Highway service area wastewater treatment device and method based on aooa-mbb process

Abstract

The present application relates to the field of municipal wastewater treatment, and particularly relates to a highway service area wastewater treatment device and method based on AOOA-MBBR process. The device comprises a first anoxic tank, a first aerobic tank, a second aerobic tank and a second anoxic tank connected in sequence, and is filled with MBBR filler respectively, and the volume of the filled MBBR filler is taken as the effective volume; the first aerobic tank and the second aerobic tank are respectively provided with an aeration device; the first anoxic tank is used for inoculating hydrolytic bacteria and denitrifying bacteria; the first aerobic tank is used for inoculating hydrolytic bacteria, nitrifying bacteria and denitrifying bacteria; the second aerobic tank is used for inoculating nitrifying bacteria, and the second anoxic tank is used for inoculating hydrolytic bacteria and denitrifying bacteria; the second aerobic tank is connected with the first anoxic tank through a reflux pipe, and the reflux pipe is provided with a reflux power assembly. The present application solves the problems of existing highway service wastewater treatment with extremely low carbon-nitrogen ratio, such as the need for additional carbon source / electron donor, high operation cost, poor denitrification effect and high sludge yield.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of municipal wastewater treatment, in particular to a highway service area wastewater treatment device and method based on AOOA-MBBR process. BACKGROUND

[0002] The highway service area wastewater is mainly composed of restaurant wastewater and public toilet fecal wastewater, which accounts for more than 85% of the total wastewater. This wastewater has the following characteristics:

[0003] (1) High ammonia nitrogen concentration, ammonia nitrogen concentration up to 150 mg / L;

[0004] (2) Low carbon-nitrogen ratio, COD / TN less than 2, belonging to high ammonia nitrogen and low carbon-nitrogen ratio wastewater.

[0005] In theory, 2.86 mg of COD is needed to reduce 1 mg of nitrate nitrogen to nitrogen gas, and in practice, 4-5 mg of COD is usually consumed. Due to the severe lack of carbon source in this wastewater, it is difficult to remove nitrogen. The existing highway service area wastewater is mainly treated by A 2 O process, biological contact oxidation process, SBR process, MBR process, etc., and the denitrification effect is not good. Moreover, the existing technology usually uses traditional nitrification / denitrification technology for denitrification, but due to the lack of carbon source in the influent, additional sodium acetate, ethanol and other carbon sources need to be added to ensure the denitrification effect, which greatly increases the operation cost.

[0006] With the improvement of sewage discharge standards, the traditional nitrification / denitrification denitrification technology has obviously been difficult to meet the discharge standards when treating low carbon-nitrogen ratio wastewater. In the Chinese patent "Highway service area integrated wastewater treatment device and method" with publication number CN113860633A, iron-carbon-based composite biological carriers with carbon source providing function are added, and when the carbon-nitrogen ratio is about 5.2, the total nitrogen in the effluent is reduced to below the first level A standard of "Urban Sewage Treatment Plant Pollutant Discharge Standard" (GB 18918-2002). At the same time, this technology uses a membrane bioreactor to improve the effluent water quality, which increases the operation cost. Moreover, for the highway service area wastewater with COD / TN of only 1.63-1.71, the average value is 1.68, this technology cannot make the total nitrogen in the effluent meet the standard.

[0007] Therefore, there is an urgent need for a highway service area wastewater treatment technology that can treat extremely low carbon-nitrogen ratio highway service area wastewater, has low operation cost, low sludge yield, and good total nitrogen removal effect. SUMMARY

[0008] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a highway service area wastewater treatment device based on the AOOA-MBBR process. It solves the problems of existing highway service area wastewater treatment with extremely low carbon-nitrogen ratios requiring external carbon sources / electron donors, high operating costs, poor denitrification effect, and high sludge production.

[0009] To solve the above-mentioned technical problems, the technical solution of the present invention is: a highway service area wastewater treatment device based on the AOOA-MBBR process, comprising a first anoxic tank, a first aerobic tank, a second aerobic tank, and a second anoxic tank connected in sequence; wherein...

