Initial rainwater diversion and purification ecological ditch

Abstract

An initial rainwater diversion and purification ecological ditch comprises a precipitation unit, an initial rainwater diversion unit and a primary purification unit which are sequentially connected in series. The precipitation unit comprises a precipitation area, a precipitation area water inlet is formed in the upper part of the side wall of the precipitation area, and a sludge discharge mechanism is arranged at the bottom of the precipitation area; the initial rainwater diversion unit comprises a diversion dam, the diversion dam sequentially comprises a settling area limiting table, a filler filtering area, a rainwater drainage area and a flood drainage area from bottom to top, and the rainwater drainage area and the flood drainage area are externally connected with a rainwater and flood drainage channel; the first-stage purification unit comprises a first-stage treatment area, the first-stage treatment area is communicated with the settling area through a filler filtering area, a water retaining wall which is not lower than a diversion dam is arranged in the water flow direction of the first-stage treatment area, and the two sides of the diversion dam are adjacent to the settling area and the first-stage treatment area respectively. Through reasonable arrangement of the structure, effective diversion of initial rainwater and efficient drainage of middle and later rainwater are achieved, the residence time of the initial rainwater in the ecological ditch is prolonged, and the purification effect on pollutants in the rainwater is improved.

Description

Technical Field

[0001] The invention belongs to the field of urban rainwater treatment, and in particular relates to an ecological ditch for diverting and purifying initial rainwater. Background Art

[0002] Ecological ditch technology is an important technology for removing surface runoff pollution. It is widely used in the treatment of agricultural non-point source pollution formed by rainfall. In recent years, it has also been gradually applied to the treatment of urban rainwater. However, the pollution characteristics of urban rainwater runoff are different from those of agricultural rainwater runoff. Due to the high hardening rate of the underlying surface in urban areas, the instantaneous flow of rainwater runoff is large, especially during heavy rain, the flow increases sharply; and urban rainwater pollutants are mainly concentrated in the early stage of rainfall, while the pollutant content of rainwater in the middle and later stages is relatively low, and it can be directly discharged without treatment. Therefore, municipal rainwater ecological ditches cannot be directly designed using the method of agricultural non-point source runoff pollution. Given that the main pollution of municipal rainwater is concentrated in the initial rainwater, as long as the initial rainwater is effectively treated, the ecological safety requirements can be met, and at the same time, the scouring and damage of the ecological ditch by the peak runoff should be avoided. However, the existing ecological ditch technology cannot achieve effective separation of the initial rainwater, and there are problems such as low pollutant removal efficiency, easy clogging of fillers, and high maintenance costs. Summary of the invention

[0003] In view of the above problems, the purpose of the present invention is to provide an ecological ditch for diverting and purifying initial rainwater, so as to achieve effective separation and treatment of initial rainwater, and solve the problems that the existing ecological ditch cannot adapt to the large amount of urban rainwater runoff, has low pollutant removal efficiency, and has high system operation and maintenance costs.

[0004] To achieve the above object, the technical solution adopted by the present invention includes:

[0005] An ecological ditch for diverting and purifying initial rainwater comprises a sedimentation unit, an initial rainwater diversion unit and a primary purification unit connected in series in sequence; the sedimentation unit comprises a sedimentation area, the sedimentation area is provided with a sedimentation area water inlet, and a mud discharge mechanism is provided at the bottom of the sedimentation area; the initial rainwater diversion unit comprises a diversion dam, and the diversion dam comprises a sedimentation area limit platform, a filler filtration area, a rainwater discharge area and a flood discharge area in sequence from bottom to top, and the rainwater discharge area and the flood discharge area are connected to a rainwater discharge channel; the primary purification unit comprises a primary treatment area, the primary treatment area is connected with the sedimentation area through the filler filtration area, a retaining wall not lower than the diversion dam is provided in the water flow direction of the primary treatment area, and the two sides of the diversion dam are respectively adjacent to the sedimentation area and the primary treatment area.

