CN114291875A - Flow electrode capacitance ammonia nitrogen recovery and purification method based on monovalent cation exchange membrane - Google Patents
Flow electrode capacitance ammonia nitrogen recovery and purification method based on monovalent cation exchange membrane Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 51
- 239000012528 membrane Substances 0.000 title claims abstract description 40
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- 238000011084 recovery Methods 0.000 title claims abstract description 34
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- 239000003245 coal Substances 0.000 claims abstract description 29
- 238000002309 gasification Methods 0.000 claims abstract description 28
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims abstract description 24
- 235000011114 ammonium hydroxide Nutrition 0.000 claims abstract description 24
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- 239000002351 wastewater Substances 0.000 claims abstract description 15
- 229910000069 nitrogen hydride Inorganic materials 0.000 claims abstract description 13
- 239000003011 anion exchange membrane Substances 0.000 claims abstract description 10
- 150000001450 anions Chemical class 0.000 claims abstract description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 42
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- 238000002242 deionisation method Methods 0.000 description 10
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- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 1
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 description 1
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- FAPWRFPIFSIZLT-UHFFFAOYSA-M sodium chloride Inorganic materials [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 1
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Abstract
The invention relates to a flow electrode capacitance ammonia nitrogen recovery and purification method based on a monovalent cation exchange membrane, which comprises the steps of supplying wastewater to be treated to a desalting chamber, applying voltage to an anode flow electrode chamber and a cathode flow electrode chamber, and enabling anions to pass through an anion exchange membrane to enter the anode flow electrode chamber through the electro-adsorption effect and contain NH4 +Passes through the monovalent cation exchange membrane into the cathode flow electrode chamber, and in the cathode flow electrode chamber, promotes NH on the electrode using the cathode Faraday reaction4 +To NH3And then the ammonia water is converted and desorbed, so that the high-purity ammonia water is obtained. Compared with the prior art, the invention has the advantages of simple operation, high deamination efficiency, good recovery effect, high product purity, effective scale inhibition, stable operation and the like,the method can realize the recovery of ammonia nitrogen in the coal gasification ash water in the form of ammonia water on the premise of not increasing energy consumption, not increasing cost, not adding chemical agents and facilitating subsequent treatment, and has very important significance for the development of the coal gasification industry.
Description
Technical Field
The invention belongs to the technical field of flowing electrode capacitive deionization technology application and water treatment, relates to a method for recovering and purifying flowing electrode capacitive ammonia nitrogen based on a monovalent cation exchange membrane, and particularly relates to a method for recovering ammonia nitrogen in coal gasification ash water by using a flowing electrode capacitive deionization technology coupled with the monovalent cation exchange membrane.
Background
Coal gasification technology is widely used throughout the world. The energy structure of rich coal, poor oil and less gas in China enables the coal gasification industry to develop vigorously. However, a large amount of coal gasification grey water is generated in the coal gasification process, and the coal gasification grey water contains a large amount of ammonia nitrogen, phenol, polycyclic aromatic hydrocarbon, cyanide and the like, so that the biodegradability of the wastewater is reduced. Treatment of low C/N wastewater in sewage treatment systems is often limited due to nitrification inhibition. Reports have shown that 250 ten thousand tons of ammonia nitrogen are discharged into water every year in China, resulting in severe eutrophication and acute or chronic toxicity to aquatic organisms. In addition, nitrogen demand is expected to increase further due to global population growth and increased living standards. Therefore, ammonia nitrogen should be recovered to improve the biodegradability of the coal gasification grey water and realize the sustainable development of the global environment. In addition, the grey water also has the characteristic of high hardness. The problem of scaling is therefore of particular concern when treating coal gasification grey water.
At present, gas stripping, forward osmosis, electrodialysis and the like are mostly adopted for recovering ammonia nitrogen from sewage (wastewater). The gas stripping requires a large amount of reagent investment and is very costly. Also, gas stripping columns face fouling challenges. Forward osmosis has efficient water recovery and ammonia nitrogen concentration performance; however, forward osmosis membranes have a high rejection capacity for all ions, so the purity of the ammonia nitrogen product reduces its economic value. ED has proven to require a large amount of chemicals to adjust pH. Therefore, it is necessary to obtain a simple and economical technology for selectively separating and recovering high-purity ammonia nitrogen from wastewater.
