Pyrite coupled corncob mixed nutrition type denitrification vertical flow artificial wetland system

Abstract

The invention discloses a pyrite coupled corncob mixed nutritional denitrification vertical flow artificial wetland system, relates to the field of sewage treatment and water ecological restoration, and relates to an artificial wetland. The invention aims to solve the problem that nitrate nitrogen pollutants in farmland recession enter peripheral surface water and underground water due to excessive application of nitrogen fertilizer. The artificial wetland system consists of wetland plants, a coarse sand layer, a functional layer and a gravel layer from top to bottom. According to the iron ore coupled corncob mixed nutritional denitrification vertical flow constructed wetland system, full supply of autotrophic and heterotrophic electron donors is realized in the integrated vertical flow constructed wetland, and high-efficiency treatment of wastewater with different types of carbon-nitrogen ratios is facilitated. The nitrate nitrogen removal rate and the TN removal rate can exceed 98% and 90% respectively.

Description

Technical Field

[0001] The present invention relates to the field of sewage treatment and water ecological restoration, and in particular to an artificial wetland. Background Art

[0002] Nitrogen pollution poses a serious threat to the sustainable development of the ecological environment and social economy. Traditional artificial wetlands and drainage ditches can purify some pollutants, but the treatment efficiency is relatively low. Therefore, the development of a new type of enhanced integrated vertical flow artificial wetland technology has important practical significance. Summary of the invention

[0003] The purpose of the present invention is to solve the technical problem that excessive application of nitrogen fertilizer causes nitric nitrogen pollutants in farmland runoff to enter surrounding surface water and groundwater, and provides a pyrite-coupled corncob mixed nutrition denitrification vertical flow artificial wetland system.

[0004] The pyrite-coupled corncob mixed trophic denitrification vertical flow artificial wetland system consists of wetland plants, coarse sand layer, functional layer and gravel layer from top to bottom. The thickness of the coarse sand layer does not exceed 5 cm, the thickness of the functional layer does not exceed 20 cm, and the gravel layer does not exceed 5 cm. The functional layer is composed of pyrite and corncob in a volume ratio of 1:1. The pyrite particle size is 3-8 mm, and the corncob particle size is 3-8 mm. The wetland plants are planted in the coarse sand layer with a planting density of 0.025 plants / cm 2 .

[0005] The coarse sand particle size in the coarse sand layer is 1 to 2 mm.

[0006] The gravel particle size in the gravel layer is 10 to 30 mm.

[0007] The thickness of the coarse sand layer is 5 cm, the thickness of the functional layer is 20 cm, and the thickness of the gravel layer is 5 cm.

[0008] The wetland plants are single species or mixed species of cattail, canna and calamus.

[0009] The pyrite-coupled corncob mixed nutrition type denitrification vertical flow artificial wetland system has an inner diameter of 10 cm and a height of 40 cm.

[0010] The pyrite-coupled corncob mixed trophic denitrification vertical flow constructed wetland system is an integrated single wetland system. Wastewater enters from the coarse sand layer on the top of the wetland, passes through the functional layer and then to the gravel layer, and then is discharged from the wetland system. The entire system adopts a top-inlet and bottom-out continuous flow operation mode. Through the strengthening effect of the mixed trophic denitrification functional zone, an efficient denitrification process of the integrated system is achieved.

[0011] The core matrix of the pyrite-coupled corncob mixed nutrition denitrification vertical flow constructed wetland system is a mixed filler of pyrite and corncob (volume ratio 1:1), with a filling thickness of no more than 20cm and a particle size of 3-8mm; in addition, the upper layer is coarse sand and the stratum is gravel, with a filling thickness of no more than 5cm and a particle size of 1-2mm and 10-30mm respectively. Through the positive particle size grading method, the filler with a smaller particle size is arranged on the top, and the filler particle size increases step by step from top to bottom, which can effectively delay the blockage of the constructed wetland and improve the purification efficiency of the constructed wetland.

