A system for treating wastewater containing complexed heavy metals

Abstract

The present application relates to a kind of heavy metal wastewater containing complex state processing system, including raw water device, water pump, first filling column, second filling column, water outlet device, wherein first filling column is connected with the water pump, the first filling column is loaded with UiO-66 (Zr) packing, the pH of wastewater passing through the UiO-66 (Zr) packing is quickly reduced to 3~4, and most of the complex heavy metal is dissociated into free metal ions and organic ligand;Second filling column is connected with the first filling column, for the free metal ion in the wastewater after passing through the first filling column generates metal hydroxide M n+ (OH) n Precipitation;Compared with prior art, the present application has the advantages of high water treatment capacity, packing regeneration, etc.;Simple operation, can be automatically and continuously operated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wastewater treatment, in particular to a treatment system for wastewater containing complex heavy metals. BACKGROUND

[0002] With the accelerated development of tanning, electroplating and printing and dyeing industries, a series of heavy metal pollution problems have been brought about, especially complex heavy metal pollution. Heavy metal ions usually form complex heavy metals with organic matters such as ethylenediaminetetraacetic acid (EDTA), citric acid, tartaric acid and nitrilotriacetic acid. Compared with free heavy metal ions, complex heavy metals have high water solubility, can exist stably in a wide pH range and have complex forms, and their potential toxicity is usually higher than that of single heavy metal ions and organic ligands, and they are difficult to remove. In order to control the concentration of copper ions in industrial wastewater, the total copper concentration is not more than 0.5 mg / L in the Discharge Standard of Industrial Pollutants for Copper, Nickel and Cobalt (GB 25467-2010) of China.

[0003] At present, there are many studies on the treatment of wastewater containing heavy metals, but the studies on the treatment of wastewater containing complex heavy metals are limited, and most of the studies are limited to static treatment, and there are few dynamic treatments close to actual application, so it is urgent to establish a packed column system suitable for flowing water bodies, which meets the actual migration and transformation process of pollutants and can provide technical support for solving the pollution problem of wastewater containing complex heavy metals. SUMMARY

[0004] The present application is to overcome the defects of the prior art and provide a treatment system for wastewater containing complex heavy metals, which has the advantages of high water treatment capacity and elution and regeneration of adsorbents, and is simple to operate and can be automatically and continuously operated when the device is stable, and has the potential to become an in-situ water treatment facility.

[0005] The object of the present application can be achieved by the following technical solutions:

[0006] The present application provides a treatment system for wastewater containing complex heavy metals, comprising a raw water device, a water pump, a first packed column, a second packed column and a water outlet device.

[0007] The raw water device is used for transferring and storing wastewater containing complex heavy metals.

[0008] The water pump is connected with the raw water device, and the water pump is used to provide conveying power.

[0009] The first filling column is connected with the water pump, the first filling column is filled with UiO-66(Zr) filler, the UiO-66(Zr) filler is used for quickly reducing the pH of the passing wastewater to 3-4, and most of the complex heavy metals are decomplexed into free metal ions and organic ligands, and the lower the initial concentration of the complex heavy metals, the higher the decomplexing rate;

[0010] The second filling column is connected with the first filling column, and is used for generating metal hydroxide M n+ (OH) n precipitation;

[0011] The water outlet device is connected with the second filling column, and is used for dumping the treated wastewater.

[0012] Further, the second filling column is filled with CaCO3 filler.

[0013] Further, in the first filling column, the organic ligand and the complex heavy metal can be adsorbed by the UiO-66(Zr), and the UiO-66(Zr) with positive electricity due to electrostatic repulsion does not adsorb the free metal ions.

[0014] Further, the inlet end of the water pump is further connected with an acid liquid storage tank device, and the acid liquid storage tank device is used for regeneration of the first filling column.

[0015] Further, the acid liquid storage tank device is filled with an acid eluent, and the acid eluent is a 0.01M HCl solution.

[0016] Further, the inlet end of the first filling column is connected with the outlet end of the water pump, the outlet end of the first filling column is connected with an eluent collection device, and the eluent collection device is used for collecting the eluent passing through the first filling column.

[0017] Further, in the second filling column, the filler CaCO3 is partially dissolved in water and hydrolysis reaction occurs, thereby showing alkalinity, and the free heavy metal ions not adsorbed by the UiO-66(Zr) in the wastewater flowing out of the first filling column react with OH - to generate Cu(OH)2 precipitate, and finally achieve the effect of removing the complex heavy metals.

