CN114853220A - Method for removing COD (chemical oxygen demand) and recycling high-ammonia nitrogen high-salt organic wastewater - Google Patents
Method for removing COD (chemical oxygen demand) and recycling high-ammonia nitrogen high-salt organic wastewater Download PDFInfo
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Abstract
The invention provides a method for removing COD (chemical oxygen demand) from high-ammonia nitrogen high-salt organic wastewater, which comprises the following steps of: (1) adding alkali into the high ammonia nitrogen wastewater for deamination to obtain a deaminated solution; (2) standing the deaminated solution to separate out sodium sulfate crystal salt, and performing solid-liquid separation to obtain a crystallized solution; (3) adjusting the pH value of the crystallized liquid, and aerating; (4) carrying out electrocatalytic oxidation on the solution obtained in the step (3); (5) carrying out a Fenton reaction on the solution obtained in the step (4); (6) adding alkali liquor to adjust the solution obtained in the step (5) to be alkaline; (7) and (4) adding a flocculating agent into the solution obtained in the step (6), and carrying out solid-liquid separation to obtain a COD removing solution. The method can realize the high-efficiency removal of COD in the high-ammonia nitrogen high-salt organic wastewater, can recover ammonium salt and sodium sulfate, and has the advantages of low treatment cost, small slag amount, and simple and convenient treatment steps.
Description
Technical Field
The invention relates to the field of wastewater treatment in new energy industry, in particular to a COD (chemical oxygen demand) removal and recycling method for high-ammonia nitrogen high-salt organic wastewater.
Background
In the processes of nickel, cobalt and manganese smelting and nickel, cobalt and manganese recovery of waste batteries, P507 or P204 is commonly used for nickel and cobalt enrichment and purification. The extraction method can realize the enrichment and purification of nickel, cobalt and manganese, and generally comprises the steps of firstly diluting an extracting agent (mainly phosphate extracting agents, such as P507 and P204) with a solvent such as sulfonated kerosene and the like before extraction, then saponifying with ammonia water or liquid alkali and the like, and using a saponified organic phase for extraction. After the extraction reaction is finished, the raffinate (water phase) and the extract phase (cobalt-rich or nickel-rich organic phase) are obtained through mechanical clarification and phase separation, wherein the main component of the extract phase is cobalt (nickel) sulfate or cobalt (nickel) chloride and is used for producing ternary lithium battery precursor materials, metal nickel, metal cobalt and other nickel cobalt salt products. The raffinate mainly comprises sodium sulfate, ammonium sulfate, sodium chloride and ammonium chloride. In actual production, due to the reasons that the organic phase has hydrophilicity (the extraction rate is inconsistent with the hydrophilicity of the organic phase, and the organic phase must have certain hydrophilicity to ensure high extraction rate) and insufficient phase separation, and the like, the extraction liquid often carries some oil substances, so that a large amount of high-ammonia nitrogen high-salt organic degradation-resistant wastewater can be generated after the raffinate is evaporated and crystallized.
The high ammonia nitrogen high salt organic wastewater is mainly wastewater generated in nickel, cobalt and manganese smelting and waste battery nickel-cobalt-manganese recovery processes, salt in the wastewater mainly comprises sodium sulfate, sodium chloride, ammonium sulfate, ammonium chloride, magnesium sulfate and the like, and the TDS is 25-40%. The organic substances mainly include P507 (2-ethylhexyl phosphate mono-2-ethylhexyl), P204 bis (2-ethylhexyl phosphate), diluents (e.g., sulfonated kerosene, solvent oil, etc.), P507 ammonia soap, P204 ammonia soap, P507 sodium soap, P204 sodium soap, cobalt extract, nickel extract, hydrolyzate (2-ethylhexanol, phosphoric acid by-product, etc.), modifiers (long-chain alcohols, etc.), and the like. The COD concentration in the wastewater is 1000-30000mg/L, the ammonia nitrogen concentration is 5-15g/L, and the salinity can also reach 30-400g/L, and the wastewater has the characteristics of high salinity, high COD, strong acidity and alkalinity, high toxicity, complex chemical components, poor biodegradability and the like, so the treatment difficulty of the high ammonia nitrogen and high salt organic wastewater is very high.
