CN116514329B - Method and system for synchronously separating and increasing carbon and nitrogen in sewage - Google Patents

Method and system for synchronously separating and increasing carbon and nitrogen in sewage Download PDF

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CN116514329B
CN116514329B CN202310575526.1A CN202310575526A CN116514329B CN 116514329 B CN116514329 B CN 116514329B CN 202310575526 A CN202310575526 A CN 202310575526A CN 116514329 B CN116514329 B CN 116514329B
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sewage
anode
cathode
electrochemical
ammonia
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CN116514329A (en
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周杰钦
马金星
何佳洲
杨奎
张万瑞
张众
罗亮
林骏培
祖道远
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Guangdong University of Technology
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    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00Multistage treatment of water, waste water or sewage
    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07CACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/42Separation; Purification; Stabilisation; Use of additives
    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25BELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00Electrolytic production of inorganic compounds or non-metals
    • C25B1/01Products
    • C25B1/27Ammonia
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/001Processes for the treatment of water whereby the filtration technique is of importance
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/30Treatment of water, waste water, or sewage by irradiation
    • C02F1/32Treatment of water, waste water, or sewage by irradiation with ultraviolet light
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/42Treatment of water, waste water, or sewage by ion-exchange
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/46Treatment of water, waste water, or sewage by electrochemical methods
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/48Treatment of water, waste water, or sewage with magnetic or electric fields
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/72Treatment of water, waste water, or sewage by oxidation
    • C02F1/76Treatment of water, waste water, or sewage by oxidation with halogens or compounds of halogens
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/72Treatment of water, waste water, or sewage by oxidation
    • C02F1/78Treatment of water, waste water, or sewage by oxidation with ozone
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/42Treatment of water, waste water, or sewage by ion-exchange
    • C02F2001/422Treatment of water, waste water, or sewage by ion-exchange using anionic exchangers
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00Nature of the contaminant
    • C02F2101/10Inorganic compounds
    • C02F2101/16Nitrogen compounds, e.g. ammonia
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00Nature of the contaminant
    • C02F2101/30Organic compounds
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2303/00Specific treatment goals
    • C02F2303/04Disinfection
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00Biological treatment of water, waste water, or sewage
    • C02F3/02Aerobic processes
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00Biological treatment of water, waste water, or sewage
    • C02F3/02Aerobic processes
    • C02F3/12Activated sludge processes
    • C02F3/1236Particular type of activated sludge installations
    • C02F3/1268Membrane bioreactor systems
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00Biological treatment of water, waste water, or sewage
    • C02F3/28Anaerobic digestion processes

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
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  • Hydrology & Water Resources (AREA)
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Abstract

The invention provides a method and a system for synchronously separating and high-valued carbon and nitrogen in sewage, belonging to the fields of environmental protection and sewage treatment. The method comprises the following steps: hydrolyzing, acidifying and filtering sewage, and then placing the sewage in an electric field to enable ions with negative charges to move to an anode and ions with positive charges to move to a cathode; SCFAs volatile gas and ammonia gas are respectively obtained through electrochemical reaction; enabling volatile gas to react with alkaline absorption liquid, enabling ammonia gas to react with acidic absorption liquid, and respectively obtaining organic acid feed liquid and ammonia feed liquid; finally, the regenerated water is obtained after rapid biological treatment and disinfection. The invention directly recovers carbon and nitrogen elements from sewage in the form of high-purity organic acid and ammonia, realizes directional conversion and fractional purification of resources in the sewage, and achieves the purposes of sewage treatment regeneration and recycling synchronously.

Description

Method and system for synchronously separating and increasing carbon and nitrogen in sewage
Technical Field
The invention relates to the field of environmental protection and sewage treatment, in particular to a method and a system for treating carbon-nitrogen synchronous electrochemical separation and high-value conversion in sewage.
