Device and method for treating high-nitrogen low-carbon wastewater by coupling iron-based porous combined filler with biological enhancement

Abstract

The invention discloses a device and a method for treating high-nitrogen low-carbon wastewater by coupling iron-based porous combined filler with biological enhancement. The device comprises a sewage tank, a biochemical reaction device and a sludge controllable screening type sedimentation tank which are communicated in sequence, wherein the biochemical reaction device is divided into a front anoxic zone, an aerobic zone, a micro-aerobic zone and a rear anoxic zone according to the water flow direction; iron-based porous combined fillers are placed in the front anoxic zone and the rear anoxic zone, and porous fillers are placed in the aerobic zone and the micro-aerobic zone; the sludge controllable screening type sedimentation tank is provided with a partition plate, the front end area of the partition plate is a first screening area which is communicated with the front anoxic area, and the rear end area of the partition plate is a second screening area which is communicated with a sludge discharge pipe and a water outlet pipe. According to the present invention, the carbon source requirement can be substantially saved in the treatment of high ammonia nitrogen and low carbon nitrogen ratio sewage, the excess sludge yield is reduced, the sludge sedimentation performance is improved, and the effluent quality is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and in particular relates to a device and a method for treating high-nitrogen and low-carbon wastewater by coupling iron-based porous composite fillers with biological enhancement. Background Art

[0002] The treatment of high-nitrogen, low-carbon wastewater such as landfill leachate, sludge / kitchen waste digestion supernatant, and livestock and poultry wastewater has always been a challenge in the field of wastewater biological treatment. On the one hand, there are some difficult-to-degrade organic matter in these wastewaters, resulting in high effluent COD concentrations and difficulty in meeting discharge standards; on the other hand, the carbon source required for denitrification is insufficient, and usually requires the addition of carbon sources such as methanol and sodium acetate, which increases operating costs and carbon emissions.

[0003] In recent years, technologies such as short-range nitrification-endogenous denitrification and anaerobic ammonium oxidation have received widespread attention, which can effectively improve denitrification efficiency and reduce carbon source consumption. However, there are still few reports on scientific research and technological inventions on how to synergistically couple physicochemical and biochemical processes such as iron-based filler micro-electrolysis, short-range nitrification, endogenous denitrification and anaerobic ammonium oxidation in the treatment device, and simultaneously achieve effective control of sludge bulking under hypoxic conditions. The patent of this invention is based on the dosing of iron-based porous composite fillers in a biochemical reaction device, and through the changes in anoxic and hypoxic conditions and the multi-stage coordinated control of sludge bulking, it effectively realizes the multi-pathway synchronous and efficient treatment of high-nitrogen and low-carbon wastewater. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a device and method for treating high-nitrogen and low-carbon wastewater by coupling bio-enhancement with an iron-based porous composite filler. The present invention can greatly save carbon source demand, reduce excess sludge production, improve sludge settling performance, and improve effluent water quality in treating high-ammonia nitrogen and low carbon-nitrogen ratio wastewater.

[0005] To achieve the above objectives, the present invention provides the following technical solutions:

[0006] A device for treating high-nitrogen and low-carbon wastewater by coupling iron-based porous composite filler with bio-augmentation, comprising:

[0007] The sewage tank, biochemical reaction device and sludge controllable screening sedimentation tank are connected in sequence; among them,

[0008] The biochemical reaction device includes four zones, which are divided into a front anoxic zone, an aerobic zone, a micro-oxic zone, and a rear anoxic zone according to the direction of water flow, and each zone is sequentially connected; an iron-based porous composite filler is placed in the front anoxic zone and the rear anoxic zone, and a porous filler is placed in the aerobic zone and the micro-oxic zone;

[0009] The sludge controllable screening sedimentation tank is provided with a partition, the front end area of ​​the partition is the first screening area, the first screening area is connected with the front anoxic area, the rear end area of ​​the partition is the second screening area, and the second screening area is connected with the sludge discharge pipe and the water outlet pipe.

[0010] Preferably, the iron-based porous composite filler includes a porous filler and an iron-based filler, the porous filler is a polyurethane sponge filler, a high-density polyethylene suspension carrier or a polypropylene ball ring filler, and the iron-based filler is a iron shavings, iron-carbon particles, or sponge iron.

[0011] Preferably, each reaction zone of the biochemical reaction device is provided with a stirrer and a water hole, and an aeration head is provided in the aerobic zone and the micro-aerobic zone.

[0012] Preferably, the partition includes a fixed partition and a rotating partition.