In recent years, the technology based on Capacitive Deionization (CDI) has brought about a hot research trend in the academic world due to its advantages of low cost, environmental protection, easy electrode management, high water recovery rate, and the like. Flow electrode capacitive deionization (FCDI) has the potential for continuous desalination and scale-up as the flow electrode suspension negates the fixed electrodes of CDI and MCDI, and the fluidity of the electrodes allows them to be regenerated outside of the FCDI. The use of FCDI for the recovery of ammonia nitrogen from contaminated (waste) water has been studied, but the recovered product is a low purity ammonium salt. Compared with ammonium salt, the ammonia water has wider application range and higher added value. Also has been studied to utilize NH4 +And NH3The pH-dependent equilibrium reaction between the two enables the production of ammonia-rich solutions, but the product grade is low. Compared with the prior art, the gasified ash water has higher ammonia nitrogen concentration and high Ca concentration2+Therefore, the running mode which has high denitrification efficiency, good recovery effect and high product purity and can effectively inhibit the scaling of the device and the matched flow electrode capacitance deionization device are obtained, and the device has very important significance for low cost, low energy consumption, high efficiency and stable recovery of ammonia nitrogen in the gasified ash water.
Disclosure of Invention
The invention aims to provide a method for recycling and purifying flowing electrode capacitance ammonia nitrogen based on a monovalent cation exchange membrane, which is simple to operate, free of chemical agent addition, high in deamination efficiency, good in recycling effect, high in product purity, capable of effectively inhibiting scaling, low in treatment cost, low in treatment energy consumption, stable in operation and free of secondary pollution.
The purpose of the invention can be realized by the following technical scheme:
a method for recycling and purifying flowing electrode capacitance ammonia nitrogen based on a monovalent cation exchange membrane comprises the steps of treating wastewater to be treated by adopting an FCDI device coupled with the Monovalent Cation Exchange Membrane (MCEM);
the FCDI device comprises a cathode flowing electrode chamber, a monovalent cation exchange membrane, a desalting chamber, an anion exchange membrane and an anode flowing electrode chamber which are sequentially arranged in parallel, wherein an anode flowing electrode is arranged in the anode flowing electrode chamber, and a cathode flowing electrode is arranged in the cathode flowing electrode chamber;
the recovery and purification method specifically comprises the following steps:
supplying wastewater to be treated to the desalting chamber, applying voltage to the anode flowing electrode chamber and the cathode flowing electrode chamber, and making anions pass through the anion exchange membrane to enter the anode flowing electrode chamber by electro-adsorption effect and contain NH4 +Passes through the monovalent cation exchange membrane into the cathode flow electrode chamber, and in the cathode flow electrode chamber, promotes NH on the electrode using the cathode Faraday reaction4 +To NH3And then the ammonia water is converted and desorbed, so that the high-purity ammonia water is obtained.
Wherein, the monovalent cation exchange membrane can isolate anions on one hand and can effectively prevent Ca in wastewater to be treated on the other hand2+、Mg2+、Fe3+Plasma enters the cathode chamber, thereby effectively reducing scaling.
Furthermore, an anode circulating chamber is arranged outside the anode flowing electrode chamber, and the anode flowing electrode circularly flows between the anode flowing electrode chamber and the anode circulating chamber;
and the cathode flow electrode chamber is provided with a cathode circulation chamber, and the cathode flow electrode circularly flows between the cathode flow electrode chamber and the cathode circulation chamber.
Furthermore, the anode flow electrode and the cathode flow electrode both comprise a conductive agent and a solvent; the conductive agent comprises at least one of activated carbon and carbon black, and the solvent comprises water.
Further, the conductive agent is a mixture of activated carbon and carbon black in a mass ratio of 4:1, and the mass fraction (i.e., carbon content) of the conductive agent in the anode flow electrode or the cathode flow electrode is not more than 10%, preferably not more than 5%, and more preferably 2-5%.
Further, the circulation flow rate of the anode flow electrode or the cathode flow electrode is 20-100 mL/min.
Furthermore, the hydraulic retention time of the wastewater to be treated flowing through the desalting chamber is 0.5-1.5 min.