[0018] Further, the wastewater containing complex heavy metals is copper tartrate-containing wastewater.

[0019] Further, both ends of the first filling column and the second filling column are connected with matched pipelines through quick connectors, so as to realize the detachable function of the first filling column and the second filling column.

[0020] Further, a stop valve is arranged between the first filling column and the second filling column.

[0021] The principle of the present application is as follows:

[0022] When the copper tartrate wastewater in the raw water device flows through the first filling column by the water pump, Zr-OH (pKa=8.30) and Zr-OH2 (pKa=6.79) existing as defect sites in the filler UiO-66(Zr) can undergo deprotonation in water, and μ3-OH (pKa=3.52) in UiO-66(Zr) can also undergo deprotonation, so that the pH of the copper tartrate wastewater system is quickly reduced to 3-4. At this pH, most of the copper tartrate will be dissociated into free copper ions and tartrate ligands. The lower the initial concentration of copper tartrate, the higher the dissociation rate. At this time, UiO-66(Zr) can adsorb tartrate ligands and copper tartrate complexes, but due to electrostatic repulsion, positively charged UiO-66(Zr) does not adsorb free copper ions. When the wastewater continues to flow through the second filling column, the filler CaCO3 partially dissolves in water and undergoes hydrolysis reaction, thereby showing alkalinity. Therefore, the free copper ions in the wastewater flowing out of the first filling column which are not adsorbed by UiO-66(Zr) can react with OH - Cu(OH)2 precipitate is generated, and finally the effect of removing complex heavy metals is achieved. The specific reaction mechanism is shown in formulas 1-6:

[0023] HO-[UiO-66(Zr)] + H2O = O - -[UiO-66(Zr)] + H3O + Formula 1

[0024] CuTA + H + = Cu 2+ + HTA - Formula 2

[0025] UiO-66(Zr) + HTA - = UiO-66(Zr)-HTA - Formula 3

[0026]

[0027] Cu 2+ + 2OH - = Cu(OH)2 ↓ Formula 6

[0028] Compared with the prior art, the present application has the beneficial effects that:

[0029] The traditional commercial adsorption material represented by activated carbon has low adsorption capacity (generally less than 5 mg / g) for complex heavy metals in water, short service life and low treatment efficiency. The device of the application first uses metal organic framework material UiO-66(Zr) and cheap CaCO3 as fillers. When the total copper concentration in the influent is 5 mg / L, the total copper concentration in the effluent is 0.37 mg / L within the range of 1832 BV (i.e. within the range of 2507 mL of effluent volume), which meets the Copper, Nickel and Cobalt Industrial Pollutant Discharge Standard (GB 25467-2010) of China. The device has the advantages of high water treatment capacity, elution and regeneration of adsorbents, simple operation, automatic continuous operation when the device runs stably, and potential to become an in-situ water treatment facility. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 A device structure schematic diagram for treating wastewater containing complex heavy metals is provided.

[0031] Figure 2 An effect detection diagram of the application for purifying wastewater containing complex heavy metals.

[0032] In the figure: raw water device-1, water pump-2, first filling column-3, second filling column-4, effluent device-5, acid liquid storage tank device-6, eluent collection device-7, filler-UiO-66(Zr)-8, filler-CaCO3-9, first pipeline connecting the raw water device and the water pump-10, second pipeline connecting the water pump and the upper end water inlet of the first filling column-11, third pipeline connecting the lower end water outlet of the first filling column and the upper end water inlet of the second filling column-12, fourth pipeline connecting the lower end water outlet of the second filling column and the effluent device-13, fifth pipeline connecting the acid liquid storage tank device and the water pump-14, sixth pipeline connecting the lower end water outlet of the first filling column and the eluent collection device-15, first detachable accessory-16, second detachable accessory-17. DETAILED DESCRIPTION

[0033] In the specific implementation, the technical solution provided by the application can be: a device for treating wastewater containing complex heavy metals, which comprises a raw water device, a water pump, a first filling column, a second filling column, an effluent device, an acid liquid storage tank device and an eluent collection device. Each filling column is provided with a water inlet at the upper end and a water outlet at the lower end. The water inlet of the first filling column is connected to the raw water device through the water pump, the water outlet of the first filling column is connected to the water inlet of the second filling column through a pipeline, and the water outlet of the second filling column is connected to the effluent device through a pipeline. The water inlet of the first filling column can also be connected to the acid liquid storage tank device through the water pump, and the water outlet of the first filling column is connected to the eluent collection device through a pipeline. The first filling column and the second filling column are detachable devices.

