System for treating tunnel construction wastewater

Abstract

The utility model belongs to the field of wastewater treatment, and particularly provides a system for treating tunnel construction wastewater, which comprises a secondary sedimentation tank, a tertiary sedimentation tank and integrated equipment which are sequentially arranged along the flow direction of the wastewater, as well as three on-line sensors for monitoring the pH value of the wastewater and two on-line sensors for monitoring the SS value of the wastewater, 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. The system for treating the tunnel construction wastewater provided by the utility model can accurately meter the dosage of chemicals, automatically configure the concentration of the chemical liquid and accurately control the flow of the chemical liquid according to the change of the concentration and the water quantity of the tunnel construction wastewater, and also can adjust in real time according to the change of the quality and the water quantity of the wastewater.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of wastewater treatment, and particularly relates to a system for treating tunnel construction wastewater. BACKGROUND

[0002] The main sources of tunnel construction wastewater are: 1) gushing water produced when the tunnel construction passes through poor geological units; 2) fissure water of bedrock; 3) wastewater produced during drilling construction; 4) wastewater produced for dust reduction during tunnel blasting; 5) wastewater produced during cleaning of the rock surface before shotcrete; and 6) wastewater produced during shotcrete and grouting. The main pollutants of these wastewaters are inorganic suspended solids, and the wastewater is generally alkaline or weakly alkaline, with a pH value of 7.0-13.0. The alkaline substances are mainly derived from cement, various additives, grouting materials and their hydrolysis products during construction. For example, tricalcium silicate, dicalcium silicate and calcium hydroxide produced by the hydrolysis of cement, which will cause the pH value to rise after dissolving in water. The characteristics of tunnel construction wastewater are: first, the discharge amount is not fixed due to the changes in season, location and construction progress; second, the wastewater concentration is different due to the different construction period, seepage size in the tunnel, rock mass condition and drainage facilities. Overall, tunnel construction wastewater mainly contains inorganic pollutants, and the first consideration is the physical and chemical treatment method. For the main pollutants in wastewater, suspended solids and alkaline water quality, coagulation and neutralization methods are used respectively. Both coagulation and neutralization methods require the addition of reagents to the wastewater, and coagulants, flocculants and acidic reagents must be added to the water to make the tunnel construction wastewater meet the discharge standard.

[0003] The applicant's prior invention patent CN201910875105.4 relates to a tunnel construction wastewater treatment method, belonging to the technical field of wastewater treatment. The wastewater treated by the invention has SS≥20000mg / L. The tunnel construction wastewater treatment method of the invention includes the following steps: S1, adjusting the raw water quality, trapping particulate matter, and then adding a first coagulant for the first coagulation; S2, adding a first flocculant to the effluent of step S1 for the first flocculation to remove sludge, and the sludge is resourcefully treated; S3, adding a second coagulant to the effluent of step S2 for the second coagulation; S4, adding a second flocculant to the effluent of step S3 to mix with the resourcefully treated sludge in S2 for the second flocculation; S5, precipitating the effluent of step S4, and discharging the clear water after adjusting the pH value. The treated wastewater meets the first level standard of the "Integrated Wastewater Discharge Standard" (GB8978-1996), and the removal rate of suspended solids can reach more than 98%.

[0004] In fact, most of the tunnel wastewater treatment equipment currently has an automatic dosing system, which can realize automatic configuration and dosing of reagents. However, the automatic dosing system is generally limited to water quality and quantity within a specific range. Because the concentration and quantity of wastewater change frequently with the change of construction period, rock mass condition, drainage facilities, etc., the concentration and quantity of reagents in the automatic dosing system are fixed values, which cannot accurately match the changes of water quality and quantity of tunnel construction wastewater, resulting in unstable effluent quality. The conventional method is to manually sample at the inlet, conduct a small-scale test, and then manually adjust the dosing quantity. However, this method can only monitor the surface water quality, consumes a large amount of manpower, and cannot adapt to real-time changes in water quality and quantity. When the water quantity of tunnel construction wastewater reaches the maximum value, it is difficult to match the dosing quantity, and in some cases, manual dosing is required, resulting in excessive dosing of reagents and increased operating costs.

