Treatment system for arsenic-containing wastewater

Abstract

The utility model provides an arsenic-containing wastewater treatment system. The arsenic-containing wastewater treatment system comprises a pretreatment unit, an arsenic removal unit, a primary DTRO (Disk Tubular Reverse Osmosis) unit and a secondary RO unit which are sequentially connected from wastewater collection to discharge, the pretreatment unit is used for receiving arsenic-containing wastewater and pre-removing arsenic-containing large-particle-size substances in the wastewater through precipitation, sedimentation and low-pressure filtration; the arsenic removal unit is used for removing soluble arsenic in the wastewater by adding sodium sulfide and a ferrous ion arsenic removal agent to form a precipitate; the first-stage DTRO unit at least comprises a first-stage reverse osmosis high-pressure plunger pump, and wastewater subjected to pretreatment and arsenic removal treatment passes through the first-stage reverse osmosis high-pressure plunger pump to generate a first-stage concentrated solution and a first-stage permeate; and the second-stage RO unit is connected behind the first-stage DTRO unit and is used for further treating the first-stage permeate. According to the treatment system for the arsenic-containing wastewater, efficient purification and resource utilization of the arsenic-containing wastewater are achieved through a multi-stage treatment process, and the treatment cost is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of industrial wastewater treatment, and particularly relates to a disposal system for arsenic-containing wastewater. BACKGROUND

[0002] Arsenic exists widely in nature and can enter the biosphere and food chain through various channels, thereby affecting human beings and ecological balance. The channel that causes relatively serious pollution to the environment is human production activities. Arsenic-containing wastewater mainly comes from non-ferrous metal mining, ore dressing, smelting, sulfuric acid production, pesticide production, hazardous waste disposal, etc., among which, the largest proportion comes from non-ferrous metal smelting. Non-ferrous metal resources in China also mainly exist in arsenic deposits, arsenic is a metallogenic element group, and also belongs to a semi-metal and heavy mineralizing agent group. Natural arsenic or arsenic metal compounds are rarely seen in nature, and most of them are in the form of sulfides and are inlaid in gold, copper, lead, zinc, tin, nickel, diamond mines. Arsenic deposits associated with non-ferrous metals account for 80%, and arsenic-like deposits are not utilized due to low grade and other reasons in the development of arsenic-containing non-ferrous metal deposits, thereby forming arsenic pollution, among which, mine arsenic-containing wastewater is the main pollution source. The discharge of arsenic-containing wastewater poses a serious threat to the environment and human health. Traditional wastewater treatment methods often have problems such as low treatment efficiency, high cost, secondary pollution, etc. Therefore, it is of great significance to develop an efficient, economical and environmentally friendly arsenic-containing wastewater disposal system. CONTENT OF THE UTILITY MODEL

[0003] Therefore, the technical problem to be solved by the present application is to provide a disposal system for arsenic-containing wastewater, which can realize efficient purification and resource utilization of arsenic-containing wastewater.

[0004] In order to solve the above problems, the present application provides a disposal system for arsenic-containing wastewater, comprising: a pretreatment unit, an arsenic removal unit, a first DTRO reverse osmosis unit and a second RO reverse osmosis unit connected in sequence from the wastewater collection to the discharge direction, the pretreatment unit is used for receiving arsenic-containing wastewater, and arsenic in the wastewater is formed into large-particle substances such as sulfides for sedimentation or low-pressure filtration; the arsenic removal unit is used for removing soluble arsenic in the wastewater by adding sodium sulfide and ferrous ion arsenic removal agent to form a precipitate; the first DTRO reverse osmosis unit at least comprises a first reverse osmosis high-pressure plunger pump, and the wastewater treated by pretreatment and arsenic removal is treated by the first reverse osmosis high-pressure plunger pump to generate a first concentrated liquid and a first permeate liquid;

[0005] The second RO reverse osmosis unit is connected behind the first DTRO reverse osmosis unit and is used for further treating the first permeate liquid.

[0006] Further, the pretreatment unit comprises a wastewater collection tank, a first sedimentation tank, a second sedimentation tank and an arsenic-containing wastewater raw water tank connected in sequence.