[0010] The first anoxic tank, the first aerobic tank, the second aerobic tank, and the second anoxic tank are each filled with MBBR packing material, and the volume of the MBBR packing material is used as the effective volume.

[0011] The first aerobic tank and the second aerobic tank are respectively equipped with aeration devices. The aeration device in the first aerobic tank is configured to make the dissolved oxygen concentration in the first aerobic tank 0.3-0.5 mg / L, and the aeration device in the second aerobic tank is configured to make the dissolved oxygen concentration in the second aerobic tank 2.0-2.5 mg / L.

[0012] The first anoxic tank is used to inoculate hydrolyzing bacteria and denitrifying bacteria; the first aerobic tank is used to inoculate hydrolyzing bacteria, nitrifying bacteria and denitrifying bacteria; the second aerobic tank is used to inoculate nitrifying bacteria, and the second anoxic tank is used to inoculate hydrolyzing bacteria and denitrifying bacteria.

[0013] The second aerobic tank is connected to the first anoxic tank via a return pipe, and the return pipe is equipped with a return power component.

[0014] Furthermore, the upper end of the first anoxic tank is provided with a sewage inlet, and the lower end is connected to the lower end of the first aerobic tank; the upper end of the first aerobic tank is connected to the upper end of the second aerobic tank; the lower end of the second aerobic tank is connected to the lower end of the second anoxic tank; and the upper end of the second anoxic tank is provided with a clean water outlet.

[0015] Furthermore, the highway service area wastewater treatment device based on the AOOA-MBBR process also includes an inlet pipe, which is connected to the wastewater inlet and is equipped with a peristaltic pump for providing inflow force.

[0016] Furthermore, the MBBR packing has a diameter of 10 mm and a specific surface area of ​​60 m². 2 / m 3 .

[0017] This invention also relates to a method for treating wastewater in highway service areas based on an AOA-MBBR process, comprising:

[0018] Wastewater from the highway service area flows sequentially through the first anoxic tank, the first aerobic tank, the second aerobic tank, and the second anoxic tank; among them,

[0019] Hydrolyzing bacteria and denitrifying bacteria are inoculated in the first anoxic tank; hydrolyzing bacteria, nitrifying bacteria, and denitrifying bacteria are inoculated in the first aerobic tank; nitrifying bacteria are inoculated in the second aerobic tank, and hydrolyzing bacteria and denitrifying bacteria are inoculated in the second anoxic tank; the dissolved oxygen concentration in the first aerobic tank is 0.3-0.5 mg / L; the dissolved oxygen concentration in the second aerobic tank is 2.0-2.5 mg / L; the hydraulic retention time is 48 h; the nitrification liquor reflux ratio is 200%, and it is refluxed from the second aerobic tank to the first anoxic tank;

[0020] After the water has been running stably for a preset time, the hydraulic residence time is gradually shortened to 36 hours and then 24 hours to enter the stable stage.

[0021] Furthermore, the COD / TN ratio of wastewater from highway service areas is 1.63-1.71.

[0022] Furthermore, during the inoculation process:

[0023] In the first anoxic tank, hydrolytic bacteria were inoculated once every 10 days, with 200 mL each time and a bacterial concentration of 3-5 g / L, for a total of 8 inoculations; denitrifying bacteria were inoculated once every 5 days, with 300 mL each time and a bacterial concentration of 8-10 g / L, for a total of 4 inoculations.

[0024] In the first aerobic tank, hydrolyzing bacteria are inoculated once every 10 days, with 150 mL each time and a bacterial concentration of 3-5 g / L, for a total of 8 inoculations; nitrifying bacteria and denitrifying bacteria are inoculated once every 5 days, with 100 mL each time and a bacterial concentration of 8-10 g / L, for a total of 4 inoculations.

[0025] In the second aerobic tank, nitrifying bacteria are inoculated once every 5 days, with 400 mL of bacteria solution each time and a bacterial concentration of 8-10 g / L, for a total of 4 inoculations.

