Tunnel construction wastewater treatment method

Abstract

The invention belongs to the field of wastewater treatment, and provides a tunnel construction wastewater treatment method, which uses a system, the system comprises a secondary sedimentation tank, a tertiary sedimentation tank, an integrated device, three on-line sensors for wastewater pH value monitoring and two on-line sensors for wastewater SS value monitoring, the system further comprises a pH first-stage adding device, a pH second-stage adding device, a coagulant adding device and a flocculant adding device, and the online sensor and the adding devices are electrically connected with the controller. According to the treatment method provided by the invention, the dosage of chemicals can be accurately metered according to the change of the concentration and the water quantity of the tunnel construction wastewater, the concentration of the chemical liquid is automatically configured, the flow of the chemical liquid is accurately controlled, and real-time adjustment can be realized according to the change of the water quality and the water quantity of the wastewater. According to the treatment method, a dead-corner-preventing wastewater treatment device is used, so that the problems of sludge deposition and hardening at the bottoms of tank bodies of the coagulation tank and the flocculation tank, especially at the four corners of the tank bodies can be effectively solved.

Description

Technical Field

[0001] The invention belongs to the field of wastewater treatment, and in particular relates to a method for treating tunnel construction wastewater. Background Art

[0002] The main sources of tunnel construction wastewater are: 1) gushing water generated when tunnel construction passes through unfavorable geological units; 2) bedrock fissure water; 3) wastewater generated during drilling rig construction; 4) wastewater used for dust reduction during tunnel blasting; 5) wastewater generated by cleaning the rock surface before tunnel shotcrete; 6) wastewater generated during shotcrete and grouting. The main pollutants of these wastewaters are inorganic suspended solids. The wastewater is generally alkaline or weakly alkaline, with a pH value of 7.0-13.0. Among them, alkaline substances mainly come from cement, various admixtures, grouting materials and their hydrolysis products during construction. For example, tricalcium silicate, dicalcium silicate, calcium hydroxide, etc. produced by cement hydrolysis will cause the pH value to increase after dissolving in water. Characteristics of tunnel construction wastewater: First, the discharge volume is not fixed due to changes in seasons, locations, and construction progress; second, the quality of wastewater varies with the construction period, the size of seepage in the tunnel, the rock mass conditions, and drainage facilities. In general, because tunnel construction wastewater mainly contains inorganic pollutants, physical and chemical treatment methods are the first consideration. In view of the main pollutants, suspended solids and alkaline water quality in the wastewater, coagulation and neutralization methods are used respectively. Both coagulation and neutralization methods require the addition of reagents to the wastewater. Coagulants, flocculants and acidic agents must be added to the water at the same time to make the tunnel construction wastewater meet the discharge standards.

[0003] The applicant's prior invention patent CN201910875105.4 relates to a method for treating sewage from tunnel construction, and belongs to the field of sewage treatment technology. The invention targets sewage with SS ≥ 20000 mg / L. The method for treating sewage from tunnel construction of the invention comprises the following steps: S1, adjusting the quality of raw water, intercepting particulate matter, and then adding coagulant No. 1 for the first coagulation; S2, adding flocculant No. 1 to the effluent of step S1, performing the first flocculation, removing sludge, and recycling the sludge; S3, adding coagulant No. 2 to the effluent of step S2 for the second coagulation; S4, adding flocculant No. 2 to the effluent of step S3, and mixing it with the recycled sludge in S2 for the second flocculation; S5, precipitating the effluent of step S4, and discharging the clean water after adjusting the pH. The treated sewage meets the first-level standard of the "Comprehensive Sewage Discharge Standard" (GB8978-1996), and the removal rate of suspended matter can reach more than 98%.

[0004] In fact, most of the tunnel wastewater treatment equipment is currently equipped with an automatic dosing system, which can realize the automatic configuration and addition of reagents, but the automatic dosing system is generally limited to water quality and water volume within a specific range. However, because the concentration and water volume of tunnel construction wastewater change frequently with the changes in construction period, rock mass conditions, drainage facilities, etc., and the concentration and dosage of the automatic dosing system are fixed values, it is impossible to accurately match the changes in the water quality and water volume of tunnel construction wastewater, resulting in unstable effluent water quality. The conventional method is to manually take samples at the water inlet, conduct small tests, and then manually adjust the dosage, but this method can only monitor the surface water quality, and it also consumes a lot of manpower and cannot adapt to the real-time changes in water quality and water volume. And when the amount of tunnel construction wastewater reaches the maximum value, because the dosage is difficult to match, in some cases it is even necessary to change to manual dosing, resulting in excessive dosage of reagents and increased operating costs.

[0005] Therefore, the art needs to provide a new method for treating tunnel construction wastewater, so that the coagulant, flocculant and powdered acid required in the system can be automatically and accurately added to the appropriate position in the system.