[0006] Preferably, the junction of the filler filtration area and the rainwater discharge area is the highest liquid level of the initial rainwater, the rainwater discharge area is provided with a rainwater discharge outlet, and the flood discharge area is provided with a flood discharge outlet, and the lowest point of the flood discharge outlet is the liquid level during heavy rain; the sedimentation area water inlet includes high and low position water inlets, the bottom of the high position inlet of the sedimentation area water inlet is at the same height as the top of the flood discharge outlet, and the bottom of the low position inlet of the sedimentation area water inlet is at the same height as the highest liquid level of the initial rainwater.

[0007] Preferably, the mud discharge mechanism comprises a plurality of mud discharge branch pipes, the outlets of the mud discharge branch pipes are connected via a mud discharge main pipe, and the outlet of the mud discharge main pipe is connected to the mud discharge pool.

[0008] Preferably, a water pond and emergent plants are also provided at the bottom of the sedimentation area.

[0009] Preferably, the maximum bottom elevation of the sludge drainage main pipe is lower than the liquid level during heavy rain and higher than the highest liquid level of initial rainwater, and the highest liquid level of the sludge drainage pool is lower than the highest liquid level of initial rainwater.

[0010] Preferably, the interior of the filler filtration zone is hollow and filled with matrix filler, the side wall of the filler filtration zone is provided with evenly distributed filter holes, and the side wall of the filler filtration zone is also provided with an inspection hole.

[0011] Preferably, a partition wall is vertically arranged inside the filler filtration zone, water distribution holes are arranged on the partition wall and the partition wall divides the inner cavity of the filler filtration zone into two areas along the water flow direction, and the matrix fillers in each area are of different types or different grades.

[0012] Furthermore, it also includes a composite waterfall purification unit connected in series with the primary purification unit, the retaining wall faces the composite waterfall purification area, and a plurality of water outlet branches connected to the primary treatment area are provided on one side of the retaining wall, each water outlet branch pipe is connected through a water outlet main pipe, a control valve is provided near the outlet of the water outlet main pipe, and a water outlet is provided at the outlet of the water outlet main pipe.

[0013] Preferably, the composite waterfall purification area includes packing steps arranged from top to bottom along the water flow direction, filter holes are arranged on the surface of the packing steps, the inside of the steps is filled with matrix material, and water retaining bars are arranged on the surface of each packing step.

[0014] Furthermore, it also includes a secondary purification unit connected in series with the composite waterfall purification unit.

[0015] Compared with the prior art, the advantages of the present invention are:

[0016] (1) The initial rainwater diversion and purification ecological ditch of the present invention can effectively divert the initial rainwater through the reasonable setting of the ditch structure. The runoff entering the rainwater ecological ditch is mainly the runoff formed in the initial 15-30 minutes of rainfall, avoiding the strong runoff formed during heavy rain and the scouring and damage to the ecological ditch facilities.

[0017] (2) The ecological ditch for diverting and purifying initial rainwater of the present invention can adjust the speed of initial rainwater entering the downstream ecological treatment facilities within a certain range through the reasonable setting of the ditch structure and the buffering effect of the sedimentation area and the primary treatment area, thereby prolonging the retention time of rainwater in the ecological ditch and realizing efficient purification of initial rainwater.

[0018] (3) The ecological ditch for diverting and purifying initial rainwater of the present invention realizes static pressure sludge discharge / self-siphonage sludge discharge in the sedimentation area and countercurrent self-backwashing in the filling area through the reasonable setting of the ditch structure, and realizes self-cleaning of the sedimentation area and the matrix filler of the diversion dam to a certain extent, reduces the maintenance cost of the system, prolongs the service life of the materials, and improves the system's efficiency in removing pollutants.

