Device and method for treating autotrophic nitrogen removal and detoxification of coking wastewater through two-stage low-oxygen short-cut nitrification, sulfur autotrophic denitrification and anaerobic ammonia oxidation

Abstract

The invention discloses an autotrophic nitrogen removal and detoxification device and method for treating coking wastewater through two-stage low-oxygen short-cut nitrification, sulfur autotrophic denitrification and anaerobic ammonia oxidation, and belongs to the field of sewage treatment. The device comprises a water inlet tank, a sequencing batch reactor, a middle water tank and an up-flow anaerobic sludge blanket reactor. The method comprises the following steps: enabling the coking wastewater which is subjected to carbon capture and contains ammonia nitrogen and thiocyanate to enter a sequencing batch reactor, oxidizing the ammonia nitrogen into nitrite under a limited oxygen condition, and generating nitrogen, sulfate and ammonia nitrogen from the thiocyanate and the nitrite by autotrophic denitrifying bacteria; reaction effluent mixed with coking wastewater enters an upflow anaerobic sludge blanket, and anaerobic ammonium oxidation bacteria convert ammonia nitrogen and nitrite into nitrogen and generate a small amount of nitrate; and the residual nitrate, nitrite and thiocyanate are continuously and thoroughly removed through the sulfur autotrophic denitrification effect. The method provides a new idea for economical and efficient autotrophic nitrogen removal and detoxification of the coking wastewater containing thiocyanate and ammonia nitrogen.

Description

Technical Field

[0001] The invention discloses a device and method for autotrophic nitrogen and toxin removal from coking wastewater by two-stage hypoxia short-range nitrification-sulfur autotrophic denitrification-anaerobic ammonium oxidation, belonging to the field of sewage treatment. Background Art

[0002] Coking wastewater is a typical industrial wastewater with a low C / N ratio, containing a large amount of ammonia nitrogen, refractory organic matter and toxic substances. The ammonia nitrogen concentration in the coking wastewater entering the biochemical pool is 100-1000 mg / L, the COD is 1500-3000 mg / L, and the total nitrogen concentration is 200-1000 mg / L. The traditional anoxic / aerobic (A / O) process is the current mainstream biochemical treatment process. However, due to the lack of available carbon sources in the wastewater, the denitrification is limited, and the denitrification cost is greatly increased by adding external carbon sources to strengthen denitrification. Therefore, the traditional biochemical treatment process faces bottleneck problems such as unqualified treatment and high treatment cost.

[0003] Anaerobic ammonium oxidation technology is a currently promising biological nitrogen removal technology that is economical, energy-saving and sustainable. The anaerobic ammonium oxidation process refers to the process in which under anoxic conditions, anaerobic ammonium oxidizing bacteria use nitrite as an electron acceptor to oxidize ammonia nitrogen to nitrogen gas, and at the same time produce a small amount of nitrate. Compared with the traditional nitrification and denitrification nitrogen removal process, the anaerobic ammonium oxidation technology can save 60% of the aeration energy consumption, 100% of the organic carbon source, and reduce 90% of the sludge production. Therefore, applying the anaerobic ammonium oxidation technology to the treatment of coking wastewater can achieve efficient nitrogen removal and greatly alleviate the investment and operation costs of wastewater nitrogen removal treatment. However, the toxic substances in coking wastewater may have a certain impact and inhibition on anaerobic ammonium oxidizing bacteria, which restricts the application of the anaerobic ammonium oxidation technology in the treatment of coking wastewater.

[0004] Thiocyanate is the main toxic substance in coking wastewater, with a concentration as high as 200-1000 mg / L, which has a significant impact on the activity of anaerobic ammonium oxidizing bacteria. At the same time, thiocyanate contains nitrogen and has strong reducibility, and also contributes to the total nitrogen and COD of the wastewater. In recent years, studies have shown that under anoxic conditions, specific autotrophic denitrifying bacteria use thiocyanate as an electron donor, nitrate and nitrite as electron acceptors, and through a series of redox reactions, reduce nitrate and nitrite to nitrogen gas, and at the same time the toxic thiocyanate is oxidized to non-toxic sulfate and ammonia nitrogen, thereby realizing the removal of thiocyanate and the synchronous removal of nitrogen.