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

[0006] Therefore, the present application provides a system for treating tunnel construction wastewater, which 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, the integrated device (3) comprising a coagulation tank (31), a flocculation tank (32) and a clarification tank (33) arranged in sequence along the flow direction of the wastewater, an online sensor pH monitor A (4) being arranged at the outlet of the secondary sedimentation tank (1), a pH primary dosing device (5) being arranged on the pipeline between the secondary sedimentation tank (1) and the tertiary sedimentation tank (2) or at the inlet of the tertiary sedimentation tank (2), an online sensor pH monitor B (6) being arranged at the outlet of the tertiary sedimentation tank (2), a pH secondary dosing device (7) being arranged on the pipeline between the tertiary sedimentation tank (2) and the integrated device (3) or at the inlet of the integrated device (3), an online sensor SS monitor A (8) being further arranged at the outlet of the tertiary sedimentation tank (2), a coagulant dosing device (9) being connected to the coagulation tank (31), a flocculant dosing device (10) being connected to the flocculation tank (32), an online sensor pH monitor C (11) and an online sensor SS monitor B (12) being further arranged at the outlet of the clarification tank (33) of the integrated device (3), the online sensor pH monitor A (4), the online sensor pH monitor B (6), the online sensor SS monitor A (8), the online sensor pH monitor C (11) and the online sensor SS monitor B (12) being electrically connected to a controller, and the pH primary dosing device (5), the pH secondary dosing device (7), the coagulant dosing device (9) and the flocculant dosing device (10) being electrically connected to the controller for control.

[0007] In a specific embodiment, the pH primary dosing device (5) and the pH secondary dosing device (7) each comprise a conveying device for conveying a certain amount of organic acid powder, a stirring device for mixing with tap water to form a liquid medicine, and a liquid pump for adding the prepared liquid medicine to the wastewater; and the coagulant dosing device (9) and the flocculant dosing device (10) each comprise a conveying device for conveying a certain amount of medicine powder, a stirring storage device for mixing with tap water to form a liquid medicine, and a liquid pump for adding the prepared liquid medicine to the wastewater.

[0008] In a specific embodiment, the organic acid powder is citric acid powder or oxalic acid powder, and the medicine powder used in the coagulant dosing device (9) and the flocculant dosing device (10) is coagulant and flocculant.

[0009] In the application, the pH primary dosing device (5) is used to make rough adjustment to the pH value of the wastewater, which mainly adjusts the concentration of the powder and the amount of the liquid medicine according to the data of the online sensor pH monitoring A (4), and can also refer to the data of the online sensor pH monitoring B (6) to determine whether it is necessary to increase or decrease, and the pH primary dosing device (5) is generally in the state of frequent work; wherein the pH secondary dosing device (7) is used to make fine adjustment to the pH value of the wastewater, which 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 when adjustment is needed, the concentration of the liquid medicine and the amount of the liquid medicine are determined by the computer and the controller. The liquid medicine concentration is fed back to the change of the powder addition amount and the tap water addition amount of the conveying device, and the amount of the liquid medicine is fed back to the change of the flow rate or flow of the liquid pump. The coagulant dosing and the flocculant dosing are controlled according to the values of the online sensor SS monitoring A (8) and the online sensor SS monitoring B (12), and the computer accurately calculates the dosing concentration of the coagulant and flocculant powder and the flow of the liquid medicine dosing, and the liquid medicine concentration is fed back to the change of the powder addition amount and the tap water addition amount of the conveying device, and the amount of the liquid medicine is fed back to the change of the flow rate or flow of the liquid pump.

[0010] The application at least has the following beneficial effects: the system for treating tunnel construction wastewater provided by the application comprises multiple precise dosing equipment, which can accurately measure the dosing amount of the medicament, automatically configure the liquid medicine concentration and accurately control the liquid medicine flow rate or flow according to the concentration and water volume of the tunnel construction wastewater, and can also be adjusted in real time according to the change of the wastewater quality and water volume. That is, the application at least can realize the following functions and effects. 1) accurately matching three kinds of medicaments and four dosing places according to the change of the wastewater quality and water volume; 2) automatically configuring the medicament and automatically adjusting the dosing amount; 3) reducing the manual workload and saving the medicament; 4) stabilizing the effluent quality and achieving good treatment effect; 5) flexible adjustment, simple equipment and convenient operation. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 The system for treating tunnel construction wastewater provided by the application is shown in the accompanying drawings. DETAILED DESCRIPTION

[0012] The precise dosing system for tunnel construction wastewater mainly comprises a monitoring system, a dosing adjustment system and a control system. The system can analyze the main pollutants, suspended solids and acid-base in the tunnel construction wastewater, real-time monitor in combination with the requirements of the effluent quality, and feed back the monitoring information to the control system to realize the adjustment of the dosing concentration and the dosing amount through the dosing adjustment system connected with the control system, realize the automatic acquisition and monitoring of the data, and realize the remote automatic monitoring while real-time understanding the operation of the tunnel wastewater.

