System and method for strengthening sewage treatment and carbon and nitrogen recovery through combination of granulation fluidized bed and capacitive deionization

Abstract

According to the system, a first inlet end of a stirring tank is communicated with sewage and an outlet end of a first dosing barrel respectively, and outlet ends of the stirring tank and a second dosing barrel are both communicated with an inlet end of the granulation fluidized bed; a water outlet of the granulation fluidized bed is sequentially communicated with the reservoir and the capacitive deionization system; the method comprises the following steps: sewage and a coagulation agent enter the stirring tank, the destabilized sewage flows out of the stirring tank and enters the granulation fluidized bed, and a flocculation agent enters the granulation fluidized bed and is mixed with the sewage; carrying out solid-liquid separation on a mixture in the granulation fluidized bed, enabling supernatant at the upper part to enter a water storage tank, and recycling a carbon-enriched product at the lower part in a sludge discharging manner; supernate in the water storage tank enters a capacitive deionization system for nitrogen removal and nitrogen recovery; according to the invention, the purposes of high-standard discharge, resource recovery and low-carbon sewage treatment can be realized, and the method has important significance for developing a new green and low-carbon sewage treatment process of the next generation.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment and resource utilization thereof, and specifically relates to a system and method for strengthening sewage treatment and carbon-nitrogen recovery by combining a granulation fluidized bed and capacitive deionization. Background Art

[0002] At present, sewage treatment plants mostly use biological treatment processes to degrade and remove pollutants. The degradation process consumes energy, is not conducive to resource recovery, and produces greenhouse gases. About 90% of sewage treatment plants use traditional biological processes, in which organic matter and ammonia nitrogen require aeration during the removal process, which consumes a lot of energy. In addition, CO2, N2O, etc. are inevitably produced in this process, causing greenhouse gas emissions. At the same time, the biological treatment process stores phosphorus in sewage in sludge and removes it through sludge discharge, resulting in a waste of resources. Although other processes such as anaerobic ammonium oxidation can reduce greenhouse gas N2O emissions and save aeration volume, there are still problems such as the need to strictly control aeration time, aeration volume, suitable pH and high temperature to ensure the activity of anaerobic ammonia oxidizing bacteria.

[0003] For example, the patent with publication number CN117985851A discloses a pre-anoxic modified sequential batch intermittent reaction sewage treatment system and operation method. Through reasonable improvements in the structure and operation mode of the traditional sequential batch activated sludge reactor, it can efficiently treat township sewage and remove organic matter, nitrogen, phosphorus and other pollutants. Although this system can achieve standard discharge of pollutants, aeration is required during operation, resulting in high energy consumption. No resources are recycled during the process operation, resulting in resource waste. Another example is the patent with publication number CN117843149A, which discloses a method for synchronously treating landfill leachate and sulfur-containing wastewater by coupling short-range nitrification with sulfur autotrophic short-range denitrification / anaerobic ammonia oxidation. By organically combining short-range nitrification, anaerobic ammonia oxidation, and sulfur autotrophic short-range denitrification, complete autotrophic biological denitrification is achieved. However, this process requires strict control of dissolved oxygen and pH, and the operating conditions are relatively complex. Summary of the invention

[0004] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to propose a system and method for enhanced sewage treatment and carbon-nitrogen recovery by combining a granulation fluidized bed and a capacitor deionization. The sewage is treated by a granulation fluidized bed to remove insoluble organic matter and total phosphorus in the sewage, and the carbon is captured and recovered. The treated effluent enters a reservoir and then enters a capacitor deionization system to further remove and recover ammonia nitrogen. The system can achieve high-standard sewage discharge and resource recovery, while avoiding the problems of high aeration energy consumption, the need for additional carbon source addition, greenhouse gas emissions, and the need to strictly control operating conditions during the process of process operation.

