CN102583764B - Combined packing multistage terrace type vertical flow constructed wetland sewage treatment method - Google Patents

Abstract

The invention belongs to the technical field of environmental protection, and discloses a method for treating sewage in a multi-stage terraced vertical flow constructed wetland with combined packing. In the terraced vertical flow artificial wetland, the water quality is purified. The method of the invention has the advantages of good treatment effect, high efficiency, strong impact load resistance, stable operation, low investment cost and the like. The discharge limit of pollutants in the effluent after treatment reaches the first-class A standard in the "Pollutant Discharge Standards for Urban Sewage Treatment Plants" (GB18918-2002), in which COD is below 50mg/L, ammonia nitrogen is below 5mg/L, and total phosphorus Below 0.5mg/L, total nitrogen below 15mg/L, can be discharged directly.

Description

A combined packing multi-stage terraced vertical flow artificial wetland sewage treatment method

technical field

The invention belongs to the technical field of environmental protection and relates to a method for treating sewage in a multi-stage terraced field vertical flow constructed wetland with combined fillers.

Background technique

my country's small agricultural towns are mostly concentrated in the central and western mountainous and hilly areas, which are economically underdeveloped areas. Limited by the level of economic development, they often cannot bear the high construction, operation and maintenance costs of large sewage treatment plants. Due to the small population of agricultural small towns and scattered living, domestic sewage has the characteristics of scattered discharge and large fluctuations in water quality and water quantity. The existing sewage treatment methods in small agricultural towns are still mostly dispersed treatment in first-level septic tanks and then directly discharged into nearby rivers. With the development of urban economy, sewage discharge continues to increase, which will cause serious pollution to receiving water bodies. my country is a mountainous country. Due to the terrain conditions and the local economic development level, the traditional large-scale centralized sewage treatment method will encounter relatively great difficulties. Therefore, it is urgent to research and develop low-energy sewage treatment technology and practical sewage treatment process according to local natural, economic and social conditions.

As a new ecological sewage treatment process, constructed wetland has attracted more and more attention. The process is simple to operate and maintain, and can better cope with load shocks. It can also effectively remove organic matter, nitrogen, and phosphorus in sewage. A sewage treatment method with wide application prospect. Compared with traditional treatment techniques, constructed wetlands have lower construction and operating costs, simpler operation and management, and better treatment effects. Through the design of wetland structure, selection of fillers, plants, and adjustment of operating conditions, etc., the effluent can meet the "Surface Water Environmental Quality Standards" (GB3838-2002) Class I to Class IV standards, and the treated water can be used as landscape water and irrigation water for farmland. At present, there are more than 300 invention patents applied for around constructed wetlands, and their technical types can be roughly divided into the following categories: constructed wetland technology designed around specific influent water quality, such technology is mostly aimed at advanced treatment of industrial wastewater, such as CN101254974 A method for treating arsenic-containing wastewater with centipede grass constructed wetland; the optimization of constructed wetland technology generally includes the optimization of the components of constructed wetland, the use of new fillers, the study of new wetland plants or the joint use of constructed wetland and other processes , such as CN101514053, a eutrophic water body artificial wetland treatment system using steelmaking waste slag as a substrate, and CN101445300, a low-energy swimming bed-artificial wetland combined treatment method for eutrophic water body. However, these inventions mostly start from the processing objects or processing methods, and do not take local ecological resources and topographic features into consideration. In addition, because the power of constructed wetlands to treat sewage mainly comes from solar energy, researchers often ignore the issue of further reducing energy consumption in wetland technologies. The areas where small agricultural towns in our country are located have the characteristics of large topographical height differences. Sometimes the topographical height difference of the same small town can reach tens of meters or even hundreds of meters. If this part of potential energy can be fully utilized to develop a new type of constructed wetland device, it will not only It can greatly reduce the energy consumption cost of sewage treatment, and can provide sufficient oxygen for the constructed wetland, which is conducive to improving the water purification efficiency of the constructed wetland.