[0006] In addition, the integrated equipment for tunnel wastewater treatment adopts coagulation and sedimentation technology, the purpose of which is to add coagulants and flocculants to the wastewater to make the colloids and fine suspended matter in the wastewater condense into floccules, and then separate and remove them. After the equipment is put into use, the following problems are prone to occur during operation: the coagulation tank and flocculation tank are rectangular tanks. When the stirring intensity does not meet the requirements, the mixing time of wastewater and reagents is short, and the reagents cannot fully react, resulting in dead corners in the water distribution area, and a large amount of floating mud accumulates and cannot be discharged; at the same time, as the amount of mud accumulated in the tank increases, the volume of the tank gradually decreases, further shortening the reaction time between wastewater and reagents, increasing the burden on the agitator, causing a vicious cycle, resulting in the equipment's effluent not meeting the standards, and even causing the equipment to shut down due to excessive sludge accumulation. That is to say, in the prior art, most of the integrated equipment for tunnel wastewater treatment uses the most convenient square pool, and sets the coagulation pool, flocculation pool and clarification pool in sequence in the direction of wastewater flow, and sets agitators in the coagulation pool and flocculation pool. Because the stirring space formed by the agitator is approximately cylindrical, four dead corners and sludge accumulation are easy to appear on the side wall of the square pool at a distance outside the cylindrical stirring space. The sludge in the dead corners needs to be discharged in time, otherwise it will form a vicious circle. The existing solution is generally ventilation.

[0007] For example, patent CN201720699316.3 relates to a new type of coagulation inclined plate sedimentation tank. The new type of coagulation inclined plate sedimentation tank includes a mixing tank, a flocculation tank, an inclined plate sedimentation tank and an aeration pipe. A rotating aeration disk is provided at the bottom of the new type of coagulation inclined plate sedimentation tank. The rotating aeration disk rotates continuously, driving the water flow to rotate, so that the reagent and sewage are fully mixed, so that the dosing effect is more significant; an aeration pipe is provided in the sedimentation hopper at the bottom of the inclined plate sedimentation tank, and a plurality of aeration ports are provided on the aeration pipe. The sedimentation hopper area is air-flushed once every period of time, so that the mud discharge function does not change with the passage of time when the equipment is used, so that there is no mud discharge dead corner at the bottom of the sedimentation hopper, and the mud is ensured to be discharged smoothly from the mud outlet main pipe. In addition, the structural design of the new type of coagulation inclined plate sedimentation tank is simple and reasonable, the purification effect of wastewater is significant, it is convenient and reliable to use, and it is suitable for promotion and use.

[0008] In addition, patent CN202121024821.0 discloses a desulfurization wastewater treatment system, comprising a triple box, a clarifier and a water outlet box connected in sequence; the triple box is divided into a neutralization zone, a sedimentation zone and a flocculation zone by a first partition and a second partition; a water inlet is arranged at the top of the neutralization zone, and a water outlet is arranged in the middle of the side wall of the flocculation zone, and the water outlet is connected to the clarifier; a stirring shaft is arranged in the neutralization zone, the sedimentation zone and the flocculation zone, and a stirring paddle is evenly arranged on the stirring shaft along the axial direction; a spoiler is also arranged at the corner of the bottom of the neutralization zone, the sedimentation zone and the flocculation zone, and the spoiler includes a fixed shaft respectively installed at the bottom of the two side walls at the corner, a sleeve rotatable around the fixed shaft is arranged on the fixed shaft, and a soft curtain is arranged on the sleeve; the lowest stirring paddle is in contact with the soft curtain, and the free end of the stirring paddle is bent; the bottom of the soft curtain is close to the bottom surface of the triple box, the treatment system has low investment, can overcome the stirring dead angle, and can ensure stable water outlet.

[0009] The method in the first patent mentioned above is to use air impact to prevent dead corners, and the method in the second patent is to set up a soft curtain to swing to prevent dead corners. However, both methods are likely to cause significant disturbances to the flocs in the coagulation tank and the flocculation tank, and are likely to blow the flocs away; and setting up a soft curtain to swing to prevent dead corners is also likely to increase energy consumption and equipment investment in the coagulation tank and the flocculation tank.

