Domestic sewage treatment system and method based on iron-based material biological redox cycle

Abstract

The present invention proposes a domestic sewage treatment system and method based on an iron-based material biological redox cycle, comprising a primary anaerobic biological pool, a secondary anaerobic biological pool, a micro aeration tank and a sedimentation tank which are connected in sequence, wherein a first water inlet pipe is arranged on the side wall of the primary anaerobic biological pool, a water outlet pipe is arranged on the side wall of the micro aeration tank, and a second water inlet pipe is arranged on the bottom, sewage flows through the primary anaerobic biological pool, the secondary anaerobic biological pool and the micro aeration tank in sequence through the first water inlet pipe for purification, and the purified water flows into the sedimentation tank through the water outlet pipe; a return pipe is arranged between the primary anaerobic biological pool, the secondary anaerobic biological pool and the micro aeration tank respectively; an aeration device is arranged at the bottom of the micro aeration tank, the present invention combines iron oxidation with iron reduction, utilizes iron-based materials to participate in and couple the synchronous decarbonization, denitrification and dephosphorization of sewage in the biological redox cycle, so as to solve the contradiction between synchronous denitrification and dephosphorization in the traditional domestic sewage treatment process and improve the domestic sewage treatment efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of domestic sewage treatment, and in particular relates to a domestic sewage treatment system and method based on iron-based material biological oxidation-reduction cycle. Background Art

[0002] The main pollutants in domestic sewage include organic matter, total nitrogen, total phosphorus, etc. At present, the domestic sewage treatment process mainly adopts A / O, A 2 / O, SBR, oxidation ditch and other treatment processes, the basic principles of which are: the removal of organic matter is mainly achieved through oxidative decomposition by aerobic microorganisms; nitrogen is mainly first nitrified by nitrifying bacteria to produce nitrate from ammonia nitrogen, and then denitrifying bacteria use organic matter to denitrify nitrate under anoxic conditions, reducing nitrate to nitrogen gas to achieve system denitrification; phosphorus is removed by polyphosphate bacteria releasing a small amount of phosphorus under anaerobic conditions, and under aerobic conditions, polyphosphate bacteria absorb a large amount of phosphorus, and remove phosphorus from sewage through sedimentation and sludge discharge.

[0003] The biochemical simultaneous removal of nitrogen and phosphorus is relatively complex, involving multiple biochemical reaction processes such as nitrification, denitrification, phosphorus release and phosphorus absorption. Each of the above processes has different purposes and different requirements for the composition of microorganisms, substrate types and environmental conditions. Therefore, to complete the denitrification and phosphorus removal processes in one system at the same time, it is necessary to closely combine different or contradictory reaction processes, such as carbon source competition, nitrification and denitrification, phosphorus release and phosphorus absorption. This kind of biochemical reaction process that needs to be carried out in different environments must be organically combined, which is difficult in practical applications, which also limits the simultaneous denitrification and phosphorus removal in sewage treatment.

[0004] Iron has the properties of multiple forms, multiple valence states and multiple reaction processes in the environment. Iron-based materials are widely available, cheap and easy to obtain. Their complex cycle processes have an impact on various biogeochemical effects in the environment, such as the degradation of organic pollutants, the cycle of N elements, and the removal of P. Therefore, the study of iron-based materials and the biological redox cycle of iron has important theoretical and practical significance for the simultaneous decarbonization, denitrification and dephosphorization of wastewater treatment. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a domestic sewage treatment system and method based on a biological redox cycle of iron-based materials in response to the above-mentioned problems, combining iron oxidation with iron reduction, and utilizing iron-based materials to participate in and couple the simultaneous decarbonization, denitrification and dephosphorization of sewage in the biological redox cycle, so as to solve the contradiction between simultaneous denitrification and dephosphorization in traditional domestic sewage treatment processes and improve the efficiency of domestic sewage treatment.

