Enhanced removal method for nitrate nitrogen and organic matters in regenerated water source of constructed wetland

Abstract

The invention belongs to the technical field of artificial wetland regenerated water treatment, and particularly relates to an enhanced removal method for nitrate nitrogen and organic matters in an artificial wetland regenerated water source. According to the method, glucose, manganese ions and copper ions are added into a regenerated water source, heterotrophic bacteria are enriched in a constructed wetland packed bed, metal ions are loaded in the constructed wetland packed bed, extracellular active enzymes are generated through stress reaction of the heterotrophic bacteria to the metal ions, and then the enzymolysis process of humus organic matters difficult to biodegrade is achieved. The biodegradability of the recycled water is improved, and finally, the removal process of nitrate nitrogen and organic matters is enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of reclaimed water treatment in constructed wetlands, and particularly relates to a method for enhancing the removal of nitrate nitrogen and organic matter in the reclaimed water source of constructed wetlands. Background Art

[0003] Reclaimed water is the effluent from urban sewage treatment plants that meets the discharge standards, and has the characteristics of large water volume and stable water quality, and is a stable "second water source" in cities. At present, using reclaimed water as a make-up water source is an important measure to solve the shortage of water resources and ecological degradation. Among them, the constructed wetland water purification project plays a key role in improving the quality of reclaimed water.

[0004] The purification of pollutants in constructed wetlands is completed through the synergistic action of microorganisms, filler matrices and aquatic vegetation. However, due to the particularity of the quality of reclaimed water sources, the purification efficiency of constructed wetlands for nitrate nitrogen and organic matter is limited. After the urban domestic sewage passes through the "secondary biological treatment + tertiary advanced treatment" process, the residual nitrogen in the produced reclaimed water source mainly exists in the form of nitrate, and the organic matter is mainly humic-like organic matter. On the one hand, humic-like organic matter has a complex molecular structure and a huge molecular weight, and it is difficult to be purified and removed in constructed wetlands through microbial degradation, filler adsorption and vegetation absorption; on the other hand, the removal of nitrate nitrogen mainly relies on denitrification, but due to the lack of biodegradable carbon sources, the denitrification process cannot be effectively constructed in constructed wetlands, and the fillers and vegetation have obvious effects on the removal of ammonia nitrogen and phosphate, but limited ability to remove nitrate nitrogen. Therefore, it is of great significance to explore a method for removing nitrate nitrogen and organic matter. Summary of the Invention

[0005] The present invention discloses a method for enhancing the removal of nitrate nitrogen and organic matter in the reclaimed water source of constructed wetlands. Using the humic-like organic matter in the reclaimed water source as an organic carbon source for denitrification can achieve the simultaneous removal of organic matter and nitrate nitrogen. By adding glucose, manganese ions and copper ions to the reclaimed water source, enriching heterotrophic bacteria and loading metal ions in the constructed wetland filler bed, and generating extracellular active enzymes through the stress response of heterotrophic bacteria to metal ions, the enzymatic hydrolysis process of difficult-to-biodegradable humic-like organic matter can be realized, the biodegradability of reclaimed water can be improved, and finally the removal process of nitrate nitrogen and organic matter can be enhanced.

[0006] To achieve the above object, the technical solution of the present invention is:

[0007] A method for enhancing the removal of nitrate nitrogen and organic matter in the reclaimed water source of constructed wetlands, comprising: using the humic-like organic matter in the reclaimed water source as an organic carbon source for denitrification to achieve the simultaneous removal of humic-like organic matter and nitrate nitrogen.

[0008] Preferably, in the method, glucose, manganese ions, and copper ions are added to the reclaimed water source. Heterotrophic bacteria are enriched and metal ions are loaded in the artificial wetland filler bed. Extracellular active enzymes are produced through the stress response of heterotrophic bacteria to metal ions, thereby realizing the enzymatic hydrolysis process of refractory biodegradable humus-like organic matter, improving the biodegradability of the reclaimed water source, and ultimately strengthening the removal process of nitrate nitrogen and humus-like organic matter.

[0009] Preferably, the method includes the following specific steps:

[0010] (1) Manganese ore sand is laid in the bottom area of the artificial wetland at a filling rate of 35%-50%.

[0011] (2) During the process of the artificial wetland starting to operate and purifying reclaimed water, with nitrate nitrogen as the water quality indicator, when the removal effect of nitrate nitrogen by the artificial wetland reaches a stable state, a glucose solution with a COD equivalent concentration of 3 mg / L is added to the influent.

[0012] (3) After the artificial wetland continues to operate for 40-50 days, the addition of the glucose solution is stopped, and a divalent copper ion solution is added to the influent to make the divalent copper ion concentration in the influent 0.02 mg / L.

[0013] (4) When the divalent copper ion concentration in the effluent of the artificial wetland is greater than 0.01 mg / L, the addition of divalent copper ions is stopped, and divalent manganese ions are started to be added to make the divalent manganese ion concentration in the influent 3 mg / L.

[0014] (5) When the divalent manganese ion concentration in the effluent of the artificial wetland is greater than 0.10 mg / L, the addition of divalent manganese ions is stopped, and then the artificial wetland continues to operate normally.