Further, the recovery and purification method further comprises the following steps: after the anode flow electrode chamber and the cathode flow electrode chamber are applied with forward voltage for charging, the anode flow electrode chamber and the cathode flow electrode chamber are applied with backward voltage for discharging so that Na in the cathode flow electrode chamber+、K+And the monovalent cations are forced back to the desalting chamber, so that the purity of the ammonia water in the cathode flow electrode chamber is improved.
Further, the forward voltage is 1.2-4.5V, and the electrifying time is 75-85 min;
the reverse voltage is 0.1-0.3V, and the electrifying time is 10-30 min.
Further preferably, the recovery and purification method further comprises: and repeating the steps of introducing the coal gasification water, applying the forward voltage and applying the reverse voltage to improve the ammonia water concentration in the cathode flow electrode chamber.
The invention provides a method for recycling ammonia nitrogen in wastewater to be treated (particularly coal gasification grey water) by utilizing a flowing electrode capacitive deionization (FCDI) technology of a coupled Monovalent Cation Exchange Membrane (MCEM), which adopts an FCDI device of the coupled Monovalent Cation Exchange Membrane (MCEM) to treat the wastewater to be treated. Wherein MCEM has effectively slowed down the scale deposit, through simple regulation charge-discharge process, has realized retrieving the ammonia nitrogen in the pending waste water with the form of aqueous ammonia.
Compared with the prior art, the invention has the following characteristics:
1) the invention skillfully utilizes the pH change brought by an independent closed circulation mode: since the anode flow electrode and the cathode flow electrode are circulated in the respective pipes, respectively, the faraday reaction causes the pH of the cathode chamber to increase and the pH of the anode chamber to decrease. When pK is reacheda>At 9.3, NH4 +Is more easily converted into NH3(aq). By simply adjusting the charging and discharging processes, the generation of NH in the charging process is realized3(aq)And the purity of the product is improved in the reverse discharge process. That is, NH is first made by charging FCDI4 +And Na+Migrate to the cathode compartment and NH is driven by the pH rise caused by the Faraday reaction4 +Conversion to NH3(aq)Then discharging reversely to charge Na+The ammonia water is forced back to the desalting chamber, so that the purity of the ammonia water is improved;
2) according to the invention, by optimizing the voltage applied in the charging process to 4.5V, compared with 1.2V, the removal rate and removal efficiency of 4.5V are respectively improved by 23% and 12%, so that the ammonia nitrogen in the effluent meets the standard of industrial wastewater entering municipal sewage pipelines (GB/T31962. sub.2015), and meanwhile, under the charging voltage, carbon particles of the cathode are not oxidized, because the resistance of different CDI components is different, the electrode potential is lower than the applied battery potential difference. That is, the present invention can achieve better treatment effects without sacrificing long-term stability;
3) the invention enables Ca to be generated by arranging a Monovalent Cation Exchange Membrane (MCEM) between a cathode chamber and a desalting chamber2+、Mg2+Plasma can not enter the cathode chamber, so that scaling is effectively inhibited, and long-term stability and treatment effect of the device are ensured. After continuous operation for 6 times, the method still shows high stability, deamination efficiency, recovery efficiency and recoverability are not reduced, and the product purity is improved, which shows that the method can be suitable for recycling ammonia nitrogen by multi-cycle inflow. Therefore, the method for recycling ammonia nitrogen in the gasified ash water by utilizing the flowing electrode capacitive deionization device has the advantages of simple operation, no need of adding chemical agents, high deamination efficiency, good recycling effect, high product purity, effective scale inhibition, low treatment cost, low treatment energy consumption, stable operation and the like, and can be used for recycling ammonia nitrogen in the gasified ash water without increasing the cost or adding chemical agentsThe method realizes the recovery of ammonia nitrogen in the gasified ash water in the form of ammonia water on the premise of no secondary pollution caused by chemical agents and convenience for subsequent treatment, and has very important significance for the development of the coal gasification industry;
4) for the flow electrode, the invention can obtain the best recovery efficiency by optimizing the carbon content of the flow electrode to be not more than 5 percent under the condition, and has higher cost performance: when the carbon content of the flow electrode is 10%, the activated carbon itself adsorbs a large amount of NH3And high carbon content can inhibit Faraday reaction, so that NH in ammonia nitrogen in the cathode chamber4 +The proportion of the ammonia nitrogen is large, so that the ammonia nitrogen is forced out of the cathode chamber during the discharging process, less than 30% of the ammonia nitrogen obtained in the charging process is left in the cathode flow electrode after discharging, and 50% of the ammonia nitrogen can be left in the cathode flow electrode under the condition of 5% of carbon content. Thus, for maximum efficiency and cost savings, the carbon content of the flow electrode of the present invention is preferably ≦ 5%.