[0019] (4) Compared with ordinary ecological ditches, the initial rainwater diversion and purification ecological ditch of the present invention can reduce COD, ammonia nitrogen, phosphorus and SS discharged into the downstream river by 57.42%, 50.51%, 54.47% and more than 46.40% respectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0021] Figure 1 Process flow chart;

[0022] Figure 2 Schematic diagram of the ecological ditch structure for the diversion and purification of initial rainwater;

[0023] Figure 3 Schematic diagram of the mud discharge system structure in the sedimentation area;

[0024] Figure 4 Changes in the pollutant rates discharged into the downstream river during rainfall in the initial rainwater diversion eco-ditch and the ordinary eco-ditch: (a) COD, (b) ammonia nitrogen, (c) phosphorus, (d) SS;

[0025] Figure 5 Pollutant concentrations entering downstream treatment facilities when there is no filler and when there is a mixture of ceramsite and zeolite fillers in the stormwater diversion dam: (a) COD, (b) ammonia nitrogen, (c) phosphorus, and (d) SS;

[0026] Figure 6 Pollutant concentrations of rainwater entering downstream treatment facilities before and after sludge discharge from the sedimentation area: (a) COD, (b) ammonia nitrogen, (c) phosphorus, and (d) SS;

[0027] Figure 7Pollutant concentrations of rainwater entering downstream treatment facilities before and after countercurrent self-backwashing: (a) COD, (b) ammonia nitrogen, (c) phosphorus, and (d) SS.

[0028] The symbols in the figure represent:

[0029] A sedimentation unit, B initial rainwater diversion unit, C primary purification unit, D composite waterfall purification unit, E secondary purification unit;

[0030] 1-water inlet of sedimentation area, 2-sedimentation area, 3-water pond, 4-sludge branch pipe, 5-maximum height of sludge during the discharge cycle, 6-diversion dam, 7-filler filtration area, 8-filter hole, 9-matrix filler, 10-partition wall, 11-manhole, 12-maximum liquid level of initial rainwater, 13-rainwater discharge port, 14-liquidity level during heavy rain, 15-flood discharge port, 16-rainwater discharge channel, 17-rainwater discharge channel support structure, 1 8-flood level, 19-primary treatment area, 20-retaining wall, 21-working liquid level, 22-peak liquid level, 23-outlet branch pipe, 24-outlet main pipe, 25-outlet diffuser, 26-control valve, 27-water drop aeration area, 28-filling step, 29-retaining grid, 30-vegetation, 31-sludge discharge main pipe, 32-maximum pipe bottom elevation, 33-sludge discharge valve, 34-sludge collecting pool, 35-highest liquid level in the sludge collecting pool. DETAILED DESCRIPTION

[0031] The invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the invention.

[0032] It should be noted that the directional terms mentioned in this article, such as "inner cavity", "side wall", etc., are consistent with the specific directions on the paper in the drawings of the specification or the corresponding directions of the space shown in the drawings; all components and equipment in the present invention, unless otherwise specified, are all components and equipment known in the prior art.

[0033] Example 1

[0034] like Figure 1-3As shown, the present embodiment is an ecological ditch for diverting and purifying initial rainwater, comprising a sedimentation unit A, an initial rainwater diversion unit B, a primary purification unit C, a composite waterfall purification unit D and a secondary purification unit E connected in series in sequence; the sedimentation unit A comprises a sedimentation area 2, a sedimentation area water inlet 1 is provided on the upper part of the side wall of the sedimentation area 2, and a mud discharge mechanism is provided at the bottom of the sedimentation area 2; the initial rainwater diversion unit B comprises a diversion dam 6, and the diversion dam 6 comprises a sedimentation area limit platform, a filler filter area 7, a rainwater discharge port 13 and a flood discharge port 15 from bottom to top, and the rainwater discharge port 13 and the flood discharge port 15 are connected to a rainwater discharge channel 16; the primary purification unit C comprises a primary treatment area 19, and the primary treatment area 19 is connected to the sedimentation area 2 through the filler filter area 7, and a retaining wall 20 not lower than the diversion dam 6 is provided in the water flow direction of the primary treatment area 19, and the two sides of the diversion dam 6 are adjacent to the sedimentation area 2 and the primary treatment area 19 respectively.

