Method for synergistically removing perchlorate and nitrate in wastewater and application thereof

Abstract

The invention discloses a method for synergistically removing perchlorate and nitrate in wastewater and application thereof, and relates to the technical field of wastewater, the method comprises the following steps: S1, carrying out denitrification reaction on wastewater and denitrification sludge; s2, carrying out reduction reaction on effluent after the denitrification reaction and reduced sludge; and S3, carrying out aerobic biochemical treatment on the effluent after the reduction reaction. According to the method, nitrified sludge and reduced sludge are matched with each other, the metabolic environment of microorganisms is optimized, the high nitrate and perchlorate degradation efficiency is achieved, and compared with the prior art, the method has the advantages of being high in treatment efficiency, high in adaptability, low in engineering cost, high in economic benefit and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater, and specifically, to a method for co-removing perchlorate and nitrate in wastewater and its application. Background Art

[0002] The wastewater from fireworks and firecrackers contains composite pollutants such as perchlorate, nitrate, and COD. The wastewater containing a large amount of perchlorate ions is discharged into the environment without effective treatment, causing pollution to surrounding mountain ponds, reservoirs, and groundwater. After entering the human body, perchlorate interferes with the normal function of the human thyroid gland, causing nerve damage and threatening human health, especially having a serious impact on infants and young children.

[0003] Perchlorate has characteristics such as non-volatility, high solubility, and kinetic stability, and its concentration is extremely high. Conventional treatment technologies are difficult to effectively remove it. Currently, the methods for treating the composite pollution of nitrate and perchlorate mainly include ion exchange, membrane separation, chemical reduction, and biological methods. Although the ion exchange and membrane separation processes can remove nitrate and perchlorate in water, the selectivity of their ion exchange resins is not very good and they need to be regenerated frequently. Moreover, they only concentrate and transfer the pollutants without harmlessly converting the pollutants, and the operation cost is relatively high. For the chemical reduction method, noble metal catalysts are mostly used, which are expensive and the catalysts are easily deactivated. CN118515366A discloses a biological co-reduction system for nitrate and perchlorate in fireworks wastewater, which includes an anaerobic tank for removing pollutants in the wastewater and improving water quality; a co-reduction tank for receiving the wastewater treated by the anaerobic tank and reducing and converting perchlorate and nitrate; an aeration tank for receiving the wastewater treated by the co-reduction tank and deodorizing the wastewater, as well as removing the remaining organic matter and ammonia nitrogen; a membrane separation tank for receiving the wastewater treated by the aeration tank and deeply purifying and discharging the wastewater. The invention solves the problems of high equipment cost, low treatment efficiency, and easy generation of secondary pollution in the physicochemical treatment process of the composite pollution wastewater of nitrate and perchlorate, and thus greatly reduces the investment and operation costs. However, the invention is only effective for the removal of perchlorate and nitrate at low concentrations. In wastewater with high concentrations of perchlorate and nitrate, NO3 - has an inhibitory effect on the biological reduction of ClO4 - and cannot ensure the stable discharge of water quality. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a method for co-removing perchlorate and nitrate in wastewater and its application.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: In the first aspect, the invention provides a method for co-removing perchlorate and nitrate in wastewater, including the following steps: S1. Performing a denitrification reaction on the wastewater and denitrifying sludge; S2. The effluent after denitrification reaction and the reduced sludge undergo a reduction reaction; S3. The effluent after the reduction reaction is subjected to aerobic biochemical treatment, and that's it.

[0006] In step S1 of the present invention, the number of viable bacteria per milliliter of denitrifying sludge Pseudomonas is above 1×10 9 CFU, Azonexu the number of viable bacteria is above 5×10 8 CFU, Thauera the number of viable bacteria is above 3×10 8 CFU. The present invention utilizes the denitrifying sludge for denitrification, gradually converting nitrate nitrogen into nitrogen gas, completing the removal of most of the nitrate nitrogen, and partially reducing perchlorate to harmless substances such as chloride. At the same time, it effectively removes suspended solids and precipitates in the wastewater, providing good water quality conditions for the subsequent treatment process.

[0007] In some embodiments, the addition amount of the denitrifying sludge in step S1 is 1% - 10% of the volume of the wastewater; preferably 3% - 8%.

[0008] In some embodiments, the carbon source for the denitrification reaction in step S1 is at least one of sodium acetate, citric acid, methanol, ethanol, and glucose; preferably sodium acetate.