[0034] The raw water device is used for the transfer of the original complex heavy metal wastewater. The water pump is connected with the raw water device through a pipeline, and the water pump is used for providing conveying power. The water inlet of the first packed column is connected with the water pump through a pipeline.

[0035] The filler of the first packed column is metal organic framework material UiO-66(Zr), and the pH of the complex heavy metal wastewater can be quickly reduced to 3-4 when passing through the first packed column, so that most of the complex heavy metal is decomplexed into free metal ions and organic ligands, and the lower the initial concentration of the complex heavy metal is, the higher the decomplexing rate is. Under this condition, the organic ligand and the complex heavy metal can be adsorbed by UiO-66(Zr), but the positively charged UiO-66(Zr) does not adsorb free metal ions due to electrostatic repulsion.

[0036] The water inlet of the second packed column is connected with the water outlet of the first packed column through a pipeline. The filler of the second packed column is CaCO3, and the free metal ions in the wastewater after passing through the first packed column generate metal hydroxide M n+ (OH) n in the second packed column. The precipitation is precipitated. The effluent device is used for the transfer of the treated complex heavy metal wastewater.

[0037] The effluent device is connected with the water outlet of the second packed column through a pipeline.

[0038] The flow rate of the water pump is 0.1 mL / min. The specifications of the packed columns are all 1BV (mL) = 0.3421*h (cm).

[0039] The complex heavy metal is copper tartrate.

[0040] During the water treatment process, the effluent in the effluent device is collected every certain time, and the treatment capacity of the filler to the complex heavy metal is calculated according to the concentration difference between the original wastewater in the raw water device and the effluent in the effluent device, so as to evaluate the dynamic purification effect of the complex heavy metal in the wastewater.

[0041] The acid liquid storage tank is used for the transfer of dilute hydrochloric acid, and is used for the elution and regeneration of UiO-66(Zr) after adsorbing the complex heavy metal in the first packed column.

[0042] The first packed column and the second packed column are both detachable structures.

[0043] The present application will be described in detail below in combination with the drawings and specific embodiments. In the technical solution, the component models, material names, connection structures, control methods, algorithms and other features not explicitly described are regarded as common technical features disclosed in the prior art.

[0044] Example 1

[0045] The main elements in the embodiment are described as follows: raw water device 1, water pump 2, first filling column 3, second filling column 4, water outlet device 5, acid liquid storage tank device 6, eluent collection device 7, filler UiO-66(Zr) 8, filler CaCO3 9, first pipeline 10 connecting the raw water device and the water pump, second pipeline 11 connecting the water pump and the water inlet at the upper end of the first filling column, third pipeline 12 connecting the water outlet at the lower end of the first filling column and the water inlet at the upper end of the second filling column, fourth pipeline 13 connecting the water outlet at the lower end of the second filling column and the water outlet device, fifth pipeline 14 connecting the acid liquid storage tank device and the water pump, sixth pipeline 15 connecting the water outlet at the lower end of the first filling column and the eluent collection device, and first detachable matching part 16 and second detachable matching part 17, the first detachable matching part 16 and the second detachable matching part 17 are quick connectors arranged at the two ends of the first filling column 3 and the second filling column 4 respectively, and the quick connectors are used for quick connection with the pipelines, so as to realize quick replacement of the first filling column 3 and the second filling column 4.

[0046] The operation effect of the device for treating wastewater containing complex heavy metals is as follows: in the dynamic treatment test, 0.48g of UiO-66(Zr) is filled in the first filling column 3, and 0.90g of CaCO3 is filled in the second filling column 4. Under the condition of room temperature (25℃), the wastewater containing copper tartrate is transported into the first filling column 3 through the water pump 2, the concentration of copper tartrate is 5mg / L (calculated by [Cu]), and the flow rate is set to 0.1mL / min. During the water treatment process, the effluent in the water outlet device 5 is collected every certain time, and the treatment capacity of the filler for copper tartrate is calculated according to the concentration difference between the original wastewater in the raw water device 1 and the effluent in the water outlet device 5.