Contents of the invention

In view of the deficiencies in the prior art, the purpose of the present invention is to provide a combined filler multi-stage terraced vertical flow artificial wetland sewage treatment method, the limit value of pollutant discharge in the treated effluent can reach the "Urban Sewage Treatment Plant Pollutant Discharge Standard" "(GB18918-2002) Class A standard.

Technical scheme of the present invention is as follows:

The invention provides a method for treating sewage in a multi-level terraced vertical flow constructed wetland with combined fillers. The method includes the following steps: after the domestic sewage after secondary biochemical treatment settles, it enters the multilevel terraced vertical flow constructed wetland composed of combined fillers. In the middle, stay for 2 to 5 days, the water quality is purified.

The aspect ratio of the multi-level terraced vertical flow artificial wetland is 1:1.5-1:3, and there are 4 levels of wetland devices running in series, and the height difference between each level is 400-800mm.

The plant combination used in the multi-level terraced vertical flow artificial wetland is the first-level wetland: reed; the second-level wetland: canna; the third-level wetland: ghost needle grass; the fourth-level wetland: calamus.

The combined filler is the first level wetland: large gravel with a particle size of 15-18mm; the second level wetland: small gravel with a particle size of 8-10mm; the third level wetland: large gravel with a particle size of 15-18mm Mixed gravel with small gravels with a particle size of 8-10mm, the volume ratio of large gravels to small gravels is 1:1; fourth-level wetlands: small gravels with a particle size of 8-10mm and bamboo charcoal with a particle size of 3mm, both The ratio range is 1:1～1:3.

The thickness of the combined packing layer is 50-80 cm.

The first-level wetland, the second-level wetland, the third-level wetland and the fourth-level wetland are divided into a water inlet area, a wetland treatment main unit area, and a water outlet area; the water flows into the water inlet area through the water inlet pipe, and then passes through the water distribution pipe It enters the wetland treatment main unit area vertically, and then flows into the water outlet area through the perforated outlet pipe.

The residence time of the domestic sewage in the multi-level terraced vertical flow artificial wetland is 2 to 5 days.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

1. The construction cost of the present invention is low, the investment can be greatly saved, the operation and management are convenient, and the processing cost is low;

2. The present invention develops a multi-level terraced vertical flow artificial wetland according to the characteristics of large terrain height differences in small agricultural towns. This practical sewage treatment device has the characteristics of low power and energy saving. At the same time, the series connection of four-level artificial wetland devices The operation can greatly improve the purification efficiency of domestic sewage, and can be widely used in small towns in mountainous areas.

3. The invention develops a new type of inexpensive filler based on local ecological resources, bamboo charcoal and gravel with different particle sizes as combined fillers. The artificial wetland is used for advanced treatment of domestic sewage in small agricultural towns, which not only takes into account the cost of wetland construction, but also gives full play to the performance of each filler. Performance; Bamboo charcoal has a relatively special pore structure, which can not only strengthen the adsorption and removal of organic matter in sewage, but also provide a good carrier for the attachment of microorganisms; gravel, as a traditional filler, also ensures the removal of nitrogen, phosphorus and other pollutants.

4. In terms of plant screening and combination, the present invention selects the native wetland plant ghost needle grass that has a good removal effect on nitrogen, phosphorus and other pollutants, and at the same time matches the wetland plant reed, canna and calamus with strong sewage purification ability and landscape effect The combination of the above four wetland plants can bring beautiful landscape effects to the wetland while increasing the processing capacity of the wetland system.

5. The method of the present invention has the advantages of good treatment effect, high efficiency, strong impact load resistance, stable operation, and low investment cost. The discharge limit of pollutants in the effluent after treatment reaches the first-class A standard in the "Pollutant Discharge Standards for Urban Sewage Treatment Plants" (GB18918-2002), in which COD is below 50mg/L, ammonia nitrogen is below 5mg/L, and total phosphorus Below 0.5mg/L, total nitrogen below 15mg/L, can be discharged directly.

Description of drawings

Fig. 1 is a schematic diagram of a method for treating sewage in a multi-stage terraced vertical flow constructed wetland with combined packing according to Example 1 of the present invention.

Figure 2 is a schematic side view of a single-stage constructed wetland device.

Figure 3 is a schematic top view of a single-stage constructed wetland device.

