CN114772857A - Chromium-containing waste liquid treatment process - Google Patents
Chromium-containing waste liquid treatment process Download PDFInfo
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- CN114772857A CN114772857A CN202210456225.2A CN202210456225A CN114772857A CN 114772857 A CN114772857 A CN 114772857A CN 202210456225 A CN202210456225 A CN 202210456225A CN 114772857 A CN114772857 A CN 114772857A
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
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- C—CHEMISTRY; METALLURGY
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- C02F2101/00—Nature of the contaminant
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Abstract
The application relates to the technical field of wastewater treatment processes, and particularly discloses a chromium-containing waste liquid treatment process, which comprises the following steps: (1) adding an acid agent into the chromium-containing wastewater, and adjusting the pH value to 2-3; (2) adding a reducing agent and sodium hydroxide into the chromium-containing wastewater, adjusting the pH value to 9-9.5, aerating, stirring, precipitating, filtering, and feeding effluent into an anaerobic tank; wherein, the anaerobic tank is internally provided with activated sludge containing phosphorus accumulating bacteria; (3) sequentially adding starch and acetic acid which is excessive relative to sodium hydroxide into an anaerobic tank, stirring, discharging water, and performing filter pressing on the discharged water to obtain a product A and a filtrate A; (4) evaporating and concentrating the filtrate A, and filtering to obtain a product B, a filtrate B and distilled water; (5) the filtrate B was repeatedly concentrated by evaporation. Has the advantages of reducing the occurrence of chromium hydroxide reverse dissolution caused by alkaline conditions and having better effect of removing chromium from wastewater.
Description
Technical Field
The application relates to the technical field of wastewater treatment processes, in particular to a chromium-containing waste liquid treatment process.
Background
The hot galvanizing process comprises the working procedures of hanging, acid cleaning rinsing, plating assisting, galvanizing, cooling and passivating. The main purpose of the passivation treatment is to reduce the phenomenon that galvanized steel parts are rusted due to humidity in a humid environment with poor ventilation condition, so that the appearance quality of products is influenced.
The waste water generated by the passivation treatment is passivation waste water, and the main pollutant of the passivation waste water is Cr with strong toxicity6+Passivation of wastewater in the related artThe method is a reduction precipitation method, and Cr is firstly reduced by using a reducing agent6+Reduced to Cr3+Followed by addition of sodium hydroxide to make Cr3+Generating chromium hydroxide, precipitating, filtering to remove Cr in the wastewater6+The process has the advantage of simple and convenient operation.
In view of the above-mentioned related technologies, the inventors found that, since chromium hydroxide is bi-soluble and easily soluble in alkali, in actual production, in order to ensure the precipitation effect of all metal ions in the chromium-containing wastewater, an excessive amount of alkali agent is added to fully precipitate the metal ions, so that there is a case where part of chromium hydroxide is re-dissolved, and the treatment effect of chromium removal from wastewater is reduced.
Disclosure of Invention
In order to reduce the phenomenon of chromium hydroxide reverse dissolution caused by alkaline conditions and ensure the treatment effect of chromium removal of wastewater, the application provides a chromium-containing waste liquid treatment process.
The application provides a chromium-containing waste liquid treatment process adopts following technical scheme:
a chromium-containing waste liquid treatment process comprises the following steps:
(1) adding an acid agent into the chromium-containing wastewater, and adjusting the pH value to 2-3;
(2) adding a reducing agent and sodium hydroxide into the chromium-containing wastewater, adjusting the pH value to 9-9.5, aerating, stirring, precipitating, filtering, and feeding effluent into an anaerobic tank;
wherein, the anaerobic tank is internally provided with activated sludge containing phosphorus accumulating bacteria;
(3) sequentially adding starch and acetic acid which is excessive relative to sodium hydroxide into an anaerobic tank, stirring, discharging water, and performing filter pressing on the discharged water to obtain a product A and a filtrate A;
(4) evaporating and concentrating the filtrate A, and filtering to obtain a product B, a filtrate B and distilled water;
(5) the filtrate B was repeatedly concentrated by evaporation.
By adopting the technical scheme, the chromium-containing wastewater is introduced into the anaerobic tank, phosphorus-accumulating bacteria in the activated sludge in the anaerobic tank play a role in releasing phosphorus under the anaerobic action, the released phosphorus exists in the form of phosphate and can dissolve Cr3+Or Cr (OH)3Into more stable, e.g. chromium, phosphatesPrecipitation of phosphorus-containing minerals of basic chromium phosphate with reduced Cr (OH)3Reverse dissolution to form Cr6+The situation of (1) occurs.