[0026] In the second anoxic tank, hydrolytic bacteria are inoculated once every 10 days, with 100 mL each time and a bacterial concentration of 3-5 g / L, for a total of 8 inoculations; denitrifying bacteria are inoculated once every 5 days, with 100 mL each time and a bacterial concentration of 8-10 g / L, for a total of 4 inoculations.

[0027] Furthermore, during the initial startup phase of the highway service area wastewater treatment device based on the AOOA-MBBR process, the temperature was 30-31℃ and the pH was 7.8-8.2.

[0028] After 30 days, the temperature dropped to 25-27℃, while the pH remained unchanged.

[0029] By adopting the above technical solution, the present invention has the following beneficial effects:

[0030] (1) Good total nitrogen removal effect: When treating wastewater from a highway service area with an extremely low carbon-to-nitrogen ratio (average COD / TN of 1.68), the total nitrogen decreased from about 150 mg / L to 14.05 mg / L with a hydraulic retention time of 24 h, and the removal rate was 90.68%. The total nitrogen in the effluent met the Class A discharge standard of the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" (GB18918-2002).

[0031] (2) Extremely low sludge production: The present invention uses most of the sludge as a carbon source after hydrolysis. Therefore, the sludge production coefficient in the system of the present invention is only 0.028, which is much lower than the sludge production coefficient (0.72-0.86) produced by conventional denitrification processes, which significantly reduces sludge treatment costs.

[0032] (3) Solved the problem of insufficient carbon source during denitrification: This invention uses most of the sludge as a carbon source after hydrolysis, and also uses the recalcitrant organic matter in the influent as a carbon source after hydrolysis, thus solving the problem of insufficient carbon source during denitrification. Theoretically, reducing 1 mg of nitrate nitrogen to nitrogen gas requires 2.86 mg of COD, but in practice it usually requires 4-5 mg of COD; this invention removes 1 mg of total nitrogen by consuming only 1.80 mg of COD.

[0033] (4) Low operating costs: This invention does not require an external carbon source / electron donor, achieving highly efficient denitrification of highway service area wastewater with an extremely low carbon-to-nitrogen ratio (average COD / TN of 1.68), significantly reducing operating costs. Dissolved oxygen in the first aerobic tank is controlled at 0.3-0.5 mg / L. This low dissolved oxygen concentration helps improve oxygen mass transfer efficiency during aeration, thereby reducing the aeration volume and lowering operating costs.

[0034] (5) No secondary pollution will be generated: This invention does not introduce any chemical agents when treating wastewater from highway service areas and significantly reduces sludge production, thus preventing secondary pollution.

[0035] In summary, this invention effectively solves the problems of high operating costs, secondary pollution, and poor total nitrogen removal in the treatment of wastewater with low carbon-to-nitrogen ratios (average COD / TN of 1.68) from highway service areas. It achieves low-cost and efficient removal of total nitrogen. After treatment by the A00A-MBBR process, the wastewater meets the Class A discharge standard of the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" (GB18918-2002), which requires total nitrogen ≤15 mg / L. It has high application value and is conducive to widespread application. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the wastewater treatment device for highway service areas based on the AOOA-MBBR process of the present invention.

[0037] Figure 2 This is a diagram illustrating the COD removal effect during the processing in an embodiment of the present invention;

[0038] Figure 3 This is a diagram illustrating the ammonia nitrogen removal effect during the treatment process in an embodiment of the present invention.

[0039] Figure 4 This is a diagram illustrating the effect of nitrate nitrogen removal during the treatment process in an embodiment of the present invention;

[0040] Figure 5 This is a diagram illustrating the effect of nitrite nitrogen removal during the treatment process in an embodiment of the present invention;

[0041] Figure 6 This is a diagram illustrating the total nitrogen removal effect during the treatment in an embodiment of the present invention;

[0042] Figure 7 This is a microbial detection diagram of the highway service area wastewater treatment device based on the AOOA-MBBR process of the present invention during the stable phase.