[0010] Therefore, the art also needs to provide a new method for treating tunnel construction wastewater to successfully solve the problem of preventing dead corners in the coagulation tank and flocculation tank of the integrated equipment. Summary of the invention

[0011] Therefore, in order to solve at least part of the technical problems in the background technology, the present invention provides a method for treating tunnel construction wastewater, comprising using a system for treating tunnel construction wastewater, wherein the system comprises a secondary sedimentation tank (1), a tertiary sedimentation tank (2) and an integrated device (3) arranged in sequence along the flow direction of the wastewater, and comprises three online sensors for monitoring the pH value of the wastewater and two online sensors for monitoring the SS value of the wastewater, the system further comprises a primary pH dosing device (5), a secondary pH dosing device (7), a coagulant dosing device (9) and a flocculant dosing device (10), and the online sensors and dosing devices are electrically connected to a controller; the integrated device (3) comprises a coagulation tank (31), a flocculation tank (32) and a clarification tank (33) arranged in sequence along the flow direction of the wastewater;

[0012] In the treatment method, the controller controls the addition of an acidic agent of the pH primary dosing device (5) online based on data of the pH monitoring sensor A (4) arranged at the water outlet of the secondary sedimentation tank (1); or the controller controls the addition of an acidic agent of the pH primary dosing device (5) online based on data of the pH monitoring sensor A (4) and data of the pH monitoring sensor B (6) arranged at the water outlet of the tertiary sedimentation tank (2);

[0013] The controller controls the addition of the acidic agent of the pH secondary dosing device (7) online according to the data of the online sensor pH monitoring B (6) and the data of the online sensor pH monitoring C (11) arranged at the water outlet of the clarification tank (33) of the integrated device (3);

[0014] The controller online controls the addition of reagents by the coagulant dosing device (9) and the flocculant dosing device (10) based on data from an online sensor SS monitoring A (8) arranged at the water outlet of the tertiary sedimentation tank (2) and data from an online sensor SS monitoring B (12) arranged at the water outlet of the clarification tank (33) of the integrated device (3).

[0015] In a specific embodiment, the pH primary dosing device (5) is arranged on the pipeline between the secondary sedimentation tank (1) and the tertiary sedimentation tank (2) or at the water inlet in the tertiary sedimentation tank (2); the pH secondary dosing device (7) is arranged on the pipeline between the tertiary sedimentation tank (2) and the integrated device (3) or at the water inlet in the integrated device (3); the coagulant dosing device (9) is connected to the coagulation tank (31), and the flocculant dosing device (10) is connected to the flocculation tank (32).

[0016] In a specific embodiment, the pH primary dosing device (5) and the pH secondary dosing device (7) both include a conveying device for conveying a certain amount of organic acid powder, a stirring device for mixing the organic acid powder with tap water to form a liquid medicine, and a liquid pump for adding the prepared liquid medicine to the wastewater; the coagulant dosing device (9) and the flocculant dosing device (10) both include a conveying device for conveying a certain amount of powder medicine, a stirring and storing device for mixing the powder medicine with tap water to form a liquid medicine, and a liquid pump for adding the prepared liquid medicine to the wastewater; and the conveying device, stirring device, stirring and storing device and liquid pump in the dosing device are all electrically connected to the controller for control.

[0017] In a specific embodiment, the organic acid powder is citric acid or oxalic acid, and the powders used in the coagulant dosing device (9) and the flocculant dosing device (10) are coagulants and flocculants.

[0018] In the present invention, the pH primary dosing device (5) is used to make a rough adjustment to the pH value of the wastewater. It mainly adjusts the concentration of the medicine powder and the dosage of the medicine liquid according to the data of the online sensor pH monitoring A (4). The pH primary dosing device (5) can also refer to the data of the online sensor pH monitoring B (6) to determine whether it is necessary to increase or decrease the amount. The pH primary dosing device (5) is generally in a state of regular operation; wherein the pH secondary dosing device (7) is used to make a fine adjustment to the pH value of the wastewater. It will determine whether it is necessary to further adjust the pH of the wastewater according to the data of the online sensor pH monitoring B (6) and the online sensor pH monitoring C (11), and determine the concentration and dosage of the medicine liquid through the computer and the controller when adjustment is required. The concentration of the medicine liquid is fed back to the changes in the amount of medicine powder added and the amount of tap water added of the conveying device, and the dosage of the medicine liquid is fed back to the changes in the flow rate or flow of the liquid pump. The addition of coagulant and flocculant is controlled based on the values ​​of online sensor SS monitoring A (8) and online sensor SS monitoring B (12). The computer accurately calculates the dosage concentration of coagulant and flocculant powder and the flow rate of liquid addition. The concentration of liquid is fed back to the changes in the amount of powder added to the conveying equipment and the amount of tap water added, while the amount of liquid is fed back to the changes in the flow rate or flow of the liquid pump.

[0019] In a specific embodiment, the treatment method also includes setting up a dead-angle-proof wastewater treatment device, and the dead-angle-proof wastewater treatment device includes a suction pipe (36) and an injection pipe (37) arranged at the coagulation tank (31) and / or the flocculation tank (32), the suction pipe (36) is connected to the inlet of the slurry pump (34), and the injection pipe (37) is connected to the outlet of the slurry pump (34), the suction pipe (36) includes a perforated pipe (361) arranged in the coagulation tank and / or the flocculation tank and an external pipe (362) for connecting the perforated pipe (361) to the outside of the coagulation tank and / or the flocculation tank, and the injection pipe (37) includes a perforated pipe (371) arranged in the coagulation tank and / or the flocculation tank and an external pipe (372) for connecting the perforated pipe (371) to the outside of the coagulation tank and / or the flocculation tank.