Background
At present, the paths for separating and recovering carbon and nitrogen resources from sewage can be divided into the following two types: (1) And in the front-end recovery mode, organic matters are directly enriched and recovered from sewage, and meanwhile, the organic load of a subsequent treatment unit is reduced, and the sludge yield is reduced. The application number CN201210012247.6 discloses a low-energy-consumption sewage treatment process and a device based on carbon source recovery, wherein the process firstly adsorbs and enriches organic carbon sources in sewage through a pretreatment unit, and effluent is subjected to independent materialized dephosphorization and denitrification treatment; concentrating the discharged sludge, performing anaerobic fermentation, and recovering methane. (2) The post-positioned recovery mode, namely a process for recovering methane or ammonia by fermenting residual sludge generated in the sewage treatment process, such as CN201811113595.6 discloses a device and a process for coupling ethanol fermentation of corn straw with anaerobic co-digestion of municipal sludge.
However, from the viewpoints of energy loss and recovery efficiency, the conventional recycling process and system have problems such as complicated operation units, low recovery rate of carbon and nitrogen elements, low purity of the product (< 90%), and the like. Because carbon and nitrogen recovery does not have resource urgency as phosphorus recovery, the carbon and nitrogen recovered from sewage has higher requirements on the type and quality of the carbon and nitrogen to ensure that the recovered carbon and nitrogen product has higher market acceptance will so as to avoid the recovered product becoming a new pollutant.
In addition, in the prior art, when the product obtained after sewage treatment is further treated, a catalytic conversion and degradation method with high energy consumption is generally adopted. For example, CN114634953a provides an organic garbage treatment method and an energy utilization system thereof, which require electrocatalytic conversion of short-chain fatty acids obtained after garbage treatment, and then can be further removed; CN106799393a provides a low temperature desorption device that requires electrolysis of the recovered water to form hydrogen and oxygen. The technology has complex process, high catalyst cost, long reaction time and poor recovery effect, and does not meet the requirement of sustainable development.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a treatment method and a system for synchronous electrochemical separation and high-value conversion of carbon and nitrogen in sewage. According to the invention, through the coupling of short Cheng Shuijie acidification and electrochemical membrane stripping processes, carbon and nitrogen elements are directly recovered from sewage in the form of high-purity organic acid and ammonia, so that the purposes of directional conversion and fractional purification of resources in the sewage and synchronous sewage treatment regeneration and recycling are achieved.
The technical scheme of the invention is as follows:
the invention firstly provides a treatment method for synchronous electrochemical separation and high-value conversion of carbon and nitrogen in sewage, which comprises the following steps:
s1: hydrolyzing and acidifying sewage, converting the solubility and colloid organic matters into short chain fatty acid SCFAs, and simultaneously precipitating and removing inorganic particles;
s2: filtering the sewage obtained in the step S1 to remove suspended particles;
s3: placing the filtered sewage obtained in the step S2 in an electric fieldThe negatively charged ions move to the anode, the positively charged ions move to the cathode, and the treated sewage is obtained after the charged pollutants/ions are removed; the negatively charged ions comprise SCFAs, cl - The positively charged ions comprise NH 4 + 、Na + The method comprises the steps of carrying out a first treatment on the surface of the At the same time the anode surface generates H + OH is generated on the surface of the cathode -
S4: the electrochemical reaction in the step S3 is adopted to reduce the pH value of the anode liquid near the anode to 2-3, and the pH value of the cathode liquid near the cathode to 10-12, and the interface Joule heat generated by the electrochemical reaction is adopted to raise the temperature of the electrode interface to 40-80 ℃ to obtain SCFAs volatile gas A respectively 1 Ammonia A 2
S5: volatilizing the SCFAs obtained in the step S4 to obtain a gas A 1 Reacting with alkaline absorption liquid to make ammonia A 2 Reacting with an acid absorption liquid to obtain an organic acid feed liquid and an ammonia feed liquid respectively; the purity of the organic acid feed liquid is not less than 99%;
s6: and (3) carrying out rapid biological treatment and disinfection on the treated sewage obtained in the step (S3) to obtain reclaimed water.
Preferably, in step S2, the back flushing liquid is mixed with the inlet water during filtering and then enters step S1 for treatment.
Preferably, in step S3, the electric field has a current density of 1-100A/m 2 The method comprises the steps of carrying out a first treatment on the surface of the The residence time of the sewage in the electric field is 20-360 min.
Preferably, in the step S5, the alkaline absorption liquid is any one of NaOH and KOH solution, and the concentration is 1-10mol/L; the acidic absorption liquid is any one of sulfuric acid, hydrochloric acid, nitric acid, carbonic acid or phosphoric acid, and the concentration is 1-10mol/L.