[0009] In some embodiments, the conditions for the denitrification reaction in step S1 are: C / N is 4 - 5, dissolved oxygen is 0.3 - 0.5 mg / L, stirring speed is 50 - 150 rpm, temperature is 25 - 35 °C, pH is 6 - 9, and hydraulic retention time is 0.5 - 2 h.

[0010] The reactor for the denitrification reaction in the present invention is a conventional reaction vessel in the art. Preferably, the reactor for the denitrification reaction in step S1 is a CSTR reactor.

[0011] In step S2 of the present invention, the number of viable bacteria per milliliter of reduced sludge Dechloromonas is above 1.2×10 9 CFU, Azospira the number of viable bacteria is above 7×10 8 CFU. The present invention further reduces perchlorate under anaerobic conditions using reduced sludge, reducing perchlorate to harmless chloride ions, and at the same time further reducing the residual nitrate nitrogen content.

[0012] In some embodiments, the addition amount of the reduced sludge in step S2 is 1% - 10% of the volume of the wastewater; preferably 3% - 8%.

[0013] In some embodiments, the carbon source for the reduction reaction in step S2 is at least one of sodium acetate, citric acid, methanol, ethanol, and glucose; preferably sodium acetate.

[0014] In some embodiments, the conditions for the reduction reaction in step S2 are as follows: CH3COOH - / ClO 4- The molar ratio is 1.5 - 3, the dissolved oxygen is 0.01 - 0.2 mg / L, the temperature is 25 - 35 °C, the pH is 7 - 9, and the hydraulic retention time is 6 - 12 h.

[0015] The reactor for the reduction reaction in the present invention is a conventional reactor in the art. Preferably, the reactor for the reduction reaction in step S2 is an upflow reactor, and more preferably a UASB reactor, and the upflow velocity of the UASB reactor is 1 - 3 m / h.

[0016] In some embodiments, the conditions for the aerobic biochemical treatment in step S3 are as follows: the dissolved oxygen is 0.5 - 1.0 mg / L, and the hydraulic retention time is 3 - 6 h.

[0017] In some embodiments, the carbon source for the aerobic biochemical treatment in step S3 is at least one of sodium acetate, citric acid, methanol, ethanol, and glucose; preferably sodium acetate.

[0018] In some embodiments, the aerobic biochemical treatment is at least one of oxidation ditch, SBR, CASS, biological filter, biological rotating disk, biological contact oxidation method, biological fluidized bed, MBR, or MBBR. Preferably, it is a biological filter. The biological filter enriches microorganisms through fillers, reduces sludge production while maintaining a high biomass, does not require sludge reflux, and further removes residual perchlorate, organic matter, and nitrogen source to ensure that the effluent quality meets relevant discharge standards.

[0019] In a second aspect, the present invention provides the application of the method for co - removing perchlorate and nitrate in the above - mentioned wastewater in wastewater treatment.

[0020] In some embodiments, the wastewater is at least one of fireworks wastewater, wastewater from surrounding mountain ponds and reservoirs polluted by fireworks wastewater, and groundwater polluted by fireworks wastewater. Preferably, the ClO4 - concentration of the wastewater is 180 μg / L - 1000 mg / L, and the NO3 - -N concentration is 5.0 - 462 mg / L; more preferably, the ClO4 - concentration is 200 μg / L - 970 mg / L, and the NO3 - -N concentration is 5.0 - 420 mg / L.

[0021] In some embodiments, the concentration of ClO4 in the wastewater is - 180 μg / L - 990 μg / L, and the concentration of NO3 - -N is 4.5 - 16.5 mg / L; preferably, the concentration of ClO4 - is 200 μg / L - 900 μg / L, and the concentration of NO3 - -N is 5.0 - 15.0 mg / L.

[0022] In some embodiments, the concentration of ClO4 in the wastewater is - 1.8 - 11 mg / L, and the concentration of NO3 - -N is 1 - 7 mg / L; preferably, the concentration of ClO4 - is 2.1 - 9.6 mg / L, and the concentration of NO3 - -N is 1.2 - 5.7 mg / L.