[0013] The present invention also provides an operation method of the above-mentioned device for treating high-nitrogen and low-carbon wastewater by coupling the iron-based porous composite filler with bio-augmentation, comprising:

[0014] The high-nitrogen and low-carbon wastewater enters the front anoxic zone, aerobic zone, micro-oxic zone and post-anoxic zone in sequence through the water inlet pump; the aerobic zone and the micro-oxic zone are continuously aerated through the air pump, gas flow meter and aeration head; the reflux liquid from the micro-oxic zone flows back to the front anoxic zone through the reflux pump; the mud-water mixture in the post-anoxic zone enters the sludge controllable screening sedimentation tank, the sludge in the first screening zone at the front end of the baffle flows back to the front anoxic zone, and the sludge in the second screening zone at the rear end of the baffle is discharged as residual sludge through the sludge discharge pipe, and the effluent is discharged through the outlet pipe.

[0015] Preferably, the total nitrogen (TN) of the high-nitrogen, low-carbon wastewater is 500-2000 mg / L, the chemical oxygen demand (COD) / TN is 1-4, and the pH is 7-9.

[0016] Preferably, the volume ratio of the porous filler added in the front anoxic zone is 10-30%, and the dosage of the iron-based filler is 5-25g iron-based filler / (L influent·day); the volume ratio of the porous filler added in the aerobic zone is 5-15%; the volume ratio of the porous filler added in the microaerobic zone is 20-30%; 2-4g / L of anaerobic ammonia-oxidizing bacteria is inoculated in the rear anoxic zone, the volume ratio of the porous filler added is 20-30%, and the dosage of the iron-based filler is 5-25g iron-based filler / (L influent·day).

[0017] Limited, the replacement period of the iron-based filler is 3-12 months.

[0018] Preferably, the hydraulic retention time of the front anoxic zone, the aerobic zone, the microaerobic zone and the rear anoxic zone are 5-10 h, 5-10 h, 1-5 h and 15-20 h respectively.

[0019] Preferably, the dissolved oxygen (DO) in the front anoxic zone, aerobic zone, microaerobic zone and post anoxic zone are 0.1-0.5 mg / L, 2-3 mg / L, 0.5-1.5 mg / L and 0.1-0.5 mg / L respectively.

[0020] Preferably, when the water inlet flow rate is 1Q, the reflux ratio of the micro-oxygen zone is 2-4Q.

[0021] Preferably, the rotating partition is 45° to the right at the beginning of the operation of the device, gradually rotates to the left during the operation, and turns 45° to the left after the operation stabilizes.

[0022] Preferably, the sludge return ratio of the first screening zone is 0.5-1.0Q, the sludge of the second screening zone is discharged, and the sludge retention time (SRT) of the suspended sludge in the biochemical reaction device is controlled to be 20-30 days.

[0023] The biochemical reaction device of the present invention includes four zones. The iron-based porous filler in the front anoxic zone strengthens the carbon source of the raw water to achieve denitrification and denitrification. The released iron ions efficiently remove phosphorus. The iron-based porous composite filler not only strengthens the removal of refractory substances and chemical phosphorus removal, but also reduces the dissolved oxygen concentration to create a better anoxic environment; the aerobic zone realizes short-range nitrification, converting a large amount of NH4 + -N is converted to NO2 - -N, the porous filler in this zone can effectively increase the biomass and enrich nitrifying bacteria, thereby strengthening the removal of ammonia nitrogen; the microaerobic zone continues short-range nitrification by controlling low dissolved oxygen, and realizes simultaneous nitrification and denitrification. At the same time, the control of low oxygen conditions is conducive to the operation of the post-anoxic zone; the post-anoxic zone further reduces TN through endogenous denitrification. At the same time, the iron-based porous composite filler can increase the sludge concentration, enrich anaerobic ammonia-oxidizing bacteria, further chemically remove phosphorus and remove difficult-to-degrade substances, thereby strengthening endogenous denitrification and anaerobic ammonia-oxidation denitrification.

[0024] The sludge controllable screening sedimentation tank of the present invention screens activated sludge with different sedimentation performance. The activated sludge with good sedimentation performance is precipitated in the front zone of the double-zone sedimentation and returned to the front anoxic tank. The sludge with poor sedimentation performance enters the rear zone of the double-zone sedimentation and is discharged as residual sludge. + / Fe3 + The release and precipitation reactions can also alleviate the deterioration of sludge settling caused by low oxygen conditions, thereby achieving multi-level coordinated control of sludge bulking.