Drawings
FIG. 1 is a schematic structural diagram of a Monovalent Cation Exchange Membrane (MCEM) coupled FCDI apparatus used in example 1;
FIG. 2 is a graph showing the change in the concentration of each component when the mobile electrode capacitive deionization apparatus in example 1 recovers ammonia nitrogen from coal gasification ash;
FIG. 3 is the effect of carbon content in the anode flow electrode and the cathode flow electrode on the ammonia nitrogen recovery and purification treatment effect in example 2: (a) NH during charging4 +-N removal rate (charging time 80 min); (b) NH during charging4 +-N average removal rate and average current density; (c) cathode chamber NH at different discharge times3Recovery (discharge time 30 minutes); (d) cathode chamber NH at different discharge times4 +-the mean migration rate of N from the cathodic compartment to the desalination compartment and the maximum pH;
FIG. 4 shows the water NH discharged at different hydraulic retention times in example 33-N(NH4 +-N) concentration contrast plot;
FIG. 5 shows the effect of discharge voltage on ammonia nitrogen recovery and purification in example 4Influence: NH in the cathode chamber4 +/Na+Selectivity;
FIG. 6 shows the effect of discharge voltage on ammonia nitrogen recovery and purification treatment in example 4: the mean migration rate of cations from the cathode compartment back into the desalination chamber;
FIG. 7 shows the effect of discharge voltage on ammonia nitrogen recovery and purification treatment in example 4: per kilogram NH3-N recovered electrical energy consumption.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments.
A method for recycling and purifying ammonia nitrogen through a flow electrode capacitor based on a monovalent cation exchange membrane comprises the step of treating coal gasification grey water by adopting an FCDI device coupled with the Monovalent Cation Exchange Membrane (MCEM).
The FCDI device structure is shown in figure 1, and comprises a cathode flowing electrode chamber 1, a monovalent cation exchange membrane 2, a desalting chamber 3, an anion exchange membrane 4 and an anode flowing electrode chamber 5 which are sequentially arranged in parallel, wherein an anode circulating chamber 6 is further arranged outside the anode flowing electrode chamber 5, an anode flowing electrode circularly flows between the anode flowing electrode chamber and the cathode circulating chamber 6, a cathode circulating chamber 7 is further arranged outside the cathode flowing electrode chamber 1, a cathode flowing electrode circularly flows between the cathode flowing electrode chamber and the cathode flowing electrode, and the circulating flow rate is controlled to be 20-100 mL/min.
Specifically, the anode flow electrode and the cathode flow electrode both comprise a conductive agent and a solvent, wherein the solvent can be water, and the conductive agent comprises at least one of activated carbon and carbon black, and is preferably an activated carbon/carbon black mixture with a mass ratio of 4: 1. The mass fraction of the conductive agent in the anode flow electrode or the cathode flow electrode is not more than 10%, preferably not more than 5%, and more preferably 2 to 5%.
The recovery and purification method specifically comprises the following steps:
1) driving the coal gasification ash water to continuously flow through the desalting chamber 3, and controlling the hydraulic retention time to be 0.5-1.5 min;
2) applying 1.2-4.5V forward voltage to the anode flow electrode chamber 5 and the cathode flow electrode chamber 1, and electrifying for 75-85 min;
by electric attractionThe anion passes through the anion exchange membrane 4 into the anode flow electrode chamber 5 by the action of adsorption, containing NH4 +Passes through the monovalent cation exchange membrane 2 into the cathode flow electrode chamber 1, and in the cathode flow electrode chamber 1, promotes the NH on the electrode by means of the cathode faradaic reaction4 +To NH3Conversion and desorption; and effectively prevents Ca in the gasified ash water by the monovalent cation exchange membrane 22+、Mg2+、Fe3+Plasma enters the cathode chamber, so that scaling is effectively reduced;
3) applying reverse voltage of 0.1-0.3V to the anode flow electrode chamber 5 and the cathode flow electrode chamber 1 for 10-30min (preferably 10-20min, more preferably 15 min); flowing Na in the cathode electrode chamber 1+、K+The monovalent cations are forced back to the desalting chamber 3, thereby improving the purity of the ammonia water in the cathode flowing electrode chamber 1.