[0023] In some embodiments, the concentration of ClO4 in the wastewater is - 683 - 1000 mg / L, and the concentration of NO3 - -N is 279 - 462 mg / L; preferably, the concentration of ClO4 - is 759 - 970 mg / L, and the concentration of NO3 - -N is 310 - 420 mg / L.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) High treatment efficiency: The present invention adopts the mutual cooperation of nitrifying sludge and reducing sludge, optimizes the metabolic environment of microorganisms, and has a high degradation efficiency of nitrate and perchlorate.

[0025] 2) Comprehensive treatment of multiple pollutants: In view of the coexistence of various organic and inorganic compounds that may exist in the fireworks wastewater, the present invention can effectively remove perchlorate, high-concentration nitrate in the wastewater and other organic pollutants at the same time, especially overcomes the inhibitory effect of NO3 - on the biological reduction of ClO4 - and realizes the comprehensive treatment of multiple pollutants.

[0026] 3) Strong adaptability and wide application prospect: The present invention has strong adaptability and flexibility, can adapt to the treatment requirements of fireworks production wastewater with different concentrations and components, and has a wide application prospect.

[0027] 4) Low project cost and high economic benefits: The present invention reduces the project cost, improves the treatment efficiency and stability, reduces the operation and maintenance costs, and has high economic benefits. Detailed implementation manners

[0028] The following description of the embodiments is only for helping to understand the method of the present invention and its core idea. It should be noted that for those of ordinary skill in the art of this technology, without departing from the principle of the present invention, several improvements and modifications can also be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention. The following description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but can be applied to a wider range consistent with the principles and novel features disclosed herein.

[0029] All numerical values or expressions related to component amounts, process conditions, etc. used in the present invention should be understood to be modified by "about" in all cases. When the term "about" refers to a quantity or a numerical range, it means that the indicated quantity or numerical range is an approximate value within the experimental variability (or within the statistical experimental error). In the present invention, the term "about" should have the meaning of within 10% of the specified value or range, preferably within 5%.

[0030] When the embodiments give numerical ranges, it should be understood that unless otherwise specified in the present invention, both endpoints of each numerical range and any value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. Unless otherwise specified, the solvents involved in the present invention are all water, the carbon sources used are all sodium acetate, and the temperatures involved are all room temperature (20 - 25 °C).

[0031] Example 1 The method for acclimating denitrifying sludge is as follows: Using the aerobic activated sludge from a municipal wastewater treatment plant as the initial inoculum, in a continuously stirred sequencing batch reactor (SBR), it is cultured with simulated influent water of specific composition (see Table 1), the influent nitrate load is 100 mg / L, and at the same time, the concentration of sodium acetate as the electron donor is adjusted accordingly to maintain an appropriate carbon-nitrogen ratio (C / N = 5), and DO (0.3 - 0.5 mg / L), pH (7.5 - 8.0), temperature (30 ± 2 °C) and a sufficient sludge retention time (SRT = 20 d) are controlled. After 60 days of acclimation culture, the denitrification efficiency (evaluated by nitrate removal rate) and sludge properties (such as sedimentation performance, biomass) are regularly monitored during this period. At the end of the acclimation, the sludge shows stable and efficient denitrification performance under a high nitrate load (100 mg / L), and the denitrification rate is stably greater than 90%. It is confirmed by 16S rRNA sequencing that it contains: Pseudomonas(Pseudomonas, accounting for about 28%): The dominant bacterium for efficient denitrification Azonexus (Arcobacter nitrofigilis, accounting for about 15%): Simultaneously degrading COD and nitrogen fixation Thauera (Thauera, accounting for about 12%). The viable count per milliliter of denitrifying sludge Pseudomonas is above 1×10 9 CFU, Azonexu the viable count of 8 is above 5×10 Thauera CFU, 8 and the viable count of