[0012] The pyrite-coupled corncob mixed nutrition denitrification vertical flow artificial wetland system is planted with wetland plants on the upper layer, with a planting density of 0.025 plants / cm 2 , through root oxygen secretion and atmospheric diffusion, sufficient oxygen supply is provided for the nitrification process. Pyrite and corn cob mixed filler provides sufficient electron supply for autotrophic and heterotrophic denitrification. All system fillers are filled in a free arrangement and cannot be compacted.

[0013] The present invention adopts the coupling form of sulfur / iron autotrophic denitrification of pyrite and heterotrophic denitrification of corn cobs to achieve sufficient supply of autotrophic and heterotrophic electron donors in the integrated vertical flow artificial wetland, thereby ensuring the efficient denitrification process of the vertical flow artificial wetland. In order to achieve efficient denitrification of decentralized sewage such as farmland drainage. It is suitable for denitrification treatment of decentralized domestic sewage, farmland drainage, contaminated groundwater, etc. The system has the advantages of low cost, simple operation, high efficiency and stability.

[0014] The iron ore coupled corncob mixed nutrition type denitrification vertical flow artificial wetland system of the present invention belongs to an integrated vertical flow artificial wetland system, wastewater enters through the top and exits at the bottom, and wetland plants are planted above the system. The system operates in a continuous operation mode. The addition of pyrite and corncob mixed filler effectively promotes the iron / sulfur autotrophic denitrification coupled heterotrophic denitrification process, and effectively enhances the efficient removal of nitrate and nitrogen; in addition, the addition of slow-release carbon source corncob provides the necessary carbon source and energy supply for denitrification; the organic combination of mixed nutrition type denitrification process in the integrated system leads to the system having good denitrification efficiency.

[0015] The present invention has the following advantages:

[0016] 1. The iron ore coupled corncob mixed trophic denitrification vertical flow constructed wetland system of the present invention adopts pyrite and corncob mixed filler, and ensures the efficient denitrification process of the vertical flow constructed wetland through the coupling of sulfur / iron autotrophic denitrification and heterotrophic denitrification.

[0017] 2. The iron ore coupled corncob mixed nutrition denitrification vertical flow constructed wetland system of the present invention realizes sufficient supply of autotrophic and heterotrophic electron donors in the integrated vertical flow constructed wetland, which is conducive to the efficient treatment of wastewater with different types of carbon-nitrogen ratios. The nitrate nitrogen and TN removal rates can exceed 98% and 90% respectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the pyrite-coupled corncob mixed nutrition type denitrification vertical flow artificial wetland system of the present invention, in which 1 represents a coarse sand layer, 2 represents a functional layer, 3 represents a gravel layer, 4 represents a water flow direction, 5 represents wetland plants, and 6 represents a water surface. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is not limited to the specific implementation modes listed below, but also includes any combination of the specific implementation modes.

[0020] Specific implementation method 1: In this implementation method, the pyrite-coupled corncob mixed nutrition type denitrification vertical flow artificial wetland system consists of wetland plants 5, coarse sand layer 1, functional layer 2 and gravel layer 3 from top to bottom. The thickness of the coarse sand layer 1 does not exceed 5 cm, the thickness of the functional layer 2 does not exceed 20 cm, and the gravel layer 3 does not exceed 5 cm. The functional layer 2 is composed of pyrite and corncobs in a volume ratio of 1:1. The particle size of pyrite is 3-8 mm, and the particle size of corncobs is 3-8 mm. The wetland plants 5 are planted in the coarse sand layer 1, and the planting density is 0.025 plants / cm 2 .

[0021] Specific embodiment 2: This embodiment is different from the specific embodiment 1 in that the coarse sand particle size in the coarse sand layer 1 is 1-2 mm. The rest is the same as the specific embodiment 1.

[0022] Specific embodiment 3: This embodiment is different from specific embodiment 1 or 2 in that the particle size of the gravel in the gravel layer 3 is 10-30 mm. The rest is the same as specific embodiment 1 or 2.