The wastewater treated by the process is subjected to water quality detection, and Cr in the wastewater treated by the process6+The chromium content is 0.36mg/L, the total chromium content is 1.33mg/L, and the chromium content is lower than the limit value in the national emission standard, so that the emission requirement is met; compared with the wastewater treated by the treatment process without using the anaerobic tank, the Cr in the wastewater is reduced6+The reduction of 0.09mg/L and the reduction of 4.52mg/L of total chromium show that the process is a treatment process with good treatment effect; compared with the treatment process without adding starch and acetic acid in the anaerobic tank, the treatment process has the advantage that Cr is added into the anaerobic tank6+The reduction of 0.06mg/L and the reduction of 0.03mg/L of total chromium indicate that the addition of starch and acetic acid in the anaerobic tank can improve the removal of Cr in wastewater6+The effect of (1);
the reason for this analysis may be that starch on the one hand itself can adsorb and stabilize Cr3+Thereby reducing the potential for Cr to be present during subsequent acetic acid addition3+Oxidation back to Cr6+The condition (1) occurs; and the starch and acetic acid produce esterification reaction to produce starch acetate as Cr3+Stabilizer and further increase Cr3+Thereby increasing Cr after adding sodium hydroxide3+Formation of Cr (OH)3The conversion rate of the method can generate more phosphorus-containing mineral precipitates; on the other hand, the starch increases the BOD value of the wastewater, improves the biodegradability of the wastewater and finally plays a role in promoting Cr (OH)3The effect of forming a phosphorus-containing mineral.
Acetic acid is easily utilized by phosphorus accumulating bacteria, has strong capability of inducing phosphorus release, and decomposes polyphosphate stored in vivo to release phosphorus for Cr (OH)3Converted into a phosphorus-containing mineral precipitate. In conclusion, under the synergistic effect of the starch, the acetic acid and the phosphorus-accumulating bacteria, the process has a better chromium removal effect.
Preferably, the weight ratio of the acetic acid to the starch is (4-8): 1.
By adopting the technical scheme, when the weight ratio of the acetic acid to the starch is in the range, the process has better treatment effect on the chromium in the wastewater. The reason for this analysis may be that acetic acid is compared to starchExcessive powder promotes the reaction of redundant acetic acid and phosphorus-accumulating bacteria, so that the phosphorus-accumulating bacteria play a better role in releasing phosphorus and improve Cr (OH)3Conversion to form phosphorus-containing minerals. Wherein, when the weight ratio of the acetic acid to the starch is 6:1, the Cr is6+0.32mg/L and 1.21mg/L of total chromium, and the effect of removing chromium in the wastewater is optimal.
Preferably, in the step (3), after the pH is adjusted, the addition of starch is stopped when the BOD of the chromium-containing wastewater is increased to 0.15 to 0.2mg/L by the addition of starch.
By adopting the technical scheme, the biochemical performance of the wastewater can be improved by adding the starch, and when the BOD value of the wastewater is increased to 0.15-0.2mg/L by adding the starch, phosphorus-accumulating bacteria release phosphorus to remove Cr in the water3+The effect of (2) is better.
Preferably, the concentration of the dissolved oxygen in the anaerobic pool is 0.1-0.25 mg/L.
By adopting the technical scheme, when the concentration of the dissolved oxygen in the anaerobic tank is in the range, the process has better effect of removing chromium from the wastewater.
Preferably, the sludge age of the activated sludge in the anaerobic tank is 2.5-4 d.
By adopting the technical scheme, when the sludge age of the activated sludge in the anaerobic tank is in the range, the wastewater treated by the process is subjected to water quality detection, and Cr is detected6+The total chromium content is reduced from 0.27 to 0.23mg/L and from 1.10 to 1.03mg/L, which shows that the process has better effect of removing chromium from wastewater, and the analysis probably results in that the activity of the phosphorus-accumulating bacteria is higher, the phosphorus-releasing amount is higher, and more Cr (OH) is promoted3Form phosphorus-containing mineral sediment and reduce the chromium content in the wastewater.
Preferably, the hydraulic retention time in the anaerobic tank is 5-7 h.
By adopting the technical scheme, when the hydraulic retention time in the anaerobic tank is within the range, the wastewater treated by the process is subjected to water quality detection, and Cr6+Total chromium, total zinc and total iron, and shows that the process has good effect of removing chromium from wastewater. The reason for this analysis may be that Cr (OH) in the wastewater3Sufficiently contacting with phosphate to formThe amount of the formed phosphorus-containing minerals is large, and the reduction range is obvious by observing the total iron concentration, which shows that the sedimentation effect is better, and a large amount of Cr3+And (4) settling.
Preferably, the chromium-containing waste liquid treatment process comprises the following specific steps:
(1) adding an acid agent into the chromium-containing wastewater, and adjusting the pH value to 2-3;
(2) adding a reducing agent and sodium hydroxide into the chromium-containing wastewater, adjusting the pH value to 9-9.5, aerating, stirring, precipitating, filtering, and feeding effluent into an anaerobic tank;
wherein, the anaerobic tank is internally provided with activated sludge containing phosphorus accumulating bacteria;
(3) adding starch into the anaerobic tank, stirring and mixing, wherein the reaction temperature is 20-30 ℃;
(4) adding acetic acid excessive relative to sodium hydroxide into the anaerobic tank, stirring, reacting for 2 hours, heating to 60-70 ℃, precipitating, discharging water, and performing pressure filtration on the discharged water to obtain a product A and a filtrate A;
(5) evaporating and concentrating the filtrate A, and filtering to obtain a product B, a filtrate B and distilled water;
(6) the filtrate B was concentrated by repeated evaporation.