Further, in steps S4 and S5, the anode and alkaline absorption liquid, and the cathode and acidic absorption liquid of the electrochemical recoverer are separated by a hydrophobic membrane, and are not in direct contact, and only SCFAs volatilize gas A 1 Ammonia A 2 Can permeate through the hydrophobic membrane and respectively react with alkaline absorption liquid and acidic absorption liquid.
The invention also provides a treatment system for synchronous electrochemical separation and high-value conversion of carbon and nitrogen in sewage, which is operated based on the treatment method for synchronous electrochemical separation and high-value conversion of carbon and nitrogen in sewage;
the system comprises the following devices connected in sequence: a hydrolysis acidification tank (1), a separation filter (2), an electrochemical recoverer (3), a rapid biological treatment tank (6), a sterilizer (7) and a regeneration water tank (8);
the effluent of the separation filter (2) is connected to the middle water inlet of the electrochemical recoverer (3); the electrochemical recoverer (3) is provided with an anode (10) and a cathode (11) respectively at two sides of the middle water inlet;
the electrochemical recoverer (3) is externally connected with an organic acid recovery tank (4) and an ammonia recovery tank (5) at the outer ends of the anode (10) and the cathode (11) in two directions respectively;
the hydrolysis acidification tank (1) is used for carrying out hydrolysis acidification on sewage, converting organic matters in solubility and colloid state into SCFAs, and simultaneously removing inorganic particles by precipitation;
the separation filter (2) is used for removing suspended particulate matters in the sewage;
the electrochemical recoverer (3) is used for directly recovering carbon and nitrogen elements from sewage in the form of organic acid and ammonia;
the organic acid recovery tank (4) is used for storing alkaline absorption liquid and organic acid feed liquid obtained after anode generation and absorption; the ammonia recovery tank (5) is used for storing an acidic absorption liquid and ammonia liquid obtained after cathode generation and absorption;
the rapid biological treatment tank (6) is used for deeply removing carbon and nitrogen pollutants remained in the sewage;
the sterilizer (7) is used for sterilizing the regenerated water;
the regeneration water tank (8) is used for storing regeneration water;
each of the above devices is connected by a pipe.
Preferably, a precipitation and clarification device (9) is arranged in the hydrolysis acidification tank (1) to effectively separate the hydrolyzed and acidified sewage from inorganic particulate matters.
One of the anode and cathode schemes is: the anode (10) and the cathode (11) are made of one or more materials selected from carbon materials and metal oxides,
another scheme of the anode and the cathode is as follows: the anode (10) and the cathode (11) are made of granular substances with the particle size of 1-1000 mu m, and are suspended in 0.01-1mol/L electrolyte solution;
the material of the particulate matter includes but is not limited to Sb-SnO 2 、Ti 4 O 7
The electrolyte includes, but is not limited to, naCl, na 2 SO 4 、NaNO 3 、KCl、K 2 SO 4 、KNO 3 Any one of the following.
Further, the anode (10) of the electrochemical recoverer (3) is separated from the middle water inlet by an anion exchange membrane (12);
the cathode (11) of the electrochemical recoverer (3) is separated from the middle water inlet by a cation exchange membrane (13);
the alkaline absorption liquid in the organic acid recovery tank (4) and the organic acid feed liquid obtained after the generation and absorption of the anode (10) are separated from the anode (10) of the electrochemical recoverer (3) by a hydrophobic air film (15) after passing through a pipeline (14);
the acidic absorption liquid in the ammonia recovery tank (5) and the ammonia feed liquid obtained after the generation and absorption of the cathode (11) are separated from the cathode (11) of the electrochemical recoverer (3) by a hydrophobic gas film (15) after passing through a pipeline (14).
Further, the sewage in step S1 includes any one of domestic sewage, urine and cultivation wastewater.
The concentration of organic matters in the sewage is 150-10000 mg/L, for example, 200 mg/L, 300 mg/L, 500 mg/L, 900 mg/L, 1000 mg/L, 2000 mg/L, 5000 mg/L or 8000 mg/L; more preferably 200-5000 mg/L; the concentration of the organic matters is calculated according to Chemical Oxygen Demand (COD).