[0005] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0006] A granulation fluidized bed and capacitor deionization combined enhanced sewage treatment and carbon-nitrogen recovery system comprises a stirring tank 1, wherein a first inlet end 1-1 of the stirring tank 1 is connected to sewage via a lifting pump 7, a second inlet end 1-2 of the stirring tank 1 is connected to a first dosing barrel outlet end 2-1 of a first dosing barrel 2 via a first dosing pump 8, an outlet end 1-3 of the stirring tank 1 is connected to an inlet end 4-1 of a granulation fluidized bed 4 via a water inlet pump 9, a second dosing barrel outlet end 3-1 of a second dosing barrel 3 is connected to an inlet end 4-1 of the granulation fluidized bed 4 via a second dosing pump 10, a water outlet 4-3 of the granulation fluidized bed 4 is connected to a water tank inlet end 5-1 of a water tank 5, a water tank outlet end 5-2 of the water tank 5 is connected to a capacitive deionization system inlet end 6-1 of a capacitive deionization system 6, and the capacitive deionization system 6 is provided with a capacitive deionization system outlet 6-2.

[0007] The reflux outlet 4 - 2 of the granulation fluidized bed 4 is connected to the inlet 4 - 1 of the granulation fluidized bed 4 through a reflux pump 11 ; the reflux outlet 4 - 2 is located at the upper part of the granulation fluidized bed 4 ; the inlet 4 - 1 is located at the bottom of the granulation fluidized bed 4 .

[0008] The water outlet 4 - 3 of the granulation fluidized bed 4 is located at the upper part of the granulation fluidized bed 4 .

[0009] A carbon recovery outlet 4 - 4 is provided at the bottom of the granulation fluidized bed 4 .

[0010] The capacitive deionization system 6 is provided with a nitrogen recovery outlet 6 - 3 .

[0011] A method for strengthening sewage treatment and carbon and nitrogen recovery by combining a granulation fluidized bed and capacitive deionization, comprising the following steps:

[0012] Step 1, the lifting pump 7 and the first dosing pump 8 respectively lift the sewage and the agent used for coagulation in the first dosing barrel 2 into the stirring tank 1 for mixing, so that the sewage is destabilized, and the destabilization time is 30s-180s;

[0013] Step 2, the destabilized sewage flows out of the stirring tank 1 and enters the granulation fluidized bed 4 through the water inlet pump 9, and at the same time, the agent used for flocculation in the second dosing barrel 3 is pumped into the granulation fluidized bed 4 through the second dosing pump 10 to mix with the sewage to form a mixture;

[0014] Step 3, the mixture in the granulation fluidized bed 4 is separated into solid and liquid in the upward process, wherein the supernatant at the top enters the water reservoir 5, and the carbon-enriched product at the bottom is recovered;

[0015] In step 4, the supernatant in the water reservoir 5 then enters the capacitive deionization system 6 for nitrogen removal and nitrogen recovery.

[0016] In the step 1, the agent used for coagulation in the first dosing barrel 2 is PAC, and the concentration is 20-120 mg / L; in the step 2, the agent used for flocculation in the second dosing barrel 3 is PAM, and the concentration is 1-9 mg / L.

[0017] In the step 2, different types of crystal nuclei can be added to the granulation fluidized bed 4 to improve the effluent quality of the granulation fluidized bed 4.

[0018] In the step 3, the supernatant of the granulation fluidized bed 4 increases the ascending flow rate in a reflux manner and re-flocculates the flocs in the supernatant; the reflux ratio of the supernatant of the granulation fluidized bed 4 is 0.1-1.

[0019] In step 3, the rising flow rate of the granulation fluidized bed 4 is 0.1-6 mm / s.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1) Achieve high-standard sewage discharge

[0022] The present invention is based on the principle of material separation. In the granulation fluidized bed 4, insoluble organic matter, total phosphorus, part of dissolved organic matter and part of ammonia nitrogen can be removed; in the capacitive deionization system 6, ammonia nitrogen, total phosphorus and the remaining organic matter can be removed, so that the effluent of the system can meet the Class IV water discharge standard and realize the high-standard discharge of sewage.

[0023] 2) Recycling carbon and nitrogen resources

[0024] Sewage contains abundant carbon and nitrogen resources. The present invention utilizes the granulation fluidized bed 4 to remove and recycle organic matter in sewage, captures carbon, and can effectively recycle carbon resources. In addition, the present invention utilizes the capacitive deionization system 6 to recycle ammonia nitrogen in the effluent of the granulation fluidized bed, which can achieve the purpose of resource recovery and effectively alleviate the resource crisis.