[0025] The beneficial effects of the present invention are:

[0026] (1) The iron-based porous composite filler of the present invention can increase the concentration of system sludge, remove refractory pollutants and chemically remove phosphorus, enrich anaerobic ammonia-oxidizing bacteria, improve sludge settling performance, and realize multi-path coupled bio-enhanced treatment.

[0027] (2) The present invention is based on the anoxic, aerobic, micro-aerobic and anoxic process flow of the iron-based porous composite filler, which enhances the multi-path synergistic denitrification efficiency of exogenous denitrification, short-range nitrification, short-range denitrification, endogenous denitrification and anaerobic ammonia oxidation, while also effectively reducing sludge production.

[0028] (3) The sludge controllable screening sedimentation tank of the present invention can effectively screen sludge with good settling performance in a continuous flow process, and prevent sludge expansion through coordinated control with iron-based fillers, thereby improving the stability of system operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the device for treating high-nitrogen and low-carbon wastewater by coupling the iron-based porous composite filler with bio-augmentation according to the present invention.

[0030] Figure symbols: 1-sewage tank, 2-biochemical reaction device, 3-sludge controllable screening sedimentation tank, 1.1-water inlet pump, 1.2-water inlet, 2.1-front anoxic zone, 2.2-aerobic zone, 2.3-microaerobic zone, 2.4-rear anoxic zone, 2.5-agitator, 2.6-porous filler, 2.7-iron-based porous composite filler, 3.1-fixed partition, 3.2-rotating partition, 3.3-sludge return pump, 3.4-sludge discharge port, 3.5-water outlet, 4.1-air pump, 4.2-flow meter, 4.3-aeration head. DETAILED DESCRIPTION

[0031] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0032] Unless otherwise defined, technical or scientific terms used in the present disclosure shall have the common meanings understood by one of ordinary skill in the art to which the present invention belongs.

[0033] Figure 1 A schematic diagram of a device for treating high-nitrogen and low-carbon wastewater by coupling iron-based porous composite fillers with bio-enhanced treatment according to the present invention.

[0034] like Figure 1 As shown, the device comprises a sewage tank (1), a biochemical reaction device (2) and a sludge controllable screening sedimentation tank (3) which are connected in sequence, and the sewage tank (1) is connected to the biochemical reaction device (2) via a water inlet pump (1.1).

[0035] The biochemical reaction device comprises four zones, which are divided into a front anoxic zone (2.1), an aerobic zone (2.2), a micro-aerobic zone (2.3) and a rear anoxic zone (2.4) according to the direction of water flow. Each zone is sequentially connected and is provided with a stirrer (2.5) and a water hole.

[0036] The front anoxic zone (2.1) and the rear anoxic zone (2.4) are provided with iron-based porous composite fillers (2.7), which include porous fillers and iron-based fillers. The porous filler is a polyurethane sponge filler, a high-density polyethylene suspension carrier or a polypropylene ball ring filler, and the iron-based filler is a kind of iron shavings, iron-carbon particles or sponge iron.

[0037] The porous filler (2.6) is placed in the aerobic zone (2.2) and the micro-aerobic zone (2.3), and aeration is continuously performed through an air pump (4.1), a gas flow meter (4.2) and an aeration head (4.3). The porous filler is a polyurethane sponge filler, a high-density polyethylene suspension carrier or a polypropylene ball ring filler.

[0038] The sludge controllable screening sedimentation tank (3) is provided with a partition, wherein the partition comprises a fixed partition (3.1) and a rotating partition (3.2), wherein the front end area of ​​the partition is a first screening area, which is connected to the front anoxic area, and the rear end area of ​​the partition is a second screening area, which is connected to the sludge discharge pipe (3.4) and the water outlet pipe (3.5).

[0039] The operating method of the device for treating high-nitrogen and low-carbon wastewater by coupling biological enhancement with the iron-based porous composite filler comprises: the high-nitrogen and low-carbon wastewater enters the front anoxic zone (2.1), the aerobic zone (2.2), the micro-aerobic zone (2.3), and the rear anoxic zone (2.4) in sequence through the water inlet (1.2); the aerobic zone (2.2) and the micro-aerobic zone (2.3) are continuously aerated through an air pump (4.1), a gas flow meter (4.2), and an aeration head (4.3); the reflux liquid of the micro-aerobic zone (2.3) is refluxed to the front anoxic zone (2.1) through a reflux pump; the sludge-water mixture of the rear anoxic zone (2.4) enters the sludge controllable screening sedimentation tank (3), the sludge of the first screening zone at the front end of the baffle is refluxed to the front anoxic zone (2.1), the sludge of the second screening zone at the rear end of the baffle is discharged as residual sludge through a sludge discharge pipe (3.4), and the effluent is discharged through a water outlet pipe (3.5). The rotating baffle (3.2) of the sludge controllable screening sedimentation tank (3) is 45° to the right at the initial stage of operation, gradually rotates to the left during the operation, and rotates to the left 45° after the operation becomes stable.