By adopting the technical scheme, the temperature of the anaerobic pool is controlled in the step (3), so that the phosphorus-accumulating bacteria have better reaction activity, and Cr is enabled to be6+The final effect of forming the phosphorus-containing mineral is better, and then the temperature is increased in the step (4), so that the reaction of the acetic acid and the starch is promoted more fully, more starch acetate is generated, and part of Cr (OH) is reduced3The situation of desolvation occurs.
Preferably, the chromium-containing wastewater is one of landfill leachate, hot galvanizing passivation solution, metallurgical wastewater and electroplating wastewater.
By adopting the technical scheme, the process can be used for treating garbage leachate, hot galvanizing passivation solution, metallurgical wastewater and electroplating wastewater, and has higher practicability.
Preferably, the reducing agent is one or a mixture of sodium metabisulfite, sodium bisulfite, sodium sulfite, sodium dithionite and sodium thiosulfate.
By adopting the aboveAccording to the technical scheme, when the reducing agent is a mixture consisting of one or more of sodium metabisulfite, sodium bisulfite, sodium sulfite, sodium hydrosulfite and sodium thiosulfate, Cr can be effectively treated6+The removal effect of (1).
In summary, the present application has the following beneficial effects:
1. the application promotes the soluble Cr by anaerobic treatment and phosphorus release by phosphorus-accumulating bacteria3+Or Cr (OH)3Converting into more stable phosphorus-containing mineral precipitate, reducing Cr (OH)3The reverse dissolution occurs, and simultaneously, by adding acetic acid and starch, on one hand, the starch and the acetic acid are subjected to esterification reaction to generate starch acetate which can be used as Cr3+Stabilizer of (3), reduction of Cr3+Is oxidized into Cr6+Increase Cr6+Converting and generating Cr (OH)3The conversion of (a); on the other hand, acetic acid promotes phosphorus accumulating bacteria to release more phosphorus for Cr (OH)3The chromium-free wastewater is converted into phosphorus-containing minerals, and the effect of the process on chromium removal of wastewater is improved under the synergistic effect of phosphorus-accumulating bacteria, acetic acid and starch;
2. according to the method, the weight ratio of acetic acid to starch is controlled, so that the acetic acid is excessive relative to the starch, and the acetic acid is promoted to be utilized by phosphorus accumulating bacteria to release more phosphorus while the starch acetate is generated, so that the chromium removal effect of the process is improved;
3. by controlling the dissolved oxygen content in the anaerobic tank, the method reduces the occurrence of the condition that the anaerobic phosphorus release of phosphorus-accumulating bacteria is limited, and ensures the chromium removal effect of the process.
Detailed Description
According to the regulation of GB13456-2012 discharge Standard of Water pollutants for the iron and Steel industry in China: cr6+：0.5mg/L，Cr3 +: 1.5mg/L, total zinc: 2mg/L, total iron: 10mg/L, and provides a treatment process of chromium-containing waste liquid, so that the chromium-containing waste water reaches the discharge standard.
Examples
Example 1
A chromium-containing waste liquid treatment process comprises the following steps:
(1) pumping the passivation solution into a reaction tank, adding an acid agent into the chromium-containing wastewater, and adjusting the pH value to 3; wherein, the acid agent adopts hydrochloric acid with the concentration of 36 wt%;
(2) adding a reducing agent into the chromium-containing wastewater, aerating and stirring, reacting for 1h, and adding Cr6+Reduced to Cr3+(ii) a Adding sodium hydroxide, adjusting the initial pH to 9, and reacting for 1h to ensure that Zn in the chromium-containing wastewater2+、Cr3+And Fe3+Forming hydroxide precipitate by using metal ions, filtering by using a fine grid, and enabling effluent to enter an anaerobic tank;
wherein the reducing agent is ferrous sulfate; the anaerobic tank is internally provided with activated sludge containing phosphorus accumulating bacteria, and the phosphorus accumulating bacteria play a role in releasing phosphorus so that chromium hydroxide generates phosphorus-containing mineral sediment;
in the anaerobic tank: the concentration of the activated sludge is 5000 mg/L; the sludge age of the activated sludge is 6 days; the concentration of dissolved oxygen is 0.2 mg/L; the concentration of the polyphosphate accumulating bacteria is 2 g/L;
(3) sequentially adding starch and acetic acid which is excessive relative to sodium hydroxide into an anaerobic tank, stirring, reacting for 4 hours (namely hydraulic retention time is 4 hours), pumping muddy water to a filter press through a filter press water pump, carrying out filter pressing to obtain a product A and a filtrate A, and introducing the filtrate A into a liquid storage tank;
(4) pumping the filtrate A in the liquid storage tank to an evaporator, evaporating and concentrating, and filtering to obtain a product B, a filtrate B and distilled water;
(5) introducing the filtrate B into a crystallization tank, standing, and returning the upper concentrated solution to an evaporator for repeated evaporation and concentration; and introducing distilled water into a distilled water storage tank, and pumping and supplementing the distilled water in the distilled water storage tank to the passivation process.