[0025] 3) Low carbonization of sewage treatment

[0026] The carbon emissions during the operation of the system are calculated. Since there is no biological treatment process and no greenhouse gas is generated, the carbon emissions generated by the loss of electricity and drugs during operation are only half of those of the traditional biological treatment process. In addition, the carbon source stored in the granulation fluidized bed 4 has considerable recycling potential, showing a better low-carbon concept and environmental friendliness, and has important environmental significance and a wide range of energy recovery application prospects.

[0027] In summary, the present invention removes most of the organic matter and total phosphorus and recovers carbon resources through the granulation fluidized bed 4, and further removes ammonia nitrogen, total phosphorus and a small amount of organic matter through the capacitive deionization system 6, and recovers nitrogen resources. It can achieve deep treatment and high-standard discharge of sewage, and recover potential energy in sewage, which is of great significance for resource recovery. The system carbon emissions are lower than those of traditional processes, and low-carbon sewage treatment is achieved, which is of great significance for the development of the next generation of green and low-carbon new sewage treatment processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings described herein are used to provide a further understanding of the present invention, constitute a part of the present application, and do not constitute an improper limitation of the present invention. In the drawings:

[0029] Figure 1 It is a schematic diagram of the system structure of the present invention.

[0030] Figure 2 It is a process flow chart of the present invention.

[0031] Among them, 1. stirring tank; 1-1. first inlet end; 1-2. second inlet end; 1-3. outlet end; 2. first dosing barrel; 2-1. first dosing barrel outlet end; 3. second dosing barrel; 3-1. second dosing barrel outlet end; 4. granulation fluidized bed; 4-1. inlet end; 4-2. reflux outlet end; 4-3. water outlet; 4-4. carbon recovery outlet; 5. reservoir; 5-1. reservoir water inlet end; 5-2. reservoir water outlet end; 6. capacitor deionization system; 6-1. capacitor deionization system water inlet end; 6-2. capacitor deionization system water outlet; 6-3. nitrogen recovery outlet; 7. lifting pump; 8. first dosing pump; 9. water inlet pump; 10. second dosing pump; 11. reflux pump. DETAILED DESCRIPTION

[0032] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The illustrative embodiments of the present invention are used to explain the present invention but are not intended to limit the present invention.

[0033] like Figure 1As shown, a granulation fluidized bed and capacitor deionization combined enhanced sewage treatment and carbon nitrogen recovery system comprises a stirring tank 1, wherein a first inlet end 1-1 of the stirring tank 1 is connected to the sewage through a lifting pump 7, a second inlet end 1-2 of the stirring tank 1 is connected to a first dosing barrel outlet end 2-1 of a first dosing barrel 2 through a first dosing pump 8, an outlet end 1-3 of the stirring tank 1 is connected to an inlet end 4-1 of a granulation fluidized bed 4 through a water inlet pump 9, a second dosing barrel outlet end 3-1 of a second dosing barrel 3 is connected to an inlet end 4-1 of a granulation fluidized bed 4 through a second dosing pump 10, and the inlet end 4-1 is located at the bottom of the granulation fluidized bed 4. The reflux outlet end 4-2 of the fluidized bed 4 is connected to the inlet end 4-1 of the granulating fluidized bed 4 through the reflux pump 11, the reflux outlet end 4-2 is located at the upper part of the granulating fluidized bed 4, the water outlet 4-3 of the granulating fluidized bed 4 is connected to the water inlet end 5-1 of the water reservoir 5, the water outlet 4-3 is located at the upper part of the granulating fluidized bed 4, the water outlet end 5-2 of the water reservoir 5 is connected to the capacitive deionization system water inlet end 6-1 of the capacitive deionization system 6, the capacitive deionization system 6 is provided with a capacitive deionization system outlet 6-2, the bottom of the granulating fluidized bed 4 is provided with a carbon recovery outlet 4-4, and the capacitive deionization system 6 is provided with a nitrogen recovery outlet 6-3.