[0040] Example 1

[0041] High-nitrogen and low-carbon wastewater is anaerobic digestion liquid of kitchen waste, and the chemical oxygen demand (COD), total nitrogen (TN), ammonia nitrogen (NH4 + -N) and phosphorus (PO4 3-) concentrations were 2002±318mg / L, 816±34mg / L, 845±48mg / L and 7±1mg / L respectively.

[0042] The volume distribution ratio of the front anoxic zone (2.1), aerobic zone (2.2), microaerobic zone (2.3) and rear anoxic zone (2.4) of the biochemical reaction device is 2:3:2:6, the hydraulic retention time is 6h, 9h, 6h and 18h ​​respectively, and the dissolved oxygen (DO) is 0.1mg / L, 3mg / L, 0.5mg / L and 0.1mg / L respectively.

[0043] The iron-based filler is iron shavings, the dosage is 10g iron-based filler / (L water intake day), the replacement frequency is 120d, and the porous filler is polyurethane sponge filler, the dosage ratio is 30%. The post-anoxic zone is inoculated with 3g / L anaerobic ammonia oxidizing bacteria.

[0044] The reflux ratio in the reactor is 200% of the water, the sludge reflux ratio is 100% of the water, all the remaining sludge is discharged from the sludge outlet of the sludge controllable screening sedimentation tank, the sludge retention time (SRT) is 25 days, and the activated sludge concentration is maintained at about 5000 mg / L.

[0045] The sludge controllable screening sedimentation tank screens activated sludge with different settling properties. The activated sludge with good settling performance is precipitated in the front zone of the double-zone sedimentation and returned to the front anoxic tank. The sludge with poor settling performance enters the rear zone of the double-zone sedimentation and is discharged as residual sludge.

[0046] After treatment, the wastewater COD is less than 250mg / L, TN is less than 50mg / L, NH4 + -N is lower than 30mg / L, TP is lower than 0.5mg / L, COD removal rate: 83.5±1.8%, TN removal rate: 92.7±3.1%, NH4 + -N removal rate: 95.7±2.7%, TP removal rate: 90.6±3.3%, yield coefficient (Y obs ): 0.116±0.012gVSS / gCOD, SVI 30 :77.8±7.2mL / g.

[0047] Example 2

[0048] The system is basically the same as that in Example 1, except that the influent concentration is lower. The high-nitrogen and low-carbon wastewater is the anaerobic digestion liquid of kitchen waste, and the chemical oxygen demand (COD), total nitrogen (TN), ammonia nitrogen (NH4 + -N) and phosphorus (PO4 3- ) concentrations were 1356±149mg / L, 532±37mg / L, 558±25mg / L and 5±1mg / L, respectively.

[0049] After treatment, the wastewater COD is less than 200mg / L, TN is less than 30mg / L, NH4 + -N is lower than 20mg / L, TP is lower than 0.5mg / L, COD removal rate: 86.9±2.1%, TN removal rate: 95.8±2.5%, NH4 + -N removal rate: 97.7±1.4%, TP removal rate: 85.6±3.5%, yield coefficient (Y obs ): 0.093±0.013gVSS / gCOD, SVI 30 :80.5±5.9mL / g.

[0050] Comparative Example 1

[0051] The system is basically the same as that in Example 1, except that no iron shavings filler is added.

[0052] After treatment, COD removal rate: 75.5±3.6%, TN removal rate: 85.2±6.2%, NH4 + -N removal rate: 93.4±2.8%, TP removal rate: 20.3±10.4%, yield coefficient (Y obs ): 0.166±0.022gvss / gCOD, SVI 30 :124.2±18.5mL / g.

[0053] Comparative Example 2

[0054] The system is basically the same as that in Example 1, except that no porous iron-based composite filler is added. After treatment, COD removal rate: 74.1±3.2%, TN removal rate: 64.1±7.3%, NH4 + -N removal rate: 87.2±5.2%, TP removal rate: 23.2±16.8%, yield coefficient (Y obs ): 0.210±0.046gvss / gCOD, SVI 30 :135.7±15.2mL / g.

