HJ 2005-2010Technical specification of constructed wetlands for wastewater treatment engineering (English PDF)

4.1 Design water quantity

The determination of the amount of water to be designed shall comply with the relevant provisions of GB 50014.

4.2 Design water quality

4.2.1 When the project accepts urban domestic sewage, the design water quality can refer to the relevant provisions of GB 50014; the nature of acceptance and domestic sewage when other sewage is similar, the design water quality can be determined through investigation.

4.2.2 When the project accepts the water from the urban sewage treatment plant, the design water quality shall be in accordance with the provisions of GB 18918.

4.2.3 The influent water quality of the constructed wetland system shall meet the requirements of Table 1.

Table 1 Influent water quality requirements of constructed wetland system Unit. mg/L

Constructed wetland type BOD5 CODCr SS NH3-N TP Surface flow constructed wetland <=50 <=125 <=100 <=10 <=3 Horizontal subsurface flow constructed wetland <=80 <=200 <=60 <=25 <=5 Vertical subsurface flow constructed wetland <=80 <=200 <=80 <=25 <=5

4.3 Contaminant removal efficiency of constructed wetland system

The pollutant removal efficiency of the constructed wetland system can be referred to the data in Table 2.

Table 2 Contaminant removal efficiency of constructed wetland system Unit. %

Constructed wetland type BOD5 CODCr SS NH3-N TP Surface flow constructed wetland 40~70 50~60 50~60 20~50 35~70 Horizontal submerged artificial wetland 45~85 55~75 50~80 40~70 70~80 Vertical subsurface flow constructed wetland 50~90 60~80 50~80 50~75 60~80

5.1 Construction scale

5.1.1 Factors such as the amount of sewage generated, the distribution, development planning and trends in the service area should be considered comprehensively.

The term is mainly based on the principle that the scale can be expanded in the long run.

5.1.2 The construction scale is classified according to the following rules.

a) The daily treatment capacity of the small constructed wetland sewage treatment project is 6 Process design

6.1 General requirements

6.1.1 Process design should comprehensively consider the amount of treated water, raw water quality, floor space, construction investment, operating costs, emission standards, and stability.

Sex, as well as climatic conditions, vegetation types and geographical conditions in different regions, and should determine appropriate options through technical and economic comparisons.

6.1.2 System design such as pretreatment, post-treatment, sludge treatment, and odor treatment shall comply with the relevant regulations in GB 50014 and related industry specifications.

set.

6.1.3 When the constructed wetland system consists of multiple artificial wetland units of the same type or different types, it can be divided into parallel, series and mixed.

Combination method.

6.2 Process

The basic process flow is as follows.

a) When the project accepts urban domestic sewage and other sewage with similar properties to domestic sewage, the basic process is.

Sewage pretreatment artificial wetland post-treatment discharge or reuse Sludge treatment

Figure 1 Process flow chart for accepting urban domestic sewage or other sewage similar in nature to domestic sewage

b) When the project accepts the water from the urban sewage treatment plant, the basic process flow is.

Sewage artificial wetland post-treatment discharge or reuse

Figure 2 Process flow chart for project acceptance of effluent from urban sewage treatment plant

6.3 Pretreatment

6.3.1 The degree and method of pretreatment should take into account factors such as sewage water quality, type of constructed wetland and effluent water quality requirements.

Primary treatment such as grit, primary sedimentation, homogenization, physicochemical strengthening method, pre-AB method, hydrolysis acidification, floating biological bed, etc.

Process, as well as secondary treatment processes such as SBR, oxidation ditch, A/O, and biological contact oxidation.

6.3.2 When the BOD5/CODCr of wastewater is less than 0.3, the hydrolysis acidification treatment process should be adopted.

6.3.3 When the SS content of sewage is greater than 100 mg/L, a sedimentation tank should be provided.

6.3.4 If the oil content in the sewage is greater than 50 mg/L, degreasing equipment should be provided.

6.3.5 When the DO of the sewage is less than 1.0 mg/L, an aeration device should be provided.

6.4 Constructed wetlands

6.4.1 Design parameters

6.4.1.1 The area of constructed wetland shall be determined according to the surface organic load of BOD on the 5th, and the requirements of hydraulic load shall be met.

6.4.1.2 The main design parameters of constructed wetlands should be determined according to the test data; when there is no test data, empirical data can be used or according to Table 3.

The value of the data.