Wherein, the product A and the product B are industrially recycled;
when the addition amount of the starch is to increase the BOD of the chromium-containing wastewater to 0.13mg/L, stopping adding the starch;
the weight ratio of the addition amount of the acetic acid to the starch is 3: 1;
the chromium-containing wastewater adopts hot galvanizing passivation solution wastewater, and the water quality and the content of various pollutants are shown in the following table.
TABLE 1 quality of the passivating liquid waste water and the content of various pollutants (mg/L)
| Item | Cr6+ | Cr6+ | Zn2+ | Fe3+ | BOD |
| Passivating liquid waste water | 243 | 32.8 | 218 | 1.86 | 0.11 |
Example 2
A chromium-containing waste liquid treatment process, which is different from the embodiment 1 in that the weight ratio of acetic acid to starch is 4: 1.
Example 3
A chromium-containing waste liquid treatment process, which is different from the process of the embodiment 1 in that the weight ratio of acetic acid to starch is 6: 1.
Example 4
A chromium-containing waste liquid treatment process, which is different from the embodiment 1 in that the weight ratio of acetic acid to starch is 8: 1.
Example 5
A process for treating a chromium-containing waste liquid, which is different from that in example 1, in the step (3), after the pH is adjusted, when the BOD of the chromium-containing waste liquid is increased to 0.15mg/L by adding starch, the addition of starch is stopped.
Example 6
A process for treating a chromium-containing waste water, which is different from that of example 1, is characterized in that in step (3), after pH adjustment, when BOD of the chromium-containing waste water is increased to 0.17mg/L by addition of starch, addition of starch is stopped.
Example 7
A process for treating a chromium-containing waste water, which is different from that of example 1, is characterized in that in step (3), after pH adjustment, when BOD of the chromium-containing waste water is increased to 20mg/L by addition of starch, addition of starch is stopped.
Example 8
A chromium-containing waste liquid treatment process, which is different from the embodiment 6 in that the sludge age of the activated sludge in the anaerobic tank is 2.5 days.
Example 9
A process for treating a chromium-containing waste liquid, which is different from that in example 6 in that the sludge age of activated sludge in an anaerobic tank is 3 days.
Example 10
A chromium-containing waste liquid treatment process, which is different from the embodiment 6 in that the sludge age of the activated sludge in the anaerobic tank is 4 days.
Example 11
A chromium-containing waste liquid treatment process, which is different from the embodiment 9 in that in the step (3), the hydraulic retention time in an anaerobic tank is 5 hours.
Example 12
A chromium-containing waste liquid treatment process, which is different from the embodiment 9 in that in the step (3), the hydraulic retention time in an anaerobic tank is 6 hours.
Example 13
A chromium-containing waste liquid treatment process, which is different from the process of example 9 in that in the step (3), the hydraulic retention time in an anaerobic tank is 7 hours.
Example 14
A treatment process of chromium-containing waste liquid comprises the following steps:
(1) pumping the passivation solution into a reaction tank, adding an acid agent into the chromium-containing wastewater, and adjusting the pH value to 3; wherein, the acid agent adopts hydrochloric acid with the concentration of 36 wt%;
(2) adding a reducing agent into the chromium-containing wastewater, aerating and stirring, reacting for 1h, and adding Cr6+Reduced to Cr3+(ii) a Adding sodium hydroxide, adjusting the initial pH value to 9, and reacting for 1h to ensure that Zn in the chromium-containing wastewater2+、Cr3+And Fe3+Forming hydroxide precipitate by using metal ions, filtering by using a fine grid, and enabling effluent to enter an anaerobic tank;
wherein the reducing agent is ferrous sulfate; the anaerobic tank comprises activated sludge containing phosphorus-accumulating bacteria, and the phosphorus-accumulating bacteria play a role in releasing phosphorus to enable chromium hydroxide to generate phosphorus-containing mineral sediment;
in the anaerobic tank: the concentration of the activated sludge is 5000 mg/L; the sludge age of the activated sludge is 3 d; the concentration of dissolved oxygen is 0.2 mg/L; the concentration of the polyphosphate accumulating bacteria is 2 g/L;
(3) adding starch into the anaerobic tank, and reacting for 1h at 25 ℃;
(4) adding acetic acid which is excessive relative to sodium hydroxide into an anaerobic tank, stirring, reacting for 4 hours, heating to 60 ℃, continuing to react for 2 hours (namely hydraulic retention time is 6 hours in total), pumping muddy water to a filter press through a filter press water pump, carrying out filter pressing to obtain a product A and a filtrate A, and introducing the filtrate A into a liquid storage tank;
(4) pumping the filtrate A in the liquid storage tank to an evaporator, evaporating and concentrating, and filtering to obtain a product B, a filtrate B and distilled water;
(5) introducing the filtrate B into a crystallization tank, standing, and returning the upper concentrated solution to an evaporator for repeated evaporation and concentration; and (3) introducing distilled water into a distilled water storage tank, and pumping and supplementing the distilled water in the distilled water storage tank to the passivation process.