[0023] Specific embodiment 4: This embodiment is different from specific embodiments 1 to 3 in that the thickness of the coarse sand layer 1 is 5 cm, the thickness of the functional layer 2 is 20 cm, and the thickness of the gravel layer 3 is 5 cm. The rest is the same as specific embodiments 1 to 3.

[0024] Specific implementation mode 5: This implementation mode is different from specific implementation modes 1 to 4 in that the wetland plants 5 are single species or mixed species of cattail, canna and calamus. The rest is the same as specific implementation modes 1 to 4.

[0025] In this embodiment, when the wetland plants 5 are mixed, the wetland plants can be in any ratio.

[0026] Specific implementation example 6: This implementation example is different from specific implementation examples 1 to 5 in that the pyrite-coupled corncob mixed nutrition type denitrification vertical flow artificial wetland system has an inner diameter of 10 cm and a height of 40 cm. The rest is the same as specific implementation examples 1 to 5.

[0027] The following experiments were used to verify the effect of the present invention:

[0028] Experiment 1:

[0029] The pyrite-coupled corncob mixed nutrition denitrification vertical flow artificial wetland system consists of wetland plants 5, coarse sand layer 1, functional layer 2 and gravel layer 3 from top to bottom. The thickness of the coarse sand layer 1 does not exceed 5 cm, the thickness of the functional layer 2 does not exceed 20 cm, and the gravel layer 3 does not exceed 5 cm. The functional layer 2 is composed of pyrite and corncob in a volume ratio of 1:1. The pyrite particle size is 3 mm, and the corncob particle size is 3 mm. The wetland plants 5 are planted in the coarse sand layer 1, and the planting density is 0.025 plants / cm 2 .

[0030] The coarse sand particle size in the coarse sand layer 1 is 1 mm.

[0031] The particle size of the gravel in the gravel layer 3 is 10 mm.

[0032] The thickness of the coarse sand layer 1 is 5 cm, the thickness of the functional layer 2 is 20 cm, and the thickness of the gravel layer 3 is 5 cm.

[0033] The wetland plant 5 is cattail.

[0034] The pyrite-coupled corncob mixed nutrition type denitrification vertical flow artificial wetland system has an inner diameter of 10 cm and a height of 40 cm.

[0035] The pyrite-coupled corncob mixed trophic denitrification vertical flow constructed wetland system was set to treat 0.785 L of water per day, the average concentrations of influent COD and TN were 90 and 15 mg / L, respectively, and the hydraulic retention time (HRT) was set to 3 days.

[0036] The results showed that under continuous operation conditions, the removal efficiencies of nitrate-nitrogen and TN in the pyrite-coupled corncob mixed trophic denitrification vertical flow constructed wetland system exceeded 95% and 85%, respectively.

[0037] Experiment 2:

[0038] The pyrite-coupled corncob mixed nutrition denitrification vertical flow artificial wetland system consists of wetland plants 5, coarse sand layer 1, functional layer 2 and gravel layer 3 from top to bottom. The thickness of the coarse sand layer 1 does not exceed 5 cm, the thickness of the functional layer 2 does not exceed 20 cm, and the gravel layer 3 does not exceed 5 cm. The functional layer 2 is composed of pyrite and corncob in a volume ratio of 1:1. The pyrite particle size is 8 mm, and the corncob particle size is 8 mm. The wetland plants 5 are planted in the coarse sand layer 1, and the planting density is 0.025 plants / cm 2 .

[0039] The coarse sand particle size in the coarse sand layer 1 is 2 mm.

[0040] The particle size of the gravel in the gravel layer 3 is 30 mm.

[0041] The thickness of the coarse sand layer 1 is 5 cm, the thickness of the functional layer 2 is 20 cm, and the thickness of the gravel layer 3 is 5 cm.

[0042] The wetland plant 5 is canna.

[0043] The pyrite-coupled corncob mixed nutrition type denitrification vertical flow artificial wetland system has an inner diameter of 10 cm and a height of 40 cm.

[0044] The pyrite-coupled corncob mixed trophic denitrification vertical flow constructed wetland system was set to treat 0.785 L of water per day, the average concentrations of influent COD and TN were 90 and 15 mg / L, respectively, and the hydraulic retention time (HRT) was set to 0.6 d.