[0005] Coupling anaerobic ammonium oxidation and thiocyanate autotrophic denitrification technologies can theoretically achieve the simultaneous removal of ammonia nitrogen and thiocyanate, realizing the denitrification and detoxification of coking wastewater. The coupling principle is to subject coking wastewater containing ammonia nitrogen and thiocyanate that has undergone carbon capture to simultaneous shortcut nitrification and thiocyanate denitrification in a low-oxygen aeration reactor. The final effluent contains ammonia nitrogen, nitrite, and sulfate. The effluent from the low-oxygen aeration reactor is mixed with coking wastewater and enters the anaerobic ammonium oxidation reactor, where synchronous anaerobic ammonium oxidation and thiocyanate denitrification for nitrogen removal are carried out by adjusting the ratio of the mixed wastewater. Therefore, how to construct the process and regulate the operation strategy to achieve the coupling of these two technologies plays an important role in the application of anaerobic ammonium oxidation bacteria in coking wastewater treatment. Summary of the Invention

[0006] The present invention discloses a device and method for autotrophic denitrification and detoxification of coking wastewater by two-stage low-oxygen shortcut nitrification - sulfur autotrophic denitrification - anaerobic ammonium oxidation. The method involves introducing coking wastewater containing ammonia nitrogen and thiocyanate that has undergone carbon capture into a low-oxygen aeration sequencing batch reactor. The ammonia nitrogen in the influent is oxidized by ammonia-oxidizing bacteria into nitrite and accumulated under oxygen-limiting conditions. At the same time, the thiocyanate and nitrite in the influent are utilized by autotrophic denitrifying bacteria to generate nitrogen gas, sulfate, and ammonia nitrogen. The SBR effluent containing ammonia nitrogen and nitrite nitrogen is mixed with coking wastewater containing ammonia nitrogen and thiocyanate and enters an upflow anaerobic sludge bed. In the UASB, ammonia nitrogen and nitrite are utilized by anaerobic ammonium oxidation bacteria to generate nitrogen gas and nitrate, and the remaining nitrate, nitrite, and thiocyanate are utilized by autotrophic denitrifying bacteria to generate nitrogen gas. The two-stage process can ultimately achieve the simultaneous removal of ammonia nitrogen and thiocyanate in the wastewater.

[0007] The object of the present invention is solved by the following technical solutions: A device for autotrophic denitrification and detoxification of coking wastewater by two-stage low-oxygen shortcut nitrification - sulfur autotrophic denitrification - anaerobic ammonium oxidation, characterized in that:

[0008] The device used includes: a feed water tank (1), a sequencing batch reactor (2), an intermediate water tank (3), and an upflow anaerobic sludge bed reactor (4).

[0009] The feed water tank (1) includes a heating rod (1.1) and a third peristaltic pump (1.2); the sequencing batch reactor (2) includes a first peristaltic pump (2.1), a first water inlet (2.2), a pH / DO meter (2.3), a stirrer (2.4), an aeration disc (2.5), a gas flow meter (2.6), an air pump (2.7), and a first water outlet (2.8); the intermediate water tank (3) includes a heating rod (3.1); the upflow anaerobic sludge bed reactor (4) includes a second peristaltic pump (4.1), a second water inlet (4.2), a heating tape (4.3), a second water outlet (4.4), and a pH / DO meter (4.5).

[0010] The coking wastewater containing ammonia nitrogen and thiocyanate in the inlet water tank (1) enters in the form of artificial water distribution (NH 4 + -N concentration is 100 - 120 mg / L, SCN - concentration is 100 - 350 mg / L). It is pumped into the sequencing batch reactor (2) from the first water inlet (2.2) through the first peristaltic pump (2.1) to start short-cut nitrification and thiocyanate denitrification. The effluent is discharged into the intermediate water tank (3) through the first water outlet (2.8). The SBR effluent containing ammonia nitrogen and nitrite nitrogen is mixed with the coking wastewater containing ammonia nitrogen and thiocyanate and enters the upflow anaerobic sludge bed (4) from the second water inlet (4.2) through the second peristaltic pump (4.1) and the third peristaltic pump (1.2). When the liquid level in the reactor reaches the effective volume of the UASB, the effluent is discharged through the water outlet (4.4).

[0011] The present invention has the following advantages:

[0012] 1) Adopting the synchronous short-cut nitrification coupling thiocyanate denitrification process is beneficial to ammonia oxidation, improves the nitrogen removal efficiency, realizes the synchronous removal of ammonia nitrogen and thiocyanate, and realizes the accumulation of nitrite.