Wherein, the product A and the product B are industrially recycled;
when the addition amount of the starch is to increase the BOD of the chromium-containing wastewater to 0.17mg/L, stopping adding the starch;
the weight ratio of the addition amount of the acetic acid to the starch is 3: 1;
the chromium-containing wastewater was the same as in example 1.
Example 15
A process for treating a chromium-containing waste liquid, which is different from that in example 14, is carried out in that an equivalent amount of sodium metabisulfite is used in place of ferrous sulfate.
Example 16
A process for treating a chromium-containing waste liquid, which is different from that in example 14, is carried out in that an equivalent amount of sodium thiosulfate is used in place of ferrous sulfate.
Example 17
A chromium-containing waste liquid treatment process, which is different from the embodiment 14 in that the reducing agent is used differently, and the ferrous sulfate is replaced by the mixture of the same amount of sodium metabisulfite and sodium thiosulfate;
wherein, the sodium pyrosulfite and the sodium thiosulfate are mixed according to the weight ratio of 1: 1.
Comparative example
Comparative example 1
A treatment process of chromium-containing waste liquid comprises the following steps:
(1) pumping the passivation solution into a reaction tank, adding an acid agent into the chromium-containing wastewater, and adjusting the pH value to 3; wherein, the acid agent adopts hydrochloric acid with the concentration of 36 wt%;
(2) adding a reducing agent into the chromium-containing wastewater, aerating and stirring, reacting for 1h, and adding Cr6+Reduced to Cr3+(ii) a Adding sodium hydroxide, adjusting the initial pH to 9, and reacting for 1h to ensure that Zn in the chromium-containing wastewater2+、Cr3+And Fe3+Forming hydroxide precipitate by metal ions; wherein the reducing agent is ferrous sulfate;
(3) pumping muddy water to a filter press by a filter press water pump, carrying out filter pressing to obtain a product C and a filtrate C, and introducing the filtrate into a liquid storage tank;
(4) pumping the filtrate in the liquid storage tank to an evaporator, evaporating and concentrating, and filtering to obtain a product D, a filtrate D and distilled water;
(5) introducing the filtrate F into a crystallization tank, standing, and returning the upper-layer concentrated solution to an evaporator for repeated evaporation and concentration; and introducing distilled water into a distilled water storage tank, and pumping and supplementing the distilled water in the distilled water storage tank to the passivation process.
Wherein, the product C and the product D are industrially recycled;
the chromium-containing wastewater was the same as in example 1.
Comparative example 2
A chromium-containing waste liquid treatment process comprises the following steps:
(1) pumping the passivation solution into a reaction tank, adding an acid agent into the chromium-containing wastewater, and adjusting the pH value to 3; wherein, the acid agent adopts hydrochloric acid with the concentration of 36 wt%;
(2) adding a reducing agent into the chromium-containing wastewater, aerating and stirring, reacting for 1h, and adding Cr6+Reduced to Cr3+(ii) a Adding sodium hydroxide, adjusting the initial pH to 9, and reacting for 1h to ensure that Zn in the chromium-containing wastewater2+、Cr3+And Fe3+Forming hydroxide precipitate by using metal ions, filtering by using a fine grid, and enabling effluent to enter an anaerobic tank;
wherein the reducing agent is ferrous sulfate; the anaerobic tank comprises activated sludge containing phosphorus-accumulating bacteria, and the phosphorus-accumulating bacteria play a role in releasing phosphorus to enable chromium hydroxide to generate phosphorus-containing mineral sediment;
in the anaerobic tank: the concentration of the activated sludge is 5000 mg/L; the sludge age of the activated sludge is 6 days; the concentration of dissolved oxygen is 0.2 mg/L; the concentration of the polyphosphate accumulating bacteria is 2 g/L;
(3) after reacting for 5 hours (namely the hydraulic retention time is 5 hours) in the anaerobic tank, pumping the effluent to a filter press by a filter press water pump, carrying out filter pressing to obtain a product E and a filtrate E, and introducing the filtrate into a liquid storage tank;
(4) pumping the filtrate in the liquid storage tank to an evaporator, evaporating and concentrating, and filtering to obtain a product F, a filtrate F and distilled water;
(5) introducing the filtrate F into a crystallization tank, standing, and returning the upper concentrated solution to an evaporator for repeated evaporation and concentration; and (3) introducing distilled water into a distilled water storage tank, and pumping and supplementing the distilled water in the distilled water storage tank to the passivation process.