The existing methods for removing COD in wastewater mainly comprise physical methods such as coagulating sedimentation, activated carbon adsorption and the like, advanced oxidation methods such as ozone oxidation, Fenton oxidation, electrooxidation and the like, and biochemical methods such as aerobic/anaerobic microbial decomposition and the like. But the existing methods for treating the high-ammonia nitrogen high-salt organic wastewater have great limitations, such as low removal rate of soluble substances, low reuse rate of activated carbon and high cost by a coagulating sedimentation method; the traditional Fenton method has high treatment cost, a large amount of iron-containing sludge is generated in the degradation process of organic matters to cause secondary pollution, meanwhile, a large amount of ammonia gas is generated in Fenton reaction due to the large amount of ammonium sulfate in the solution to pollute air, and the removal efficiency of organic wastewater COD is reduced due to high-concentration salt; because a large amount of ammonium sulfate, oil and the like exist in the wastewater, and the electrooxidation process has no selectivity, organic matters and ammonium ions are required to be oxidized in the electrooxidation process, so that the power consumption is overhigh; the high salt water environment is not beneficial to the growth of microorganisms, the phenomenon of microorganism poisoning and the like can occur, so that the biochemical method is not suitable for treating the wastewater. Therefore, a new method aiming at the high ammonia nitrogen and high salt organic wastewater with low treatment cost, good treatment effect and small slag amount is urgently needed to be developed.
Disclosure of Invention
The invention provides a COD removing and recycling method for high-ammonia nitrogen high-salt organic wastewater, which can efficiently remove COD in high-ammonia nitrogen high-salt refractory organic wastewater, has the removal effect of over 90 percent, has the characteristics of small amount of generated slag, low treatment cost, recycling, wide application range and the like, and can realize the recycling of wastewater.
To achieve the above object, the present invention is achieved as follows:
a method for removing COD (chemical oxygen demand) and recycling high-ammonia nitrogen high-salt organic wastewater comprises the following steps:
(1) adding alkali into the high ammonia nitrogen wastewater for deamination to obtain a deaminated solution;
(2) standing the deaminated solution to separate out sodium sulfate crystal salt, and performing solid-liquid separation to obtain a crystallized solution;
(3) adjusting the pH value of the crystallized liquid, and aerating;
(4) carrying out electrocatalytic oxidation on the solution obtained in the step (3);
(5) carrying out a Fenton reaction on the solution obtained in the step (4);
(6) adding alkali liquor to adjust the solution obtained in the step (5) to be alkaline;
(7) and (4) adding a flocculating agent into the solution obtained in the step (6), and carrying out solid-liquid separation to obtain a COD removing solution.
The high ammonia nitrogen high salt organic wastewater is mainly wastewater generated in nickel, cobalt and manganese smelting and waste battery nickel-cobalt-manganese recovery processes, salt in the wastewater mainly comprises sodium sulfate, sodium chloride, ammonium sulfate, ammonium chloride, magnesium sulfate and the like, and the TDS is 25-40%. The organic substances mainly include P507 (2-ethylhexyl phosphate mono-2-ethylhexyl), P204 di (2-ethylhexyl phosphate), diluents (such as sulfonated kerosene, solvent oil, etc.), P507 ammonia soap, P204 ammonia soap, P507 sodium soap, P204 sodium soap, cobalt extract, nickel extract, hydrolysate (2-ethylhexanol, phosphoric acid by-product, etc.), modifiers (long-chain alcohols, etc.), and the like. The COD concentration in the wastewater is 1000-30000mg/L, the ammonia nitrogen concentration is 5-15g/L, and the salinity can also reach 30-400g/L, and the wastewater has the characteristics of high salinity, high COD, strong acidity and alkalinity, high toxicity, complex chemical components, poor biodegradability and the like, so the treatment difficulty of the high ammonia nitrogen and high salt organic wastewater is very high.