[0043] In the diagram, 1 is the first anoxic tank; 2 is the first aerobic tank; 3 is the second aerobic tank; 4 is the second anoxic tank; 5 is the MBBR packing material; 6 is the aeration device; 7 is the return pipe; 8 is the return power component; and 9 is the inlet pipe. Detailed Implementation

[0044] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0045] like Figure 1 As shown, a highway service area wastewater treatment device based on the AOA-MBBR process includes a first anoxic tank 1, a first aerobic tank 2, a second aerobic tank 3, and a second anoxic tank 4 connected in sequence; wherein,

[0046] The first anoxic tank 1, the first aerobic tank 2, the second aerobic tank 3, and the second anoxic tank 4 are respectively filled with MBBR packing material 5, and the volume of the filled MBBR packing material 5 is used as the effective volume.

[0047] Aeration devices 6 are respectively installed in the first aerobic tank 2 and the second aerobic tank 3. The aeration device 6 in the first aerobic tank 2 is configured to make the dissolved oxygen concentration in the first aerobic tank 2 0.3-0.5 mg / L, and the aeration device 6 in the second aerobic tank 3 is configured to make the dissolved oxygen concentration in the second aerobic tank 3 2.0-2.5 mg / L.

[0048] The first anoxic tank 1 is used for inoculating hydrolyzing bacteria and denitrifying bacteria; the first aerobic tank 2 is used for inoculating hydrolyzing bacteria, nitrifying bacteria and denitrifying bacteria; the second aerobic tank 3 is used for inoculating nitrifying bacteria; and the second anoxic tank 4 is used for inoculating hydrolyzing bacteria and denitrifying bacteria.

[0049] The second aerobic tank 3 is connected to the first anoxic tank 1 through a return pipe 7, and the return pipe 7 is equipped with a return power component 8.

[0050] In this embodiment, as Figure 1 As shown, the upper end of the first anoxic tank 1 is provided with a sewage inlet, and the lower end is connected to the lower end of the first aerobic tank 2; the upper end of the first aerobic tank 2 is connected to the upper end of the second aerobic tank 3; the lower end of the second aerobic tank 3 is connected to the lower end of the second anoxic tank 4; and the upper end of the second anoxic tank 4 is provided with a clean water outlet.

[0051] In this way, the wastewater can be fully treated in each pool.

[0052] In this embodiment, as Figure 1 As shown, the highway service area wastewater treatment device based on the AOOA-MBBR process also includes an inlet pipe 9, which is connected to a sewage inlet and is equipped with a peristaltic pump to provide inflow force.

[0053] The wastewater treatment method of the highway service area wastewater treatment device based on the AOOA-MBBR process involved in the above embodiments will be described in detail below with reference to specific embodiments.

[0054] The effective volumes of the first anoxic tank 1, the first aerobic tank 2, the second aerobic tank 3, and the second anoxic tank 4 are 10.8L, 8.1L, 8.1L, and 5.4L, respectively. Packing material is added to each of the above tanks at amounts of 10.8L, 8.1L, 8.1L, and 5.4L, respectively, ensuring that all microorganisms adhere to the packing material, which is beneficial for the growth of microorganisms with long generation cycles. The MBBR packing material 5 has a diameter of 10mm and a specific surface area of ​​60m². 2 / m 3 This packing material only provides a carrier for microbial growth and cannot be decomposed by microorganisms.

[0055] The simulated COD, ammonia nitrogen, total nitrogen, and total phosphorus concentrations of wastewater from a highway service area were approximately 250 mg / L, 140 mg / L, 150 mg / L, and 5.0 mg / L, respectively. Wastewater treatment methods for highway service areas include:

[0056] Start-up phase: Simulated wastewater from a highway service area flows sequentially through the first anoxic tank 1, the first aerobic tank 2, the second aerobic tank 3, and the second anoxic tank. The COD / TN ratio of the highway service area wastewater is 1.63-1.71, with an average of 1.68; among which,

[0057] Hydrolyzing bacteria and denitrifying bacteria were inoculated in the first anoxic tank 1. Hydrolyzing bacteria were inoculated once every 10 days, with 200 mL each time and a bacterial concentration of 3-5 g / L, for a total of 8 inoculations. Denitrifying bacteria were inoculated once every 5 days, with 300 mL each time and a bacterial concentration of 8-10 g / L, for a total of 4 inoculations.