Wherein, the product E and the product F are industrially recycled;
the chromium-containing wastewater was the same as in example 1.
Performance detection
The chromium-containing waste liquids after the treatments in examples 1 to 17 and comparative examples 1 to 2 were subjected to water quality tests, and the results are shown in Table 2.
TABLE 2 concentration of contaminants (mg/L) in wastewater after treatment in examples 1-6 and comparative examples 1-2
The following description will be made of a process for treating chromium-containing waste liquid according to the present application with reference to examples 1 to 6, comparative examples 1 to 2, and corresponding data in Table 2.
The pollutant concentration in the wastewater treated by the process in the comparative examples 1 to 6 is lower than the limit value in the national emission standard, and the wastewater can be discharged, which shows that the process for treating the chromium-containing wastewater has good treatment effect.
Example 1 differs from comparative example 1 in that comparative example 1 was not subjected to anaerobic treatment and starch and acetic acid were not added to the wastewater, and Cr in the wastewater was detected6+0.45mg/L, which is lower than the standard limit value, and 5.85mg/L of total chromium which is higher than the standard limit value; cr in the wastewater treated by the process in example 16+0.36mg/L and 1.33mg/L of total chromium, which are lower than those of comparative example 1, and the total chromium content is greatly reduced. Therefore, the method shows that after the sodium hydroxide is added into the wastewater, the wastewater is subjected to anaerobic treatment, and the starch and the acetic acid are added into the anaerobic treatment, so that the effect of removing chromium from the wastewater is improved.
The reason for this analysis may be that the phosphorus-accumulating bacteria release phosphorus in the form of phosphate, phosphate and Cr (OH) in the anaerobic treatment3The reaction generates more stable phosphorus-containing mineral sediment, thereby reducing the occurrence of chromium hydroxide reverse dissolution, further reducing the total chromium content in the wastewater and improving the effect of chromium removal of the wastewater.
Example 1 is different from comparative example 2 in that, in comparative example 2, when the wastewater is anaerobically treated, starch and acetic acid are not added, and Cr in the wastewater is detected6+0.42mg/L, 1.36mg/L of total chromium, higher pollutant content than that of example 1, and Cr in example 16+The concentration is obviously reduced, thereby showing that the addition of the starch and the acetic acid can reduce the Cr in the wastewater in the process of anaerobic treatment of the wastewater6+Content, further improves wastewater removalThe effect of chromium.
The reason for this analysis may be that starch on the one hand itself can adsorb and stabilize Cr3+Thereby reducing the potential for Cr to be present during subsequent acetic acid addition3+Oxidation back to Cr6+Thereby reducing Cr6+Content (c); and starch and acetic acid are esterified to generate starch acetate which can be used as Cr3+Stabilizer for increasing Cr3+Thereby increasing Cr after adding sodium hydroxide3+Formation of Cr (OH)3The conversion rate of (2) to produce more phosphorus-containing mineral precipitates;
on the other hand, the starch increases the BOD value of the wastewater, improves the biodegradability of the wastewater and finally plays a role in promoting Cr (OH)3The effect of forming a phosphorus-containing mineral; acetic acid has strong capability of inducing phosphorus release, and promotes phosphorus-accumulating bacteria to release more phosphorus for Cr (OH)3Converted into a phosphorus-containing mineral precipitate. In conclusion, under the synergistic effect of starch, acetic acid and phosphorus-accumulating bacteria, the process has better chromium removal effect;
it should be noted that, before adding acetic acid, a large amount of metal ions already form hydroxide precipitate, although the added acetic acid is neutralized with sodium hydroxide, the precipitation effect of the metal ions is not affected, and the excessive sodium hydroxide in the wastewater is removed; in addition, the chromium hydroxide has good solubility in strong acid, and the addition of acetic acid with weak acidity in the water solution does not influence the chromium removal effect of the process wastewater.
Examples 2 to 4 are different from example 1 in that the weight ratio of acetic acid and starch is different from that of example 1 and that of examples 2 to 4 in that Cr in the waste water is different from that of example 16+The concentration is respectively reduced by 0.03-0.05mg/L, and the total chromium concentration is respectively reduced by 0.11-0.14 mg/L. The reason for this analysis may be that when the weight ratio of acetic acid to starch is in the range of (4-8):1, the acetic acid and starch act synergistically better, producing more starch acetate, which may further improve the chromium removal effect of the process on wastewater.