The alkali added in the step (1) comprises at least one of sodium hydroxide, potassium hydroxide, calcium hydroxide and calcium oxide; the base is preferably added as a solution.
The alkali is added in an amount to at least reduce NH in the water body 4 + Conversion to NH 3 For this reason, the preferred amount of n (OH) added is - ):n(NH 4 + ) 1.2-1.5; it is further preferable that the concentration of the alkaline solution is not less than 30% by mass.
The deamination temperature in the step (1) is controlled to be 45-100 ℃, and preferably 55-80 ℃.
And (2) absorbing ammonia gas by using acid in the step (1) to obtain an ammonium salt solution. The acid comprises at least one of sulfuric acid, nitric acid and hydrochloric acid.
The acidic solution is added in an amount to at least reduce NH in the water body 3 The preferred amount of n (H) is added for complete absorption + ):n(NH 3 ) 1.1-2.0; further preferably, the mass concentration of the acidic solution is not less than 50%.
Further, the liquid after deamination is cooled to room temperature, ammonium salt crystals are separated out and then filtered, and crystallized liquid with low salt content is obtained, so that the removal effect of COD in the waste water at the rear can be improved.
And (3) adding an acid solution to adjust the pH value of the crystallized liquid to be 1-5, wherein the aeration time is 10-60 min, and the aeration intensity is 5-25L/min.
And (3) adjusting the pH of the liquid after crystallization by adopting at least one of sulfuric acid, nitric acid and hydrochloric acid, filtering and then aerating, so that organic matters insoluble in acid can be removed, and the primary removal of COD in the wastewater is realized.
Due to the particularity of the electrocatalytic oxidation electrode, the pH value of the wastewater is required to be less than 12, so that the pH value of the wastewater needs to be adjusted by at least one of sulfuric acid, nitric acid and hydrochloric acid, otherwise, the electrode plate is damaged, and the removal efficiency of COD is reduced.
Because the pH of the reaction solution is required to be 2-4 during the Fenton reaction, and the subsequent electrocatalytic oxidation and Fenton reaction effects are ensured by reducing the dosage of the acid-base agent, the step (1), the step (2) and the step (3) need to be strictly performed in this order.
The current density of the electrocatalytic oxidation in the step (4) is controlled to be 30-100 mA/cm 2 The reaction time is 10-30 min.
The Fenton reagent in the step (5) comprises ferrous sulfate and hydrogen peroxide, the concentration ratio of the hydrogen peroxide to COD in the solution is 1: 1-2: 1mg/L, the concentration ratio of the hydrogen peroxide to ferrous ions is 1: 1-10: 1mg/L, and the Fenton oxidation time is 20-40 min. Preferably, the hydrogen peroxide solution has a mass fraction of 30%.
And (6) adding alkali liquor to adjust the solution obtained in the step (5) to be alkaline. The concentration of the alkali liquor is 3% -30%, and the pH value of the solution is adjusted to 7-9, so that hydrolytic precipitation of iron ions in the wastewater is realized.
The flocculating agent in the step (7) comprises at least one of PAM, polyaluminium chloride, polyaluminium sulfate, polyferric sulfate and polyferric chloride, and the dosage of the flocculating agent is 1-5 g/m 3 The reaction time is 1-10 min, the hair potential of the colloid in the solution can be effectively reduced or eliminated through a flocculating agent, the colloid is condensed through the electric neutralization, the adsorption bridging and the rolling and sweeping action of flocs, and Fe (OH) with high polymerization degree is formed 3 Gelling, improving the sedimentation performance and shortening the sedimentation time.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
(1) the present invention avoids the following disadvantages of the prior art: a, the removal rate of soluble substances by a coagulating sedimentation method is low, the recycling rate of the activated carbon is low, and the cost is high; b, the traditional Fenton method has high treatment cost, and a large amount of iron-containing sludge is generated in the degradation process of organic matters, so that secondary pollution is caused; c, because a large amount of ammonium sulfate exists in the solution, a large amount of ammonia gas is also generated in the Fenton reaction, and the air is polluted; d, the removal efficiency of the organic wastewater COD can be reduced by high-concentration salt; because a large amount of ammonium sulfate, oil and the like exist in the wastewater, and the electrooxidation process has no selectivity, organic matters and ammonium ions are required to be oxidized in the electrooxidation process, so that the power consumption is overhigh; e, the high saline water environment is not beneficial to the growth of microorganisms, and the phenomenon of microbial poisoning and the like can occur, so that the biochemical method is not suitable for treating the wastewater.