[0020] In a specific embodiment, the external pipe 1 (362) is connected to a pipeline access point, which is arranged on the pipeline between the switch valve at the bottom of the clarification tank (33) and the inlet of the slurry pump (34), and a valve 2 (39) is arranged on the external pipe 1 (362); the external pipe 2 (372) is connected to a pipeline outlet point, which is arranged on the pipeline between the outlet of the slurry pump (34) and a switch valve downstream thereof, and a valve 1 (38) is arranged on the external pipe 2 (372).

[0021] In a specific embodiment, the valve one (38) and valve two (39) are both flow-adjustable regulating valves and both are electrically connected to a controller so as to achieve automatic switching of the valves and flow adjustment.

[0022] In a specific embodiment, the perforated tube 1 (361) is square in shape as a whole or has the same shape as the coagulation tank (31) and / or the flocculation tank (32), is arranged at a height of 0.4 to 0.8 m from the bottom of the tank, and has a plurality of suction holes on the tube body; the perforated tube 2 (371) is square in shape as a whole or has the same shape as the coagulation tank (31) and / or the flocculation tank (32), is arranged at a height of 0.1 to 0.3 m from the bottom of the tank, and has a plurality of water outlet holes on the tube body.

[0023] In a specific embodiment, the suction hole and the water outlet hole are both arranged on the side or below the side of the tube body, and the diameter of the suction hole is larger than the diameter of the water outlet hole. The suction holes and the water outlet holes are evenly distributed on the tube bodies of the perforated tube 1 (361) and the perforated tube 2 (371).

[0024] In the present invention, the suction hole and the water outlet hole are both arranged on the side or below the side of the pipe body, which can effectively prevent the sludge deposited at the bottom from entering the pipeline and keep the pipeline unobstructed.

[0025] In a specific embodiment, the diameter of the suction hole is 10-20 mm, and the diameter of the water outlet hole is 3-8 mm. The suction hole and the water outlet hole are both arranged at a position 30°-60° below the side of the tube body, and the water outlet holes of the perforated tube 2 (371) are all facing the surrounding pool walls rather than the center of the pool, and the distance between the suction hole and the water outlet hole is 5-20 cm.

[0026] The present invention has at least the following beneficial effects: the system for treating tunnel construction wastewater provided by the present invention comprises a plurality of precise dosing equipment, which can accurately measure the dosage of the reagent, automatically configure the concentration of the liquid medicine, and accurately control the flow rate or flow velocity of the liquid medicine according to the changes in the concentration and water volume of the tunnel construction wastewater, and can also make real-time adjustments according to the changes in the quality and volume of the wastewater. In other words, the present invention can at least achieve the following functions and effects.

[0027] 1) According to the changes in the water quality and quantity of the wastewater inlet, the three chemicals and the dosing in four places are accurately matched.

[0028] 2) Realize automatic configuration of medicines and automatic adjustment of dosage.

[0029] 3) Reduce manual workload and save medicines.

[0030] 4) The effluent quality is stable and the treatment effect is good.

[0031] 5) Flexible adjustment, simple equipment and easy operation.

[0032] In a preferred embodiment of the present invention, when the treatment method further includes providing a wastewater treatment device to prevent dead angles, the method also has at least the following beneficial effects.

[0033] 6) Without adding additional equipment, the existing slurry pump is used to effectively solve the problem of sludge deposition and compaction at the bottom of the coagulation tank and flocculation tank, especially at the four corners of the tank body, through pipeline modification.

[0034] 7) The integrated equipment does not need to be shut down for silting. When the sludge concentration at the bottom of the coagulation tank and flocculation tank is too high, the sludge can be pumped out by opening valve 2 and closing valve 1.

[0035] 8) Regulating valves are added to the suction pipe and the injection pipe, that is, the valve one and the valve two are adjustable valves, which can adjust the flow of the slurry pump by controlling the valve opening according to the sludge compaction and stirring floc conditions, while disturbing the deposited sludge without affecting the floc formation in the pool.

[0036] 9) The perforated pipe of the suction pipe connected to the slurry pump is set 600mm above the bottom of the pool and is opened at a 45° angle downward on the pipe. The suction hole is facing downward to prevent sludge from entering the pipe and causing pipe blockage.

[0037] 10) The perforated pipe of the injection pipe connected to the slurry pump is set 200mm above the bottom of the pool and is opened at a 45° angle downward on the pipe. The outlet hole is facing downward, which can effectively prevent the sludge at the bottom of the pool from entering the pipe. At the same time, pressure is formed in the pipe. Through the water jet effect, the sludge at the bottom of the pool is disturbed, and the clumped sludge at the bottom of the pool is broken up, completely solving the sludge sedimentation problem in the pool body.