The concentration of ammonia nitrogen in the sewage is 30-5000 mg/L, for example, 50 mg/L, 100 mg/L, 200 mg/L, 500 mg/L, 1000 mg/L, 2000 mg/L, 2400 mg/L or 3000 mg/L; more preferably 100-4000 mg/L; the ammonia nitrogen concentration is calculated by N element.
Preferably, in step S1, the residence time of the hydrolytic acidification of the wastewater is determined by the organic matter concentration load and is in the range of 0.5 to 12 h, more preferably 1 to 6 h.
Preferably, in step S2, the filtering removes suspended particulate matter greater than 1 μm from the wastewater.
Preferably, in step S3, the current density of the electric field may be 1A/m 2 、5 A/m 2 、10 A/m 2 、20 A/m 2 、50 A/m 2 Or 100A/m 2 More preferably 20-80A/m 2
Preferably, in step S3, the residence time of the wastewater in the electric field may be 30 min, 60 min, 120min or 240 min, more preferably 30-120 min.
More preferably, in step S5, the alkaline absorption liquid is a NaOH solution, and the concentration is 2-5 mol/L.
More preferably, in step S5, the acidic absorption liquid is sulfuric acid, and the concentration is 2-5 mol/L.
Preferably, the separation filter (2) comprises any one of a cloth filter, a rapid filter, a V-shaped filter and a membrane filter.
Preferably, when the anode (10) and the cathode (11) are made of metal oxide, the material includes but is not limited to Sb-SnO 2 、Ti 4 O 7
Preferably, the rapid biological treatment tank (6) comprises any one of a biological aerated filter, an aerobic membrane bioreactor and a moving bed bioreactor.
Preferably, the sterilizer (7) comprises any one of an ultraviolet sterilizer, a chlorination sterilizer, an ozone sterilizer and an electric sterilizer.
Preferably, the types of the anion exchange membrane (12) include, but are not limited to, quaternary ammonium type, polysulfone type, brominated poly-2, 6-dimethyl-p-benzene oxide, polyketone type, polybenzimidazole type anion exchange membrane; the kind of the cation exchange membrane (13) includes, but is not limited to, sulfonic acid group, phosphoric acid group, carboxylic acid group, phenol group, and arsenic group and selenium group cation exchange membranes.
Preferably, the material of the hydrophobic membrane (15) includes, but is not limited to, polypropylene, polytetrafluoroethylene or polytetrafluoroethylene, and the pore size thereof is 0.02-0.45 μm.
The beneficial technical effects of the invention are as follows:
1. in the process of the invention, the sewage is>80% of organic matters are converted into SCFAs with higher added value, about 100% of nitrogen is hydrolyzed into ammonia nitrogen/ammonium, and anions comprising the SCFAs and cations comprising the ammonia nitrogen/ammonium in the sewage are respectively adsorbed to an anode and a cathode by an electrochemical method; in situ generation of H at anode by electrochemical reaction + Acidifying and generating OH at cathode Alkalizing, raising the electrode interface temperature to 40-80 ℃ by utilizing Joule heat generated by the electrode under the electrochemical action, promoting the volatilization of SCFAs and ammonia nitrogen/ammonium at the respective electrode interfaces, and ensuring the separation, purification and recovery of carbon and nitrogen.
2. In the process of the invention, cl is added by the anode pair - 、SO 4 2- Strong electrostatic adsorption of isociste anions, and maintaining pH of anode liquid in 2-3 interval, so as to avoid interference of hetero ions to SCFAs interface volatilization and ensure purity of SCFAs in organic acid liquid>99% purity of ammonia nitrogen in ammonia feed liquid>99.9%. Can realize the recycling recovery of nutrients, and the energy substances in the sewage are recovered in high-quality forms such as organic acid feed liquid, ammonia feed liquid and the like.
3. In the process, the concentration of the products in the organic acid feed liquid and the ammonia feed liquid formed by the reaction of the alkaline absorption liquid and the acidic absorption liquid is high, and the two feed liquids can be directly used for industrial production, so that economic benefits are generated; the sewage treated by the process can reach the national first-grade A discharge standard stably. The invention can efficiently treat low-concentration organic sewage in an anaerobic way under the normal temperature condition, and can maximally realize energy conservation and consumption reduction of sewage treatment. Greatly improves the high efficiency and economy of the electrochemical recovery of ammonia and promotes the development of the field of sewage electrochemical resource recovery.