[0013] 2) Compared with the traditional biochemical treatment process facing bottleneck problems such as unqualified treatment and high treatment cost, the two-stage low-oxygen short-cut nitrification - anaerobic ammonia oxidation nitrogen removal process has the advantages of low energy consumption, less residual sludge volume, no need to add organic carbon, and high nitrogen removal efficiency.

[0014] 3) Adopting the thiocyanate autotrophic denitrification coupling anaerobic ammonia oxidation process, thiocyanate is used as an electron donor to reduce nitrate and nitrite to nitrogen in the anoxic system, realizing the synchronous removal of ammonia nitrogen and thiocyanate, and realizing the denitrification and detoxification of coking wastewater.

[0015] In summary, using the present invention to treat coking wastewater containing thiocyanate and ammonia nitrogen has the advantages of saving aeration energy consumption, not needing to add organic carbon source, and synchronously and efficiently detoxifying and denitrifying. Description of the Drawings

[0016] Figure 1 It is: a device and method for autotrophic denitrification and detoxification of coking wastewater by two-stage low-oxygen short-cut nitrification - sulfur autotrophic denitrification - anaerobic ammonia oxidation.

[0017] Figure 1In the figure: 1 - water inlet tank, 2 - sequencing batch reactor, 3 - intermediate water tank, 4 - upflow anaerobic sludge bed reactor; 1.1 - heating rod, 1.2 - third peristaltic pump, 2.1 - first peristaltic pump, 2.2 - first water inlet, 2.3 - pH / DO meter, 2.4 - stirrer, 2.5 - aeration disc, 2.6 - gas flow meter, 2.7 - air pump, 2.8 - first water outlet; 3.1 - heating rod; 4.1 - second peristaltic pump, 4.2 - second water inlet, 4.3 - heating tape, 4.4 - second water outlet, 4.5 - pH / DO meter Detailed implementation manners

[0018] The implementation manners of the present invention will be described in detail below with reference to the accompanying drawings and embodiments:

[0019] As Figure 1 shown, the device for autotrophic nitrogen and toxicity removal from coking wastewater by two-stage low-oxygen short-cut nitrification-sulfur autotrophic denitrification-anaerobic ammonium oxidation includes a water inlet tank (1), a sequencing batch reactor (2), an intermediate water tank (3), and an upflow anaerobic sludge bed reactor (4).

[0020] The method for autotrophic nitrogen and toxicity removal from coking wastewater by two-stage low-oxygen short-cut nitrification-sulfur autotrophic denitrification-anaerobic ammonium oxidation is characterized by including the following steps:

[0021] Step I: Inoculate ordinary activated sludge. The coking wastewater containing ammonia nitrogen and thiocyanate in the water inlet tank (1) enters in the form of artificial water distribution (NH 4 + -N concentration is 100 - 120 mg / L, SCN - concentration is 100 - 350 mg / L), and is pumped into the sequencing batch reactor (2) from the first water inlet (2.2) through the first peristaltic pump (2.1) to start short-cut nitrification and thiocyanate denitrification. The effluent is discharged into the intermediate water tank (3) through the first water outlet (2.8).

[0022] Step II: The SBR effluent containing ammonia nitrogen and nitrite nitrogen is mixed with the coking wastewater containing ammonia nitrogen and thiocyanate and enters the upflow anaerobic sludge bed (4) from the second water inlet (4.2) through the second peristaltic pump (4.1) and the third peristaltic pump (1.2). When the liquid level in the reactor reaches the effective volume of the UASB, the effluent is discharged through the water outlet (4.4).

[0023] The test system is as Figure 1 shown. Both the short-cut nitrification and anaerobic ammonium oxidation reactors are made of plexiglass. The effective volume of the SBR is 10 L, and the effective volume of the UASB is 4 L.

[0024] During the experiment, simulated wastewater was used as the specific experimental water, with ammonium bicarbonate and sodium thiocyanate as the substrates. The specific water quality was as follows: NH 4 + -N was 100 - 120 mg / L, SCN - was 100 - 350 mg / L, and an appropriate amount of sodium bicarbonate was added to adjust the pH to 7 - 8.