[0015] The beneficial effects of the method for strengthening the removal of nitrate nitrogen and organic matter in the reclaimed water source by the artificial wetland of the present invention are as follows:

[0016] 1. Aiming at the water quality characteristics of reclaimed water, using the glucose solution as the electron donor for heterotrophic microorganisms to increase the microbial enrichment amount on the surface of manganese ore sand in the artificial wetland.

[0017] 2. By loading divalent copper ions and divalent manganese ions on the surface of manganese ore sand, the microorganisms use divalent copper ions as the active center site and divalent manganese ions as the inducer to produce extracellular stress active enzymes.

[0018] 3. According to the current reclaimed water discharge standard, the COD concentration in reclaimed water is generally less than 30 mg / L. The present invention can reduce the COD concentration to less than 15 mg / L, and the removal amount of nitrate nitrogen concentration is more than 3 mg / L.

[0019] In summary, in the present invention, glucose, manganese ions, and copper ions are added to the reclaimed water source. Heterotrophic bacteria are enriched in the artificial wetland filler bed and loaded with metal ions. Extracellular active enzymes are produced through the stress response of the heterotrophic bacteria to the metal ions, thereby realizing the enzymatic hydrolysis process of humus-like organic matter that is difficult to biodegrade, improving the biodegradability of the reclaimed water source, and ultimately strengthening the removal process of nitrate nitrogen and humus-like organic matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 : Schematic diagram of the device for purifying reclaimed water in an artificial wetland (in the figure, 1, reclaimed water source; 2, water pump; 3, purified water; 4, aquatic plants; 5, manganese ore sand layer; 6, support layer; 7, quartz sand layer).

[0021] Figure 2 : Purification effect of nitrate nitrogen in the reclaimed water source by the artificial wetland.

[0022] Figure 3 : Purification effect of COD in the reclaimed water source by the artificial wetland. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The following description is only for the preferred embodiments of the present invention and is not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0024] The following embodiments can be understood as separately expressing a part of the local structure or method of the present invention, or can also be understood as the embodiments combined with each other to explain the connotation of the structure or method in a larger scope of the present invention.

[0025] Embodiment 1

[0026] A method for enhancing the removal of nitrate nitrogen and organic matter in the reclaimed water source of an artificial wetland, comprising: using the humus-like organic matter in the reclaimed water source as an organic carbon source for denitrification to achieve the synchronous removal of humus-like organic matter and nitrate nitrogen.

[0027] On the one hand, humus-like organic matter has a complex molecular structure and a huge molecular weight, and it is difficult to be purified and removed through microbial degradation, filler adsorption, and vegetation absorption in the artificial wetland. On the other hand, the removal of nitrate nitrogen mainly relies on denitrification. However, due to the lack of biodegradable carbon sources, the denitrification process cannot be effectively constructed in the artificial wetland, and the filler and vegetation have obvious removal effects on ammonia nitrogen and phosphate, but have limited removal ability for nitrate nitrogen. Based on the above problems, the present invention uses the humus-like organic matter in the reclaimed water source as an organic carbon source for denitrification to achieve the synchronous removal of humus-like organic matter and nitrate nitrogen.

[0028] Embodiment 2

[0029] Based on Example 1, this example discloses:

[0030] In the described method, by adding glucose, manganese ions, and copper ions to the reclaimed water source, enriching heterotrophic bacteria and loading metal ions in the artificial wetland filler bed, extracellular active enzymes are produced through the stress response of heterotrophic bacteria to metal ions, thereby realizing the enzymatic hydrolysis process of refractory biodegradable humus-like organic matter, improving the biodegradability of the reclaimed water source, and ultimately strengthening the removal process of nitrate nitrogen and humus-like organic matter.

[0031] Example 3

[0032] Based on Example 2, this example discloses:

[0033] The described method includes the following specific steps:

[0034] (1) Lay manganese ore sand in the bottom area of the artificial wetland at a filling rate of 35%-50%.

[0035] (2) During the process of the artificial wetland starting to operate and purifying reclaimed water, taking nitrate nitrogen as the water quality indicator, when the removal effect of the artificial wetland on nitrate nitrogen reaches a stable state, add a glucose solution with a COD equivalent concentration of 3 mg / L to the influent.

[0036] (3) After the artificial wetland continues to operate for 40-50 days, stop adding the glucose solution and add a divalent copper ion solution to the influent to make the divalent copper ion concentration in the influent 0.02 mg / L.

[0037] (4) When the divalent copper ion concentration in the effluent of the artificial wetland is greater than 0.01 mg / L, stop adding the divalent copper ion and start adding divalent manganese ions to make the divalent manganese ion concentration in the influent 3 mg / L.

[0038] (5) When the divalent manganese ion concentration in the effluent of the artificial wetland is greater than 0.10 mg / L, stop adding the divalent manganese ion, and then the artificial wetland continues to operate normally.