[0034] The present invention also proposes a method for strengthening sewage treatment and carbon and nitrogen recovery by combining a granulation fluidized bed and capacitive deionization, comprising the following steps:

[0035] Step 1, after a series of pretreatments, the sewage enters the stirring tank 1 through the first inlet end 1-1 through the lifting pump 7, and at the same time, the first dosing pump 8 causes the coagulant PAC in the first dosing barrel 2 to flow out from the first dosing barrel outlet end 2-1 and enter the stirring tank 1 through the second inlet end 1-2, and the sewage and the coagulant PAC are quickly mixed to destabilize the sewage, the destabilization time is 30s-180s, and the coagulant PAC concentration is 20-120mg / L;

[0036] Step 2, the destabilized sewage flows out from the outlet end 1-3 of the stirring tank 1, enters the granulation fluidized bed 4 through the inlet end 4-1 through the water inlet pump 9, and the flocculating agent PAM in the second dosing barrel 3 flows out from the outlet end 3-1 of the second dosing barrel through the dosing pump 10, and is pumped into the granulation fluidized bed 4 through the inlet end 4-1, and is mixed with the raw water in the granulation fluidized bed 4 and then solid-liquid separation is performed. The concentration of the flocculating agent PAM is 1-9 mg / L, and different types of crystal nuclei can be added to the granulation fluidized bed 4 to improve the effluent water quality of the granulation fluidized bed;

[0037] Step 3, after destabilization, the raw water removes most of the insoluble organic matter and total phosphorus in the granulation fluidized bed 4 through coagulation and adsorption. At the same time, the supernatant in the granulation fluidized bed 4 flows out from the reflux outlet 4-2, flows back to the bottom through the inlet 4-1 to increase the rising velocity and flocculate the flocs in the supernatant again, and realizes solid-liquid separation under the impact of the rising velocity. The supernatant reflux ratio of the granulation fluidized bed 4 is 0.1-1, and the rising velocity of the fluidized bed is ensured to be 0.1-6mm / s. Then, the supernatant in the effluent of the granulation fluidized bed is 0.1-1. The clear liquid flows out from the water outlet 4-3, enters the water reservoir 5 through the water inlet end 5-1 of the water reservoir, and then flows out through the water outlet end 5-2 of the water reservoir and enters the capacitor deionization system 6 for nitrogen removal and nitrogen recovery, and the effluent is discharged; the granulation fluidized bed 4 here is not limited to adding reagents to achieve fluidized bed solid-liquid separation, and the seed addition and other measures for controlling the fluidized bed mud bed should be included in the protection content of the present invention. The capacitor deionization system 6 here is not limited to a single capacitor deionization system, and any other mode of capacitor deionization system is applicable;

[0038] Step 4, collecting the carbon-enriched product separated in the granulation fluidized bed 4, and recovering the carbon through the carbon recovery outlet 4-4 by means of sludge discharge.

[0039] The effects of the present invention are further illustrated by means of specific examples below.

[0040] Example 1

[0041] A method for strengthening sewage treatment and carbon and nitrogen recovery by combining a granulation fluidized bed and capacitive deionization, comprising the following steps:

[0042] Step 1, taking the effluent from the aerated grit tank of a sewage treatment plant in Xi'an as the sewage of the granulation fluidized bed, the sewage enters the stirring tank 1 through the lifting pump, and at the same time, the first PAC dosing barrel injects PAC agent into the stirring tank through the first PAC dosing pump, and the concentration of the PAC agent is 90 mg / L, and the sewage is destabilized. The effective volume of the stirring tank 1 is 125 ml, the stirring speed is 200 r / min, the destabilization time is 120 s, and the sewage flow rate is 60 ml / min;

[0043] Step 2, the destabilized sewage flows out from the stirring tank and enters the granulation fluidized bed 4 through the granulation fluidized bed water inlet pump, the PAM agent in the second PAM dosing barrel enters the granulation fluidized bed 4 through the second PAM dosing pump, and is mixed with the destabilized sewage and then solid-liquid separation is performed. The concentration of the PAM agent is 6 mg / L. The main body of the granulation fluidized bed reactor is made of organic glass, with an inner diameter of 8 cm, a total height of 145 cm, an effective height of 100 cm, and a reflux port height of 90 cm;