[0025] The specific operation is as follows:

[0026] (1) Start-up of the system:

[0027] (1.1) Start-up of the low-oxygen aeration SBR: First, inoculate ordinary activated sludge with a sludge concentration maintained at 3000 - 4000 mg / L. The wastewater contains 100 - 120 mg / L of ammonia nitrogen. Then, under the conditions of a low thiocyanate concentration of 100 - 120 mg / L and high dissolved oxygen, control the dissolved oxygen concentration at 2–5 mg / L to domesticate SCN - degrading bacteria and stable ammonia oxidation performance. When the SCN - removal rate reaches over 90%, start to increase the influent SCN - concentration to 100–200 mg / L. After the SCN - removal rate stably reaches over 90%, increase the concentration to 200–300 mg / L, and at the same time adjust the aeration volume to create a limited oxygen environment to keep the dissolved oxygen concentration at 0.1 - 0.3 mg / L to domesticate thiocyanate denitrifying bacteria. When the thiocyanate removal rate reaches over 95%, it is considered that the start-up of the low-oxygen aeration SBR is successful.

[0028] (1.2) Start-up of the UASB: First, inoculate anaerobic ammonium oxidation granular sludge with a sludge concentration maintained at 20000 ± 500 mg / L. Start in wastewater containing 50 - 75 mg / L of ammonia nitrogen and 60 - 100 mg / L of nitrite. Subsequently, set the thiocyanate concentration in the reactor at 75 - 150 mg / L to domesticate the coupling of anaerobic ammonium oxidation and thiocyanate autotrophic denitrification. When the UASB nitrogen removal efficiency reaches over 72%, it is considered that the start-up is successful.

[0029] (2) Operation of the system:

[0030] (2.1) Operation of the low-oxygen aeration SBR: The influent NH 4 + -N concentration is 100 - 120 mg / L, SCN -The wastewater containing ammonia nitrogen and thiocyanate with a concentration of 300 - 350 mg / L is pumped into the shortcut nitrification SBR reactor (2) by the first peristaltic pump (2.1). A heating rod is placed in the reactor to control the operating temperature in the reactor at 25 - 30 °C. The way of aeration in the reactor is blast aeration, and the dissolved oxygen concentration is controlled at 0.1 - 0.3 mg / L by a gas flow meter, and continuous stirring is carried out during the aeration process. During the reaction process, ammonia nitrogen is oxidized to nitrite by ammonia-oxidizing bacteria, and at the same time, the thiocyanate and nitrite in the influent are utilized by autotrophic denitrifying bacteria to generate nitrogen, sulfate and ammonia nitrogen. The low-oxygen shortcut nitrification effluent containing ammonia nitrogen and nitrite enters the intermediate water tank (3).

[0031] (2.2) Operation of UASB: This step is continuous influent, and the reactor is in a light-shielded, anaerobic and constant-temperature environment. Control the raw water in the influent water tank (1) to be pumped into the UASB reactor (4) by the third peristaltic pump (1.2); at the same time, the effluent of the sequencing batch reactor in the intermediate water tank (3) enters the UASB reactor (4) through the second peristaltic pump (4.1), and the volume ratio of the two influents is 1:1; the outside of the device is wrapped with a heating tape (4.3) to maintain the reactor temperature at 30 - 35 °C, and the ammonia nitrogen and nitrite in the influent are utilized by anaerobic ammonia-oxidizing bacteria to generate nitrogen and nitrate; the generated nitrate, together with the nitrite and thiocyanate in the influent, are utilized by autotrophic denitrifying bacteria to generate nitrogen. The reaction effluent is discharged through the outlet (4.4).

[0032] The test results show that: after the system operates stably, thiocyanate-degrading bacteria are successfully domesticated to achieve autotrophic denitrification of thiocyanate, and the coupling of shortcut nitrification and anaerobic ammonia oxidation processes realizes efficient detoxification and denitrification of coking wastewater containing ammonia nitrogen and thiocyanate, and the effluent quality meets the treatment requirements.

[0033] The above are specific embodiments of the present invention, which are convenient for those skilled in the art of this technology to better understand and apply the present invention. However, the implementation of the present invention is not limited thereto. Therefore, simple improvements made by those skilled in the art of this technology to the present invention are within the protection scope of the present invention.