As a preferred embodiment, the recovery and purification method of the present invention further comprises: repeating steps 1) to 3) to further increase the concentration of ammonia in the cathode flow electrode chamber 1.
The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.
Example 1:
in this embodiment, an FCDI device is used to recover and purify ammonia nitrogen from coal gasification grey water, wherein the coal gasification grey water is obtained from Ningbo Zhehai refinery, and comprises the following components and concentrations: 241.64 + -16.08 mg/L NH4 +-N，52.60±1.40mg/L Na+，10.63±0.38mg/L K+，353.53±6.92mg/L Ca2+，12.89±0.54mg/L Mg2+，2.53±0.23mg/L Fe3+，0.47±0.81mg/L Mn2+，0.73±1.27mg/L Al3+，476.10±0.09mg/L TOC，pH＝7.60。
The FCDI device structure is shown in figure 1, and comprises a cathode flowing electrode chamber 1, a monovalent cation exchange membrane 2, a desalting chamber 3, an anion exchange membrane 4 and an anode flowing electrode chamber 5 which are sequentially arranged in parallel, wherein an anode circulating chamber 6 is further arranged outside the anode flowing electrode chamber 5, an anode flowing electrode circularly flows between the anode flowing electrode chamber and the desalting chamber, a cathode circulating chamber 7 is further arranged outside the cathode flowing electrode chamber 1, and a cathode flowing electrode circularly flows between the cathode flowing electrode chamber and the cathode circulating chamber. Wherein a monovalent cation exchange membrane (CIMS, Astom, Japan) and an anion exchange membrane (1201, Hangzhou environmental protection technology, China) are used for selectively permeating ions and separating water inflow and flowing electrodes.
The anode flow electrode and the cathode flow electrode both use water as a solvent, an activated carbon/carbon black mixture with a mass ratio of 4:1 as a conductive agent, and the carbon content of the suspension is controlled to be 5%. The conductive agent can be prepared by the following method: and (3) weighing 40g of active carbon and 10g of carbon black, adding the active carbon and the carbon black into 950mL of water, and uniformly mixing the active carbon and the carbon black by magnetic stirring to obtain the mobile electrode. Wherein the activated carbon is YEC-8A type activated carbon (Fuzhou Yihuan carbon Co., Ltd.); the carbon black used was Cabot Vulcan XC-72 type conductive carbon black (CABOT, USA).
The recovery and purification method specifically comprises the following steps:
1) continuously and unidirectionally pumping the coal gasification grey water into a desalting chamber 3 through a peristaltic pump, and controlling the hydraulic retention time to be 1.2 min; at the same time, the anode flowing electrode and the cathode flowing electrode are respectively and independently circulated between the anode flowing electrode chamber 5 and the anode circulating chamber 6 and between the cathode flowing electrode chamber 1 and the cathode circulating chamber 7 at the flow rate of 50 mL/min;
2) after the conductivity is stable, applying 4.5V forward voltage to the collector plates in the anode flowing electrode chamber 5 and the cathode flowing electrode chamber 1, and entering an ammonia water production stage, wherein the electrifying time is 80 min;
the anions are caused to pass through the anion exchange membrane 4 by electro-adsorption into the anode flow electrode compartment 5, containing NH4 +Passes through the monovalent cation exchange membrane 2 into the cathode flow electrode chamber 1, and in the cathode flow electrode chamber 1, promotes the NH on the electrode by means of the cathode faradaic reaction4 +To NH3Conversion and desorption; simultaneously effectively prevents Ca in the gasified ash water through the monovalent cation exchange membrane 22+、Mg2+、Fe3+Plasma enters the cathode chamber and is thus effectiveScale formation is slowed down;
3) reverse electrification, namely applying reverse voltage of 0.2V to the current collecting plates in the anode flowing electrode chamber 5 and the cathode flowing electrode chamber 1, wherein the electrification time is 15 min; flowing Na in the cathode electrode chamber 1+、K+The monovalent cations are forced back to the desalting chamber 3, thereby improving the purity of the ammonia water in the cathode flowing electrode chamber 1.