[0038] 11) The device of the present invention can ensure the stable operation of the entire system, with low cost and significant effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic diagram of a system for treating tunnel construction wastewater in the treatment method described in the present invention.

[0040] Figure 2 This is an overall structural diagram of the dead angle-preventing wastewater treatment device in the treatment method described in the present invention.

[0041] Figure 3 It is a partial three-dimensional structural diagram of the dead angle prevention wastewater treatment device in the treatment method described in the present invention.

[0042] In the figure, 1. secondary sedimentation tank, 2. tertiary sedimentation tank, 3. integrated equipment, 4. online sensor pH monitoring A, 5. pH primary dosing equipment, 6. online sensor pH monitoring B, 7. pH secondary dosing equipment, 8. online sensor SS monitoring A, 9. coagulant dosing equipment, 10. flocculant dosing equipment, 11. online sensor pH monitoring C, 12. online sensor SS monitoring B, 31. coagulation tank, 311. coagulation tank agitator, 32. flocculation tank, 321. flocculation tank agitator, 322. agitator bracket, 33. clarification tank, 34. slurry pump, 35. reflux pump, 36. suction pipe, 361. perforated pipe one, 362. external pipe one, 37 injection pipe, 371. perforated pipe two, 372. external pipe two, 38. valve one, 39. valve two. DETAILED DESCRIPTION

[0043] like Figure 1 As shown in the figure, the precise dosing system for tunnel construction wastewater mainly includes a monitoring system, a dosing adjustment system, and a control system. The system can analyze the main pollutants, suspended solids and acidity and alkalinity in the tunnel construction wastewater, conduct real-time monitoring in combination with the requirements of the effluent water quality, and feed back the monitoring information to the control system. The dosing concentration and dosing amount can be adjusted through the dosing adjustment system connected to the control system, and the automatic data collection and monitoring can be realized. While understanding the operation status of the tunnel wastewater in real time, remote automatic monitoring can also be realized.

[0044] The monitoring system includes an online sensor pH monitoring A4, an online sensor pH monitoring B6, an online sensor SS monitoring A8, an online sensor pH monitoring C11 and an online sensor SS monitoring B12, all of which are electrically connected to the controller in the control system; the dosing adjustment system includes a pH primary dosing device 5, a pH secondary dosing device 7, a coagulant dosing device 9 and a flocculant dosing device 10, all of which are electrically connected to the controller in the control system for control.

[0045] Specifically, the monitoring system mainly includes two online suspended solids measuring instruments and three online pH meters. The suspended solids measuring instrument can monitor the turbidity of wastewater and the suspended solids concentration, and has a self-cleaning function of the probe, which can adapt to a variety of installation methods; preferably, a shading device is provided for the suspended solids measuring instrument, which can effectively avoid the influence of sunlight on the measurement accuracy of the suspended solids measuring instrument, and the measurement data is more accurate. The three pH monitoring points are respectively located at the outlet of the secondary sedimentation tank, the outlet of the tertiary sedimentation tank, and the outlet of the integrated equipment; the two suspended solids monitoring points are respectively located at the outlet of the tertiary sedimentation tank and the outlet of the integrated equipment; the settings of these five monitoring points are representative, and the flow of wastewater is stable and will not cause a large impact on the detection equipment; in the present invention, the pH meter and the suspended solids measuring instrument are both installed in an immersed manner, which is easy to install and can be fixed on the wall of the device using a fixing bracket without the need for additional auxiliary tools. The fixing bracket used to install the pH meter and the suspended solids measuring instrument is telescopic, and the length can be adjusted according to the depth of the pool, and the installation position can be adjusted according to the actual situation. At the same time, the telescopic bracket is convenient for cleaning and maintenance of the instrument.

[0046] The dosing system is mainly composed of a dispensing system and a dosing system; specifically, it includes automatic coagulant dosing equipment, automatic flocculant dosing equipment, and automatic acid dosing equipment; the present invention sets two acid dosing points, which are respectively located at the entrance of the tertiary sedimentation tank and the entrance of the integrated equipment or on the pipeline upstream thereof; the present invention sets a total of one coagulant dosing point, which is located at the entrance of the coagulation tank in the integrated equipment; a total of one flocculant dosing point is set, which is located at the entrance of the flocculation tank in the integrated equipment; the dispensing system is equipped with an automatic feeding device, and after the data is analyzed by the calculation model, the feeding amount is adjusted to realize the automatic control of the agent concentration; the dosing system can realize the automatic control of the dosing amount by frequency conversion control of the liquid pump.