[0058] In the first aerobic tank 2, hydrolytic bacteria, nitrifying bacteria and denitrifying bacteria were inoculated. Hydrolytic bacteria were inoculated once every 10 days, with 150 mL each time, and the bacterial concentration was 3-5 g / L, for 8 times. Nitrifying bacteria and denitrifying bacteria were inoculated once every 5 days, with 100 mL each time, and the bacterial concentration was 8-10 g / L, for 4 times each.

[0059] Nitrifying bacteria were inoculated in the second aerobic tank 3. Nitrifying bacteria were inoculated once every 5 days, with 400 mL of nitrifying bacteria each time. The bacterial concentration was 8-10 g / L. The inoculation was repeated 4 times.

[0060] In the second anoxic tank 4, hydrolytic bacteria and denitrifying bacteria were inoculated. Hydrolytic bacteria were inoculated once every 10 days, with 100 mL each time and a bacterial concentration of 3-5 g / L, for 8 times. Denitrifying bacteria were inoculated once every 5 days, with 100 mL each time and a bacterial concentration of 8-10 g / L, for 4 times.

[0061] The dissolved oxygen concentration in the first aerobic tank 2 is 0.3-0.5 mg / L; the dissolved oxygen concentration in the second aerobic tank 3 is 2.0-2.5 mg / L.

[0062] To facilitate the attachment and growth of functional bacteria on the packing material, and to acclimatize and cultivate them, the initial temperature was controlled at 30-31℃, and the pH at 7.8-8.2. After 30 days, the temperature was lowered to 25-27℃, while the pH remained unchanged. The dissolved oxygen concentrations in the first aerobic tank 2 and the second aerobic tank 3 were 0.3-0.5 mg / L and 2.0-2.5 mg / L, respectively, with a hydraulic retention time of 48 hours and a nitrification liquor recirculation ratio of 200%, which was then recirculated from the second aerobic tank 3 to the first anoxic tank 1. After the effluent had been running stably for 15 days, the hydraulic retention time was shortened to 36 hours. Once the effluent stabilized again, the hydraulic retention time was shortened to 24 hours. After the effluent stabilized again, the system entered a stable phase.

[0063] exist Figures 2 to 6 In the data, the stabilization phase of the effluent with a hydraulic residence time of 48 hours is from day 34 to day 48, the stabilization phase with a hydraulic residence time of 36 hours is from day 84 to day 98, and the stabilization phase with a hydraulic residence time of 24 hours is from day 120 to day 134.

[0064] The recirculation ratio refers to the ratio of the flow rate of nitrified liquid recirculated from the second aerobic tank 3 to the first anoxic tank 1 to the flow rate of highway service area wastewater entering the first anoxic tank 1 from the wastewater inlet. Stable effluent means that the relative average concentrations of COD, ammonia nitrogen, total nitrogen, and total phosphorus in the effluent do not fluctuate by more than 10% over a continuous 13-day period.

[0065] During the stabilization phase (days 120 to 134), with a hydraulic retention time of 24 hours, the effluent COD ranged from 10.62 to 13.04 mg / L, with an average concentration of 11.87 mg / L; the removal efficiency was 94.84% to 95.84%, with an average removal efficiency of 95.34%. The effluent total nitrogen ranged from 14.05 to 14.77 mg / L, with an average concentration of 14.33 mg / L; the removal efficiency was 90.25% to 90.64%, with an average removal rate of 90.49%. Both the effluent COD and total nitrogen met the Class A discharge standards of the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" (GB18918-2002) (COD ≤ 50 mg / L, total nitrogen ≤ 15 mg / L).