Claims

1. A two-stage low oxygen short-term nitrification-sulfur autotrophic denitrification-anaerobic ammonia oxidation device for treating coking wastewater autotrophic denitrification and detoxification, characterized in that: include: Inlet tank (1), sequencing batch reactor (2), intermediate water tank (3), upflow anaerobic sludge blanket reactor (4); The water inlet tank (1) comprises a heating rod (1.1) and a third peristaltic pump (1.2); the sequencing batch reactor (2) comprises a first peristaltic pump (2.1), a first water inlet (2.2), a pH / DO measuring instrument (2.3), a stirrer (2.4), an aeration plate (2.5), a gas flow meter (2.6), an air pump (2.7), and a first water outlet (2.8); the intermediate water tank (3) comprises a heating rod (3.1); the upflow anaerobic sludge blanket reactor (4) comprises a second peristaltic pump (4.1), a second water inlet (4.2), a heating belt (4.3), a second water outlet (4.4), and a pH / DO measuring instrument (4.5); The coking wastewater containing ammonia nitrogen and thiocyanate in the water inlet tank (1) is fed in the form of artificial water distribution, and is pumped into the sequencing batch reactor (2) from the first water inlet (2.2) through the first peristaltic pump (2.1), and the short-range nitrification and thiocyanate denitrification are started, and the effluent is discharged into the intermediate water tank (3) through the first water outlet (2.8); the SBR effluent containing ammonia nitrogen and nitrite nitrogen is mixed with the coking wastewater containing ammonia nitrogen and thiocyanate, and enters the upflow anaerobic sludge bed (4) from the second water inlet (4.2) through the second peristaltic pump (4.1) and the third peristaltic pump (1.2); the effluent after the reaction is discharged through the water outlet (4.4).

2. A method for applying the device as claimed in claim 1, characterized in that: The following steps are involved: (1) System startup: (1.1) Start-up of hypoxic aerated SBR: First, inoculate ordinary activated sludge, keep the sludge concentration at 3000-4000 mg / L, and the wastewater contains 100-120 mg / L of ammonia nitrogen. Then, first control the dissolved oxygen concentration to 2-5 mg / L under low thiocyanate concentration of 100-120 mg / L and high dissolved oxygen conditions to domesticate SCN. - Degradation bacteria and stable ammonia oxidation performance, when SCN - When the removal rate reaches over 90%, start to increase the SCN of the influent - Concentration to 100–200 mg / L, SCN - After the removal rate reaches more than 90%, the concentration is increased to 200-300 mg / L, while the dissolved oxygen concentration is maintained at 0.1-0.3 mg / L to acclimate the thiocyanate denitrifying bacteria; when the thiocyanate removal rate reaches more than 95%, the hypoxic aeration SBR is considered to be successfully started; (1.2) Start-up of UASB: First, inoculate anaerobic ammonium oxidation granular sludge, and keep the sludge concentration at 20000±500mg / L; start in wastewater containing 50-75mg / L ammonia nitrogen and 60-100mg / L nitrite, and then set the thiocyanate concentration in the reactor to 75-150mg / L to acclimate the coupling of anaerobic ammonium oxidation and thiocyanate autotrophic denitrification. The startup is considered successful when the UASB denitrification efficiency reaches more than 72%; (2) System operation: (2.1) Operation of low oxygen aeration SBR: influent NH4 + -N concentration is 100-120mg / L, SCN - Wastewater containing ammonia nitrogen and thiocyanate at a concentration of 300-350 mg / L is pumped into a short-range nitrification SBR reactor (2) through a first peristaltic pump (2.1), and the operating temperature in the reactor is controlled at 25-30° C. Aeration is added to the reactor, and the dissolved oxygen concentration is controlled at 0.1-0.3 mg / L through a gas flow meter, and stirring is performed continuously during the aeration process. During the reaction, ammonia nitrogen is oxidized into nitrite by ammonia oxidizing bacteria, and at the same time, thiocyanate and nitrite in the influent are utilized by autotrophic denitrifying bacteria to generate nitrogen, sulfate and ammonia nitrogen. Low-oxygen short-range nitrification effluent containing ammonia nitrogen and nitrite enters an intermediate water tank (3); (2.2) Operation of UASB: This step is continuous water inflow, and the reactor is in a light-proof, anaerobic and constant temperature environment; the raw water in the water inlet tank (1) is controlled to be pumped into the UASB reactor (4) through the third peristaltic pump (1.2); at the same time, the effluent of the sequencing batch reactor in the intermediate water tank (3) enters the UASB reactor (4) through the second peristaltic pump (4.1), and the volume ratio of the two inlet waters is 1:1; the outside is wrapped with a heating belt (4.3) to maintain the reactor temperature at 30-35°C, and the effluent is discharged through the outlet (4.4).

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