(2) The invention can realize the removal of COD in the wastewater, and the removal rate of COD in the wastewater is more than 90 percent.
(3) Compared with the prior art, the invention has the advantages of low treatment cost, high efficiency, low slag yield and no secondary pollution.
(4) The method can realize the high-efficiency removal of COD in the high-ammonia nitrogen high-salt organic wastewater, and can also recover ammonium salt solution and high-purity sodium sulfate crystallized salt, and has the advantages of low treatment cost, less slag amount and simple and convenient treatment steps.
Drawings
FIG. 1 is a process flow chart of COD removal of high ammonia nitrogen high salt organic wastewater.
Detailed Description
The following examples are intended to further illustrate the invention without limiting it.
Example 1
Firstly, 1.0L of high-ammonia nitrogen high-salt refractory organic wastewater generated in the nickel-cobalt hydrometallurgy process is taken, the ammonia nitrogen concentration in the wastewater is 5g/L, the main salt content (the concentration is 37.59%) in the wastewater comprises ammonium sulfate, sodium chloride and ammonium chloride, the TDS of the wastewater is 39.63%, organic matters comprise P204, P204 ammonia soap, P204 sodium soap, sulfonated kerosene and the like, the TOC concentration is 12560.75mg/L, and the COD concentration is 11778.9 mg/L. Putting the wastewater into a round-bottom flask, adding a stirrer, appropriately heating, controlling the temperature of the wastewater to be 70 ℃, dropwise adding an appropriate amount of NaOH with the mass fraction of 60% into the solution according to the characteristics of the wastewater until no ammonia gas is generated in the solution, and absorbing the ammonia gas by using sulfuric acid with the concentration of 98%, wherein the purity of the obtained ammonium salt solution is about 85 percent. When the temperature of the waste water is reduced to the room temperature from 70 ℃, the sodium sulfate is crystallized and separated out, and the purity of the sodium sulfate crystal salt is about 70.2 percent. Regulating pH of the deaminated solution to about 2.5 with 10% sulfuric acid, and aerating for 30min at an aeration intensity of 10L/min. Adding the aerated wastewater (pH is less than 12) into an electrocatalytic oxidation device, and adding the current density of 75mA/cm 2 After electrocatalytic oxidation reaction for 30min, the pH value is 3, and FeSO is added 4 ·7H 2 O 2.5g，30％H 2 O 2 3.0mL, reacting for 40min, adjusting the pH to 8.5 by adopting 5% calcium hydroxide, reacting for 30min, adding 2 mL0.1% PAM, reacting for 5min, standing, and completing solid-liquid separation. COD in the wastewater is reduced from 11778.9mg/L to 117.2mg/L, and the removal rate of the COD can reach 99.0 percent; the TOC in the wastewater is reduced to 75.7mg/L from 12560.75mg/L, the TOC removal rate can reach 99.4%, the salinity removal rate is 63.9%, and the ammonia nitrogen removal rate is 97.4%.