As shown in FIG. 2, the concentration of various ions and TOC in the effluent from the cathode flow electrode and the desalination chamber varies with the treatment time. It can be seen from the figure that when the method in the embodiment is used for recovering ammonia nitrogen in coal gasification ash water, the effluent state of the desalting chamber gradually tends to be stable in the charging process. 81.0% NH4 +-N、82.5％Na+、71.3％Ca2+、43.5％K+、48.7％Mg2+And 71.3% TOC was removed. After 15 minutes of discharge, 33.8% of ammonia water with the purity of 64.6% is harvested in the cathode chamber in the form of ammonia water, the final concentration reaches more than 170mg/L, and other competitive cations of the actual wastewater have only extremely low Na concentration+And K+And (4) remaining. The monovalent cation exchange membrane effectively blocks hardness ions from entering the cathode compartment. The average energy consumption for ammonia recovery and water treatment was 16.2kWh/kg N and 4.19kWh/m, respectively3And (3) water.
In conclusion, the method for recovering ammonia nitrogen from coal gasification ash water by using the flowing electrode capacitive deionization (FCDI) technology of the coupled Monovalent Cation Exchange Membrane (MCEM) has the advantages of simple operation, no need of chemical agent addition, high deamination efficiency, good recovery effect, high product purity, effective scale inhibition, low treatment cost, low treatment energy consumption, stable operation and the like, can realize the recovery of ammonia nitrogen from coal gasification ash water in the form of ammonia water on the premise of not increasing the cost, adding chemical agent, causing no secondary pollution and facilitating subsequent treatment, and has very important significance for the development of the coal gasification industry.
Example 2:
the present example examined the influence of the carbon content (activated carbon/carbon black mass ratio 4:1) in the anode flow electrode and the cathode flow electrode on the ammonia nitrogen recovery and purification treatment effect, wherein,the carbon content was 2.5, 5, 10 wt%, and the discharge time was 30 minutes. The inlet water is simulated coal gasification grey water and adopts super pure NH4Cl、CaCl2NaCl and deionized water, and the concentration of the specific components is as follows: 240mg/L NH4 +-N，370mg/L Ca2+，70mg/L Na+And the pH value is 7.60. The rest of the process conditions were the same as in example 1, and the results are shown in fig. 3, and it can be seen from fig. 3a and 3b that the greater the carbon content, the better the charging process, regardless of the removal rate or removal rate, due to the higher carbon content, the highly interconnected particle network is formed in the flow electrode, the resistance of the system is reduced, and the removal efficiency of the capacitive deionization technology to ions is proportional to the current. The effect is rather poor in the reverse-looking discharge phase, with a higher carbon content (FIG. 3c), on the one hand because the activated carbon adsorbs NH3On the other hand, the pH of the cathode compartment was lower at 10% (fig. 3d), the lower the pH, NH, calculated according to the software minteQ3The smaller the proportion of (A), the more NH4 +Is forced out of the cathode chamber. Thus, the optimum carbon content in the present system is 5%.
Example 3:
in this embodiment, the influence of the Hydraulic Retention Time (HRT) of the coal gasification grey water in the desalting chamber 3 on the ammonia nitrogen recovery and purification treatment effect is examined, wherein the hydraulic retention time is 0.5, 1, 1.2 and 1.5 minutes respectively. And reverse discharging for 15 minutes. The feed water used was the same as the simulated coal gasification grey water of example 2, and the rest of the process conditions were the same as in example 1, and as shown in FIG. 4, it can be seen from the table in FIG. 4 that the increase in ammonia nitrogen removal rate showed a tendency of HRT dependence. In China, the industrial wastewater needs to be pretreated to meet the subsequent biochemical treatment regulations, wherein the ammonia nitrogen concentration is controlled within 45mg/L (GB/T31962-2015). Therefore, it is more appropriate to select a larger HRT, but in consideration of the process efficiency, an HRT of 1.2 minutes is optimal.
