waste water of N is separated from the mud and water in the sedimentation tank and discharged up to the standard, and the sedimented sludge is returned to the anoxic tank.

The denitrification reaction in the anoxic pond is carried out at PH=7.5-9.2, the dissolved oxygen (DO) is less than 0.5mg/L; the denitrification reaction in the anaerobic pond is at PH=7.0-8.5, the dissolved oxygen (DO) is carried out under the condition of less than 0.2mg/L; the denitrification reaction in the micro-aerobic pool is carried out at PH=7.4-8.3, and the dissolved oxygen (DO) is carried out under the condition of 0.5-1.0mg/L; in the aerobic pool The denitrification reaction is carried out at PH=6.5-8.0, dissolved oxygen (DO) at 2.0-4.0mg/L; the reflux ratio of the mixed solution is 100-300%; the hydraulic retention time in the anoxic pool is 7-14 hours The hydraulic retention time in the anaerobic pool is 9-12 hours; the hydraulic retention time in the micro-aerobic pool is 18-30 hours; the hydraulic retention time in the aerobic pool is 13-17 hours.

The advantage of the invention is that anoxic denitrification, anaerobic ammonia oxidation and short-range nitrification and denitrification are realized in the same biological treatment system. Realize short-range nitrification and denitrification, save 25% of oxygen supply and 40% of organic carbon source, shorten reaction residence time, reduce volume; realize anaerobic ammonium oxidation, reduce energy consumption, and prevent secondary pollution; high ammonia nitrogen removal rate, reaching More than 99%; the consumption of alkali in the whole process is reduced, and the operating cost is low.

The present invention can reduce ammonia nitrogen wastewater with COD of 400-800mg/L and NH4 ⁺ -N of 150-450mg/L to COD less than 50mg/L, NH4 ⁺ -N less than 5mg/L and total nitrogen less than 15mg/L. It is lower than the national first-level emission standard. This process not only greatly improves the denitrification efficiency of traditional synthetic ammonia industrial wastewater, but also reduces operating costs and floor space.

Description of drawings

Fig. 1 is a flow chart of the ammonia nitrogen removal method in the synthetic ammonia industrial wastewater.

Detailed ways

Example 1

The treated water volume is 417m ³ /h, the COD content in the synthetic ammonia industrial wastewater is about 600mg/L, and the ammonia nitrogen content is about 350mg/L. The synthetic ammonia industrial wastewater first enters the anoxic tank, and mixes with the reflux water containing nitrate nitrogen (NO ₃ ^- -N) for denitrification reaction. The denitrifying denitrification bacteria use the organic matter in the wastewater as the electron NO ₃ ^- -N) as an electron acceptor, denitrification reaction is carried out under the condition of PH=7.5-9.2, dissolved oxygen (DO) is less than 0.5mg/L, so that NO ₃ ^- -N is reduced to nitrogen (N ₂ ) In addition, the hydraulic retention time of the anoxic tank is 12 hours; the wastewater after denitrification enters the anaerobic tank, and is mixed with the return water containing nitrite nitrogen (NO ₂ ^- -N) in the anaerobic tank for anaerobic ammonia oxidation reaction , with ammonia nitrogen (NH ₄ ⁺ -N) in wastewater as electron donor, nitrite nitrogen (NO ₂ ^- -N) as electron acceptor, at PH=7.0-8.5, dissolved oxygen (DO) is less than 0.2mg NH ₄ ⁺ -N or NO ₂ ^- -N is converted into N ₂ under the condition of /L, and the hydraulic retention time of the anaerobic tank is 9 hours; the wastewater containing NH ₄ ⁺ -N enters the microaerobic tank for nitrosation reaction. PH=7.4-8.3, dissolved oxygen (DO) oxidizes NH ₄ ⁺ -N to NO ₂ ^- -N under the condition of 0.5-1.0mg/L, and part of the sewage containing NO ₂ ^- -N is returned to the anaerobic tank, The reflux ratio is 200%, and the hydraulic retention time of the microaerobic pool is 20 hours; the remaining wastewater containing NO ₂ ^- -N enters the aerobic pool, at PH=6.5-8.0, dissolved oxygen (DO) at 2.0-4.0mg/L Nitrification reaction is carried out under the conditions, NO ₂ ^- -N is oxidized to form NO ₃ ^- -N, part of the wastewater containing NO ₃ ^- -N is returned to the anoxic pool for denitrification and denitrification, the reflux ratio is 300%, and the aerobic pool water The retention time is 17 hours. The remaining wastewater enters the sedimentation tank for mud-water separation, and the sedimented sludge returns to the water inlet of the anoxic tank. The sludge return ratio is 80%, and the treated effluent meets the standard discharge. The total hydraulic retention time of the system is about 58 hours, the effluent COD is less than 50mg/L, NH4 ⁺ -N is less than 5mg/L, and the total nitrogen is less than 15mg/L.