Example 2
Firstly, 1.0L of high-ammonia nitrogen high-salt refractory organic wastewater generated in the nickel-cobalt hydrometallurgy process is taken, the ammonia nitrogen concentration in the wastewater is 14.7g/L, the main salt content (the salt content is 21.93%) in the wastewater comprises ammonium sulfate, magnesium chloride and ammonium chloride, the TDS of the wastewater is 27.93%, organic matters comprise P507, P507 ammonia soap, P507 sodium soap, sulfonated kerosene and the like, the TOC concentration is 1914.27mg/L, and the COD concentration is 5832 mg/L. Putting the wastewater into a round-bottom flask, adding a stirrer, appropriately heating, controlling the temperature of the wastewater to be 70 ℃, dropwise adding an appropriate amount of NaOH with the mass fraction of 60% into the solution according to the characteristics of the wastewater until no ammonia gas is generated in the solution, and absorbing the ammonia gas by using sulfuric acid with the concentration of 85%, wherein the purity of the obtained ammonium salt solution is about 90%. When the temperature of the waste water is reduced to the room temperature from 70 ℃, the sodium sulfate is crystallized and separated out, and the purity of the sodium sulfate crystal salt is about 81.4 percent. Regulating pH of the deamination solution to about 3.0 with 5% sulfuric acid, and aerating for 20min at an aeration intensity of 15L/min. Adding the aerated wastewater (pH is less than 12) into an electrocatalytic oxidation device, and adding the current density of 100mA/cm 2 After electrocatalytic oxidation reaction for 30min, the pH value is 3, and FeSO is added 4 ·7H 2 O 5.0g，30％H 2 O 2 4.5mL, reacting for 40min, adjusting pH to 8.0 with 30% calcium hydroxide, reacting for 15min, adding 2 mL0.1% PAM, reacting for 1min, standing, and finishingAnd (4) solid-liquid separation is carried out. COD in the wastewater is reduced from 5832mg/L to 216.2mg/L, and the removal rate of the COD can reach 96.29 percent; the TOC in the wastewater is reduced from 1914.27mg/L to 82.84mg/L, the TOC removal rate can reach 95.67%, the salinity removal rate is 57.36%, and the ammonia nitrogen removal rate is 99.41%.
Example 3
Firstly, 1.0L of high-ammonia-nitrogen high-salt refractory organic wastewater generated in the nickel cobalt hydrometallurgy process is taken, the ammonia nitrogen concentration in the wastewater is 14.67g/L, the main salt content (salt content is 17.86%) in the wastewater comprises ammonium sulfate, magnesium chloride, ammonium chloride, nickel sulfate, nickel chloride and the like, the TDS of the wastewater is 19.79%, the organic matters comprise P507, P507 ammonia soap, P507 sodium soap, sulfonated kerosene and the like, the TOC concentration is 1277.31mg/L, and the COD concentration is 28732 mg/L. Putting the wastewater into a round-bottom flask, adding a stirrer, appropriately heating, controlling the temperature of the wastewater to be 70 ℃, dropwise adding an appropriate amount of NaOH with the mass fraction of 80% into the solution according to the characteristics of the wastewater until no ammonia gas is generated in the solution, and absorbing the ammonia gas by using sulfuric acid with the concentration of 90%, wherein the purity of the obtained ammonium salt solution is about 80%. When the temperature of the waste water is reduced to the room temperature from 70 ℃, the sodium sulfate is crystallized and separated out, and the purity of the sodium sulfate crystal salt is about 75 percent. Regulating pH of the deaminated solution to about 3.0 with 10% sulfuric acid, and aerating for 20min at an aeration intensity of 25L/min. Adding the aerated wastewater into an electrocatalytic oxidation device, and adding current density of 66.6mA/cm 2 After electrocatalytic oxidation reaction for 10min, adjusting the pH to 3.0, and adding FeSO 4 ·7H 2 O 6.0g，30％H 2 O 2 4.5mL, reacting for 40min, adjusting the pH to 8.5 by adopting 10% calcium hydroxide, reacting for 15min, adding 2 mL0.3% PAM, reacting for 1min, standing, and completing solid-liquid separation. COD in the wastewater is reduced from 28732mg/L to 316.9mg/L, and the removal rate of the COD can reach 98.90 percent; the TOC in the wastewater is reduced from 1277.31mg/L to 112.76mg/L, the TOC removal rate can reach 91.17%, the salinity removal rate is 64.21%, and the ammonia nitrogen removal rate is 98.69%.
Comparative example 1
Taking the waste water same as the waste water obtained in the example 3, putting the waste water into a beaker, adding 2ml of 0.3 percent PAM, reducing COD in the waste water from 28732mg/L to 28716.9mg/L, and ensuring that the removal rate of the COD is 0.053 percent; the TOC in the wastewater is reduced from 1277.31mg/L to 1275.14mg/L, the TOC removal rate is 0.17%, the salinity removal rate is 0.14%, and the ammonia nitrogen removal rate is 0.03%.