[0044] Step 3, the destabilized sewage is removed from the granulation fluidized bed 4 by coagulation and adsorption to remove most of the insoluble organic matter and total phosphorus, and the supernatant is refluxed inside the granulation fluidized bed 4 to increase the rising flow rate and re-flocculate the flocs in the supernatant. The reflux ratio of the granulation fluidized bed is 1, ensuring that the rising flow rate of the fluidized bed is 0.4 mm / s. Then the supernatant in the effluent of the granulation fluidized bed enters the reservoir 5, and then enters the capacitor deionization system 6 for nitrogen removal and nitrogen recovery. The capacitor deionization system 6 It consists of a plexiglass plate (length × width × height is 10mm × 10mm × 6mm), a graphite electrode plate engraved with an S-shaped electrode liquid flow channel (the length × width × depth of the S-shaped flow channel is 587mm × 3mm × 3mm), an anion / cation exchange membrane and a leak-proof silica gel gasket, the electrolyte mass fraction is 0.55wt%, the activated carbon mass fraction is 5wt%, the water flow rate and the electrode liquid flow rate are 20mL / min and 25mL / min respectively, the voltage is 1.2V, and the operation time is 90min;

[0045] Step 4: collect the carbon enriched product separated in the granulation fluidized bed 4, perform carbon recovery, and measure the COD, ammonia nitrogen (NH4 + -N), total phosphorus (TP), and other indicators. The results are shown in Table 1, and the carbon emissions of the entire process are calculated (refer to the "IPCC National Greenhouse Gas Inventory Guidelines" issued by the Intergovernmental Panel on Climate Change (IPCC) of the United Nations).

[0046] Table 1 Water quality of effluent at different stages of Example 1 system

[0047]

[0048] The experimental results show that the effluent COD and NH4 + The concentrations of -N and TP are 13.43 mg / L, 0.29 mg / L and 0.16 mg / L respectively, reaching the Class IV water discharge standard. The granulation fluidized bed removes and captures 70.71% of COD for carbon recovery, and the capacitive deionization system concentrates 98.76% of ammonia nitrogen for nitrogen recovery. According to the calculation of carbon emissions, the carbon emissions of the present invention are only 0.42 kg CO2 / m 3 , which is lower than the 0.78kg CO2 / m 3 At the same time, the energy consumption caused by aeration is avoided during the operation of the system.

[0049] Example 2

[0050] In order to verify the universal applicability of the system of the present invention, the effluent from the aerated grit chamber was used as the inlet water of the granulation fluidized bed and was treated according to the system of the present invention.

[0051] A system and method for enhanced wastewater treatment and carbon-nitrogen recovery using a granulation fluidized bed and capacitive deionization. The experimental process is the same as that of Example 1, and the results are shown in Table 2.

[0052] Table 2 Water quality of effluent at different stages of Example 2 system

[0053]

[0054] The experimental results show that under different water quality conditions, the present invention can make the effluent meet the Class IV water discharge standard, and the system has good operating stability. The present invention combines the granulation fluidized bed and the capacitive deionization system to remove pollutants and recover potential energy in the sewage, which can achieve deep treatment and high-standard discharge of sewage, and is of great significance to resource recovery. The system carbon emissions are lower than traditional processes, and it has the characteristics of energy saving and consumption reduction, which is of great significance to the development of the next generation of sewage treatment processes.

[0055] The above is only a preferred embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present invention should be included in the protection scope of the present invention.

Claims

1. A granulation fluidized bed and capacitive deionization combined enhanced sewage treatment and carbon and nitrogen recovery system, characterized in that: The invention comprises a stirring tank (1), wherein a first inlet end (1-1) of the stirring tank (1) is connected to sewage via a lifting pump (7), a second inlet end (1-2) of the stirring tank (1) is connected to a first dosing barrel outlet end (2-1) of a first dosing barrel (2) via a first dosing pump (8), an outlet end (1-3) of the stirring tank (1) is connected to an inlet end (4-1) of a granulating fluidized bed (4) via a water inlet pump (9), and a second dosing barrel outlet end (2-1) of a second dosing barrel (3) is connected to a first dosing barrel outlet end (2-2) of a first dosing barrel (2) via a first dosing pump (8). The outlet end (3-1) is connected to the inlet end (4-1) of the granulating fluidized bed (4) through a second dosing pump (10); the water outlet (4-3) of the granulating fluidized bed (4) is connected to the water inlet end (5-1) of the water reservoir (5); the water outlet end (5-2) of the water reservoir (5) is connected to the water inlet end (6-1) of the capacitive deionization system (6); and the capacitive deionization system (6) is provided with a capacitive deionization system outlet (6-2).