[0035] Municipal rainwater first enters the sedimentation area A for sedimentation, and the sludge generated during the sedimentation process can be discharged through the sludge discharge mechanism. The rainwater after sedimentation is diverted and discharged through the diversion dam 6, wherein the initial rainwater enters the primary purification unit C through the filler filtration area 7, while the mid-to-late rainwater or rainwater that exceeds the system load flows into the rainwater discharge channel 16 for discharge through the rainwater discharge port 13 and the flood discharge port 15. The matrix of the primary purification unit C can be self-cleaned through the countercurrent self-backwashing process. After the initial rainwater is treated by the primary purification unit C, the rainwater enters the composite waterfall purification unit D for further purification and oxygenation, and then enters the secondary purification unit E for treatment and discharge.

[0036] The sedimentation area water inlet 1 disclosed in the present embodiment is a high / low position inlet, the bottom of the high position inlet of the sedimentation area water inlet 1 is at the same height as the top of the flood discharge outlet 15, and the bottom of the low position inlet of the sedimentation area water inlet 1 is at the same height as the highest liquid level 12 of the initial rainwater; the initial rainwater and the middle and late rainwater when the rainfall is small flow in from the low position inlet, and when the rainfall is large, the rainwater flows in from the high position inlet at the same time, so as to realize the rapid discharge of the middle and late rainwater and reduce the disturbance of the middle and late rainwater and storm runoff to the initial rainwater stored in the sedimentation area A; at the same time, the sedimentation area water inlet 1 can be provided with a waterfall step or slope to reduce the scouring of the surface of the facility by rainwater.

[0037] The sedimentation area 2 disclosed in the present embodiment is provided with a water pond 3 at the bottom, and emergent plants are planted to weaken the impact force of the incoming water, retain suspended matter, and purify water; the mud discharge mechanism includes a plurality of mud discharge branch pipes 4 arranged between adjacent water ponds 3, and the outlets of the mud discharge branch pipes 4 are connected through a mud discharge main pipe 31, and the outlet of the mud discharge main pipe 31 is provided with a mud discharge valve 33 and connected to a mud discharge pool 34; the maximum pipe top elevation 32 of the mud discharge main pipe 31 is lower than the liquid level 14 during heavy rain and higher than the highest liquid level 12 of initial rainwater.

[0038] The mud discharge system in the sedimentation area 2 disclosed in the present embodiment is provided with a mud collecting pool 34, and the maximum liquid level 35 of the mud collecting pool is controlled, so that the mud can be discharged by utilizing the static pressure of rainwater itself and the self-siphon effect; when the liquid level in the sedimentation area is higher than the maximum pipe top elevation 32 of the mud discharge main pipe, the mud discharge valve 33 can be opened according to the operation needs to start the mud discharge process; specifically, during the mud discharge process, when the liquid level in the sedimentation area is higher than the maximum pipe top elevation 32 of the mud discharge main pipe, the mud is discharged by static water pressure, and when the liquid level in the sedimentation area is lower than the pipe bottom elevation of the mud discharge main pipe during the mud discharge process, the system continues to discharge the mud by utilizing the self-siphon effect generated.

[0039] The solid part of the sedimentation area limit platform at the bottom of the diverter dam 6 disclosed in this embodiment has its highest point as the maximum height 5 of the sedimentation area sludge during the discharge cycle, and appropriately considers a certain buffer area, thereby playing a role in intercepting sludge and suspended matter, and preventing sludge from entering the filler filter area 7; after the rainwater is settled in the sedimentation area to remove particulate matter and suspended matter, it enters the diverter dam 6. When the liquid level in the sedimentation area is higher than the height of the sedimentation area limit platform at the bottom of the diverter dam 6, the rainwater begins to pass through the filler filter area 7 in the diverter dam and enter the primary ecological treatment area 19.