[0007] A chemical reagent is added in the first-stage sedimentation tank to adjust the pH value to a first set value, and the second-stage sedimentation tank is used to further remove the residual suspended solids and part of the dissolved substances in the wastewater after the first-stage sedimentation;

[0008] The arsenic-containing wastewater raw water tank is used to temporarily store the wastewater after the two-stage sedimentation treatment.

[0009] Further, the arsenic-containing wastewater treatment system further comprises an oil removal pretreatment unit,

[0010] The oil removal pretreatment unit is arranged between the pretreatment unit and the arsenic removal unit, and the oil removal pretreatment unit is connected with the outlet end of the arsenic-containing wastewater raw water tank.

[0011] Further, the oil removal pretreatment unit comprises an adsorption tank and an air floatation machine.

[0012] The outlet end of the arsenic-containing wastewater raw water tank is sequentially connected with the adsorption tank and the air floatation machine.

[0013] Further, a core filter is arranged between the arsenic removal unit and the first-stage DTRO reverse osmosis unit.

[0014] Further, the first-stage DTRO reverse osmosis unit further comprises a first-stage concentrated liquid pipeline and a first-stage permeate liquid pipeline; the first-stage DTRO reverse osmosis unit receives the wastewater after the pretreatment and the arsenic removal treatment, and the wastewater enters the first-stage reverse osmosis high-pressure plunger pump through the core filter to generate the first-stage concentrated liquid and the first-stage permeate liquid.

[0015] Further, a servo machine control valve is arranged at the outlet end of the first-stage concentrated liquid pipeline to control the pressure of the membrane group in the first-stage DTRO reverse osmosis unit.

[0016] Further, the second-stage RO reverse osmosis unit comprises a second-stage RO membrane system high-pressure pump.

[0017] The second-stage RO membrane system high-pressure pump is connected after the first-stage permeate liquid pipeline of the first-stage DTRO reverse osmosis unit, and is used to pressurize the first-stage permeate liquid and send the first-stage permeate liquid to the second-stage RO membrane unit to generate the second-stage concentrated liquid and the second-stage permeate liquid.

[0018] Further, the second-stage RO reverse osmosis unit further comprises a second-stage concentrated liquid pipeline, which is connected between the outlet of the second-stage RO reverse osmosis unit and the pretreatment unit, and is used to return the water exceeding a set concentration value generated by the second-stage RO reverse osmosis unit to the pretreatment unit for reprocessing.

[0019] Further, the arsenic-containing wastewater treatment system further comprises a water inlet tank and a booster pump.

[0020] The water inlet tank is arranged between the core filter and the booster pump, and the water outlet end of the core filter is connected with the water inlet of the water inlet tank; the booster pump is arranged at the water outlet end of the water inlet tank, and is used for pressurizing the wastewater pretreated by the core filter.

[0021] Advantages

[0022] The disposal system of arsenic-containing wastewater provided in the embodiment of the utility model removes arsenic and purifies deeply through multi-stage treatment process, and the treated water quality reaches the discharge limit standard of "Integrated Wastewater Discharge Standard" (GB8978-1996) and the recycled water quality standard of "Wastewater Reuse Industrial Water Quality" (GB / T19923-2005), reduces the water intake of enterprises, improves the water recycling rate, achieves the energy saving and emission reduction target of enterprises, realizes efficient purification and resource utilization of arsenic-containing wastewater, and reduces the treatment cost and environmental risk. The setting of the pretreatment unit and the arsenic removal unit effectively removes suspended solids, dissolved substances and arsenic compounds in the wastewater, and provides favorable conditions for subsequent reverse osmosis treatment; the combination use of the first DTRO reverse osmosis unit and the second RO reverse osmosis unit further improves the purification efficiency and water quality standard of the wastewater.

[0023] In addition, according to the change of the oil type pollutants in the arsenic-containing wastewater, the oil removal pretreatment unit is arranged before the DTRO system, which can effectively remove the oil type substances in the wastewater, avoid the interference and pollution of the oil type pollutants on the subsequent treatment unit, and thus affect the purification effect of the membrane system.

[0024] Finally, the setting of the water inlet tank and the booster pump improves the stability and treatment efficiency of the system, and ensures the continuous and stable supply of the wastewater. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the disposal system of arsenic-containing wastewater of the embodiment of the utility model;

[0026] Figure 2 It is a structural schematic diagram of the disposal system of arsenic-containing wastewater of the embodiment of the utility model.