Fig. 4 is a diagram of the COD treatment effect of the multi-level terraced vertical flow constructed wetland with combined packing of the present invention.

Fig. 5 is a diagram showing the treatment effect of ammonia nitrogen in the multi-stage terraced vertical flow constructed wetland with combined packing of the present invention.

Fig. 6 is a diagram showing the treatment effect of total phosphorus in the multi-level terraced vertical flow artificial wetland with combined fillers of the present invention.

Fig. 7 is a diagram showing the effect of treating total nitrogen in the multi-level terraced vertical flow constructed wetland with combined fillers according to the present invention.

Detailed ways

The present invention will be further described below in conjunction with the embodiments shown in the accompanying drawings.

Example 1

Fig. 1 is a schematic diagram of a method for treating sewage in a multi-stage terraced vertical flow constructed wetland with combined packing according to Example 1 of the present invention. After the domestic sewage after the secondary biochemical treatment settles, it enters the multi-level terraced vertical flow artificial wetland composed of combined fillers. The aspect ratio of the multi-level terraced vertical flow artificial wetland is 1:1.5, 1:2 and 1:3. Yes, there are 4 levels of wetland devices running in series, and the height difference between each level can be 400mm, 600mm or 800mm. Fig. 2 is a side view of a single-stage constructed wetland device; Fig. 3 is a top view of a single-stage constructed wetland device. The size of the first-level wetland, the second-level wetland, the third-level wetland and the fourth-level wetland is 1m×0.6m, and the height is 0.8m. The first-level wetland, the second-level wetland, the third-level wetland and the fourth-level wetland It is divided into water inlet area, wetland treatment main unit area, and water outlet area; the water flows into the water inlet area through the water inlet pipe 1, then vertically enters the wetland treatment main unit area through the water distribution pipe 2, and then flows into the water outlet area through the perforated water outlet pipe 3.

The four vertical flow wetlands are used in series. The plant combinations used in the multi-level terraced vertical flow constructed wetland are four emergent plants: reed, canna, ghost needle grass and calamus, which are respectively planted in the first, second, third and fourth level devices of the multi-level terraced vertical flow constructed wetland middle. The thickness of the combined packing layer can be 50cm, 60cm or 80cm. In terms of packing arrangement, large gravels with a particle size of 15-18mm are arranged in the first-level wetland, small gravels with a particle size of 8-10mm are arranged in the second-level wetland, and large gravels with a particle size of 15-18mm are arranged in the third-level wetland. The mixed gravel of small gravel with a particle size of 8-10mm; the volume ratio of large gravel and small gravel is 1:1; the fourth grade wetland is a mixture of small gravel with a particle size of 8-10mm and bamboo charcoal with a particle size of 3mm. The range of ratios is 1:1, 1:2 or 1:3. This combination can not only prevent fouling and reduce water head loss, but also use the potential energy of the large drop between wetland devices at all levels to increase the oxygenation of the filler gap and provide a better growth environment for plant roots and microorganisms .

The sewage purification process of the wetland is as follows: First, the domestic sewage of small agricultural towns is pumped to the high-level water tank through the submersible pump. The sewage naturally settles in the high-level tank, and the excess sewage is returned to the sewage well through the overflow. The residence time of the sewage in the tank is 1-3 days. After simple sedimentation, the domestic sewage vertically underflows into the multi-level terrace artificial wetland through the water distribution system, and the influent flow is controlled by adjusting the flow rate through the pump. Sewage flows through constructed wetlands at all levels. At the front end of the combined wetland, the constructed wetland removes pollutants such as organic matter and SS through filtration and absorption; in the middle, pollutants such as nitrogen and phosphorus are removed through aerobic and anaerobic reactions; The substance secreted by the root system also has the effect of inhibiting pathogenic bacteria.