2. The system for strengthening wastewater treatment and carbon-nitrogen recovery by combining a granulation fluidized bed and capacitive deionization according to claim 1 is characterized in that: The reflux outlet end (4-2) of the granulating fluidized bed (4) is connected to the inlet end (4-1) of the granulating fluidized bed (4) via a reflux pump (11); the reflux outlet end (4-2) is located at the upper part of the granulating fluidized bed (4); and the inlet end (4-1) is located at the bottom of the granulating fluidized bed (4).

3. The system for strengthening wastewater treatment and carbon-nitrogen recovery by combining a granulation fluidized bed and capacitive deionization according to claim 1 is characterized in that: The water outlet (4-3) of the granulation fluidized bed (4) is located at the upper part of the granulation fluidized bed (4).

4. The system for strengthening wastewater treatment and carbon-nitrogen recovery by combining a granulation fluidized bed and capacitive deionization according to claim 1 is characterized in that: A carbon recovery outlet (4-4) is provided at the bottom of the granulation fluidized bed (4).

5. The system for strengthening wastewater treatment and carbon-nitrogen recovery by combining a granulation fluidized bed and capacitive deionization according to claim 1 is characterized in that: The capacitive deionization system (6) is provided with a nitrogen recovery outlet (6-3).

6. A recovery method based on any one of claims 1 to 5 of the granulation fluidized bed and capacitive deionization combined enhanced sewage treatment and carbon and nitrogen recovery system, characterized in that: The following steps are involved: Step 1, the lifting pump (7) and the first dosing pump (8) respectively lift the sewage and the agent used for coagulation in the first dosing tank (2) into the stirring tank (1) for mixing, so that the sewage is destabilized, and the destabilization time is 30s-180s; Step 2, the destabilized sewage flows out of the stirring tank (1) and enters the granulation fluidized bed (4) through the water inlet pump (9), and at the same time, the flocculation agent in the second dosing barrel (3) is pumped into the granulation fluidized bed (4) through the second dosing pump (10) to mix with the destabilized sewage to form a mixture; Step 3, the mixture in the granulation fluidized bed (4) is separated into solid and liquid during the upflow process, wherein the supernatant at the top enters the water reservoir (5) and the carbon-enriched product at the bottom is recovered; In step 4, the supernatant in the water reservoir (5) then enters the capacitive deionization system (6) for nitrogen removal and nitrogen recovery.

7. The method for strengthening sewage treatment and carbon and nitrogen recovery by combining a granulation fluidized bed and capacitive deionization according to claim 6, characterized in that: In the step 1, the agent used for coagulation in the first dosing barrel (2) is PAC, with a concentration of 20-120 mg / L; in the step 2, the agent used for flocculation in the second dosing barrel (3) is PAM, with a concentration of 1-9 mg / L.

8. The method for strengthening wastewater treatment and carbon and nitrogen recovery by combining a granulation fluidized bed and capacitive deionization according to claim 6, characterized in that: In the step 2, different types of crystal nuclei can be added to the granulation fluidized bed (4) to improve the effluent quality of the granulation fluidized bed (4).

9. The method for strengthening sewage treatment and carbon and nitrogen recovery by combining a granulation fluidized bed and capacitive deionization according to claim 6, characterized in that: In the step 3, the supernatant of the granulation fluidized bed (4) increases the ascending flow rate in a reflux manner and re-flocculates the flocs in the supernatant; the reflux ratio of the supernatant of the granulation fluidized bed (4) is 0.1-1.

10. The method for strengthening sewage treatment and carbon and nitrogen recovery by combining granulation fluidized bed and capacitive deionization according to claim 6, characterized in that: The rising flow rate of the granulation fluidized bed (4) in step 3 is 0.1-6 mm / s.

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