[0027] The reference signs are as follows: 1, pretreatment unit; 11, wastewater collection tank; 12, primary sedimentation tank; 13, secondary sedimentation tank; 14, arsenic-containing wastewater raw water tank; 2, arsenic removal unit; 21, core filter; 3, primary DTRO reverse osmosis unit; 31, primary reverse osmosis high-pressure plunger pump; 33, water inlet tank; 34, booster pump; 35, primary permeate pipe; 36, primary concentrate pipe; 45, cleaning water tank; 46, RO cleaning water tank; 4, secondary RO reverse osmosis unit; 41, secondary RO membrane system high-pressure pump; 42, secondary concentrate pipe; 43, secondary RO membrane unit; 44, secondary RO water inlet tank; 5, oil removal pretreatment unit; 51, adsorption tank; 52, air floatation machine. DETAILED DESCRIPTION

[0028] In the description of the present application, it needs to be understood that the orientations or positional relationships indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and are not intended to indicate or imply that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0029] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise explicitly specified and limited.

[0030] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood in a broad sense, for example, can be fixedly connected, or can be detachably connected, or integrally connected; can be mechanically connected, or can be electrically connected; can be directly connected, or can be indirectly connected through an intermediate medium, or can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0031] The preferred embodiments of the present application are described below in conjunction with the drawings, and it should be understood that the preferred embodiments described herein are only used to illustrate and explain the present application, and are not intended to limit the present application.

[0032] In conjunction with Figure 1 and Figure 2As shown, according to the embodiment of the present application, a disposal system of arsenic-containing wastewater includes a pretreatment unit 1, an arsenic removal unit 2, a first DTRO reverse osmosis unit 3, and a second RO reverse osmosis unit 4 connected in sequence from the wastewater collection to the discharge direction. The pretreatment unit 1 is used for pre-removing the arsenic-containing large-particle substances in the wastewater by sedimentation and low-pressure filtration. Specifically, the arsenic-containing large-particle substances in the wastewater are filtered by a plate-and-frame filter press. The arsenic removal unit 2 is used for removing the soluble arsenic in the wastewater by adding soluble sodium salt and ferrous ion arsenic removal agent to form a precipitate, for example, sodium sulfide, to remove the arsenide in the wastewater. The first DTRO reverse osmosis unit 3 at least includes a first reverse osmosis high-pressure plunger pump 31. The wastewater treated by the pretreatment and arsenic removal is filtered by the first reverse osmosis high-pressure plunger pump 31 to generate a first concentrated liquid and a first permeate. The second RO reverse osmosis unit 4 is connected to the first DTRO reverse osmosis unit 3 to further treat the first permeate.

[0033] In the embodiment, the first DTRO reverse osmosis unit 3 further includes a first concentrated liquid pipeline 35 and a first permeate pipeline 36. The first DTRO reverse osmosis unit 3 receives the wastewater treated by the pretreatment and arsenic removal, and the wastewater enters the first reverse osmosis high-pressure plunger pump 31 through a core filter 21 to generate the first concentrated liquid and the first permeate. Specifically, the first concentrated liquid generated by the first DTRO reverse osmosis unit 3 is directly evaporated or returned to a water inlet tank 33 of the first DTRO reverse osmosis unit 3 through the first concentrated liquid pipeline 35. In addition, a servo-controlled valve is arranged at an outlet end of the first concentrated liquid pipeline 36 to control the membrane group pressure in the first DTRO reverse osmosis unit 3.

[0034] In the embodiment, the pretreatment unit 1 includes a wastewater collection tank 11, a first sedimentation tank 12, a second sedimentation tank 13, and an arsenic-containing wastewater raw water tank 14 connected in sequence. A chemical reagent, for example, hydrochloric acid or lye, is added to the first sedimentation tank 12 to adjust the pH value to a first set value, specifically, 6.5-7.5. The second sedimentation tank 13 is used for further removing the suspended solids and part of the dissolved substances in the wastewater after the first sedimentation. The arsenic-containing wastewater raw water tank 14 is used for temporarily storing the wastewater treated by the two-stage sedimentation.