Example 2

The treated water volume is 210m ³ /h, the COD content in the synthetic ammonia industrial wastewater is about 450mg/L, and the ammonia nitrogen content is about 250mg/L. The synthetic ammonia industrial wastewater first enters the anoxic tank, and mixes with the reflux water containing nitrate nitrogen (NO ₃ ^- -N) for denitrification reaction. The denitrifying denitrification bacteria use the organic matter in the wastewater as the electron NO ₃ ^- -N) as an electron acceptor, denitrification reaction is carried out under the condition of PH=7.5-9.2, dissolved oxygen (DO) is less than 0.5mg/L, so that NO ₃ ^- -N is reduced to nitrogen (N ₂ ) In addition, the hydraulic retention time of the anoxic tank is 7 hours; the wastewater after denitrification enters the anaerobic tank, and in the anaerobic tank, it is mixed with the reflux water containing nitrite nitrogen (NO ₂ ^- -N) for anaerobic ammonia oxidation reaction , with ammonia nitrogen (NH ₄ ⁺ -N) in wastewater as electron donor, nitrite nitrogen (NO ₂ ^- -N) as electron acceptor, at PH=7.0-8.5, dissolved oxygen (DO) is less than 0.2mg NH ₄ ⁺ -N or NO ₂ ^- -N is converted into N ₂ under the condition of /L, and the hydraulic retention time of the anaerobic tank is 9 hours; the wastewater containing NH ₄ ⁺ -N enters the microaerobic tank for nitrosation reaction. PH=7.4-8.3, dissolved oxygen (DO) oxidizes NH ₄ ⁺ -N to NO ₂ ^- -N under the condition of 0.5-1.0mg/L, and part of the sewage containing NO ₂ ^- -N is returned to the anaerobic tank, The reflux ratio is 150%, the hydraulic retention time of the micro-oxygen pool 3 is 25 hours; the remaining wastewater containing NO ₂ ^- -N enters the aerobic pool, at PH=6.5-8.0, dissolved oxygen (DO) at 2.0-4.0mg/ Under the condition of L, the nitrification reaction is carried out, NO ₂ ^- -N is oxidized to form NO ₃ ^- -N, part of the wastewater containing NO ₃ ^- -N is returned to the anoxic tank for denitrification and denitrification, the reflux ratio is 200%, and the aerobic The hydraulic retention time of the pool is 13 hours. The remaining wastewater enters the sedimentation tank for mud-water separation, and the sedimented sludge returns to the water inlet of the anoxic tank. The sludge return ratio is 100%, and the treated effluent meets the standard discharge. The total hydraulic retention time of the system is about 54 hours, the effluent COD is less than 50mg/L, NH4 ⁺ -N is less than 5mg/L, and the total nitrogen is less than 15mg/L.

Claims (8)

1. ammonia nitrogen removal method in the ammonia synthesizing industry waste water; It is characterized in that: ammonia synthesizing industry waste water gets into anoxic pond, anaerobic pond, little oxygen pond, Aerobic Pond and settling tank successively; A part of sewage backflow is to anaerobic pond in little oxygen pond; A part of sewage backflow is to anoxic pond in the Aerobic Pond, and a part of sewage backflow in the settling tank is to the feed-water end of anoxic pond.

2. ammonia nitrogen removal method in the ammonia synthesizing industry waste water according to claim 1; It is characterized in that: ammonia synthesizing industry waste water is introduced in the anoxic pond; Mix with the backflow mixed liquor that contains nitric nitrogen and to carry out denitrification reaction; As electron donor, as electron acceptor(EA), nitric nitrogen is reduced to nitrogen and removes with nitric nitrogen with organism in the waste water; Waste water in the anoxic pond after the denitrogenation gets in the anaerobic pond; In anaerobic pond, mix and carry out the Anammox reaction with the recirculation water that contains nitrite nitrogen; Ammonia nitrogen with in the waste water is done electron donor, is electron acceptor(EA) with the nitrite nitrogen, and ammonia nitrogen or nitrite nitrogen are transformed into nitrogen; The waste water that contains ammonia nitrogen in the anaerobic pond gets in little oxygen pond, carries out nitrosation reaction, is oxidized to nitrite nitrogen to ammonia nitrogen, and a sewage part that contains nitrite nitrogen simultaneously in little oxygen pond is back to anaerobic pond; The remaining waste water that contains nitrite nitrogen in little oxygen pond gets in the Aerobic Pond; Carry out nitration reaction; The oxidized formation nitric nitrogen of nitrite nitrogen; A waste water part that contains nitric nitrogen in the Aerobic Pond is carried out denitrification denitrogenation through being back to anoxic pond, the remaining waste water qualified discharge after the settling tank mud-water separation that contains nitric nitrogen in the Aerobic Pond, and precipitating sludge is back to anoxic pond.

3. ammonia nitrogen removal method in the ammonia synthesizing industry waste water according to claim 1 is characterized in that: the anti-nitration reaction in anoxic pond is at PH=7.5-9.2, and dissolved oxygen is less than carrying out under the 0.5mg/L condition.

4. ammonia nitrogen removal method in the ammonia synthesizing industry waste water according to claim 1 is characterized in that: the anti-nitration reaction in anaerobic pond is at PH=7.0-8.5, and dissolved oxygen is less than carrying out under the 0.2mg/L condition.

5. ammonia nitrogen removal method in the ammonia synthesizing industry waste water according to claim 1 is characterized in that: the anti-nitration reaction in little oxygen pond is at PH=7.4-8.3, and dissolved oxygen carries out under the 0.5-1.0mg/L condition.

6. ammonia nitrogen removal method in the ammonia synthesizing industry waste water according to claim 1 is characterized in that: the anti-nitration reaction in Aerobic Pond is at PH=6.5-8.0, and dissolved oxygen carries out under the 2.0-4.0mg/L condition.

7. ammonia nitrogen removal method in the ammonia synthesizing industry waste water according to claim 1 is characterized in that: the reflux ratio of said mixed solution is 100-300%.

8. ammonia nitrogen removal method in the ammonia synthesizing industry waste water according to claim 1 is characterized in that: hydraulic detention time is 7-14 hour in the anoxic pond; Hydraulic detention time is 9-12 hour in the anaerobic pond; Hydraulic detention time is 18-30 hour in little oxygen pond; Hydraulic detention time is 13-17 hour in the Aerobic Pond.

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