[0066] in, Figure 2 This is a diagram illustrating the COD removal effect during the processing in an embodiment of the present invention; Figure 3 This is a diagram illustrating the ammonia nitrogen removal effect during the treatment process in an embodiment of the present invention. Figure 4 This is a diagram illustrating the effect of nitrate nitrogen removal during the treatment process in an embodiment of the present invention; Figure 5 This is a diagram illustrating the effect of nitrite nitrogen removal during the treatment process in an embodiment of the present invention; Figure 6 This is a diagram illustrating the total nitrogen removal effect during the treatment in an embodiment of the present invention; Figure 7 This is a microbial detection diagram of the highway service area wastewater treatment device based on the AOOA-MBBR process of the present invention during the stable phase.

[0067] The following section provides a detailed explanation of the wastewater treatment principles involved in the above embodiments.

[0068] To address the extremely low carbon-to-nitrogen ratio (COD / TN average 1.68) of highway service area wastewater, this invention develops a wastewater treatment device and method for highway service areas based on the AOA-MBBR process. The influent from the first anoxic tank 1 mixes with nitrified liquid from the second aerobic tank 3 and flows through the MBBR packing material 5 in the first anoxic tank 1. Denitrifying bacteria attached to the MBBR packing material 5 utilize the organic matter in the influent to reduce nitrate nitrogen carried in the nitrified liquid to nitrogen gas, achieving denitrification. During the start-up phase, the hydrolytic bacteria inoculated, cultivated, and acclimatized in the first anoxic tank 1 are highly efficient. Under conditions of severe carbon source deficiency, the hydrolytic bacteria attached to the packing material can hydrolyze the recalcitrant organic matter in the influent into readily degradable organic matter, thus providing a carbon source for denitrification. The COD concentration in the effluent from the first anoxic tank 1 drops below 22 mg / L (COD concentration range 16.73 mg / L-21.60 mg / L), which proves the above points. After the biofilm detaches from the MBBR packing material 5 in the first anoxic tank 1, it settles at the bottom. The debris formed after the microorganisms in the biofilm die is adsorbed by the highly active biofilm on the MBBR packing material 5 and then hydrolyzed by hydrolytic bacteria, providing a carbon source for denitrification. The debris produced after the death of microorganisms is removed by highly efficient hydrolytic and denitrifying bacteria, which will not lead to an increase in COD. In addition, denitrifying bacteria can also use recalcitrant organic matter as a carbon source for denitrification and nitrogen removal.

[0069] In the first aerobic tank 2, dissolved oxygen was controlled at 0.3-0.5 mg / L. An aerobic layer dominated by nitrifying bacteria was formed on the outer layer of the biofilm on the MBBR packing material 5, while an anoxic layer dominated by hydrolytic and denitrifying bacteria was formed on the inner layer of the biofilm on the MBBR packing material 5, achieving simultaneous nitrification and denitrification nitrogen removal. In this tank, total nitrogen decreased significantly from 43.02 mg / L (41.10 mg / L-46.59 mg / L) to 25.12 mg / L (22.86 mg / L-27.93 mg / L), proving that total nitrogen was removed through simultaneous nitrification and denitrification. However, COD only decreased from 19.44 mg / L (16.73 mg / L-21.60 mg / L) to 16.04 mg / L (14.38 mg / L-20.47 mg / L), indicating very little carbon source consumption. Nitrifying bacteria in the aerobic layer utilize dissolved oxygen to oxidize ammonia nitrogen in the effluent of the first anoxic tank 1 to nitrite or nitrate nitrogen. Hydrolytic bacteria in the anoxic layer hydrolyze recalcitrant organic matter and microbial debris into readily degradable organic matter. Denitrifying bacteria in the anoxic layer use these hydrolysis products as a carbon source to reduce nitrite and nitrate nitrogen to nitrogen gas. This invention controls the nitrification liquor reflux ratio, the hydraulic retention time of the first anoxic tank 1, the dissolved oxygen in the first aerobic tank 2, the hydraulic retention time of the first aerobic tank 2, temperature, pH, and carbon source conditions to maintain the nitrate / nitrite nitrogen ratio in the first aerobic tank 2 between 1.8 and 2.0, achieving a high concentration of nitrite nitrogen accumulation. Oxidizing ammonia nitrogen to nitrite nitrogen reduces dissolved oxygen consumption and lowers operating costs; reducing nitrite nitrogen to nitrogen gas reduces carbon source consumption, achieving efficient total nitrogen removal using a limited carbon source.