[0013] The monitoring system comprises 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, which are electrically connected with the controller in the control system; the dosing adjustment system comprises a pH primary dosing device 5, a pH secondary dosing device 7, a coagulant dosing device 9 and a flocculant dosing device 10, which are electrically connected with the controller in the control system for control.

[0014] Specifically, the monitoring system mainly comprises two online suspended solids (SS) monitors and three pH meters. The SS monitors can monitor the turbidity and the SS concentration of the wastewater, and have a self-cleaning function and can be installed in various ways. Preferably, a light shielding device is arranged on the SS monitor to effectively avoid the influence of sunlight on the determination accuracy of the SS monitor, so that the determination data is more accurate. The three pH monitoring points are located at the outlets of the secondary sedimentation tank, the tertiary sedimentation tank and the integrated equipment, respectively. The two SS monitoring points are located at the outlets of the tertiary sedimentation tank and the integrated equipment, respectively. The five monitoring points are all representative, and the flow of the wastewater is stable and will not cause a large impact on the detection equipment. In the present application, the pH meters and the SS monitors are installed in an immersion mode, which is convenient and can be fixed on the wall of the equipment by using a fixed frame without the need of additional auxiliary tools. The fixed frame for installing the pH meters and the SS monitors is telescopic, and the length can be adjusted according to the depth of the tank. The installation position can be adjusted according to the actual situation, and the telescopic support is convenient for cleaning and maintenance of the instruments.

[0015] The dosing system mainly comprises a dosing system and a dosing system. Specifically, it comprises a coagulant automatic dosing device, a flocculant automatic dosing device and an acid reagent automatic dosing device. The present application sets two acid reagent dosing points, which are located at the inlet of the tertiary sedimentation tank and the inlet of the integrated equipment or on the pipeline upstream thereof. The present application sets one coagulant dosing point, which is located at the inlet of the coagulation tank in the integrated equipment. One flocculant dosing point is set, which is located at the inlet of the flocculation tank in the integrated equipment. The dosing system is provided with an automatic feeding device. After the data is analyzed by the calculation model, the feeding amount is adjusted, and the automatic control of the reagent concentration is realized. The dosing system can realize the automatic control of the dosing amount by frequency conversion control of the liquid pump.

[0016] The control system can realize the collection of monitoring data and the automatic addition and dosage adjustment of the medicament. The control system collects the pH monitoring data of the outlet of the secondary sedimentation tank and the outlet of the tertiary sedimentation tank as the data input of the pH primary addition control model in real time, 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 device as the data input of the pH secondary addition control model in real time, 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 device as the data input of the coagulant addition and flocculant addition control model in real time, adjusts the addition amount of the coagulant and the flocculant according to the set addition target SS value.

[0017] The control system can calculate the dosage concentration (the use amount of powder and tap water) and the medicament addition amount (the use amount of the medicament solution formed by powder and tap water) according to the detection data through the model; the control model is a PID closed loop integral superposition limit linear restriction algorithm conversion adjustment medicament pump frequency to realize the addition of the medicament amount; the system output is quickly responsive and stably close to and reaches the set input target value by adjusting the PID coefficient; the control system feeds back the signal to the automatic medicament preparation link to realize the automatic preparation of the medicament;

[0018] Solution concentration formula: c = n ÷ v; wherein, solution concentration (c), drug powder mass (n), solution volume (v).

[0019] The automatic medicament preparation machine spiral conveying medicament amount function: Q = f * π * D * L / 60, wherein, Q is the addition amount, f is the addition frequency, D is the spiral blade diameter, and L is the spiral conveying length.