[0032] is above 3×10

[0033] Example 2 The domestication method of the reducing sludge is as follows: Using denitrifying sludge, sludge from the sedimentation tank of a fireworks factory (the original wastewater has not undergone biochemical treatment, and the sludge water content is 96%), and aerobic activated sludge from a municipal sewage treatment plant (mass ratio 1:1:1 - 3) as the initial inoculum, in an upflow anaerobic sludge bed reactor, cultivate with a simulated water distribution of specific components (see Table 2). The domestication process is carried out under anaerobic (DO at 0.01 - 0.2 mg / L) and constant temperature (25 ± 2 °C) conditions, the hydraulic retention time (HRT) is fixed at 8 h, the influent flow rate is 1.5 L / h, and the upflow velocity is 0.825 m / h. The influent perchlorate (ClO4 - ) concentration is set and maintained at 150 mg / L. After 72 consecutive days of domestication and cultivation, regularly monitor the perchlorate (ClO4 - ) removal efficiency of the system and the sludge properties during this period; at the end of domestication, the system shows stable perchlorate reduction performance (removal rate of 99.8 ± 0.04%) under a 150 mg / L ClO4 - load. Confirmed by 16S rRNA sequencing, it contains: Dechloromonas (Dechloromonas, initial proportion about 32%), Azospira (Azospirillum, initial proportion about 25%). The viable count per milliliter of the reducing sludge Dechloromonas is above 1.2×10 9 CFU, Azospira the viable count of 8 is above 7×10

[0034] Table 2 Simulated water distribution for perchlorate-reducing sludge domestication

[0035] Comparative Example 1 The difference between this comparative example and Example 2 lies in that some parameters in the acclimation method of the reducing sludge are different; specifically: (1) Using denitrifying sludge, sedimentation tank sludge from a fireworks factory (the original wastewater has not undergone biochemical treatment, and the sludge water content is 96%), and aerobic activated sludge from a municipal wastewater treatment plant (mass ratio 2:1:1) as the initial inoculum; (2) The hydraulic retention time (HRT) is fixed at 10 h, the influent flow rate is 1.2 L / h, and the upward flow velocity is 0.6 m / h.

[0036] Other conditions are the same as in Example 2.

[0037] Comparative Example 2 The difference between this comparative example and Example 2 lies in that some parameters in the acclimation method of the reducing sludge are different; specifically: (1) Using denitrifying sludge and sedimentation tank sludge from a fireworks factory (the original wastewater has not undergone biochemical treatment, and the sludge water content is 96%) (mass ratio 1:1) as the initial inoculum; (2) The hydraulic retention time (HRT) is fixed at 6 h, the influent flow rate is 1.8 L / h, and the upward flow velocity is 1.2 m / h.

[0038] Other conditions are the same as in Example 2.

[0039] Comparative Example 3 The difference between this comparative example and Example 2 lies in that some parameters in the acclimation method of the reducing sludge are different; specifically: Using denitrifying sludge and aerobic activated sludge from a municipal wastewater treatment plant (mass ratio 1:3) as the initial inoculum.

[0040] Other conditions are the same as in Example 2.

[0041] Example 3 A method for co-removing perchlorate and nitrate in wastewater, the steps are as follows: S1. The wastewater and denitrifying sludge carry out denitrification reaction in a CSTR reactor, gradually converting nitrate nitrogen into nitrogen gas, completing the removal of most nitrate nitrogen, and partially reducing perchlorate into harmless substances such as chloride, while effectively removing suspended solids and precipitates in the wastewater, providing good water quality conditions for the subsequent treatment process; The addition amount of the denitrifying sludge (taken from the denitrifying sludge acclimated in Example 1) is 5% of the wastewater volume; The conditions of the denitrification reaction are: C / N is 4 - 5, the dissolved oxygen is 0.3 - 0.5 mg / L, the stirring speed is controlled within the range of 50 - 150 rpm, the temperature is 25 - 35 °C, the pH is 6 - 9, and the hydraulic retention time is 0.5 - 2 h.

[0042] S2. The effluent after denitrification reaction and the reducing sludge undergo a reduction reaction in a UASB reactor. Under anaerobic conditions, the reducing sludge is used to further reduce perchlorate. Perchlorate is reduced to harmless chloride ions, and at the same time, the residual nitrate nitrogen content is further reduced. The dosage of the reducing sludge (taken from the reducing sludge domesticated in Example 2) is 5% of the volume of the wastewater. The conditions of the reduction reaction are as follows: CH3COOH - / ClO 4- The molar ratio is 1.5 - 3, the dissolved oxygen is 0.01 - 0.2 mg / L, the temperature is 25 - 35 °C, the pH is 7 - 9, and the hydraulic retention time is 6 - 12 h. The upflow velocity of the UASB reactor is 1 - 3 m / h.

[0043] S3. The effluent after the reduction reaction is treated by a biological filter. Microorganisms are enriched by the packing, reducing sludge production while maintaining a high biomass. No sludge reflux is required, and residual perchlorate, organic matter, and nitrogen sources are further removed to ensure that the effluent quality meets the relevant discharge standards. The conditions of the aerobic biochemical treatment are as follows: the dissolved oxygen is 0.5 - 1.0 mg / L, and the hydraulic retention time is 3 - 6 h.