[0047] The control system can realize the collection of monitoring data and realize automatic addition of reagents and dosage adjustment. The control system collects the pH monitoring data of the outlet of the secondary sedimentation tank and the outlet of the tertiary sedimentation tank in real time as the data input of the pH primary addition control model, and adjusts the pH primary addition amount according to the set primary addition target value; the control system collects the pH monitoring data of the outlet of the tertiary sedimentation tank and the outlet of the integrated equipment in real time as the data input of the pH secondary addition control model, and adjusts the pH secondary addition amount according to the set secondary addition target value; the control system collects the SS monitoring data of the outlet of the tertiary sedimentation tank and the outlet of the integrated equipment in real time as the data input of the coagulant addition and flocculant addition control model, and adjusts the dosage of the coagulant and flocculant according to the set addition target SS value.

[0048] The control system can calculate the dosage concentration (the amount of powder and tap water) and the dosage (the amount of liquid medicine formed by powder and tap water) through the model according to the detection data; the control model is a PID closed-loop cumulative superposition limit linear limit algorithm to convert and adjust the dosing pump frequency to achieve the dosage of the medicine; by adjusting the PID coefficient, the system output responds quickly and stably approaches and reaches the set input target value; the control system feeds back the signal to the automatic dispensing link to realize the automatic preparation of the medicine;

[0049] Solution concentration formula: c = n ÷ v; where, solution concentration (c), drug powder mass (n), solution volume (v).

[0050] The dosage function of the spiral conveyor of the automatic dispensing machine is: Q = f*π*D*L / 60, where Q is the dosage, f is the dosage frequency, D is the diameter of the spiral blade, and L is the spiral conveying length.

[0051] The operation process of the system for treating tunnel construction wastewater described in the present invention includes: sewage is collected from the tunnel entrance and enters the primary sedimentation tank, and enters the secondary sedimentation tank after natural sedimentation, a first pH monitoring point is set at the outlet of the secondary sedimentation tank, and monitoring data is transmitted to the control system, and the control system feeds back a signal to the automatic dosing equipment of the acid agent after model calculation, automatically adjusts the concentration and dosage of the agent, and starts the primary dosing system of the acid agent at the entrance of the tertiary sedimentation tank; a reagent mixing device is provided at the entrance of the tertiary sedimentation tank, which can fully and evenly mix the acid agent with the sewage to reduce the alkalinity index of the sewage; the pH value of the wastewater is fine-tuned by the secondary dosing system to achieve precise adjustment of the pH value; a second pH monitoring point is set at the outlet of the tertiary sedimentation tank, and a third pH monitoring point is set at the outlet of the integrated equipment, and these two The monitoring data is transmitted to the control system. If the pH value is within the set range, the model calculation is accurate and the secondary acid agent dosing system is not started. If the pH value deviates from the set range, the model is recalculated and the secondary acid agent dosing system is started. The secondary acid agent dosing point is set at the inlet of the integrated equipment or on the upstream pipeline. The inlet of the integrated equipment is equipped with a reagent mixing device to fully mix the acid agent with water. The first suspended matter monitoring point is set at the outlet of the tertiary sedimentation tank, and the second suspended matter monitoring point is set at the outlet of the integrated equipment. The two monitoring data are transmitted to the control system. After the model calculation, the control system feeds back the signal to the coagulant and flocculant automatic dosing equipment, automatically adjusts the dosage concentration and dosage, and adds coagulant at the inlet of the coagulation tank and flocculant at the inlet of the flocculation tank.

[0052] like Figure 2 and Figure 3 As shown, in the present invention, two pipelines are firstly added, a suction pipe and an injection pipe. Both pipelines are arranged into an overall square shape according to the shape of the pool wall. The liquid in the coagulation tank and the flocculation tank is continuously sucked out of the pool body and injected into the pool body to achieve the effect of eliminating dead corners. In the figure, the suction pipe is on the top, and it has a hole obliquely downward to allow the liquid to be sucked into the pipeline, and the injection pipe is on the bottom, and it also has a hole obliquely downward to allow the liquid to flow out of the pipeline. Both the suction pipe and the injection pipe have holes obliquely downward to avoid liquid accumulation in the pipeline. The existing slurry pump in the existing integrated equipment for tunnel wastewater treatment can realize the flow of liquid in the suction pipe and the injection pipe, thereby preventing dead corners and sludge accumulation in the coagulation tank and the flocculation tank.