[0047] The treatment result of the filling column on the copper tartrate wastewater is shown in Table 1. Figure 2The copper concentration of the effluent in the effluent device gradually increased with the increase of the water volume at a flow rate of 0.1 mL / min. When the copper concentration of the raw wastewater in the raw water device was 5 mg / L, the copper concentration in the effluent was only 0.013 mg / L when the effluent volume was 1704 BV (i.e. the effluent volume was 2332 mL), and the removal rate reached 99.74%; when the effluent volume was 1832 BV (i.e. the effluent volume was 2507 mL), the copper concentration in the effluent was 0.375 mg / L, and the removal rate was 92.5%, which still met the Copper, Nickel and Cobalt Industrial Pollutant Discharge Standard (GB 25467-2010) (0.5 mg / L) of China; after that, the copper concentration in the effluent increased significantly and exceeded the discharge concentration specified in the Copper, Nickel and Cobalt Industrial Pollutant Discharge Standard (GB 25467-2010), but the packed column still had a certain removal capacity for copper sulfate wastewater. It is shown that the packed column has a certain purification effect on complex heavy metal wastewater in the dynamic purification process.

[0048] Comparative Examples 1-2

[0049] As a comparative example, only 0.80 g of UiO-66(Zr) was filled in the first packed column 3, and no filler was filled in the second packed column 4, and other parameters were unchanged. During the water treatment process, the effluent in the effluent device was collected every certain time, and the treatment capacity of the filler for copper sulfate was calculated according to the concentration difference between the raw wastewater in the raw water device and the effluent in the effluent device.

[0050] As a comparative example, no filler was filled in the first packed column 3, and only 1.59 g of CaCO3 was filled in the second packed column 4. Other parameters were unchanged. During the water treatment process, the effluent in the effluent device was collected every certain time, and the treatment capacity of the filler for copper sulfate was calculated according to the concentration difference between the raw wastewater in the raw water device and the effluent in the effluent device.

[0051] When only the first packed column in the running device worked, i.e. the filler was only UiO-66(Zr), when the copper concentration of the raw wastewater in the raw water device was 5 mg / L, the copper concentration in the effluent was only 0.004 mg / L when the effluent volume was 283 BV (i.e. the effluent volume was 387 mL), and the removal rate reached 99.92%, which met the Copper, Nickel and Cobalt Industrial Pollutant Discharge Standard (GB 25467-2010) (0.5 mg / L) of China; after that, the copper concentration in the effluent increased significantly and exceeded the discharge concentration specified in the Copper, Nickel and Cobalt Industrial Pollutant Discharge Standard (GB 25467-2010), when the effluent volume was about 322 BV (i.e. the effluent volume was 441 mL), the copper concentration in the effluent was 5.11 mg / L, and the removal rate was 0, which indicated that the purification capacity of the filler in the column was completely exhausted at this time, and the treatment endpoint was reached.

[0052] When only the second packed column in the running device works, i.e. the packing is only CaCO3, when the effluent volume is 8.77 BV (i.e. the effluent volume is 12 mL), the copper concentration in the effluent is only 0.020 mg / L, the removal rate reaches 99.60%, and the copper concentration in the effluent meets the Copper, Nickel and Cobalt Industrial Pollutant Discharge Standard (GB 25467-2010) (0.5 mg / L); then the copper concentration in the effluent increases obviously and exceeds the discharge concentration specified in the Copper, Nickel and Cobalt Industrial Pollutant Discharge Standard (GB 25467-2010), when the effluent volume is about 263 BV (i.e. the effluent volume is 360 mL), the copper concentration in the effluent is 5.19 mg / L, and the removal rate is 0, which indicates that the treatment capacity of the packing in the column is completely exhausted at this time, and the treatment endpoint is reached.