Drawings
The embodiment of the invention of fig. 1 is used in a short Cheng Shuijie acidification and electrochemical membrane gas recovery flow scheme, it being noted that this figure is not the only implementation of the invention.
The corresponding relation between the names of all the components and the numbers of the drawings is as follows:
1-hydrolytic acidification tank, 2-separation filter, 3-electrochemical recoverer, 4-organic acid recovery tank, 5-ammonia recovery tank, 6-rapid biological treatment tank, 7-sterilizer, 8-regeneration water tank, 9-precipitation and clarification device, 10-anode, 11-cathode, 12-anion exchange membrane, 13-cation exchange membrane, 14-pipeline and 15-hydrophobic gas film.
Detailed Description
The present invention will be described in detail below with reference to the drawings and examples. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1:
1. the embodiment firstly provides a treatment system for synchronous electrochemical separation and high-value conversion of carbon and nitrogen in sewage, which comprises the following devices connected in sequence: a hydrolytic acidification tank 1, a separation filter 2, an electrochemical recoverer 3, a rapid biological treatment tank 6, a sterilizer 7 and a regeneration water tank 8.
Wherein, the hydrolysis acidification tank 1 is internally provided with a precipitation and clarification device 9, so that the hydrolyzed and acidified sewage is separated from inorganic particles with high efficiency.
The effluent of the separation filter 2 is connected to a water inlet positioned at the middle position of the bottom of the electrochemical recoverer 3; the electrochemical recoverer 3 is provided with an anode 10 and a cathode 11 respectively at two sides of the water inlet; and the water inlet is separated from the anode 10 by an anion exchange membrane 12 and from the cathode 11 by a cation exchange membrane 13;
wherein the anode 10 is made of graphite, the cathode 11 is made of graphite, the anion exchange membrane 12 is a quaternary ammonium type anion exchange membrane, and the cation exchange membrane 13 is a sulfonic acid type cation exchange membrane.
The electrochemical recoverer 3 is respectively externally connected with an organic acid recovery tank 4 and an ammonia recovery tank 5 above the liquid level at the outermost ends of the anode 10 and the cathode 11 in two directions; both recovery tanks are connected to the liquid level by respective pipes 14.
Meanwhile, a hydrophobic gas film 15 is provided under the respective pipes 14 in the vertical direction, and the anode 10, the cathode 11 are separated from the liquid under the respective pipes 14 by the hydrophobic gas film 15, respectively. Wherein the hydrophobic air film 15 is made of polytetrafluoroethylene, and has a pore size of 0.45 μm.
The rapid biological treatment tank 6 is a biological aerated filter, and the sterilizer 7 is a chlorine sterilizer.
2. The embodiment also provides a treatment method for synchronous electrochemical separation and high-value conversion of carbon and nitrogen in sewage based on the system.
The sewage to be treated in this example is urine, the composition is cod=900 mg/L, ammonia nitrogen (NH 3 -N)=2400 mg/L。
The specific treatment process comprises the following steps:
s1: hydrolyzing and acidifying the sewage in a hydrolysis acidification tank 1 to convert the organic matters in the solubility and colloid state into Short Chain Fatty Acids (SCFAs) and simultaneously precipitate and remove inorganic particles; the residence time for hydrolytic acidification was 1.0 h.
S2: the sewage obtained in the step S1 is filtered by a separation filter 2, and suspended particles larger than 1 mu m in the sewage are removed. And (3) mixing the back flushing liquid and the inlet water during filtering, and then entering the step (S1) for treatment.
S3: and (2) placing the filtered sewage obtained in the step (S2) in an electric field of an electrochemical recoverer (3), wherein negatively charged ions move to an anode (10) through an anion exchange membrane (12), positively charged ions move to a cathode (11) through a cation exchange membrane (13) under the action of the electric field, and removing charged pollutants/ions to obtain the treated sewage.
Wherein the current density of the electric field is 30A/m 2 The residence time of the sewage in the electrochemical recoverer 3 is 90 min, and the electrode interface temperature is increased to 50 ℃ in the equilibrium state.The negatively charged ions comprise SCFAs, cl - Etc., the positively charged ions include NH 4 + 、Na + Etc.