[0045] The results showed that under continuous operation conditions, the removal efficiencies of nitrate-nitrogen and TN in the pyrite-coupled corncob mixed trophic denitrification vertical flow constructed wetland system were 80% and 75%, respectively.

[0046] Experiment 3:

[0047] The pyrite-coupled corncob mixed nutrition denitrification vertical flow artificial wetland system consists of wetland plants 5, coarse sand layer 1, functional layer 2 and gravel layer 3 from top to bottom. The thickness of the coarse sand layer 1 does not exceed 5 cm, the thickness of the functional layer 2 does not exceed 20 cm, and the gravel layer 3 does not exceed 5 cm. The functional layer 2 is composed of pyrite and corncob in a volume ratio of 1:1. The pyrite particle size is 5 mm, and the corncob particle size is 5 mm. The wetland plants 5 are planted in the coarse sand layer 1, and the planting density is 0.025 plants / cm 2 .

[0048] The coarse sand particle size in the coarse sand layer 1 is 2 mm.

[0049] The particle size of the gravel in the gravel layer 3 is 20 mm.

[0050] The thickness of the coarse sand layer 1 is 5 cm, the thickness of the functional layer 2 is 20 cm, and the thickness of the gravel layer 3 is 5 cm.

[0051] The wetland plant 5 is cattail.

[0052] The pyrite-coupled corncob mixed nutrition type denitrification vertical flow artificial wetland system has an inner diameter of 10 cm and a height of 40 cm.

[0053] The pyrite-coupled corncob mixed trophic denitrification vertical flow constructed wetland system was set to treat 0.785 L of water per day, the average concentrations of influent COD and TN were 90 and 15 mg / L, respectively, and the hydraulic retention time (HRT) was set to 3 days.

[0054] The results showed that under continuous operation conditions, the removal efficiencies of nitrate-nitrogen and TN in the pyrite-coupled corncob mixed trophic denitrification vertical flow constructed wetland system exceeded 98% and 90%, respectively.

Claims

1. Pyrite coupled corncob mixed nutrition type denitrification vertical flow constructed wetland system, characterized by The pyrite-coupled corncob mixed nutrition type denitrification vertical flow artificial wetland system is composed of wetland plants (5), a coarse sand layer (1), a functional layer (2) and a gravel layer (3) from top to bottom. The coarse sand layer (1) is not thicker than 5 cm, the functional layer (2) is not thicker than 20 cm, the gravel layer (3) is not thicker than 5 cm, the functional layer (2) is composed of pyrite and corncobs in a volume ratio of 1:1, the pyrite particle size is 3 to 8 mm, and the corncob particle size is 3 to 8 mm. The wetland plants (5) are planted in the coarse sand layer (1) at a planting density of 0.025 plants / cm 2 .

2. The pyrite-coupled corncob mixed nutrition denitrification vertical flow constructed wetland system according to claim 1, characterized in that The coarse sand particle size in the coarse sand layer (1) is 1 to 2 mm.

3. The pyrite-coupled corncob mixed nutrition denitrification vertical flow constructed wetland system according to claim 1, characterized in that The gravel particle size in the gravel layer (3) is 10 to 30 mm.

4. The pyrite-coupled corncob mixed nutrition denitrification vertical flow constructed wetland system according to claim 1, characterized in that The coarse sand layer (1) has a thickness of 5 cm, the functional layer (2) has a thickness of 20 cm, and the gravel layer (3) has a thickness of 5 cm.

5. The pyrite-coupled corncob mixed nutrition denitrification vertical flow constructed wetland system according to claim 1, characterized in that The wetland plants (5) are single species or mixed species of cattail, canna and calamus.

6. The pyrite-coupled corncob mixed nutrition denitrification vertical flow constructed wetland system according to claim 1, characterized in that The pyrite-coupled corncob mixed nutrition type denitrification vertical flow artificial wetland system has an inner diameter of 10 cm and a height of 40 cm.

Images