[0040] The filter holes 8 are evenly distributed on the side wall surface of the packing filter area 7 disclosed in the present embodiment. The side wall can use porous bricks as the main strength structure, and other force-bearing structures can be set up inside according to the load requirements; the inside of the packing filter area 7 is hollow and filled with matrix fillers 9, and the matrix fillers 9 include but are not limited to adsorption and filtration materials such as ceramsite, zeolite, quartz sand, anthracite, etc., and the matrix fillers 9 can be bio-enhanced to remove pollutants such as ammonia nitrogen, phosphorus, COD and SS in the initial rainwater through adsorption, filtration and biological action; a partition wall 10 can be set inside the packing filter area 7, and the partition wall 10 is provided with water distribution holes. The partition wall 10 can use perforated flower walls or porous bricks, and the partition wall 10 divides the inner cavity of the packing filter area 7 into two areas along the water flow direction, so as to fill them with matrix fillers 9 of different types or grades respectively, thereby enhancing the pollutant removal effect; inspection holes 11 are provided on both sides of the side wall 8, and the inspection holes 11 are used for inspection, filling and replacement of the matrix fillers 9.

[0041] The diversion dam 6 disclosed in this embodiment is provided with a rainwater discharge outlet 13 and a flood discharge outlet 15 on the upper part of the filling area 7. The lowest point of the flood discharge outlet 15 is the liquid level 14 during heavy rain. The rainwater discharge outlet 13 and the flood discharge outlet 15 are connected to a rainwater and flood discharge channel 16. The rainwater discharge outlet 13 and the retaining wall 20 of the downstream primary treatment area and its outlet facilities work together to achieve normal diversion and discharge of mid- and late-stage rainwater and rainwater that exceeds the load of the ecological ditch. The flood discharge outlet 15 is used to discharge flood runoff when the water level rises during heavy rain.

[0042] When the liquid level in the sedimentation area 2 reaches the highest liquid level 12 of the initial rainwater, the rainwater level begins to continue to rise until it is discharged to the stormwater discharge channel 16 through the rainwater discharge port 13, and the rainwater continues to pass through the filler filtration area. When the rainwater level in the sedimentation area continues to rise to the liquid level 14 during heavy rain, it begins to continue to enter the stormwater discharge channel 16 through the flood discharge port 15. The stormwater discharge channel 16 directly discharges the collected rainwater with less pollution in the middle and late stages. The stormwater discharge channel 16 can be built in conjunction with the diversion dam 6, and a support structure 17 can be provided for support. It can also be connected to the rainwater discharge port 13 and the flood discharge port 15 through a pipeline, so as to be independently built.

[0043] The initial rainwater passing through the filler filtration area 7 enters the primary ecological treatment area 19. This area plants different types of plants 29 according to the purification needs and hydraulic conditions, and performs matrix filling and biological enhancement to treat the initial rainwater. The primary ecological treatment area 19 is connected to the sedimentation area 2 through the diversion dam 6. A retaining wall 20 is set at the end of the primary ecological treatment area 19. The peak liquid level 22 in the retaining wall 20 is equal to the flood level 18 in the rainwater discharge channel 16 to prevent the peak flow from continuously passing through the filtration area 7 and entering the downstream. The normal working liquid level 21 in the retaining wall is equal to the bottom height of the rainwater discharge port 13 in the diversion dam.

[0044] The retaining wall 20 disclosed in this embodiment is provided with a plurality of outlet branch pipes 23 connected to the primary treatment area 19 on the side facing the composite waterfall purification area D, and each outlet branch pipe 23 is connected through an outlet main pipe 24, and a control valve 26 and an outlet sprinkler 25 are provided near the outlet of the outlet main pipe 24; rainwater flows out through the outlet branch pipes 23 at different heights, and enters the outlet main pipe 24 after merging, and the water outlet flow rate in this area is controlled by the control valve 26, and finally the rainwater is discharged to the composite waterfall purification area 27 through the main pipe sprinkler 25.