S4: the pH of the anolyte near the anode 10 was reduced to 2.5 and the pH of the catholyte near the cathode 11 was raised to 10.5 by electrochemical reaction to obtain SCFAs volatile gas A, respectively 1 Ammonia A 2 The method comprises the steps of carrying out a first treatment on the surface of the Wherein the raw material in the organic acid recovery tank 4 is 5 mol/L NaOH solution, and the raw material in the ammonia recovery tank 5 is 5 mol/L H 2 SO 4 A solution.
S5: volatilizing the SCFAs obtained in the step S4 to obtain a gas A 1 Reacts with alkaline absorption liquid in the organic acid recovery tank 4 to make ammonia A 2 Reacting with an acid absorption liquid in an ammonia recovery tank 5 to obtain an organic acid feed liquid and an ammonia feed liquid respectively; wherein the purity of the organic acid feed liquid is not less than 99 percent;
the alkaline absorption liquid in the organic acid recovery tank 4 and the organic acid feed liquid generated by the anode 10 are separated from the anode 10 of the electrochemical recoverer 3 by a hydrophobic air film 15 after passing through a pipeline 14; the acidic absorption liquid in the ammonia recovery tank 5 and the ammonia feed liquid generated at the cathode 11 pass through a pipe 14 and are separated from the cathode 11 of the electrochemical recoverer 3 by a hydrophobic membrane 15.
S6: and (3) passing the treated sewage obtained in the step (S3) through a biological aerated filter (6) and a chlorination sterilizer (7) to obtain reclaimed water, and storing the reclaimed water in a reclaimed water tank (8).
3. After the treatment, 80 percent of organic matters (calculated by COD) and 95 percent of ammonia nitrogen (calculated by NH) are recovered from the urine 3 -N), the concentration of SCFAs in the final organic acid recovery tank 4 reaches 5 mol/L, and the concentration of ammonia nitrogen in the ammonia recovery tank 5 reaches 5 mol/L; the total hydraulic retention time in the whole process is 6 h, the COD concentration of the effluent is reduced to 20+/-5 mg/L, and the ammonia nitrogen concentration is reduced to 3+/-1 mg/L.
Example 2:
this example is based on the system and method provided in example 1, except that the anode 10 is Sb-SnO having a particle size of 1 to 200. Mu.m, unlike example 1 2 Particles suspended in 0.1 mol/L Na 2 SO 4 An electrolyte solution; the cathode 11 is Sb-SnO with the grain size of 1-200 mu m 2 Particles suspended in 0.1 mol/L Na 2 SO 4 An electrolyte solution; the anion exchange membrane 12 is a polyketone anion exchange membrane, and the cation exchange membrane 13 is a carboxylic acid group cation exchange membrane;
the raw material in the organic acid recovery tank 4 is 2 mol/L NaOH solution, and the raw material in the ammonia recovery tank 5 is 2 mol/L H 2 SO 4 A solution; the hydrophobic air film is made of polypropylene, and the pore size is 0.22 mu m; the rapid biological treatment tank 6 adopts an aerobic membrane bioreactor, and the sterilizer 7 adopts an ozone sterilizer.
The sewage treated in this example was domestic sewage, and the composition was cod=300 mg/L, ammonia nitrogen (NH 3 -N) =50 mg/L. The hydraulic retention time of the hydrolytic acidification process of step S1 is 0.5 and h, and the current density of the electrochemical recoverer 3 is 20A/m 2 The residence time of the sewage in the electric field is 30 min. The temperature of the electrode interface in the equilibrium state is raised to 45 ℃, the pH of the anolyte near the anode 10 is reduced to 2.6, and the pH of the catholyte near the cathode 11 is raised to 10.4.
After the treatment, 70 percent of organic matters (calculated by COD) and 90 percent of ammonia nitrogen (calculated by NH) are recovered from the domestic sewage 3 -N), the concentration of SCFAs in the final organic acid recovery tank 4 reaches 1mol/L, and the concentration of ammonia nitrogen in the ammonia recovery tank 5 reaches 1 mol/L; the total hydraulic retention time in the whole process is 3 h, the COD concentration of the effluent is reduced to 15+/-2 mg/L, and the ammonia nitrogen concentration is reduced to 2+/-1 mg/L.