[0055] Comparative Example 3

[0056] The system is basically the same as that in Example 1, except that no porous iron-based composite filler is added, and the sludge controllable screening sedimentation tank is replaced with a vertical flow sedimentation tank. After treatment, COD removal rate: 75.5±4.7%, TN removal rate: 70.2±5.7%, NH4 + -N removal rate: 60.3±8.1%, TP removal rate: 25.7±11.9%, yield coefficient (Y obs ): 0.240±0.033gvss / gCOD, SVI 30:156.2±9.6mL / g.

[0057] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A device for treating high-nitrogen and low-carbon wastewater by coupling iron-based porous composite fillers with bio-augmentation, characterized in that: include: The sewage tank, biochemical reaction device and sludge controllable screening sedimentation tank are connected in sequence; among them, The biochemical reaction device includes four zones, which are divided into a front anoxic zone, an aerobic zone, a micro-oxic zone, and a rear anoxic zone according to the direction of water flow, and each zone is sequentially connected; an iron-based porous composite filler is placed in the front anoxic zone and the rear anoxic zone, and a porous filler is placed in the aerobic zone and the micro-oxic zone; The sludge controllable screening sedimentation tank is provided with a partition, the front end area of ​​the partition is the first screening area, the first screening area is connected with the front anoxic area, the rear end area of ​​the partition is the second screening area, and the second screening area is connected with the sludge discharge pipe and the water outlet pipe.

2. The device for treating high-nitrogen and low-carbon wastewater by coupling iron-based porous composite filler with bio-augmentation according to claim 1, characterized in that: The iron-based porous composite filler includes a porous filler and an iron-based filler, wherein the porous filler is a polyurethane sponge filler, a high-density polyethylene suspension carrier or a polypropylene ball ring filler, and the iron-based filler is a iron shaving, iron-carbon particles or sponge iron.

3. The device for treating high-nitrogen and low-carbon wastewater by coupling iron-based porous composite filler with bio-augmentation according to claim 1, characterized in that: The partitions include fixed partitions and rotating partitions.

4. A method for operating the device for treating high-nitrogen and low-carbon wastewater by coupling the iron-based porous composite filler with bio-augmentation as described in claims 1-4, characterized in that: include: The high-nitrogen and low-carbon wastewater enters the front anoxic zone, aerobic zone, micro-oxic zone and post-anoxic zone in sequence through the water inlet pump; the aerobic zone and the micro-oxic zone are continuously aerated through the air pump, gas flow meter and aeration head; the reflux liquid from the micro-oxic zone flows back to the front anoxic zone through the reflux pump; the mud-water mixture in the post-anoxic zone enters the sludge controllable screening sedimentation tank, the sludge in the first screening zone at the front end of the baffle flows back to the front anoxic zone, and the sludge in the second screening zone at the rear end of the baffle is discharged as residual sludge through the sludge discharge pipe, and the effluent is discharged through the outlet pipe.

5. The method according to claim 5, characterized in that: The total nitrogen (TN) of high-nitrogen, low-carbon wastewater is 500-2000 mg / L, the chemical oxygen demand (COD) / TN is 1-4, and the pH is 7-9.

6. The method according to claim 5, characterized in that The volume ratio of porous filler added in the front anoxic zone is 10-30%, and the dosage of iron-based filler is 5-25g iron-based filler / (L influent·day); the volume ratio of porous filler added in the aerobic zone is 5-15%; the volume ratio of porous filler added in the microaerobic zone is 20-30%; 2-4g / L anaerobic ammonia-oxidizing bacteria is inoculated in the rear anoxic zone, the volume ratio of porous filler added is 20-30%, and the dosage of iron-based filler is 5-25g iron-based filler / (L influent·day).

7. The method according to claim 5, characterized in that The hydraulic retention times of the front anoxic zone, aerobic zone, microaerobic zone and rear anoxic zone are 5-10h, 5-10h, 1-5h and 15-20h respectively, and the dissolved oxygen (DO) is 0.1-0.5mg / L, 2-3mg / L, 0.5-1.5mg / L and 0.1-0.5mg / L respectively.

8. The method according to claim 4, characterized in that The rotating partition is 45° to the right at the initial stage of the device operation, gradually rotates to the left during the operation, and rotates 45° to the left after the operation stabilizes.

9. The method according to claim 4, characterized in that The sludge return ratio of the first screening zone is 0.5-1.0Q, the sludge of the second screening zone is discharged, and the sludge retention time (SRT) of the suspended sludge in the biochemical reaction device is controlled to be 20-30 days.

Images