Examples 5-7 differ from example 3 in that the BOD of the wastewater was raised to 0.15-0.2mg/L by the addition of different weights of starch. Compared with example 3, the concentration of each pollutant in examples 5-7 is reduced, and the total chromium content is reduced to 1.10-1.15mg/L, which shows that the process of the application has better effect on removing chromium from wastewater. The reason for analyzing the phosphorus-accumulating bacteria is probably that the BOD value of the wastewater is increased, the biochemical performance of the wastewater is improved, and the anaerobic phosphorus release of the phosphorus-accumulating bacteria is facilitated.
Examples 8 to 10 are different from example 6 in that the sludge age of the activated sludge in the anaerobic tank is different. Cr in example 9 as compared with example 66+The total chromium content is reduced from 0.27mg/L to 0.23mg/L and from 1.10mg/L to 1.03mg/L, which shows that the process has better effect on removing chromium from wastewater, and the total zinc and total iron content are reduced, and the analysis probably results in higher activity of phosphorus-accumulating bacteria and more phosphorus release amount, so that more Cr (OH)3Generating phosphorus-containing mineral sediment.
Examples 11-13 differ from example 9 in the hydraulic retention time. Compared with example 9, the total iron content in examples 11-14 is further reduced by 0.11-0.16mg/L, and the total iron content in the wastewater is detected to show that the precipitation effect is better, so that the concentration of each pollutant in the water is reduced.
Example 14 differs from example 12 in the way of adding starch and acetic acid, and the concentration of each pollutant in example 14 is lower compared with example 12, which shows that when the process of the application adopts the way of adding starch and acetic acid in example 14, the process has better effect of removing chromium from wastewater.
The reason for analyzing the above may be that the temperature of the anaerobic tank is controlled to facilitate the activity of the phosphorus-accumulating bacteria, remove chromium in the wastewater, and release more phosphorus under the use of acetic acid, wherein the phosphorus-accumulating bacteria release phosphorus in an amount satisfying Cr (OH)3A need to form a phosphorus-containing mineral;
then the temperature of the chromium-containing wastewater is raised, so that the esterification of acetic acid and starch is better, and the Cr is further reduced3+Oxidation to form Cr6+Although the temperature rise may result in partial inactivation of the polyphosphate-accumulating bacteria, it does not affect the phosphate and Cr (OH) produced3The reaction forms phosphorus-containing minerals, thereby realizing the reduction of the chromium content in the wastewater. Of course in other embodiments, the reaction is anaerobicAfter starch is added into the anaerobic tank, the temperature in the anaerobic tank can be selected within the range of 20-30 ℃; after acetic acid is added into the anaerobic tank, the temperature in the anaerobic tank can be selected within the range of 60-70 ℃, and the effect of the process on chromium removal of wastewater is not influenced.
Examples 15-17 differ from example 14 in the use of reducing agents, and in examples 15-17 the concentration of each contaminant was reduced, indicating that the process works better for chromium removal from wastewater when the reducing agent used sodium metabisulfite, sodium thiosulfate, and a mixture of sodium metabisulfite and sodium thiosulfate. The action effect of the sodium bisulfite, the sodium sulfite and the sodium dithionite is similar to that of the sodium pyrosulfite and the sodium thiosulfate, which shows that when the reducing agent is a mixture of one or more of the sodium pyrosulfite, the sodium bisulfite, the sodium sulfite, the sodium dithionite and the sodium thiosulfate, the process has better chromium removal effect.
Most preferred in this application is example 16, Cr6+The concentration is 0.11mg/L, the total chromium concentration is 0.73mg/L, the total zinc concentration is 1.20mg/L, and the total iron concentration is 4.35mg/L, which are all far lower than the limit value in the emission standard, and show that the process has excellent effects of removing chromium, zinc and iron from the wastewater.
It should be noted that, of course, in other embodiments, hydrochloric acid is added to the chromium-containing wastewater to adjust the acidity, which may be selected within a range of pH 2 to 3; sodium hydroxide is added into the chromium-containing wastewater, the alkalinity can be adjusted within the range of pH value 9-9.5, the sodium hydroxide is slightly excessive, the sedimentation effect of metal ions is guaranteed, and the chromium removal effect of the process on the wastewater is not influenced.
In other embodiments, the concentration of dissolved oxygen in the anaerobic tank may be selected within the range of 0.1-0.25mg/L without affecting the effectiveness of the process of the present application for removing chromium from wastewater.
In other embodiments, the chromium-containing wastewater can be one of landfill leachate, hot galvanizing passivation solution, metallurgical wastewater and electroplating wastewater, and the chromium removal effect of the process on the wastewater is not influenced.
The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.
Claims (9)
1. A treatment process of chromium-containing waste liquid is characterized by comprising the following steps:
(1) adding an acid agent into the chromium-containing wastewater, and adjusting the pH value to 2-3;
(2) adding a reducing agent and sodium hydroxide into the chromium-containing wastewater, adjusting the pH value to 9-9.5, aerating, stirring, precipitating, filtering, and feeding effluent into an anaerobic tank;
wherein, the anaerobic tank is internally provided with activated sludge containing phosphorus accumulating bacteria;
(3) sequentially adding starch and acetic acid which is excessive relative to sodium hydroxide into an anaerobic tank, stirring, discharging water, and performing pressure filtration on the discharged water to obtain a product A and a filtrate A;
(4) evaporating and concentrating the filtrate A, and filtering to obtain a product B, a filtrate B and distilled water;
(5) the filtrate B was repeatedly concentrated by evaporation.