[0045] By adjusting the opening degree of the control valve 26, the water outflow and liquid level of the primary purification unit C can be controlled to ensure that the outflow of the primary treatment area 19 meets the downstream inflow requirements. At the same time, it can be closed during the backwashing process to strengthen the reverse flow of water from the primary purification unit C to the sedimentation area. Specifically, the speed of the initial rainwater entering the next treatment facility can be controlled by the control valve 26. The outflow speed of the primary purification unit C is generally much lower than the discharge speed of the mid- and late-stage rainwater and storm runoff from the rainwater outlet 13 and the flood outlet 15. In the late stage of heavy rainfall, the high-level rainwater in the sedimentation area in front of the diversion dam is quickly discharged through the rainwater outlet 13 and the flood outlet 15, thereby forming a reverse liquid level difference between the sedimentation area 2 and the primary ecological treatment area 19, and then the diversion dam filler is self-backwashed. The intensity and duration of the self-backwashing can also be adjusted by reducing the opening degree of the control valve 26 until the control valve 26 is closed, and the simultaneous mud discharge in the sedimentation area is implemented.

[0046] The ecological ditch disclosed in this embodiment also includes a composite waterfall purification unit D connected in series with the primary purification unit C.

[0047] The composite waterfall purification unit D disclosed in this embodiment includes a packing step 28 arranged from top to bottom along the water flow direction. The surface of the packing step 28 can be made of materials such as porous bricks, perforated plastic plates and stainless steel plates, and the interior is filled with functional materials such as ceramsite; a water retaining bar 29 is arranged on the surface of each packing step, and its height is about 10-20mm, so that part of the water flow vertically enters the interior of the step, and then is purified by the packing, and the remaining water flow directly overflows from the water retaining bar, falls and is aerated with oxygen. At the same time, emergent plants, wet grasses, etc. can be planted on the steps to strengthen the water purification process and play a role in dispersing water flow and enhancing the aeration effect. After the initial rainwater passes through the composite waterfall purification area, it enters the next ecological treatment link for treatment and is finally discharged to the receiving water body.

[0048] Example 2

[0049] This example trial-produced the ecological ditch model disclosed in Example 1, and compared the treatment effects of ordinary ecological ditches and initial rainwater diversion ecological ditches. The model is made of plexiglass, with an effective width of 300mm and a depth of 500mm. The maximum initial rainwater interception capacity is about 44L. The average water inflow of simulated rainwater during the experiment is about 88L / h, and the fillers are zeolite and ceramsite. The duration of the treated rainwater runoff is 90min. The maximum pollutant concentration in the initial rainfall is about ammonia nitrogen = 10mg / L, phosphorus = 3mg / L, COD = 200mg / L, SS = 1000mg / L. The pollutant concentration in the middle and late rainfall is about ammonia nitrogen = 1.5mg / L, phosphorus = 0.5mg / L, COD = 30mg / L, SS = 100mg / L. This model does not include the effects of plants and microorganisms. The initial rainwater diversion effect, filler effect, sludge discharge effect and self-backwashing effect of the ecological ditch were verified. The main results are as follows Figures 4 to 7 shown.