[0006] The technical solution adopted by the present invention to solve the above technical problems is: a domestic sewage treatment system based on iron-based material biological redox circulation, characterized in that it includes a primary anaerobic biological pool, a secondary anaerobic biological pool, a micro aeration pool and a sedimentation pool connected in sequence, the side wall of the primary anaerobic biological pool is provided with a first water inlet pipe, the side wall of the micro aeration pool is provided with a water outlet pipe, and the bottom is provided with a second water inlet pipe. The sewage flows through the first water inlet pipe in sequence through the primary anaerobic biological pool, the secondary anaerobic biological pool and the micro aeration pool for purification, and the purified water flows into the sedimentation pool through the water outlet pipe; a first return pipe is provided between the primary anaerobic biological pool and the secondary anaerobic biological pool, and a second return pipe is provided between the secondary anaerobic biological pool and the mobile biological pool; an aeration device is provided at the bottom of the micro aeration pool.

[0007] According to the above scheme, the first-level anaerobic biological pool is provided with iron reducing fillers, the second-level anaerobic biological pool is provided with iron oxidizing fillers, and the micro-aeration pool is provided with suspended fillers.

[0008] According to the above scheme, the iron reduction filler is a mixed filler of lightweight ceramsite and iron oxide, and the volume ratio of the two is 10 to 20:1. The iron oxidation filler is a mixed filler of lightweight ceramsite and sponge iron, and the volume ratio of the two is 10 to 20:1. The suspended filler occupies 20% to 50% of the volume of the sewage in the micro aeration tank.

[0009] According to the above scheme, the aeration device includes a microporous aeration tube and an air pump. The microporous aeration tube is arranged at the bottom of the micro aeration tank and passes through the tank wall to be connected to the air pump.

[0010] According to the above solution, both the first reflux pipe and the second reflux pipe are provided with reflux pumps.

[0011] According to the above scheme, an inclined pipe is provided in the sedimentation tank, and a sludge discharge pipe is provided at the bottom, which is connected to the sludge pump.

[0012] According to the above scheme, a water inlet control valve is provided on the first water inlet pipe to control the water inlet flow rate to 1 / 2 to 2 / 3 of the raw water.

[0013] A treatment method for domestic sewage treatment system based on iron-based material biological redox cycle, characterized in that it comprises the following steps:

[0014] S1) Primary purification: The sewage is fed in stages, and a portion of the sewage enters the primary anaerobic bio-tank through the first water inlet pipe. The first water inlet pipe is provided with a water inlet control valve to control the water inlet flow rate to 1 / 2 to 2 / 3 of the raw water. The iron-reducing filler is used to enrich the dissimilatory iron-reducing microorganisms and reduce the Fe formed by the dissolution of the iron oxide. 3+ Simultaneous oxidation of NH4 in wastewater + , producing NO3 - , to achieve anaerobic ammonium oxidation;

[0015] S2) Secondary purification: Fe produced by the reaction in the primary anaerobic bio-tank 2+ and NO3 - Then it enters the secondary anaerobic bio-tank, where the iron-oxidizing filler dissolves to produce Fe 0 and Fe 2+ , Fe 0 Directly oxidize organic matter in sewage, while Fe 2+ Under anaerobic conditions, ferrous iron oxidizing microorganisms are enriched to oxidize Fe 2+ At the same time, it reduces the NO3 flowing into the secondary anaerobic bio-tank - , realize system denitrification;

[0016] S3) Primary return: The sewage in the secondary anaerobic bio-tank is returned to the primary anaerobic bio-tank through the first return pipe, and the Fe 3+ Return to the primary anaerobic bio-tank to provide Fe for iron reduction 3+ The iron salt dissolved in the two-stage anaerobic biological pool absorbs and precipitates phosphorus in the sewage, and then removes phosphorus from the system through sludge discharge;

[0017] S4) Enhanced treatment: The sewage from the secondary anaerobic biological pool and the other raw sewage enter the micro-aeration tank through the second water inlet pipe at the same time. A micro-aeration device is set up and suspended fillers are added to enrich various microorganisms, mainly facultative anerobic microorganisms. Fresh raw sewage provides a carbon source for denitrification and continues to reduce the remaining NO3 in the sewage. - At the same time, aerobic bacteria can oxidize organic matter in sewage, and aerobic nitrifying bacteria can aerobically oxidize NH4 in sewage. + , producing NO3 - , and oxidation of Fe under aeration conditions 2+ Fe 3+ ;

[0018] S5) Secondary return: The sewage in the micro-aeration tank is returned to the secondary anaerobic bio-tank through the second return pipe, and NO3 - and Fe 3+ Return to the secondary anaerobic bio-tank to supplement Fe 3+ and NO3 - ;

[0019] S6) Mud-water separation: The sewage treated by the above-mentioned units enters the sedimentation tank through the outlet pipe for mud-water separation. The settled sludge is discharged outside for treatment regularly, and the supernatant is discharged after meeting the standards.