[0070] In the second aerobic tank 3, dissolved oxygen is controlled at 2.0-2.5 mg / L. The MBBR packing material 5 is mainly composed of aerobic biofilm, and the biofilm is mainly composed of nitrifying bacteria. Therefore, the goal of the second aerobic tank 3 is to nitrify ammonia nitrogen into nitrite nitrogen and nitrate nitrogen. The nitrifying bacteria use dissolved oxygen to oxidize ammonia nitrogen and nitrite nitrogen in the effluent of the first aerobic tank 2 into nitrate nitrogen. The ammonia nitrogen level drops significantly from 12.70 mg / L (11.17 mg / L-14.86 mg / L) to 7.75 mg / L (7.59 mg / L-7.98 mg / L). Meanwhile, the second aerobic tank 3 contains a local anoxic zone, which can denitrify nitrate and nitrite nitrogen into nitrogen gas. In this tank, the total nitrogen level slightly decreased from 25.12 mg / L (22.86 mg / L-27.93 mg / L) to 23.60 mg / L (22.55 mg / L-24.41 mg / L). In the second aerobic tank 3, dead microorganisms are also used as a carbon source.

[0071] In the second anoxic tank 4, hydrolytic and denitrifying bacteria were also inoculated, cultivated, and acclimatized during the start-up phase. The hydrolytic bacteria attached to the MBBR packing material 5 hydrolyzed the recalcitrant organic matter in the effluent from the second aerobic tank 3 into readily biodegradable organic matter, thus providing a carbon source for denitrification. In the second anoxic tank 4, COD decreased slightly from 13.62 mg / L (15.52 mg / L - 11.40 mg / L) to 11.87 mg / L (10.62 mg / L - 13.04 mg / L), while total nitrogen decreased significantly from 23.60 mg / L (22.55 mg / L - 24.41 mg / L) to 14.33 mg / L (14.05 mg / L - 14.77 mg / L). After the biofilm detaches from the MBBR packing material 5, it settles at the bottom of the tank. The debris formed after the death of microorganisms within the biofilm is adsorbed by the highly active biofilm on the MBBR packing material 5 and then further hydrolyzed, providing a carbon source for denitrification. In addition, denitrifying bacteria can also use recalcitrant organic matter as a carbon source for denitrification and nitrogen removal.