[0050] Figure 4 The change of pollutant discharge rate into the river over time for the initial rainwater interception ecological ditch and the ordinary ecological ditch. In the ordinary ecological ditch, rainwater runoff is discharged directly into the river through the ecological ditch. The water flow velocity in the ditch is relatively high. On the one hand, it will cause erosion and damage to the bank slope and vegetation of the ecological ditch; on the other hand, due to the short contact time, only a small part of the pollutants in the rainwater are intercepted by the ecological ditch, and a large amount of pollutants are discharged directly into the river. Figure 1It can be seen that in the first 45 minutes of runoff inflow, especially in the early stage of rainfall, the rate of pollutants discharged into the river from the ordinary ecological ditch is much higher than that of the initial rainwater separation ecological ditch; when the initial rainwater is intercepted, only a small amount of rainwater is discharged through the outlet pipe of the rainwater interception system in the first 20 minutes of the system, and the number of pollutants discharged into the river is relatively small; afterwards, as the mid- and late runoff flows out of the system rainwater outlet, the rate of pollutants discharged into the river through the rainwater pipe increases. The area below the curve in the figure can be approximated as the total amount of pollutants discharged into the river during the runoff inflow process. By calculation, it can be seen that during the rainfall period, the COD, ammonia nitrogen, phosphorus and SS flowing into the downstream river from the initial rainwater diversion and purification ditch are 42.58%, 49.49%, 45.53% and 53.60% of those of the ordinary ecological ditch respectively. It should be pointed out that this effect does not take into account the role of ditch plants and microorganisms. Because after interception, the amount and flow rate of water entering the ecological ditch will be greatly reduced, which provides good conditions for the further removal of pollutants in the ecosystem, so the effect will be more significant in the actual system.

[0051] Figure 5 The figure shows the change in pollutant concentration flowing into the downstream ecological ditch during rainfall when the ecological ditch diversion dam is filled with matrix material and without matrix material. In order to ensure the removal effect of ammonia nitrogen and phosphorus at the same time, zeolite and ceramsite were used in the experiment. As can be seen from the figure, after the filler was added, the concentration of pollutants entering the downstream ecological ditch was significantly reduced, especially SS, which was even lower than 20mg / L after being filtered by the filler.

[0052] Figure 6 The operating effect of the system before and after sludge discharge. It can be seen from the figure that the pollutant concentration of the effluent was high before sludge discharge, and SS once reached 600mg / L. After sludge discharge, the pollutant concentration of the effluent was significantly reduced. This proves the reliability of the sludge discharge system and the necessity of setting up a sludge discharge system in the ecological ditch.

[0053] Figure 7 The operating effect of the system before and after the countercurrent self-backwashing. When the rainwater in the primary ecological treatment area reaches the maximum liquid level and the rainwater flow into the sedimentation area begins to decrease continuously, the sludge discharge system is turned on synchronously (to eliminate the influence of the sedimentation effect, the test is carried out after the sludge deposited in the sedimentation area is cleaned). At this time, the reverse maximum liquid level difference between the sedimentation area and the primary ecological treatment area can reach 20% of the rainwater level, and the duration is 1.5 to 2.0 minutes. After that, the liquid levels on both sides gradually become the same. The backwashing time depends on the sludge discharge volume and the inflow of the ecological ditch. It can be seen from the figure that after the countercurrent self-backwashing, the concentration of pollutants in the system effluent, especially the ammonia nitrogen and the initial SS concentration, are significantly reduced. This shows that the self-backwashing effect formed by the system can effectively clean the matrix filler.

[0054] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0055] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0056] In addition, the various different implementation modes disclosed in this solution may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the content invented by the present disclosure.

Claims

1. An ecological ditch for diverting and purifying initial rainwater, characterized in that: It includes a sedimentation unit (A), an initial rainwater diversion unit (B) and a primary purification unit (C) which are connected in series in sequence; The sedimentation unit (A) comprises a sedimentation area (2), the sedimentation area (2) is provided with a sedimentation area water inlet (1), and a mud discharge mechanism is provided at the bottom of the sedimentation area (2); The initial rainwater diversion unit (B) comprises a diversion dam (6), and the diversion dam (6) comprises, from bottom to top, a sedimentation area limit platform, a filler filtration area (7), a rainwater discharge area and a flood discharge area, and the rainwater discharge area and the flood discharge area are connected to a rainwater discharge channel (16); The primary purification unit (C) comprises a primary treatment area (19), the primary treatment area (19) being connected to the sedimentation area (2) via a filler filtration area (7), a retaining wall (20) not lower than the diversion dam (6) being provided in the water flow direction of the primary treatment area (19), and the diversion dam (6) being adjacent to the sedimentation area (2) and the primary treatment area (19) on both sides, respectively.