Example 3:
this example is based on the system and method provided in example 1, except that the anode 10 is Ti having a particle size of 1 to 500. Mu.m, unlike example 1 4 O 7 Particles suspended in 0.2 mol/L Na 2 SO 4 An electrolyte solution; cathode 11 is Ti with particle size of 1-500 μm 4 O 7 Particles suspended in 0.2 mol/L Na 2 SO 4 An electrolyte solution;
the anion exchange membrane 12 is a polybenzimidazole anion exchange membrane, and the cation exchange membrane 13 is a phosphate cation exchange membrane; the raw material in the organic acid recovery tank 4 is 3 mol/L NaOH solution, and the raw material in the ammonia recovery tank 5 is 3 mol/L H 2 SO 4 A solution; the hydrophobic air film 15 is made of polyvinylidene fluoride, and the pore size is 0.22 mu m; fast growthThe object treatment tank 6 adopts a moving bed bioreactor, and the sterilizer 7 adopts an ultraviolet sterilizer.
The sewage treated in this example is a digestive juice of the cultivation wastewater, and the composition is cod=500 mg/L, ammonia nitrogen (NH 3 -N) =3000 mg/L. The hydraulic retention time of the hydrolytic acidification process of step S1 is 1.5 and h, and the current density of the electrochemical recoverer 3 is 100A/m 2 The residence time of the sewage in the electric field is 90 min. The electrode interface temperature was raised to 65 ℃ at equilibrium, the anolyte pH near the anode 10 was reduced to 2.1, and the catholyte pH near the cathode 11 was raised to 11.4.
After the treatment, 75 percent of organic matters (calculated by COD) and 92 percent of ammonia nitrogen (calculated by NH) are recovered from the digestive juice of the cultivation wastewater 3 -N), the concentration of SCFAs in the final organic acid recovery tank 4 reaches 2 mol/L, and the concentration of ammonia nitrogen in the ammonia recovery tank 5 reaches 3 mol/L; the total hydraulic retention time in the whole process is 8 h, the COD concentration of the effluent is reduced to 40+/-6 mg/L, and the ammonia nitrogen concentration is reduced to 4+/-2 mg/L.
Although the embodiments of the present invention have been disclosed in the foregoing description and drawings, it is not limited to the details of the embodiments and examples, but is to be applied to all the fields of application of the present invention, it will be apparent to those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.

Claims (8)

1. A method for treating carbon-nitrogen synchronous electrochemical separation and high-value conversion in sewage is characterized by comprising the following steps:
s1: hydrolyzing and acidifying sewage, converting the solubility and colloid organic matters into short chain fatty acid SCFAs, and simultaneously precipitating and removing inorganic particles;
s2: filtering the sewage obtained in the step S1 to remove suspended particles;
s3: placing the filtered sewage obtained in the step S2 in an electric field, wherein the sewage is provided with negative pressure under the action of the electric field forceThe electric ions move to the anode, the positively charged ions move to the cathode, and the treated sewage is obtained after the charged pollutants/ions are removed; the negatively charged ions comprise SCFAs, cl - The positively charged ions comprise NH 4 + 、Na + The method comprises the steps of carrying out a first treatment on the surface of the At the same time the anode surface generates H + OH is generated on the surface of the cathode -
S4: the electrochemical reaction in the step S3 is adopted to reduce the pH value of the anode liquid near the anode to 2-3, and the pH value of the cathode liquid near the cathode to 10-12, and the interface Joule heat generated by the electrochemical reaction is adopted to increase the temperature of the electrode interface to 40-80 ℃ to respectively obtain SCFAS volatile gas A 1 Ammonia A 2
S5: volatilizing the SCFAs obtained in the step S4 to obtain a gas A 1 Reacting with alkaline absorption liquid to make ammonia A 2 Reacting with an acid absorption liquid to obtain an organic acid feed liquid and an ammonia feed liquid respectively; the purity of the organic acid feed liquid is not less than 99%;
s6: the treated sewage obtained in the step S3 is subjected to rapid biological treatment and disinfection to obtain reclaimed water;
in step S3, the current density of the electric field is 20-100A/m 2 The method comprises the steps of carrying out a first treatment on the surface of the The residence time of the sewage in the electric field is 30-120min;
in steps S4 and S5, the anode and alkaline absorption liquid, and the cathode and acidic absorption liquid of the electric field are separated by hydrophobic membrane, and are not in direct contact, and only SCFAs volatilize gas A 1 Ammonia A 2 Can permeate through the hydrophobic membrane and respectively react with alkaline absorption liquid and acidic absorption liquid.