The wetland operation adopts the 24h continuous water intake method, and the water intake is domestic sewage from small agricultural towns. During the start-up operation period, the hydraulic retention time is 5d, and the hydraulic load is 0.96m ³ /(m ² ·d). During the operation, the hydraulic load is gradually increased according to the effluent quality, and finally the hydraulic retention time of the constructed wetland can reach 2d, and the hydraulic load is 2.4m ³ /(m ² ·d). After more than 6 months of continuous operation results show that this multi-level terraced vertical flow constructed wetland with bamboo charcoal and gravel as the combined filler has good adaptability to domestic sewage, and is resistant to COD, NH ₄ ⁺ -N, TP, TN etc. have a stable and good removal effect, and the specific treatment effects are shown in Figure 4, Figure 5, Figure 6, and Figure 7. Fig. 4 is a diagram showing the effect of treating COD by the multi-level terraced vertical flow constructed wetland of the present invention. Fig. 5 is a diagram of the treatment effect of NH ₄ ⁺ -N in the multi-level terraced vertical flow constructed wetland of the present invention. Fig. 6 is a diagram showing the treatment effect of total phosphorus in the multi-level terraced vertical flow constructed wetland of the present invention. Fig. 7 is a diagram showing the effect of treating total nitrogen in the multi-level terraced vertical flow constructed wetland of the present invention. During more than 4 months of stable operation, the average concentration of COD in the influent water was 93.58mg/L, the average concentration of TN was 19.64mg/L, the average concentration of TP was 1.55mg/L, and the concentration of NH ₄ ⁺ -N was 12.67mg/L L, the limit value of pollutant discharge in the effluent reaches the first-class A standard in the "Pollutant Discharge Standards for Urban Sewage Treatment Plants" (GB18918-2002), in which COD is below 50mg/L, ammonia nitrogen is below 5mg/L, and total nitrogen Below 15mg/L, total phosphorus below 0.5mg/L.

The above description of the embodiments is for those of ordinary skill in the art to understand and apply the present invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described here to other embodiments without creative efforts. Therefore, the present invention is not limited to the embodiments herein. Improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims (6)

1. the multistage terrace-type vertical flow constructed wetland sewage treatment method of combined stuffing, it is characterized in that: the method comprises the following steps: after the sanitary sewage precipitation after secondary biochemical treatment, enter in the multistage terrace-type vertical current constructed wetland of combined stuffing formation, water quality is purified;

Described combined stuffing is first step wetland: the large gravel that particle diameter is 15-18mm; Second stage wetland: the little gravel that particle diameter is 8-10mm; Third stage wetland: the little gravel that the large gravel that particle diameter is 15-18mm is 8-10mm with particle diameter mix gravel, large gravel and pebble stone volume ratio are 1:1; Fourth stage wetland: the bamboo charcoal that the little gravel that particle diameter is 8-10mm and particle diameter are 3mm, both proportional ranges are 1:1～1:3.

2. the multistage terrace-type vertical flow constructed wetland sewage treatment method of combined stuffing according to claim 1, it is characterized in that: described multistage terrace-type vertical current constructed wetland long-width ratio is 1:1.5～1:3, have 4 grades of wetland device series operations, between every grade, drop height is 400-800mm.

3. the multistage terrace-type vertical flow constructed wetland sewage treatment method of combined stuffing according to claim 1, is characterized in that: the combinations of plant that described multistage terrace-type vertical current constructed wetland is used is first step wetland: reed; Second stage wetland: Canna generalis Bailey; Third stage wetland: Herba Bidentis Bipinnatae; Fourth stage wetland: calamus.

4. the multistage terrace-type vertical flow constructed wetland sewage treatment method of combined stuffing according to claim 1, is characterized in that: described combined stuffing layer thickness is 50～80cm.

5. according to the multistage terrace-type vertical flow constructed wetland sewage treatment method of the combined stuffing described in claim 1 or 3, it is characterized in that: described first step wetland, second stage wetland, third stage wetland and fourth stage wetland are divided into inhalant region, wetland is processed main unit district, exhalant region; Current enter inhalant region by water inlet pipe (1), then by water distributor (2), vertically enter into wetland and process main unit district, then flow into exhalant region by perforation rising pipe (3).

6. the multistage terrace-type vertical flow constructed wetland sewage treatment method of combined stuffing according to claim 1, is characterized in that: described sanitary sewage residence time in multistage terrace-type vertical current constructed wetland is 2～5 days.

Images