Table 3 Main design parameters of constructed wetlands

Constructed wetland type BOD5 load/[kg/(hm2·d)] Hydraulic load/[m3/(m2·d)] Hydraulic retention time/d Surface flow constructed wetland 15~50 10.1, it needs to be counted.

Calculate the dead water curve;

b) The surface water artificial wetland should have a water depth of 0.3 to 0.5 m;

c) The hydraulic gradient of the surface flow constructed wetland should be less than 0.5%.

6.4.3 Set, distribution and effluent

6.4.3.1 The constructed wetland unit should adopt a device such as a perforated pipe, a distribution (collection) water pipe, and a distribution (water collection) to achieve uniformity of the water distribution.

6.4.3.2 The length of the perforated pipe shall be approximately equal to the width of the constructed wetland unit. The tube hole density should be uniform, and the size and spacing of the tube holes depend on in the sewage flow and the hydraulic conditions of the inlet and outlet water, the pipe hole spacing should not be greater than 10% of the width of the constructed wetland unit.

6.4.3.3 It is advisable to use a matrix with a larger particle size around the perforated pipe, the particle size of which should be larger than the perforation diameter of the pipe.

6.4.3.4 In cold areas, anti-freezing measures should be taken into account for the setting, distribution and inlet and outlet pipes.

6.4.3.5 The artificial wetland water can be drained, piped, well-discharged, etc., and the overflow level, adjustable pipe and gate have water level adjustment.

Features of the facility.

6.4.3.6 When the amount of water generated by the constructed wetland is large and the drop is high, energy dissipation facilities should be installed.

6.4.3.7 Emptying facilities shall be provided for the effluent of constructed wetlands.

6.4.4 Dredging and ventilation

6.4.4.1 A dredging device shall be provided at the bottom of the submerged artificial wetland.

6.4.4.2 Vertical submerged flow Constructed wetland may be provided with a snorkel connected to the drain pipe at the bottom of the constructed wetland and with the drain pipe diameter the same.

6.4.5 Matrix

6.4.5.1 The choice of substrate shall be determined by factors such as mechanical strength, specific surface area, stability, porosity and surface roughness of the substrate.

6.4.5.2 The selection of the substrate shall be based on the principle of the nearest material, and the selected matrix shall meet the particle size range required by the design.

6.4.5.3 When there is a high requirement for the concentration of nitrogen and phosphorus in the effluent, it is recommended to use a functional matrix to improve the efficiency of nitrogen and phosphorus treatment.

6.4.5.4 The initial porosity of the subsurface flow constructed wetland substrate layer should be controlled at 35% to 40%.

6.4.5.5 The thickness of the subsurface flow constructed wetland substrate layer should be greater than the deepest point that the plant root system can reach.

6.4.6 Wetland plant selection and planting

6.4.6.1 The constructed wetland should have strong anti-pollution ability, developed root system, good decontamination effect, anti-freezing and anti-pest and disease resistance, and certain Native plants that are value-for-money and easy to manage. When the effluent from the constructed wetland is directly discharged into rivers and lakes, the foreign investment such as "Eichhornia crassipes" should be carefully selected.

Invasive species.

6.4.6.2 Constructed wetlands may be planted with one or more plants as dominant species to increase plant diversity and have a landscape effect.

6.4.6.3 Submerged artificial wetlands may choose reed, bulrush, alfalfa, lotus, cress, water onion, alfalfa, cattail, lycopodium, calamus, water Ophiopogon, windmill grass, rush grass and other water plants. The surface flow constructed wetland can choose the water plants such as calamus and rush grass; the water hyacinth, duckweed and sleep Floating plants such as lotus; submerged plants such as Elodea, C. algae, Ceratophyllum, and Hydrilla verticillata.

6.4.6.4 Planting of constructed wetland plants includes root seedling transplanting, seed propagation, transplanting of harvested plants, and potted transplants.

6.4.6.5 Planting wetted plants should be planted in spring.

6.4.6.6 The planting density can be adjusted according to the plant species and engineering requirements. The planting density of the emergent plants should be 9-25 plants/m2.

The planting density of water plants and submerged plants should be 3-9 strains/m2.

6.4.6.7 Vertical subsurface flow constructed wetland plants should be planted on a substrate with a high permeability coefficient. Plants in horizontal subsurface flow constructed wetlands should be planted on the soil.

6.4.6.8...