2. The initial rainwater diversion and purification ecological ditch as claimed in claim 1, characterized in that: The junction between the filler filtration area (7) and the rainwater discharge area is the highest liquid level (12) of the initial rainwater, the rainwater discharge area is provided with a rainwater discharge outlet (13), the flood discharge area is provided with a flood discharge outlet (15), and the lowest point of the flood discharge outlet (15) is the liquid level (14) during heavy rain; The sedimentation area water inlet (1) comprises high and low position water inlets, wherein the bottom of the high position inlet of the sedimentation area water inlet (1) is at the same height as the top of the flood discharge outlet (15), and the bottom of the low position inlet of the sedimentation area water inlet (1) is at the same height as the highest liquid level (12) of initial rainwater.

3. The initial rainwater diversion and purification ecological ditch as claimed in claim 1, characterized in that: The mud discharge mechanism comprises a plurality of mud discharge branch pipes (4), the outlets of the mud discharge branch pipes (4) are connected via a mud discharge main pipe (31), and the outlet of the mud discharge main pipe (31) is connected to a mud discharge pool (34).

4. The initial rainwater diversion and purification ecological ditch as claimed in claim 3, characterized in that: A water pond (3) and emergent plants are also provided at the gaps between the mud discharge branch pipes (4) at the bottom of the sedimentation area (2).

5. The initial rainwater diversion and purification ecological ditch as claimed in claim 4, characterized in that: The maximum pipe bottom elevation (32) of the mud drainage main pipe (31) is lower than the liquid level (14) during heavy rain and higher than the highest liquid level (12) of initial rainwater. The highest liquid level of the mud drainage pool (34) is lower than the highest liquid level (12) of initial rainwater.

6. The initial rainwater diversion and purification ecological ditch as claimed in claim 1, characterized in that: The filler filter area (7) is hollow inside and filled with matrix filler (9), the side wall of the filler filter area (7) is provided with filter holes (8) distributed evenly, and the side wall of the filler filter area (7) is also provided with an inspection hole (11).

7. The initial rainwater diversion and purification ecological ditch as claimed in claim 6, characterized in that: A partition wall (10) is vertically arranged inside the filler filtration area (7), the partition wall (10) is provided with water distribution holes, and the partition wall (10) divides the inner cavity of the filler filtration area (7) into two areas along the water flow direction, and the matrix fillers (9) in the areas are of different types or different grades.

8. The initial rainwater diversion and purification ecological ditch according to any one of claims 1 to 7, characterized in that: It also includes a composite waterfall purification unit (D) connected in series with the primary purification unit (C), the retaining wall (20) faces the composite waterfall purification area (D), and a plurality of water outlet branch pipes (23) connected to the primary treatment area (19) are provided on one side of the retaining wall (20), the water outlet branch pipes (23) are connected via a water outlet main pipe (24), a control valve (26) is provided near the outlet of the water outlet main pipe (24), and a water outlet diffuser (25) is provided at the outlet of the water outlet main pipe (24).

9. The initial rainwater diversion and purification ecological ditch as claimed in claim 8, characterized in that: The composite waterfall purification area (D) comprises a packing step (28) arranged from top to bottom along the water flow direction, filter holes are arranged on the surface of the packing step (28), the inside of the step is filled with matrix material, and water retaining bars (29) are arranged on the surface of each packing step.

10. The initial rainwater diversion and purification ecological ditch according to claim 9, characterized in that: It also includes a secondary purification unit (E) connected in series with the composite waterfall purification unit (D).

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