2. The chromium-containing waste liquid treatment process according to claim 1, characterized in that: the weight ratio of the acetic acid to the starch is (4-8) to 1.
3. The chromium-containing waste liquid treatment process according to claim 2, characterized in that: in the step (3), after the pH is adjusted, when the BOD of the chromium-containing wastewater is increased to 0.15-0.2mg/L by adding starch, the addition of starch is stopped.
4. The chromium-containing waste liquid treatment process according to claim 1, characterized in that: the concentration of the dissolved oxygen in the anaerobic tank is 0.1-0.25 mg/L.
5. The chromium-containing waste liquid treatment process according to claim 1, characterized in that: the sludge age of the activated sludge in the anaerobic tank is 2.5-4 d.
6. The chromium-containing waste liquid treatment process according to claim 1, characterized in that: the hydraulic retention time in the anaerobic tank is 5-7 h.
7. The chromium-containing waste liquid treatment process according to claim 1, characterized in that: the method comprises the following specific steps:
(1) adding an acid agent into the chromium-containing wastewater, and adjusting the pH value to 2-3;
(2) adding a reducing agent and sodium hydroxide into the chromium-containing wastewater, adjusting the pH value to 9-9.5, aerating, stirring, precipitating, filtering, and allowing effluent to enter an anaerobic tank;
wherein, the anaerobic tank is internally provided with activated sludge containing phosphorus accumulating bacteria;
(3) adding starch into the anaerobic tank, stirring and mixing, wherein the reaction temperature is 20-30 ℃;
(4) adding acetic acid excessive relative to sodium hydroxide into the anaerobic tank, stirring, reacting for 2 hours, heating to 60-70 ℃, precipitating, discharging water, and performing pressure filtration on the discharged water to obtain a product A and a filtrate A;
(5) evaporating and concentrating the filtrate C, and filtering to obtain a product B, a filtrate B and distilled water;
(6) the filtrate D was concentrated by repeated evaporation.
8. The chromium-containing waste liquid treatment process according to claim 1, characterized in that: the chromium-containing wastewater is one of landfill leachate, hot galvanizing passivation solution, metallurgical wastewater and electroplating wastewater.
9. The chromium-containing waste liquid treatment process according to claim 1, characterized in that: the reducing agent is one or a mixture of sodium pyrosulfite, sodium bisulfite, sodium sulfite, sodium dithionite and sodium thiosulfate.
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4401573A (en) * | 1980-05-12 | 1983-08-30 | Luigi Stoppani S.P.A. | Continuous process for the removal of chromium from waste waters and valorization of the recovered chromium |
| CN101830600A (en) * | 2010-03-23 | 2010-09-15 | 天津大学 | Method for treating comprehensive electroplating wastewater |
| CN102616980A (en) * | 2011-12-26 | 2012-08-01 | 上海集惠环保科技发展有限公司 | Treatment method of chromium-containing high concentration organic wastewater |
| CN104829018A (en) * | 2015-04-21 | 2015-08-12 | 俞权锋 | Chromium-containing waste water treatment method |
| CN105236639A (en) * | 2015-10-30 | 2016-01-13 | 太仓东能环保设备有限公司 | Chromium-containing wastewater treatment process |
| US20200048125A1 (en) * | 2018-08-10 | 2020-02-13 | Guangzhou Ultra Union Chemicals Ltd | Method for integrated treatment of electroplating wasterwater |
-
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- 2022-04-24 CN CN202210456225.2A patent/CN114772857B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4401573A (en) * | 1980-05-12 | 1983-08-30 | Luigi Stoppani S.P.A. | Continuous process for the removal of chromium from waste waters and valorization of the recovered chromium |
| CN101830600A (en) * | 2010-03-23 | 2010-09-15 | 天津大学 | Method for treating comprehensive electroplating wastewater |
| CN102616980A (en) * | 2011-12-26 | 2012-08-01 | 上海集惠环保科技发展有限公司 | Treatment method of chromium-containing high concentration organic wastewater |
| CN104829018A (en) * | 2015-04-21 | 2015-08-12 | 俞权锋 | Chromium-containing waste water treatment method |
| CN105236639A (en) * | 2015-10-30 | 2016-01-13 | 太仓东能环保设备有限公司 | Chromium-containing wastewater treatment process |
| US20200048125A1 (en) * | 2018-08-10 | 2020-02-13 | Guangzhou Ultra Union Chemicals Ltd | Method for integrated treatment of electroplating wasterwater |
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