[0020] The beneficial effects of the present invention are as follows: providing a domestic sewage treatment system based on the biological redox cycle of iron-based materials, wherein the whole reaction connects iron reduction and iron oxidation in series, and an internal reflux is arranged, so that Fe(II) and Fe(III) can be circulated in two reactors, and reaction substrates are provided to each other, so that the recycling of Fe can be realized, and the dosage of iron-based fillers can be reduced; the I-level anaerobic biobed and the II-level anaerobic biobed are connected in series, so that carbon removal, nitrogen removal and phosphorus removal of the system under anaerobic conditions can be realized, which is more energy-efficient than traditional aeration oxidation; a mobile biobed is arranged, micro-aeration is adopted, and the organic matter therein is decomposed by utilizing the enriched facultative anaerobic microorganisms, and at the same time, aerobic nitrification can produce NO3 - , providing NO3 for ferrous iron oxidation and nitrate reduction in the Class II anaerobic biobed - , further strengthening the system's denitrification; the iron salts produced by the system can fix the phosphorus in the sewage through precipitation, adsorption, etc., and the system's phosphorus removal can be achieved through sludge discharge. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention is a process flow chart of an embodiment of the present invention. DETAILED DESCRIPTION

[0022] In order to better understand the present invention, the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0023] like Figure 1 As shown, the domestic sewage treatment system based on biological redox cycle of iron-based materials includes a primary anaerobic biological pool 1, a secondary anaerobic biological pool 2, a micro aeration pool 3 and a sedimentation pool which are connected in sequence. A first water inlet pipe 4 is provided on the side wall of the primary anaerobic biological pool, a water outlet pipe 5 is provided on the side wall of the micro aeration pool, and a second water inlet pipe 6 is provided on the bottom. The sewage flows through the first water inlet pipe in sequence through the primary anaerobic biological pool, the secondary anaerobic biological pool and the micro aeration pool for purification. The purified water flows into the sedimentation pool through the water outlet pipe for mud and water separation. The sunken sludge is regularly discharged for treatment, and the supernatant is discharged when it meets the standards. A first return pipe 7 is provided between the primary anaerobic biological pool and the secondary anaerobic biological pool, and a second return pipe 8 is provided between the secondary anaerobic biological pool and the mobile biological pool. An aeration device is provided at the bottom of the micro aeration pool.

[0024] An iron reducing filler 9 is arranged in the primary anaerobic biological pool, an iron oxidizing filler 10 is arranged in the secondary anaerobic biological pool, and a suspended filler 11 is arranged in the micro-aeration pool.

[0025] The iron reduction filler is a mixed filler of light ceramsite and iron oxide, with a volume ratio of 10 to 20:1; the iron oxidation filler is a mixed filler of light ceramsite and sponge iron, with a volume ratio of 10 to 20:1; and the suspended filler occupies 20% to 50% of the volume of the sewage in the micro aeration tank.

[0026] The primary anaerobic bio-tank is loaded with lightweight ceramsite and iron oxide, Fe3+ It can enrich dissimilatory iron-reducing microorganisms to Fe 3+ As electron acceptor, coupled to anaerobic ammonium oxidation, Fe 3+ Reduced to Fe 2+ At the same time NH4 + Oxidized to N2, or NO2 - , or NO3 - To achieve anaerobic ammonium oxidation, the reaction formula is:

[0027] NH4 + +2H2O+6Fe 3+ →NO2 - +6Fe 2+ +8H + .

[0028] The secondary anaerobic bio-tank is loaded with lightweight ceramsite and sponge iron, which is zero-valent iron and has strong reducibility. Zero-valent iron can produce hydroxyl radicals through the Fenton reaction and thus treat a series of organic compounds through degradation and oxidation. The reaction chemical equation is as follows:

[0029] Fe 0 +O2+2H + →Fe 2+ +H2O2

[0030] Fe 0 +H2O2+2H + →Fe 2+ +2H2O

[0031] Fe 2+ +H2O2→Fe 3+ +OH - + OH - .