[0044] Example 4 In the laboratory-scale example of Example 3 of the present invention, the test water is the raw water in the wastewater collection tank of a fireworks production enterprise in Liuyang City, Hunan Province. Its water quality characteristics are as follows: ClO4 - The concentration is 759 - 870 mg / L, the COD concentration is 400 - 450 mg / L, NH4 + -N concentration is 26 - 36 mg / L, NO3 - -N concentration 310 - 420 mg / L, NO2 - -N concentration is 90 - 97 mg / L, and the TP concentration is 0.54 mg / L. The test environmental temperature is 25 °C. Each reactor of the test device is made of plexiglass. The total HRT of the device is 14.0 h, and the total influent flow rate is 0.5 L / h. By adjusting the dilution multiple of the original wastewater, the influent pollutant load is changed. The experimental results show that: after stable operation, the average effluent concentration of ClO4 - is 0.2 ± 0.08 mg / L, the average removal rate is 99.7% ± 0.52%, the average effluent concentration of NO3 - -N is 0.02 ± 0.05 mg / L, and the removal rate is 99.9% ± 0.12%. The efficient, stable, and non-secondary pollution removal of perchlorate and nitrate is achieved.

[0045] Comparative Example 4 The difference between this comparative example and Example 4 is that the reduced sludge used is taken from Comparative Example 1, and other parameters (including wastewater quality, device, HRT, flow rate, temperature, etc.) are the same as those in Example 4. The experimental results show that after stable operation, the average effluent concentration of ClO4 - significantly increases to 32.7 ± 5 mg / L, and the average removal rate decreases to 88.3% ± 4.6%; the average effluent concentration of NO3 - -N significantly increases to 11.6 ± 1.2 mg / L, and the removal rate decreases to 91.5% ± 5.2%. This indicates that the reduced sludge lacking key functional bacteria genera domesticated using Comparative Example 1 (non-preferred method) cannot maintain the efficient and stable removal performance of the system for perchlorate and nitrate, and the removal efficiency is significantly lower than that of Example 4.

[0046] Comparative Example 5 The difference between this comparative example and Example 4 is that the reduced sludge used is taken from Comparative Example 2, and other parameters (including wastewater quality, device, HRT, flow rate, temperature, etc.) are the same as those in Example 4. The experimental results show that after stable operation, the average effluent concentration of ClO4 - significantly increases to 45.3 ± 18 mg / L, and the average removal rate decreases to 85.6% ± 3.9%; the average effluent concentration of NO3 - -N significantly increases to 21.1 ± 6.3 mg / L, and the removal rate significantly decreases to 85.8% ± 4.3%. This indicates that the reduced sludge lacking key functional bacteria genera domesticated using Comparative Example 2 (non-preferred method) also cannot maintain the efficient and stable removal performance of the system for perchlorate and nitrate, and the removal efficiency is significantly lower than that of Example 4.

[0047] Comparative Example 6 The difference between this comparative example and Example 4 is that the reduced sludge used is taken from Comparative Example 3, and other parameters (including wastewater quality, device, HRT, flow rate, temperature, etc.) are the same as those in Example 4. The experimental results show that after stable operation, the average effluent concentration of ClO4 - significantly increases to 72.1 ± 11 mg / L, and the average removal rate decreases to 75.9% ± 4.3%; the average effluent concentration of NO3 - -N significantly increases to 30.2 ± 7.7 mg / L, and the removal rate significantly decreases to 80.2% ± 3.2%. This indicates that the reduced sludge lacking key functional bacteria genera domesticated using Comparative Example 3 (non-preferred method) also cannot maintain the efficient and stable removal performance of the system for perchlorate and nitrate, and the removal efficiency is significantly lower than that of Example 4.