Comparative example 2
The same waste water as in example 3 was taken, the waste water was put into a beaker, the pH was adjusted to 3.0 with 10% sulfuric acid, and FeSO was added 4 ·7H 2 O 6.0g，30％H 2 O 2 4.5mL, reacting for 40min, and adjusting the pH to 8.5 by adopting calcium hydroxide to complete solid-liquid separation. COD in the wastewater is reduced from 28732mg/L to 22591.97mg/L, and the removal rate of the COD is 21.37%; the TOC in the wastewater is reduced from 1277.31mg/L to 1181.38mg/L, the TOC removal rate is 7.51 percent, the salinity removal rate is 0.72 percent, and the ammonia nitrogen removal rate is 3.93 percent.
Comparative example 3
The same waste water as in example 3 was taken and put into an electrocatalytic oxidation apparatus with an applied current density of 66.6mA/cm 2 After the electrocatalytic oxidation reaction time is 10min, the COD in the wastewater is reduced from 28732mg/L to 23066.05mg/L, and the removal rate of the COD is 19.72%; the TOC in the wastewater is reduced from 1277.31mg/L to 816.20mg/L, the TOC removal rate is 36.1 percent, the salinity removal rate is 1.73 percent, and the ammonia nitrogen removal rate is 2.77 percent.
Comparative example 4
Taking the wastewater as in example 3, putting the wastewater into a round-bottom flask, adding a stirrer, appropriately heating, controlling the temperature of the wastewater to be 70 ℃, dropwise adding an appropriate amount of NaOH with the mass fraction of 80% into the solution according to the characteristics of the wastewater until no ammonia gas is generated in the solution, and absorbing the ammonia gas by using sulfuric acid with the concentration of 98%, wherein the purity of the obtained ammonium salt solution is about 90%. When the temperature of the waste water is reduced to the room temperature from 70 ℃, the sodium sulfate is crystallized and separated out, and the purity of the sodium sulfate crystal salt is 81.4 percent. Regulating pH of the deaminated solution to about 3.0 with 10% sulfuric acid, and aerating for 20min at an aeration intensity of 10L/min. Adding 2mL0.3 percent PAM, reacting for 1min, standing, and reducing COD in the wastewater from 28732mg/L to 27579.85mg/L, wherein the removal rate of the COD is 4.01 percent; the TOC in the wastewater is reduced from 1277.31mg/L to 1262.11mg/L, the TOC removal rate is 1.19 percent, the salinity removal rate is 57.4 percent, and the ammonia nitrogen removal rate is 96.6 percent.
Comparative example 5
The same waste water as in example 3 was taken, and the waste water was charged into an electrocatalytic oxidation apparatus at an applied current density of 66.6mA/cm 2 After electrocatalytic oxidation reaction for 10min, adjusting the pH to 3.0, and adding FeSO 4 ·7H 2 O 6.0g，30％H 2 O 2 4.5mL, reacting for 40min, adjusting the pH to 8.5 by adopting 15% calcium hydroxide, reacting for 20min, adding 2 mL0.3% PAM, reacting for 5min, standing, completing solid-liquid separation, reducing the COD in the wastewater from 28732mg/L to 10806.11mg/L, and ensuring that the removal rate of the COD is 62.39%; the TOC in the wastewater is reduced from 1277.31mg/L to 1057.74mg/L, the TOC removal rate is 17.19%, the salinity removal rate is 2.17%, and the ammonia nitrogen removal rate is 22.42%.