[0072] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for treating wastewater from highway service areas, characterized in that, The wastewater treatment device for highway service areas based on the AOOA-MBBR process includes a first anoxic tank (1), a first aerobic tank (2), a second aerobic tank (3), and a second anoxic tank (4) connected in sequence; wherein, The first anoxic tank (1), the first aerobic tank (2), the second aerobic tank (3), and the second anoxic tank (4) are respectively filled with MBBR packing material (5), and the volume of the filled MBBR packing material (5) is used as the effective volume. The first aerobic tank (2) and the second aerobic tank (3) are respectively equipped with an aeration device (6). The aeration device (6) in the first aerobic tank (2) is configured to make the dissolved oxygen concentration in the first aerobic tank (2) 0.3-0.5 mg / L, and the aeration device (6) in the second aerobic tank (3) is configured to make the dissolved oxygen concentration in the second aerobic tank (3) 2.0-2.5 mg / L. The first anoxic tank (1) is used for inoculating hydrolytic bacteria and denitrifying bacteria; the first aerobic tank (2) The first aerobic tank (3) is used for inoculating hydrolyzing bacteria, nitrifying bacteria and denitrifying bacteria; the second aerobic tank (3) is used for inoculating nitrifying bacteria, and the second anoxic tank (4) is used for inoculating hydrolyzing bacteria and denitrifying bacteria. The second aerobic tank (3) is connected to the first anoxic tank (1) through a return pipe (7), and the return pipe (7) is equipped with a return power component (8); The methods include: Wastewater from the highway service area flows sequentially through the first anoxic tank (1), the first aerobic tank (2), the second aerobic tank (3), and the second anoxic tank; among which, Hydrolyzing bacteria and denitrifying bacteria were inoculated in the first anoxic tank (1); hydrolyzing bacteria, nitrifying bacteria and denitrifying bacteria were inoculated in the first aerobic tank (2); nitrifying bacteria were inoculated in the second aerobic tank (3); and hydrolyzing bacteria and denitrifying bacteria were inoculated in the second anoxic tank (4); the dissolved oxygen concentration in the first aerobic tank (2) was 0.3-0.5 mg / L; the dissolved oxygen concentration in the second aerobic tank (3) was 2.0-2.5 mg / L; the hydraulic retention time was 48h; and the nitrification liquor reflux ratio was 200%, which was refluxed from the second aerobic tank (3) to the first anoxic tank (1). After the water has been running stably for a preset time, the hydraulic residence time is gradually shortened to 36 hours and then 24 hours to enter the stable stage.

2. The method for treating wastewater from highway service areas according to claim 1, characterized in that, The upper end of the first anoxic tank (1) is provided with a sewage inlet, and the lower end is connected to the lower end of the first aerobic tank (2); the upper end of the first aerobic tank (2) is connected to the upper end of the second aerobic tank (3); the lower end of the second aerobic tank (3) is connected to the lower end of the second anoxic tank (4); the upper end of the second anoxic tank (4) is provided with a clean water outlet.

3. The wastewater treatment method for highway service areas according to claim 2, characterized in that, It also includes an inlet pipe (9) connected to the sewage inlet, and the inlet pipe (9) is equipped with a peristaltic pump for providing inlet flow force.

4. The method for treating wastewater from highway service areas according to claim 1, characterized in that, The MBBR packing (5) has a diameter of 10 mm and a specific surface area of ​​60 m². 2 / m 3 .

5. The method for treating wastewater from highway service areas according to claim 1, characterized in that, The COD / TN ratio of wastewater from highway service areas is 1.63-1.

71.

6. The method for treating wastewater from highway service areas according to claim 5, characterized in that, During the inoculation process: In the first anoxic tank (1), hydrolytic bacteria were inoculated once every 10 days, with 200 mL each time and a bacterial concentration of 3-5 g / L, for a total of 8 inoculations; denitrifying bacteria were inoculated once every 5 days, with 300 mL each time and a bacterial concentration of 8-10 g / L, for a total of 4 inoculations. In the first aerobic tank (2), hydrolytic bacteria are inoculated once every 10 days, with 150 mL each time and a bacterial concentration of 3-5 g / L, for 8 times; nitrifying bacteria and denitrifying bacteria are inoculated once every 5 days, with 100 mL each time and a bacterial concentration of 8-10 g / L, for 4 times. In the second aerobic tank (3), nitrifying bacteria are inoculated once every 5 days, with 400 mL of bacteria solution each time and a bacterial concentration of 8-10 g / L, for a total of 4 inoculations; In the second anoxic pool (4), hydrolytic bacteria are inoculated once every 10 days, with 100 mL each time and a bacterial concentration of 3-5 g / L, for a total of 8 inoculations; denitrifying bacteria are inoculated once every 5 days, with 100 mL each time and a bacterial concentration of 8-10 g / L, for a total of 4 inoculations.

7. The method for treating wastewater from highway service areas according to claim 1, characterized in that, During the initial startup phase of the highway service area wastewater treatment device based on the AOOA-MBBR process, the temperature is 30-31℃ and the pH is 7.8-8.

2. After 30 days, the temperature dropped to 25-27℃, while the pH remained unchanged.

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