[0032] Fe formed by dissolution of sponge iron in the secondary anaerobic bio-tank 2+ It can enrich nitrate-dependent ferrous oxidizing microorganisms and oxidize Fe 2+ During the process, NO3- can be coupled to reduce to achieve system denitrification, and organic matter can be oxidized to achieve simultaneous decarbonization and denitrification. The denitrification reaction formula is:

[0033] 10Fe 2+ +2NO3 - +10H2O→10Fe(OH)2+N2+18H + .

[0034] The aeration device comprises a microporous aeration pipe 12 and an air pump 13. The microporous aeration pipe is arranged at the bottom of the micro aeration tank and passes through the tank wall to be connected to the air pump.

[0035] The first reflux pipe and the second reflux pipe are both provided with a reflux pump 14, which can realize Fe 2+ with Fe 3+ By circulating in two anaerobic biological pools and providing reaction substrates to each other, Fe can be recycled and the dosage of iron-based fillers can be reduced.

[0036] There is an inclined pipe in the sedimentation tank and a sludge discharge pipe at the bottom, which is connected to the sludge pump for sludge discharge.

[0037] The first water inlet pipe is provided with a water inlet control valve to control the water inlet flow rate to 1 / 2 to 2 / 3 of the raw water.

[0038] The sewage is fed in stages. A part of the sewage enters the primary anaerobic bio-tank through the first water inlet pipe. The first water inlet pipe is equipped with a water inlet control valve to control the inlet flow rate to 1 / 2 to 2 / 3 of the raw water. The addition of lightweight ceramsite and iron oxide mixed filler can enrich the dissimilatory iron-reducing microorganisms and reduce the Fe formed by the dissolution of iron oxide. 3+ Simultaneous oxidation of NH4 in wastewater + , producing NO3 - , to achieve anaerobic ammonium oxidation.

[0039] Fe produced by the primary anaerobic bioreactor reaction 2+ and NO3 - Then it enters the secondary anaerobic bio-tank, where a mixture of lightweight ceramsite and sponge iron is added, and the sponge iron dissolves to produce Fe 0 and Fe 2+ , Fe 0 It can directly oxidize organic matter in sewage by Fenton effect. 2+ Under anaerobic conditions, ferrous iron oxidizing microorganisms can be enriched to oxidize Fe 2+ At the same time, it reduces the NO3 flowing into the secondary anaerobic bio-tank - , achieving system denitrification. The Fe produced by oxidation 3+ Return to the primary anaerobic bio-tank to provide Fe for iron reduction 3+ The iron salt dissolved in the two-stage anaerobic biobed can adsorb and precipitate phosphorus in the sewage, and then remove phosphorus from the system through sludge discharge.

[0040] Afterwards, the sewage from the secondary anaerobic bio-tank and the other raw sewage enter the micro-aeration tank through the second water inlet pipe at the same time. A micro-aeration device is set up and suspended fillers are added to enrich various microorganisms, mainly facultative anerobic microorganisms. Fresh raw sewage provides a carbon source for denitrification and continues to reduce the remaining NO3 in the sewage. - At the same time, aerobic bacteria can oxidize organic matter in sewage, and aerobic nitrifying bacteria can aerobically oxidize NH4 in sewage. + , producing NO3 - , and oxidation of Fe under aeration conditions2+ Fe 3+ ; The sewage in the micro-aeration tank flows back to the secondary anaerobic bio-tank through the second return pipe, and NO3 - and Fe 3+ Return to the secondary anaerobic bio-tank to supplement Fe 3+ and NO3 - .

[0041] Finally, the sewage treated by each unit enters the sedimentation tank for mud and water separation, the settled sludge is discharged regularly for treatment, and the supernatant is discharged when it meets the standards.