Comparative example 6
The same waste water as in example 3 was taken, the waste water was placed in a beaker, the pH was adjusted to 3.0, and FeSO was added 4 ·7H 2 O 6.0g，30％H 2 O 2 4.5mL, reacting for 40min, adjusting the pH to 8.5 by using 10% calcium hydroxide, and standing to complete solid-liquid separation. Adding the reacted solution into an electrocatalytic oxidation device, and adding current with the density of 66.6mA/cm 2 After the electrocatalytic oxidation reaction is carried out for 10min, the COD in the wastewater is reduced from 28732mg/L to 12242.71mg/L, and the removal rate of the COD is 57.39 percent; the TOC in the wastewater is reduced from 1277.31mg/L to 1154.56mg/L, the TOC removal rate is 9.61 percent, the salinity removal rate is 5.32 percent, and the ammonia nitrogen removal rate is 31.93 percent.
Comparative example 7
Taking the wastewater as in example 3, putting the wastewater into a round-bottom flask, adding a stirrer, appropriately heating, controlling the temperature of the wastewater to be 70 ℃, dropwise adding an appropriate amount of NaOH with the mass fraction of 80% into the solution according to the characteristics of the wastewater until no ammonia gas is generated in the solution, and absorbing the ammonia gas by using sulfuric acid with the concentration of 98%, wherein the purity of the obtained ammonium salt solution is about 90%. When the temperature of the waste water is reduced to the room temperature from 70 ℃, sodium sulfate is crystallized and separated out, and the purity of sodium sulfate crystal salt is about 85 percent. Regulating pH of the deaminated solution to about 3.0 with 10% sulfuric acid, adding the wastewater into an electrocatalytic oxidation device, and adding a current with the density of 66.6mA/cm 2 After electrocatalytic oxidation reaction for 10min, adjusting the pH to 3.0, and adding FeSO 4 ·7H 2 O 6.0g，30％H 2 O 2 4.5mL, reacting for 40min, adjusting pH to 8.5 with 10% calcium hydroxide, reacting for 25min, adding 2 mL0.3% PAM, reacting for 1min, standing, and finishingAnd (4) solid-liquid separation. COD in the wastewater is reduced from 28732mg/L to 6128.54mg/L, and the removal rate of the COD is 78.67%; the TOC in the wastewater is reduced from 1277.31mg/L to 797.81mg/L, the TOC removal rate is 37.54 percent, the salinity removal rate is 62.39 percent, and the ammonia nitrogen removal rate is 97.31 percent.
Comparative example 8
The wastewater as in example 3 was treated with 10% sulfuric acid to adjust the pH to about 3.0, and aerated for 20min at an aeration rate of 25L/min. Adding the aerated wastewater into an electrocatalytic oxidation device, and adding current density of 66.6mA/cm 2 After electrocatalytic oxidation reaction for 10min, adjusting the pH to 3.0, and adding FeSO 4 ·7H 2 O 6.0g，30％H 2 O 2 4.5mL, reacting for 40min, adjusting the pH to 8.5 by adopting 10% calcium hydroxide, reacting for 20min, adding 2 mL0.3% PAM, reacting for 1min, standing, and completing solid-liquid separation. COD in the wastewater is reduced from 28732mg/L to 21028.95mg/L, and the removal rate of the COD is 26.81 percent; the TOC in the wastewater is reduced from 1277.31mg/L to 1053.53mg/L, the TOC removal rate is 17.52 percent, the salinity removal rate is 3.27 percent, and the ammonia nitrogen removal rate is 22.92 percent.
Comparative example 9
Taking the wastewater as in example 3, putting the wastewater into a round-bottom flask, adding a stirrer, appropriately heating, controlling the temperature of the wastewater to be 70 ℃, dropwise adding an appropriate amount of NaOH with the mass fraction of 80% into the solution according to the characteristics of the wastewater until no ammonia gas is generated in the solution, and absorbing the ammonia gas by using sulfuric acid with the concentration of 90%, wherein the purity of the obtained ammonium salt solution is about 80%. Regulating pH of the deaminated solution to about 3.0 with 10% sulfuric acid, aerating for 20min at an aeration intensity of 25L/min, adding the aerated wastewater into an electrocatalytic oxidation device, and adding an electric current with a density of 66.6mA/cm 2 After electrocatalytic oxidation reaction for 10min, adjusting the pH to 3.0, and adding FeSO 4 ·7H 2 O 6.0g，30％H 2 O 2 4.5mL, reacting for 40min, adjusting the pH to 8.5 by adopting 10% calcium hydroxide, reacting for 25min, adding 2 mL0.3% PAM, reacting for 1min, standing, and completing solid-liquid separation. COD in the wastewater is reduced from 28732mg/L to 6561.77mg/L, and the removal rate of the COD is 77.16%; the TOC in the wastewater is reduced from 1277.31mg/L to 345.64mg/L, the TOC removal rate is 72.94%, the salinity removal rate is 61.65%, and the ammonia nitrogen removal rate is 97.57%.