[0020] The operation process of the system for treating tunnel construction wastewater provided by the application comprises the following steps: after wastewater is collected from a tunnel portal, the wastewater enters a first-stage sedimentation tank, and after natural sedimentation, the wastewater enters a second-stage sedimentation tank, a first pH monitoring point is arranged at the outlet of the second-stage sedimentation tank, monitoring data are transmitted to a control system, after model calculation, feedback signals are fed back to an automatic dosing device of acid reagents, the concentration of the reagents and the dosing amount are automatically adjusted, and an acid reagent first-stage dosing system is started at the inlet of a third-stage sedimentation tank; a reagent mixing device is arranged at the inlet of the third-stage sedimentation tank, which can fully mix and uniformly distribute the acid reagents and the wastewater, so as to reduce the alkalinity index of the wastewater; the pH value of the wastewater is finely adjusted through a second-stage dosing system, so as to realize accurate adjustment of the pH value; a second pH monitoring point is arranged at the outlet of the third-stage sedimentation tank, and a third pH monitoring point is arranged at the outlet of an integrated device, the monitoring data of the two monitoring points are transmitted to the control system, if the pH value is within the set range, the model calculation is accurate, and the acid reagent second-stage dosing system is not started; if the pH value deviates from the set range, the model is recalculated, and the acid reagent second-stage dosing system is started; the acid reagent second-stage dosing point is arranged at the inlet of the integrated device or on a pipeline upstream of the integrated device, and a reagent mixing device is arranged at the inlet of the integrated device, which can fully mix and uniformly distribute the acid reagents and water; a first suspended solid monitoring point is arranged at the outlet of the third-stage sedimentation tank, a second suspended solid monitoring point is arranged at the outlet of the integrated device, the monitoring data of the two monitoring points are transmitted to the control system, after model calculation, feedback signals are fed back to an automatic dosing device of coagulants and flocculants, the concentration of the reagents and the dosing amount are automatically adjusted, coagulants are dosed at the inlet of a coagulation tank, and flocculants are dosed at the inlet of a flocculation tank.

[0021] In general, the application provides a system for treating tunnel construction wastewater, which comprises a second-stage sedimentation tank, a third-stage sedimentation tank and an integrated device arranged in sequence along the flow direction of the wastewater, three online sensors for monitoring the pH value of the wastewater and two online sensors for monitoring the SS value of the wastewater, a pH first-stage dosing device, a pH second-stage dosing device, a coagulant dosing device and a flocculant dosing device, and the online sensors and the dosing devices are electrically connected to a controller. The system for treating tunnel construction wastewater provided by the application can accurately measure the dosing amount of reagents, automatically configure the concentration of reagent liquid and accurately control the flow of reagent liquid according to the concentration and water volume of tunnel construction wastewater, and can be real-time adjusted according to the change of the water quality and water volume of the wastewater.

[0022] Those skilled in the art will easily understand that the above description is only the preferred embodiment of the application and is not used to limit the application, and any modification, equivalent replacement and improvement made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A system for treating wastewater from tunnel construction, characterized in that The system comprises a secondary sedimentation tank (1), a tertiary sedimentation tank (2) and an integrated device (3) arranged in sequence along the wastewater flow direction, the integrated device (3) comprises a coagulation tank (31), a flocculation tank (32) and a clarification tank (33) arranged in sequence along the wastewater flow direction, an online sensor pH monitoring A (4) is arranged at the effluent outlet in the secondary sedimentation tank (1), a 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 influent inlet in the tertiary sedimentation tank (2), an online sensor pH monitoring B (6) is arranged at the effluent outlet in the tertiary sedimentation tank (2), a pH secondary dosing device (7) is arranged on the pipeline between the tertiary sedimentation tank (2) and the integrated device (3) or at the influent inlet in the integrated device (3), an online sensor SS monitoring A (8) is further arranged at the effluent outlet in the tertiary sedimentation tank (2), a coagulant dosing device (9) is connected at the coagulation tank (31), a flocculant dosing device (10) is connected at the flocculation tank (32), an online sensor pH monitoring C (11) and an online sensor SS monitoring B (12) are further arranged at the effluent outlet in the clarification tank (33) of the integrated device (3); the online sensor pH monitoring A (4), the online sensor pH monitoring B (6), the online sensor SS monitoring A (8), the online sensor pH monitoring C (11) and the online sensor SS monitoring B (12) are electrically connected with a controller, and the pH primary dosing device (5), the pH secondary dosing device (7), the coagulant dosing device (9) and the flocculant dosing device (10) are electrically connected with the controller for control.

2. The system for treating wastewater from tunneling according to claim 1, wherein The pH primary dosing device (5) and the pH secondary dosing device (7) each comprise a conveying device for conveying a certain amount of organic acid powder, a stirring device for mixing 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) each comprise a conveying device for conveying a certain amount of medicine powder, a stirring storage device for mixing with tap water to form a liquid medicine, and a liquid pump for adding the prepared liquid medicine to the wastewater.

3. The system for treating wastewater from tunneling operations of claim 2, wherein, The organic acid powder is citric acid powder or oxalic acid powder, and the medicine powder used in the coagulant dosing device (9) and the flocculant dosing device (10) is a coagulant and a flocculant.

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