2. The method according to claim 1, wherein in step S2, the backwash liquid is mixed with the feed water before proceeding to step S1.
3. The method according to claim 1, wherein in the step S5, the alkaline absorption liquid is any one of NaOH and KOH solution, and the concentration is 1-10mol/L; the acidic absorption liquid is any one of sulfuric acid, hydrochloric acid, nitric acid, carbonic acid or phosphoric acid, and the concentration is 1-10mol/L.
4. A system for simultaneous electrochemical separation and high value conversion of carbon and nitrogen in wastewater, the system being operated based on the method for simultaneous electrochemical separation and high value conversion of carbon and nitrogen in wastewater according to any one of claims 1 to 3;
the system comprises the following devices connected in sequence: a hydrolysis acidification tank (1), a separation filter (2), an electrochemical recoverer (3), a rapid biological treatment tank (6), a sterilizer (7) and a regeneration water tank (8);
the effluent of the separation filter (2) is connected to the middle water inlet of the electrochemical recoverer (3); the electrochemical recoverer (3) is provided with an anode (10) and a cathode (11) respectively at two sides of the middle water inlet;
the electrochemical recoverer (3) is externally connected with an organic acid recovery tank (4) and an ammonia recovery tank (5) at the outer ends of the anode (10) and the cathode (11) in two directions respectively;
the hydrolysis acidification tank (1) is used for carrying out hydrolysis acidification on sewage, converting organic matters in solubility and colloid state into SCFAs, and simultaneously removing inorganic particles by precipitation;
the separation filter (2) is used for removing suspended particulate matters in the sewage;
the electrochemical recoverer (3) is used for directly recovering carbon and nitrogen elements from sewage in the form of organic acid and ammonia;
the organic acid recovery tank (4) is used for storing alkaline absorption liquid and organic acid feed liquid obtained after anode generation and absorption; the ammonia recovery tank (5) is used for storing an acidic absorption liquid and ammonia liquid obtained after cathode generation and absorption;
the rapid biological treatment tank (6) is used for deeply removing carbon and nitrogen pollutants remained in the sewage;
the sterilizer (7) is used for sterilizing the regenerated water;
the regeneration water tank (8) is used for storing regeneration water;
each of the above devices is connected by a pipe.
5. The system according to claim 4, wherein a sedimentation and clarification device (9) is arranged in the hydrolytic acidification tank (1) so as to separate the hydrolyzed and acidified sewage from inorganic particulate matters efficiently.
6. The system of claim 4, wherein the anode (10) and cathode (11) materials include, but are not limited to, one or more of carbon materials and metal oxides.
7. The system according to claim 4, wherein the anode (10) and the cathode (11) are made of granular substances with particle size of 1-1000 μm, and are suspended in 0.01-1mol/L electrolyte solution;
the material of the particulate matter includes but is not limited to Sb-SnO 2 、Ti 4 O 7
The electrolyte includes, but is not limited to, naCl, na 2 SO 4 、NaNO 3 、KCl、K 2 SO 4 、KNO 3 Any one of the following.
8. The system according to claim 4, characterized in that the anode (10) and the central water inlet of the electrochemical recoverer (3) are separated by an anion exchange membrane (12);
the cathode (11) of the electrochemical recoverer (3) is separated from the middle water inlet by a cation exchange membrane (13);
the alkaline absorption liquid in the organic acid recovery tank (4) and the organic acid feed liquid obtained after anode generation and absorption are separated from the anode (10) of the electrochemical recoverer (3) by a hydrophobic air film (15) after passing through a pipeline (14);
the acidic absorption liquid in the ammonia recovery tank (5) and the ammonia feed liquid obtained after the generation and absorption of the cathode (11) are separated from the cathode (11) of the electrochemical recoverer (3) by a hydrophobic gas film (15) after passing through a pipeline (14).
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CN101475276A (en) * 2008-12-31 2009-07-08 莫一平 Treatment process for ferric oxide production wastewater
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