Claims (10)
1. A method for removing COD from high ammonia nitrogen high salt organic wastewater is characterized by comprising the following steps: the method comprises the following steps:
(1) adding alkali into the high ammonia nitrogen wastewater for deamination to obtain a deaminated solution;
(2) standing the deaminated solution to separate out sodium sulfate crystal salt, and performing solid-liquid separation to obtain a crystallized solution;
(3) adjusting the pH value of the crystallized liquid, and aerating;
(4) carrying out electrocatalytic oxidation on the solution obtained in the step (3);
(5) carrying out a Fenton reaction on the solution obtained in the step (4);
(6) adding alkali liquor to adjust the solution obtained in the step (5) to be alkaline;
(7) and (4) adding a flocculating agent into the solution obtained in the step (6), and carrying out solid-liquid separation to obtain a COD removing solution.
2. The method of claim 1, wherein: the alkali added in the step (1) comprises at least one of sodium hydroxide, potassium hydroxide, calcium hydroxide and calcium oxide; the base is preferably added as a solution.
3. The method of claim 2, wherein: the alkali is added in an amount to at least reduce NH in the water body 4 + Conversion to NH 3 For this reason, the preferred amount of n (OH) added is - ):n(NH 4 + ) 1.2-1.5; it is further preferable that the concentration of the alkaline solution is not less than 30% by mass.
4. A method according to claim 1 or 2 or 3, characterized in that: the deamination temperature in the step (1) is controlled to be 45-100 ℃, and preferably 55-80 ℃.
5. The method of claim 1, wherein: absorbing ammonia gas by using acid to obtain an ammonium salt solution; the acid comprises at least one of sulfuric acid, nitric acid and hydrochloric acid.
6. The method according to claim 1 or 5, characterized in that: the acidic solution is added in an amount to at least reduce NH in the water body 3 The preferred amount of n (H) is added for complete absorption + ):n(NH 3 ) 1.1-2.0; further preferably, the mass concentration of the acidic solution is not less than 50%.
7. The method of claim 1, wherein: and (3) adding acid to adjust the pH value of the crystallized liquid to be 1-5, wherein the aeration time is 10-60 min, and the aeration intensity is 5-25L/min.
8. The method of claim 1, wherein: the current density of the electrocatalytic oxidation in the step (4) is controlled to be 30-100 mA/cm 2 The reaction time is 10-30 min.
9. The method of claim 1, wherein: the Fenton reagent added in the step (5) comprises ferrous sulfate and hydrogen peroxide, the concentration ratio of the hydrogen peroxide to COD in the solution is 1: 1-2: 1(mg/L), the concentration ratio of the hydrogen peroxide to ferrous ions is 1: 1-10: 1(mg/L), and the Fenton oxidation time is 20-40 min.
10. The method of claim 1, wherein: adding an alkali liquor to adjust the solution obtained in the step (5) to be alkaline, preferably adjusting the pH value of the solution to be 7-9, and further preferably adjusting the concentration of the alkali liquor to be 3% -30%; the flocculant added in the step (7) comprises at least one of PAM, polyaluminium chloride, polyaluminium sulfate, polyferric sulfate and polyferric chloride, and the dosage of the flocculant is 1-5 g/m 3 The reaction time is 1-10 min.
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| CN117023854A (en) * | 2023-08-03 | 2023-11-10 | 广东威特雅环境科技有限公司 | Be used for DMM n Degradation method and equipment for pollutant in production wastewater |
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