[0053] The present invention utilizes the existing slurry pump to transform the pipeline. An upper and lower layer of pipelines are arranged in the tank body of the coagulation tank and the flocculation tank. The upper layer of pipeline is a suction pipe, which is connected to the inlet of the existing slurry pump, and the lower layer of pipeline is an injection pipe, which is connected to the outlet of the slurry pump. The suction action of the slurry pump forms a jet water flow to break up the clumped sludge at the bottom of the tank, and a valve 1 is arranged on the pipeline (i.e., external pipe 2) that connects the outlet of the slurry pump with the perforated pipe of the injection pipe, and a valve 2 is arranged on the external pipe 1. When the valve 2 is opened and the valve 1 is closed, the muddy water in the coagulation tank and the flocculation tank can be pumped to the sludge tank. On the one hand, it can effectively avoid the accumulation of sludge at the bottom of the coagulation tank and the flocculation tank to form a dead corner, and on the other hand, it can also discharge the excess sludge at the bottom of the tank.

[0054] In the prior art, the slurry pump 34 and the reflux pump 35 originally have the same function, and the two pumps are mutually standby and can be switched. The slurry pump 34 and the reflux pump 35 originally both realize the function of sludge return and sludge discharge, discharge a part of the sludge in the clarifier 33 to the sludge pool outside the integrated equipment through the equipment sludge discharge channel, and return another part of the sludge in the clarifier 33 to the flocculation tank through the reflux channel. However, in the present invention, because the pipeline of the slurry pump 34 is modified and valves are added, the slurry pump 34, compared with the reflux pump 35, has the original function of returning and discharging the sludge at the bottom of the clarification tank 33 unchanged, but has two additional functions. One function is that when valve 1 38 and valve 2 39 are both opened, the liquid spraying in the coagulation tank 31 and the flocculation tank 32 can be prevented from dead corners, and the other function is that when valve 1 38 is closed and valve 2 39 is opened, the excess sludge in the coagulation tank 31 and the flocculation tank 32 can be partially returned to the flocculation tank through the slurry pump 34, and part of the sludge can be discharged to the sludge tank outside the integrated equipment through the equipment sludge discharge channel.

[0055] The suction pipe and the injection pipe both include a perforated pipe arranged in the coagulation tank and the flocculation tank and an external pipe for connecting the perforated pipe to the outside of the tank body. The perforated pipes are evenly opened at a spacing of 100 mm in a direction of a 45° downward angle on the side of the pipeline. The hole forms a jet of water through the pressure of the slurry pump. The hole is opened on the lower side of the pipeline, which can effectively prevent the settled sludge from entering the pipeline and ensure that the inlet and outlet of the slurry pump will not be blocked.

[0056] In general, the present invention provides a method for treating tunnel construction wastewater, wherein a system is used, the system includes a secondary sedimentation tank, a tertiary sedimentation tank and an integrated device, and includes three online sensors for monitoring the pH value of wastewater and two online sensors for monitoring the SS value of wastewater, and also includes a pH primary dosing device, a pH secondary dosing device, a coagulant dosing device and a flocculant dosing device, and the online sensors and dosing devices are electrically connected to a controller. The treatment method provided by the present invention can accurately measure the dosage of the agent, automatically configure the concentration of the liquid medicine and accurately control the flow rate of the liquid medicine according to the changes in the concentration and water volume of the tunnel construction wastewater, and can also adjust in real time according to the changes in the water quality and water volume of the wastewater. The treatment method also includes the use of a dead angle-proof wastewater treatment device, which can effectively solve the problem of sludge deposition and compaction at the bottom of the coagulation tank and the flocculation tank, especially at the four corners of the tank body.

[0057] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for treating tunnel construction wastewater, characterized in that: The invention relates to a system for treating tunnel construction wastewater, wherein the system comprises a secondary sedimentation tank (1), a tertiary sedimentation tank (2) and an integrated device (3) arranged in sequence along the flow direction of the wastewater, and comprises three online sensors for monitoring the pH value of the wastewater and two online sensors for monitoring the SS value of the wastewater. The system also comprises a primary pH dosing device (5), a secondary pH dosing device (7), a coagulant dosing device (9) and a flocculant dosing device (10), and the online sensors and dosing devices are electrically connected to a controller; the integrated device (3) comprises a coagulation tank (31), a flocculation tank (32) and a clarification tank (33) arranged in sequence along the flow direction of the wastewater; In the treatment method, the controller controls the addition of the acidic agent of the pH primary dosing device (5) online according to the data of the pH monitoring A (4) of the online sensor arranged at the water outlet of the secondary sedimentation tank (1); Alternatively, the controller controls the addition of the acidic agent of the pH primary dosing device (5) online according to the data of the online sensor pH monitoring A (4) and the data of the online sensor pH monitoring B (6) arranged at the water outlet of the tertiary sedimentation tank (2); The controller controls the addition of the acidic agent of the pH secondary dosing device (7) online according to the data of the online sensor pH monitoring B (6) and the data of the online sensor pH monitoring C (11) arranged at the water outlet of the clarification tank (33) of the integrated device (3); The controller online controls the addition of reagents by the coagulant dosing device (9) and the flocculant dosing device (10) based on data from an online sensor SS monitoring A (8) arranged at the water outlet of the tertiary sedimentation tank (2) and data from an online sensor SS monitoring B (12) arranged at the water outlet of the clarification tank (33) of the integrated device (3).