[0053] It can be seen from this that when the UiO-66(Zr) or CaCO3 packed column works alone, the treatment effect of the device on the complex heavy metal wastewater is much lower than that of the combined working device of the UiO-66(Zr) and CaCO3 double packed columns. In the case of ensuring that the copper concentration in the effluent of the effluent device meets the discharge standard, the effective treatment volume of the combined working device of the UiO-66(Zr) and CaCO3 double packed columns on the copper tartrate wastewater is 6.48 and 209 times that of the single working device of the UiO-66(Zr) or CaCO3 packed column, respectively. When the combined working device of the UiO-66(Zr) and CaCO3 double packed columns works, the treatment capacity of the UiO-66(Zr) for copper tartrate is 26.11 mg / g, and the treatment capacity of the CaCO3 for copper tartrate is 13.93 mg / g; when the single working device of the UiO-66(Zr) packed column works, the treatment capacity of the UiO-66(Zr) for copper tartrate is 2.42 mg / g; when the single working device of the CaCO3 packed column works, the treatment capacity of the CaCO3 for copper tartrate is 0.038 mg / g (the above-mentioned values are calculated based on [Cu]). It can be seen from this that in the combined working device of the double columns, the treatment capacity of the UiO-66(Zr) for copper tartrate is one order of magnitude higher than that of the single column device of the UiO-66(Zr); in the combined working device of the double columns, the treatment capacity of the CaCO3 for copper tartrate is about three orders of magnitude higher than that of the single column device of the CaCO3. It is indicated that the single device of the UiO-66(Zr) or CaCO3 packed column has poor treatment effect on the complex heavy metal wastewater, which is far inferior to the treatment effect of the combined double packed column device of the two. That is, the UiO-66(Zr) adsorbs the complex heavy metal and organic ligand components, and the CaCO3 precipitates the metal ion components in the complex heavy metal, and the two complement each other and are indispensable.

[0054] The foregoing description of the embodiments has been presented for the purpose of illustration and description. It is not intended to be exhaustive or to limit the application to the precise form disclosed. Modifications and variations are possible in light of the above teachings or can be acquired from practice of the application. As well, the description is presented in the context of the preferred embodiments as a number of alternatives. It is not intended to limit the application to the precise form described.

Claims

1. A system for treating wastewater containing complexed heavy metals, characterized by, The application relates to a device for treating wastewater containing complex heavy metals, which comprises: a raw water device (1) for discharging wastewater containing complex heavy metals; a water pump (2) connected with the raw water device (1), which is used for providing conveying power; a first filling column (3) connected with the water pump (2), which is filled with UiO-66 fillers, and is used for rapidly reducing the pH of the wastewater passing through to 3-4, and making most of the complex heavy metals be decomplexed into free metal ions and organic ligands, and the lower the initial concentration of the complex heavy metals, the higher the decomplexing rate; A second filling column (4) is connected with the first filling column (3) and used to generate metal hydroxide M from the free metal ions in the wastewater after passing through the first filling column (3) n+ (OH) n precipitation; a water outlet device (5) connected with the second filling column (4), which is used for discharging the treated wastewater; the second filling column (4) is filled with CaCO3 fillers; in the first filling column (3), the organic ligands and the complex heavy metals can be adsorbed by the UiO-66, and the UiO-66 with positive electricity due to electrostatic repulsion does not adsorb the free metal ions; the inlet end of the water pump (2) is further connected with an acid liquid storage tank device (6), which is used for regenerating the first filling column (3); the wastewater containing complex heavy metals is copper tartrate-containing wastewater.

2. The system for treating wastewater containing complexed heavy metals according to claim 1, wherein the acid liquid storage tank device (6) is filled with an acid eluent, which is a 0.01 M HCl solution.

3. The system for treating wastewater containing complexed heavy metals according to claim 1, wherein the inlet end of the first filling column (3) is connected with the outlet end of the water pump (2), the outlet end of the first filling column (3) is connected with an eluent collecting device (7), and the eluent collecting device (7) is used for collecting the eluent passing through the first filling column (3).

4. The system for treating wastewater containing complexed heavy metals according to claim 1, wherein In the second packed column (4), the filler CaCO3 is partially dissolved in water and undergoes a hydrolysis reaction, thereby exhibiting alkalinity, and the free heavy metal ions that are not adsorbed by UiO-66 from the wastewater flowing out of the first packed column (3) react with OH - Cu(OH)2precipitate is generated, and finally the effect of removing heavy metals in the complex state is achieved.

5. The system for treating wastewater containing complexed heavy metals according to claim 1, wherein both ends of the first filling column (3) and the second filling column (4) are connected with matched pipelines through quick connectors, so that the first filling column (3) and the second filling column (4) have a detachable function.

6. The system for treatment of wastewater containing complexed heavy metals according to claim 1, wherein a stop valve is arranged between the first filling column (3) and the second filling column (4).

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