Example 4:
the present example examines the effect of discharge voltage (i.e. reverse voltage in step 3) on the ammonia nitrogen recovery and purification treatment effect, wherein the charge voltage is 4.5V, and the reverse discharge voltage is 0.1V, 0.2V, and 0.3V, respectively. What is needed isThe same inlet water as used for the simulated coal gasification grey water of example 2 and the same process conditions as in example 1 resulted in the same result as shown in FIG. 5, and it can be seen from FIG. 5 that the charging voltage of 0.2V exhibited a higher NH after 15 minutes of charging4 +/Na+And the ammonia water with higher purity is obtained. Wherein NH4 +/Na+The selectivity calculation formula of (a) is:
in the formula (I), the compound is shown in the specification,
the concentration of ammonia nitrogen in the cathode chamber,
the concentration of the ammonia nitrogen in the inlet water,
the concentration of sodium ions in the cathode chamber is,
is the feed water sodium ion concentration.
This phenomenon can be explained by the mean migration rate of the cations from the cathodic compartment back into the desalination chamber (fig. 6). The repulsive force due to 0.1V is too small, so the rate of migration of cations back into the desalting chamber is small, Na+Still largely stays in the cathode chamber. The invention makes NH by electrifying FCDI4 +And Na+Migrate to the cathode compartment and NH is driven by the pH rise caused by the Faraday reaction4 +Conversion to NH3(aq)Then discharging reversely to charge Na+Drives the ammonia water back to the desalting chamber, thereby improving the purity of the ammonia water. However, the pH value is remarkably reduced due to the excessively high discharge voltage, and the pH value of the cathode chamber is reduced from 11.3 to 10.2 within 30min under the discharge voltage of 0.3V; the pH of the cathode chamber is reduced to 10.7 within 30min under the discharge voltage of 0.2V; at a discharge voltage of 0.1V, the cathode compartment pH decreased by only 0.4 within 30min, resulting in partial NH3(aq)Conversion to NH4 +In view of NH4 +Hydration radius ratio of (Na)+Small, 0.3V can cause the loss of ammonia nitrogen. In addition, as can be seen from fig. 7, the longer the discharge time, the higher the energy consumption of the electric energy for recovering ammonia nitrogen. Because the longer the discharge time, the more H will be generated by the Faraday reaction+There will be more NH3(aq)Conversion to NH4 +And in this system, Na+The concentration of the ammonia nitrogen is lower, and the amount of the ammonia nitrogen is far greater than that of Na+In this case, NH4 +More tend to be forced back into the desalination chamber. After the discharge time is longer than 15 minutes, the ammonia nitrogen concentration in the cathode chamber is obviously reduced, so that the 0.2V discharge time for 15 minutes is optimal from the aspects of electric energy consumption required by unit ammonia nitrogen recovery and ammonia nitrogen recovery rate.
The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.
Claims (10)
1. A flow electrode capacitance ammonia nitrogen recovery purification method based on a monovalent cation exchange membrane is characterized in that an FCDI device comprises a cathode flow electrode chamber (1), a monovalent cation exchange membrane (2), a desalting chamber (3), an anion exchange membrane (4) and an anode flow electrode chamber (5) which are sequentially arranged in parallel, wherein an anode flow electrode is arranged in the anode flow electrode chamber (5), and a cathode flow electrode is arranged in the cathode flow electrode chamber (1);
the recovery and purification method comprises the following steps:
introducing wastewater to be treated into a desalting chamber (3), and applying voltage to an anode flowing electrode chamber (5) and a cathode flowing electrode chamber (1) to make anions pass through an anion exchange membrane (4) to enter the anode flowing electrode chamber (5) and contain NH4 +Passes through the monovalent cation exchange membrane (2) into the cathode flow electrode chamber (1) and causes NH to form4 +Conversion to NH3To obtain high-purity ammonia water.
2. The method for recovering and purifying ammonia nitrogen through the flowing electrode capacitor based on the monovalent cation exchange membrane as claimed in claim 1, wherein an anode circulating chamber (6) is arranged outside the anode flowing electrode chamber (5), and the anode flowing electrode circularly flows between the anode flowing electrode chamber (5) and the anode circulating chamber (6);
and a cathode circulating chamber (7) is arranged outside the cathode flowing electrode chamber (1), and the cathode flowing electrode circularly flows between the cathode flowing electrode chamber (1) and the cathode circulating chamber (7).