2. The method for treating tunnel construction wastewater according to claim 1, characterized in that: The first-level pH dosing device (5) is arranged on the pipeline between the second-level sedimentation tank (1) and the third-level sedimentation tank (2) or at the water inlet in the third-level sedimentation tank (2); the second-level pH dosing device (7) is arranged on the pipeline between the third-level sedimentation tank (2) and the integrated device (3) or at the water inlet in the integrated device (3); the coagulant dosing device (9) is connected to the coagulation tank (31), and the flocculant dosing device (10) is connected to the flocculation tank (32).

3. The method for treating tunnel construction wastewater according to claim 2, characterized in that: The pH primary dosing device (5) and the pH secondary dosing device (7) both include a conveying device for conveying a certain amount of organic acid powder, a stirring device for mixing the organic acid powder with tap water to form a liquid medicine, and a liquid pump for adding the prepared liquid medicine to the wastewater; the coagulant dosing device (9) and the flocculant dosing device (10) both include a conveying device for conveying a certain amount of medicine powder, a stirring and storing device for mixing the medicine powder with tap water to form a liquid medicine, and a liquid pump for adding the prepared liquid medicine to the wastewater; and the conveying device, stirring device, stirring and storing device and liquid pump in the dosing device are all electrically connected to the controller for control.

4. The method for treating tunnel construction wastewater according to claim 3, characterized in that: The organic acid powder is citric acid or oxalic acid, and the powder used in the coagulant adding device (9) and the flocculant adding device (10) is a coagulant and a flocculant.

5. The method for treating tunnel construction wastewater according to any one of claims 1 to 4, characterized in that: The treatment method also includes setting up a dead-angle-proof wastewater treatment device, which includes a suction pipe (36) and an injection pipe (37) arranged at the coagulation tank (31) and / or the flocculation tank (32), the suction pipe (36) is connected to the inlet of the slurry pump (34), and the injection pipe (37) is connected to the outlet of the slurry pump (34), the suction pipe (36) includes a perforated pipe (361) arranged in the coagulation tank and / or the flocculation tank and an external pipe (362) for connecting the perforated pipe (361) to the outside of the coagulation tank and / or the flocculation tank, and the injection pipe (37) includes a perforated pipe (371) arranged in the coagulation tank and / or the flocculation tank and an external pipe (372) for connecting the perforated pipe (371) to the outside of the coagulation tank and / or the flocculation tank.

6. The method for treating tunnel construction wastewater according to claim 5, characterized in that: The external pipe 1 (362) is connected to a pipeline access point, which is arranged on the pipeline between the switch valve at the bottom of the clarifier (33) and the inlet of the slurry pump (34), and a valve 2 (39) is arranged on the external pipe 1 (362); the external pipe 2 (372) is connected to a pipeline outlet point, which is arranged on the pipeline between the outlet of the slurry pump (34) and a switch valve downstream thereof, and a valve 1 (38) is arranged on the external pipe 2 (372).

7. The method for treating tunnel construction wastewater according to claim 6, characterized in that: The valve one (38) and valve two (39) are both flow-adjustable regulating valves and are both electrically connected to a controller so as to achieve automatic switching of the valves and flow adjustment.

8. The method for treating tunnel construction wastewater according to claim 5, characterized in that: The perforated pipe 1 (361) is square in shape or has the same shape as the coagulation tank (31) and / or the flocculation tank (32). It is arranged at a height of 0.4 to 0.8 m from the bottom of the tank, and a plurality of suction holes are arranged on the pipe body; the perforated pipe 2 (371) is square in shape or has the same shape as the coagulation tank (31) and / or the flocculation tank (32). It is arranged at a height of 0.1 to 0.3 m from the bottom of the tank, and a plurality of water outlet holes are arranged on the pipe body.

9. The method for treating tunnel construction wastewater according to claim 8, characterized in that: The suction hole and the water outlet hole are both arranged on the side or below the side of the tube body, and the diameter of the suction hole is larger than the diameter of the water outlet hole. The suction holes and the water outlet holes are evenly distributed on the tube bodies of the perforated tube 1 (361) and the perforated tube 2 (371).

10. The method for treating tunnel construction wastewater according to claim 9, characterized in that: The diameter of the suction hole is 10 to 20 mm, and the diameter of the water outlet hole is 3 to 8 mm. The suction hole and the water outlet hole are both arranged at a position 30° to 60° below the side of the pipe body, and the water outlet holes of the perforated pipe 2 (371) are all facing the surrounding pool walls rather than the center of the pool. The distance between the suction hole and the water outlet hole is 5 to 20 cm.

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