[0035] In an embodiment, the arsenic-containing wastewater treatment system further comprises an oil removal pretreatment unit 5, which is arranged between the pretreatment unit 1 and the arsenic removal unit 2 and is connected to the outlet of the arsenic-containing wastewater raw water tank 14. In the present application, various calcium, magnesium, barium, silicon and other difficult-to-dissolve salts may exist in the arsenic-containing wastewater. When these difficult-to-dissolve inorganic salts enter the reverse osmosis system and are highly concentrated, they will form a scale on the membrane surface when their concentration exceeds the solubility under the condition. The oil removal pretreatment unit 5 in the present application can effectively prevent the scaling of carbonate inorganic salts by adjusting the pH value of the raw water.

[0036] In the embodiment, the oil removal pretreatment unit 5 comprises an adsorption tank 51 and a flotation machine 52. The outlet of the arsenic-containing wastewater raw water tank 14 is sequentially connected to the adsorption tank 51 and the flotation machine 52. The treated water in the arsenic-containing wastewater raw water tank 14 first flows into the adsorption tank 51 and then passes through the flotation machine 52. The adsorption tank 51 can adsorb and remove impurities such as oil and suspended solids in the water. The flotation machine 52 further removes fine particles and oil in the water through the buoyancy of micro-bubbles, so that the water quality is further purified.

[0037] In an embodiment, a core filter 21 is arranged between the arsenic removal unit 2 and the primary DTRO reverse osmosis unit 3. Before flowing into the primary DTRO reverse osmosis unit 3, the water will first be finely treated by the core filter 21. The core function of the core filter 21 is to efficiently remove micro-particles, suspended solids and possibly remaining sulfides and other impurities in the water, thereby further improving the water quality and providing protection for the stable operation and efficient treatment of the primary DTRO reverse osmosis unit 3.

[0038] In an embodiment, the secondary RO reverse osmosis unit 4 comprises a secondary RO membrane system high-pressure pump 41. The secondary RO membrane system high-pressure pump 41 is connected to the primary permeate pipe 35 of the primary DTRO reverse osmosis unit 3, used to pressurize the primary permeate and send it to the secondary RO membrane unit 43 to produce secondary concentrated liquid and secondary permeate. Then, according to the table of the Comprehensive Discharge Standard for Sewage (GB8978-1996), it is determined whether the content of each index in the secondary permeate is less than the content of each index in the following table. If yes, the secondary permeate meets the discharge standard; if no, the secondary permeate is the secondary concentrated liquid.

[0039]

[0040] In the embodiment, the secondary RO reverse osmosis unit 4 further comprises a secondary concentrated liquid pipeline 42, a cleaning pipeline 45 and an RO cleaning water tank 46. Specifically, the secondary concentrated liquid pipeline 42 is connected between the outlet of the secondary RO reverse osmosis unit 4 and the pretreatment unit 1, for returning the water produced by the secondary RO reverse osmosis unit 4 and exceeding the set concentration value to the pretreatment unit 1 for reprocessing. Alternatively, the water produced by the secondary RO reverse osmosis unit 4 and exceeding the set concentration value is delivered to the RO cleaning water tank 46 through the cleaning water tank 45 for cleaning reprocessing. According to the Comprehensive Standard for Discharge of Sewage (GB8978-1996), it is determined whether the content of each index of the water quality after the treatment of the cleaning water tank 45 is less than the content of each index in the table,

[0041] In an available embodiment, the disposal system for arsenic-containing wastewater further comprises a water inlet tank 33, a booster pump 34 and a secondary RO water inlet tank 44. The water inlet tank 33 is arranged between the cartridge filter 21 and the booster pump 34, and the water outlet end of the cartridge filter 21 is connected to the water inlet of the water inlet tank 33. In addition, the secondary RO water inlet tank 44 is connected to the water outlet of the primary permeate pipeline 35.

[0042] In the embodiment, the booster pump 34 is arranged at the water outlet end of the water inlet tank 33. The main function of the booster pump is to pressurize the wastewater pretreated by the cartridge filter 21, so as to ensure that the wastewater can enter the subsequent processing unit, such as the primary DTRO reverse osmosis unit or other processing module, with sufficient pressure.

[0043] It is easy for those skilled in the art to understand that the above advantageous modes can be freely combined and superimposed without conflict.