[0042] The above is only a preferred specific implementation of the present invention; however, the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solution and its improved conception within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A domestic sewage treatment system based on iron-based materials biological redox cycle, characterized in that: It comprises a primary anaerobic biological pool, a secondary anaerobic biological pool, a micro aeration pool and a sedimentation pool which are connected in sequence. The side wall of the primary anaerobic biological pool is provided with a first water inlet pipe, the side wall of the micro aeration pool is provided with a water outlet pipe, and the bottom is provided with a second water inlet pipe. Sewage flows through the first water inlet pipe in sequence through the primary anaerobic biological pool, the secondary anaerobic biological pool and the micro aeration pool for purification, and the purified water flows into the sedimentation pool through the water outlet pipe; a first return pipe is provided between the primary anaerobic biological pool and the secondary anaerobic biological pool, a second return pipe is provided between the secondary anaerobic biological pool and the mobile biological pool, and a return pump is provided on the first return pipe and the second return pipe; an aeration device is provided at the bottom of the micro aeration pool; The first-level anaerobic biological pool is equipped with iron reduction filler, the second-level anaerobic biological pool is equipped with iron oxidation filler, and the micro-aeration pool is equipped with suspended filler; The iron reduction filler is a mixed filler of lightweight ceramsite and iron oxide, the volume ratio of the two is 10-20:1, the iron oxidation filler is a mixed filler of lightweight ceramsite and sponge iron, the volume ratio of the two is 10-20:1, and the suspended filler occupies 20% to 50% of the volume of the sewage in the micro-aeration tank; The aeration device comprises a microporous aeration pipe and an air pump. The microporous aeration pipe is arranged at the bottom of the micro aeration tank and passes through the tank wall to be connected with the air pump.

2. The domestic sewage treatment system based on iron-based material biological redox cycle according to claim 1 is characterized in that: An inclined pipe is arranged in the sedimentation tank, and a mud discharge pipe is arranged at the bottom, which is connected to a sludge pump.

3. The domestic sewage treatment system based on iron-based material biological redox cycle according to claim 1 or 2, characterized in that: The first water inlet pipe is provided with a water inlet control valve to control the water inlet flow rate to be 1 / 2 to 2 / 3 of the raw water.

4. The method for treating domestic sewage based on an iron-based biological oxidation-reduction cycle system according to claim 3 is characterized in that: The steps include: S1) Primary purification: Sewage is fed in stages, with a portion of the sewage entering the primary anaerobic bio-tank through the first water inlet pipe. A water inlet control valve is provided on the first water inlet pipe to control the water inlet flow rate to 1 / 2 to 2 / 3 of the raw water. The iron-reducing filler is used to enrich the dissimilatory iron-reducing microorganisms and reduce the Fe formed by the dissolution of the iron oxide. 3+ Simultaneous oxidation of NH4 in wastewater + , producing NO3 - , to achieve anaerobic ammonium oxidation; S2) Secondary purification: Fe produced by the reaction in the primary anaerobic bio-tank 2+ and NO3 - Then it enters the secondary anaerobic bio-tank, where the iron-oxidizing filler dissolves to produce Fe 0 and Fe 2+ , Fe 0 Directly oxidize organic matter in sewage, while Fe 2+ Under anaerobic conditions, ferrous iron oxidizing microorganisms are enriched to oxidize Fe 2+ At the same time, it reduces the NO3 flowing into the secondary anaerobic bio-tank - , realize system denitrification; S3) Primary return: The sewage in the secondary anaerobic bio-tank is returned to the primary anaerobic bio-tank through the first return pipe, and the Fe 3+ Return to the primary anaerobic bio-tank to provide Fe for iron reduction 3+ The iron salt dissolved in the two-stage anaerobic biological pool absorbs and precipitates phosphorus in the sewage, and then removes phosphorus from the system through sludge discharge; S4) Enhanced treatment: The sewage from the secondary anaerobic biological pool and the other raw sewage enter the micro-aeration tank through the second water inlet pipe at the same time. A micro-aeration device is set up and suspended fillers are added to enrich various microorganisms, mainly facultative anerobic microorganisms. Fresh raw sewage provides a carbon source for denitrification and continues to reduce the remaining NO3 in the sewage. - At the same time, aerobic bacteria can oxidize organic matter in sewage, and aerobic nitrifying bacteria can aerobically oxidize NH4 in sewage. + , producing NO3 - , and oxidation of Fe under aeration conditions 2+ Fe 3+ ; S5) Secondary return: The sewage in the micro-aeration tank is returned to the secondary anaerobic bio-tank through the second return pipe, and NO3 - and Fe 3+ Return to the secondary anaerobic bio-tank to supplement Fe 3+ and NO3 - ; S6) Mud-water separation: The sewage treated by each unit enters the sedimentation tank through the outlet pipe for mud-water separation. The settled sludge is discharged outside for treatment regularly, and the supernatant is discharged after meeting the standards.

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