[0039] Example 4

[0040] Based on the above examples, this example discloses:

[0041] The artificial wetland filler bed device built in the example is as Figure 1As shown, the reactor is built with transparent acrylic sheets, and the reactor size (length × width × height) is 0.9 × 0.3 × 0.5 m. The reactor packing bed is filled with cobblestones (10 cm), manganese ore sand (20 cm), and quartz sand (20 cm) from bottom to top, and the filling rate of manganese ore sand is 40%. The operating condition of the reactor is that the hydraulic retention time is 3 days. According to the technical solution of the present invention, the operation stage of the exemplified constructed wetland device includes a start-up and stable operation stage, a glucose addition stage, a divalent copper ion addition stage, and a divalent manganese ion addition stage.

[0042] As Figure 2 shown, during the start-up and stable operation stage (0 - 54 days), the removal effect of the constructed wetland on nitrate nitrogen reaches a stable state, and the removal amount of nitrate nitrogen is maintained at about 0.4 mg / L, and the removal rate is about 11%.

[0043] As Figure 2 、 3 shown, within 55 - 99 days, only a glucose solution with a COD equivalent concentration of 3 mg / L is added to the influent of the constructed wetland. The average removal amount of nitrate nitrogen by the constructed wetland is 1.05 mg / L, and the average removal rate is 25%; the average removal amount of COD is 14.5 mg / L, and the average removal rate is 43%.

[0044] As Figure 2 、 3 shown, within 100 - 125 days, only a divalent copper ion solution with a concentration of 0.02 mg / L is added to the influent of the constructed wetland. The average removal amount of nitrate nitrogen by the constructed wetland is 1.77 mg / L, and the average removal rate is 38%; the average removal amount of COD is 13.5 mg / L, and the average removal rate is 53%.

[0045] As Figure 2 、 3 shown, within 125 - 134 days, only a divalent manganese ion solution with a concentration of 3 mg / L is added to the influent of the constructed wetland. The average removal amount of nitrate nitrogen by the constructed wetland is 3.65 mg / L, and the average removal rate is 86%; the average removal amount of COD is 16.3 mg / L, and the average removal rate is 67%. The removal amount of nitrate nitrogen concentration is above 3 mg / L, and the effluent concentration of COD is below 15 mg / L.

[0046] As Figure 2 、 3 shown, within 135 - 160 days, after stopping the addition of divalent manganese ions, the constructed wetland can still operate stably, with the removal amount of nitrate nitrogen concentration above 3 mg / L and the effluent concentration of COD below 15 mg / L.

[0047] The working principle of the present invention:

[0048] 1. In view of the water quality characteristics of reclaimed water, a glucose solution is used as an electron donor for heterotrophic microorganisms to increase the microbial enrichment amount on the surface of manganese ore sand in the constructed wetland.

[0049] 2. By loading divalent copper ions and divalent manganese ions on the surface of manganese ore sand, the microorganisms use divalent copper ions as the active center sites and divalent manganese ions as inducers to produce extracellular stress active enzymes.

[0050] 3. According to the current reclaimed water discharge standard, the COD concentration in reclaimed water is generally less than 30 mg / L. The present invention can reduce the COD concentration to below 15 mg / L, and the removal amount of nitrate nitrogen concentration is more than 3 mg / L.

Claims

1. A method for enhanced removal of nitrate nitrogen and organic matter from artificial wetland regeneration water sources, characterized by: include: The humus-like organic matter in the reclaimed water source is used as an organic carbon source for denitrification to achieve the simultaneous removal of humus-like organic matter and nitrate nitrogen.

2. The method for enhanced removal of nitrate nitrogen and organic matter in artificial wetland regeneration water source according to claim 1, characterized in that: In the method described, glucose, manganese ions and copper ions are added to the regenerated water source, heterotrophic bacteria are enriched and loaded with metal ions in the artificial wetland filler bed, and extracellular active enzymes are produced through the stress response of the heterotrophic bacteria to the metal ions, thereby realizing the enzymatic hydrolysis process of the difficult-to-biodegrade humus-like organic matter, improving the biodegradability of the regenerated water source, and finally strengthening the removal process of nitrate nitrogen and humus-like organic matter.

3. The enhanced removal method of nitrate nitrogen and organic matter in artificial wetland regeneration water source according to claim 2, characterized in that: The method comprises the following specific steps: (1) laying manganese ore sand in the bottom area of ​​the artificial wetland at a filling rate of 35%-50%; (2) During the start-up of the artificial wetland to purify recycled water, nitrate nitrogen was used as the water quality indicator. When the artificial wetland reached a stable state in terms of nitrate nitrogen removal, a glucose solution with a COD equivalent concentration of 3 mg / L was added to the influent; (3) After the artificial wetland continues to operate for 40-50 days, stop adding glucose solution and add divalent copper ion solution to the influent to make the divalent copper ion concentration in the influent 0.02 mg / L; (4) When the concentration of divalent copper ions in the effluent of the artificial wetland is greater than 0.01 mg / L, stop adding divalent copper ions and start adding divalent manganese ions to make the concentration of divalent manganese ions in the influent 3 mg / L; (5) When the concentration of divalent manganese ions in the effluent of the artificial wetland is greater than 0.10 mg / L, the addition of divalent manganese ions is stopped, and the artificial wetland continues to operate normally.

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