3. The method for recovering and purifying ammonia nitrogen through the flowing electrode capacitor based on the monovalent cation exchange membrane as claimed in claim 1 or 2, wherein the anode flowing electrode and the cathode flowing electrode both comprise a conductive agent and a solvent; the conductive agent comprises at least one of activated carbon and carbon black, and the solvent comprises water.
4. The method for recovering and purifying the flowing electrode capacitance ammonia nitrogen based on the monovalent cation exchange membrane as claimed in claim 3, wherein the conductive agent is a mixture of activated carbon and carbon black in a mass ratio of 4: 1.
5. The method for recovering and purifying ammonia nitrogen through the flowing electrode capacitor based on the monovalent cation exchange membrane as claimed in claim 4, wherein the mass fraction of the conductive agent in the anode flowing electrode or the cathode flowing electrode is not more than 10%.
6. The method for recovering and purifying ammonia nitrogen through the flowing electrode capacitor based on the monovalent cation exchange membrane as claimed in claim 2, wherein the circulating flow rate of the anode flowing electrode or the cathode flowing electrode is 20-100 mL/min.
7. The method for recovering and purifying ammonia nitrogen through the flowing electrode capacitance based on the monovalent cation exchange membrane as claimed in claim 1, wherein the hydraulic retention time of the wastewater to be treated flowing through the desalting chamber (3) is 0.5-1.5 min.
8. The method for recovering and purifying ammonia nitrogen based on the flowing electrode capacitance of the monovalent cation exchange membrane as claimed in claim 1, wherein the method for recovering and purifying ammonia nitrogen further comprises: after positive voltage is applied to the anode flowing electrode chamber (5) and the cathode flowing electrode chamber (1), reverse voltage is applied to the anode flowing electrode chamber (5) and the cathode flowing electrode chamber (1) again to remove cations in the cathode flowing electrode chamber (1) and obtain high-purity ammonia water.
9. The method for recycling and purifying the ammonia nitrogen through the flowing electrode capacitor based on the monovalent cation exchange membrane as claimed in claim 8, wherein the forward voltage is 1.2-4.5V, and the electrifying time is 75-85 min;
the reverse voltage is 0.1-0.3V, and the electrifying time is 10-30 min.
10. The method for recovering and purifying ammonia nitrogen based on the flowing electrode capacitance of the monovalent cation exchange membrane as claimed in claim 8, wherein the method for recovering and purifying ammonia nitrogen further comprises: the operation steps of introducing the coal gasification water, applying the forward voltage and applying the reverse voltage are repeated to improve the concentration of the ammonia water in the cathode flow electrode chamber (1).
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| CN115849515A (en) * | 2022-12-02 | 2023-03-28 | 广东工业大学 | Roll type device for electrochemically recovering ammonia and method for recovering ammonia |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPH06315685A (en) * | 1993-05-06 | 1994-11-15 | Hoshizaki Electric Co Ltd | Electrolysis for salt water |
| US20160002082A1 (en) * | 2013-03-07 | 2016-01-07 | Saltworks Technologies Inc. | Multivalent ion separating desalination process and system |
| CN111655629A (en) * | 2017-12-04 | 2020-09-11 | 新南创新有限公司 | Ammonia nitrogen recovery equipment and method |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06315685A (en) * | 1993-05-06 | 1994-11-15 | Hoshizaki Electric Co Ltd | Electrolysis for salt water |
| US20160002082A1 (en) * | 2013-03-07 | 2016-01-07 | Saltworks Technologies Inc. | Multivalent ion separating desalination process and system |
| CN111655629A (en) * | 2017-12-04 | 2020-09-11 | 新南创新有限公司 | Ammonia nitrogen recovery equipment and method |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115849515A (en) * | 2022-12-02 | 2023-03-28 | 广东工业大学 | Roll type device for electrochemically recovering ammonia and method for recovering ammonia |
| CN115849515B (en) * | 2022-12-02 | 2023-06-16 | 广东工业大学 | Rolling type device for electrochemically recycling ammonia and ammonia recycling method |
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