[0044] The above merely describes the preferred embodiments of the present application and should not be used to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application. The above merely describes the preferred embodiments of the present application and should not be used to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A treatment system for arsenic-containing wastewater, characterized in that, include: The wastewater is connected sequentially from collection to discharge: a pretreatment unit (1), an arsenic removal unit (2), a first-stage DTRO reverse osmosis unit (3), and a second-stage RO reverse osmosis unit (4). The pretreatment unit (1) is used to receive arsenic-containing wastewater, so that the arsenic in the wastewater forms a precipitate and is filtered; The arsenic removal unit (2) is used to remove soluble arsenic from wastewater by adding soluble salts to form arsenic precipitates; The first-stage DTRO reverse osmosis unit (3) includes at least: a first-stage reverse osmosis high-pressure plunger pump (31), through which pretreated and arsenic-removed wastewater is pumped to produce first-stage concentrate and first-stage permeate; The secondary RO reverse osmosis unit (4) is connected after the primary DTRO reverse osmosis unit (3) and is used to further treat the primary permeate.

2. The arsenic-containing wastewater treatment system according to claim 1, characterized in that, The pretreatment unit (1) includes a wastewater collection tank (11), a primary sedimentation tank (12), a secondary sedimentation tank (13), and an arsenic-containing wastewater raw water tank (14) connected in sequence. Chemical reagents are added to the primary sedimentation tank (12) to adjust the pH value to the first set value. The secondary sedimentation tank (13) is used to further remove the suspended solids and some dissolved substances remaining in the wastewater after primary sedimentation. The arsenic-containing wastewater raw water tank (14) is used to temporarily store wastewater that has undergone two-stage sedimentation treatment.

3. The arsenic-containing wastewater treatment system according to claim 2, characterized in that, Also includes: An oil removal pretreatment unit (5) is provided between the pretreatment unit (1) and the arsenic removal unit (2), and the oil removal pretreatment unit (5) is connected to the outlet end of the arsenic-containing wastewater raw water tank (14).

4. The arsenic-containing wastewater treatment system according to claim 3, characterized in that, The oil removal pretreatment unit (5) includes an adsorption tank (51) and an air flotation machine (52); The outlet of the arsenic-containing wastewater raw water tank (14) is connected in sequence to the adsorption tank (51) and the air flotation machine (52).

5. The arsenic-containing wastewater treatment system according to claim 1, characterized in that, A cartridge filter (21) is also provided between the arsenic removal unit (2) and the first-stage DTRO reverse osmosis unit (3).

6. The arsenic-containing wastewater treatment system according to claim 5, characterized in that, The first-stage DTRO reverse osmosis unit (3) also includes a first-stage concentrate pipeline and a first-stage permeate pipeline; The first-stage DTRO reverse osmosis unit (3) receives wastewater that has undergone pretreatment and arsenic removal treatment, and enters the first-stage reverse osmosis high-pressure plunger pump (31) through a core filter (21) to produce first-stage concentrate and first-stage permeate.

7. The arsenic-containing wastewater treatment system according to claim 6, characterized in that, The outlet end of the primary concentrate pipeline is equipped with a servo control valve, which is used to control the membrane pressure in the primary DTRO reverse osmosis unit (3).

8. The arsenic-containing wastewater treatment system according to claim 7, characterized in that, The secondary RO reverse osmosis unit (4) includes a secondary RO membrane system high-pressure pump (41). The high-pressure pump (41) of the secondary RO membrane system is connected after the primary permeate pipeline (35) of the primary DTRO reverse osmosis unit (3) to pressurize the primary permeate and send it to the secondary RO membrane unit (43) to produce secondary concentrate and secondary permeate.

9. A treatment system for arsenic-containing wastewater according to any one of claims 1-8, characterized in that, The secondary RO reverse osmosis unit (4) also includes a secondary concentrate pipeline (42), which is connected between the outlet of the secondary RO reverse osmosis unit (4) and the pretreatment unit (1) for returning water exceeding the set concentration value generated by the secondary RO reverse osmosis unit (4) to the pretreatment unit (1) for further treatment.

10. The arsenic-containing wastewater treatment system according to claim 5, characterized in that, Also includes: Water inlet tank (33), booster pump (34); The water inlet tank (33) is located between the core filter (21) and the booster pump (34), and the outlet of the core filter (21) is connected to the inlet of the water inlet tank (33). The booster pump (34) is located at the outlet of the inlet tank (33) and is used to pressurize the wastewater after pretreatment by the core filter (21).

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