[0048] Comparative Example 7 The difference between this comparative example and Example 4 is that the reduced sludge used is taken from Example 1, and other parameters (including wastewater quality, device, HRT, flow rate, temperature, etc.) are the same as those in Example 4. The experimental results show that after stable operation, the average effluent concentration of ClO4 - significantly increased to 11.3 ± 8.9 mg / L, and the average removal rate decreased to 96.3% ± 2.1%; the average effluent concentration of NO3 - -N significantly increased to 2.3 ± 0.9 mg / L, and the removal rate decreased significantly to 98.4% ± 2.7%. This indicates that using only the denitrifying sludge domesticated in Example 1 as the reduced sludge also cannot maintain the efficient and stable removal performance of the system for perchlorate and nitrate, and the removal efficiency is significantly lower than that of Example 4.

[0049] Example 5 In the laboratory-scale example of Example 3 of the present invention, the test water is the wastewater from the mountain pond reservoir around the fireworks enterprises in Liuyang City, Hunan Province. Its water quality characteristics are as follows: the concentration of ClO4 - is 2.1 - 9.6 mg / L, the COD concentration is 20 - 30 mg / L, the concentration of NH4 + -N is 1.5 - 2.3 mg / L, the concentration of NO3 - -N is 1.2 - 5.7 mg / L, the concentration of NO2 - -N is 0.3 - 0.6 mg / L, and the TP concentration is 0.08 - 0.12 mg / L. The test environmental temperature is 25°C. Each reactor of the test device is made of plexiglass. The total HRT of the device is 16.0 h, and the total influent flow rate is 0.5 L / h. The experimental results show that after stable operation, the average effluent concentration of ClO4 - is 0.02 ± 0.01 mg / L, the average removal rate is 99.3% ± 0.2%, the average effluent concentration of NO3 - -N is 0.05 ± 0.02 mg / L, and the removal rate is 99.1% ± 0.3%, achieving the efficient, stable and non-secondary pollution removal of low-concentration perchlorate and nitrate.

[0050] Example 6 In the laboratory-scale example of Example 3 of the present invention, the test water is the polluted groundwater around the fireworks enterprises in Liuyang City, Hunan Province. Its water quality parameters are as follows: the concentration of ClO4 - is 200 - 900 μg / L, the COD concentration is 5 - 10 mg / L, the concentration of NH4 + -N is 0.5 - 1.5 mg / L, the concentration of NO3 -The concentration of -N is 5.0 - 15.0 mg / L. The test environmental temperature is 25 °C. The total hydraulic retention time (HRT) of the device is optimized to 12.0 h, and the influent flow rate is adjusted to 1.0 L / h. After stable operation, the average removal rate of ClO4 - by the system reaches 98.7% ± 0.5%, and the effluent concentration drops to 5.2 ± 1.5 μg / L; the average effluent concentration of NO3 - -N is 0.8 ± 0.3 mg / L, and the removal rate is 98.2% ± 0.6%. The efficient synchronous removal of the combined pollution of low-concentration perchlorate and nitrate is achieved, and there is no risk of nitrite accumulation and secondary pollution.

[0051] Example 7 In the pilot and pilot-scale example of the present invention, the pilot work of the treatment system is carried out at the site of the same fireworks production enterprise as in the laboratory-scale experiment. The wastewater in the company's wastewater storage tank enters the reaction device after dilution, and the wastewater treatment capacity of the test is 1 m³ / d. The water quality parameters are the same as those in Example 4 described above. Each reactor of the test device is made of plexiglass, and the total HRT is set to 14.0 h. During the pilot-scale test period, the specific operation of the system is the same as that of the laboratory scale. The specific operating conditions are shown in Table 3, and the results are shown in Table 4.

[0052] Table 3 Operating Conditions

[0053] Table 4 Treatment Effects

[0054] The operation effect of the pilot-scale test shows that the wastewater treatment effect is good. The removal rate of nitrate nitrogen is close to 100%, the removal rate of perchlorate is stably higher than 99%, and the effluent perchlorate concentration is lower than 0.4 mg / L. The effluent COD is stably lower than 50 mg / L, and there is no secondary pollution phenomenon. The effluent water quality meets the discharge standard and achieves the expected treatment effect. Through comprehensive evaluation of the operation effect of the on-site pilot device, the co-removal of high-concentration perchlorate and nitrate in fireworks wastewater can be realized, which proves that the present invention has good treatment effect and strong applicability in practical engineering applications.

[0055] The above is a further description of the present invention in combination with specific embodiments, but these embodiments are merely exemplary and do not constitute any limitation to the scope of the present invention. Those skilled in the art should understand that the details and forms of the technical solutions of the present invention can be modified or replaced without departing from the spirit and scope of the present invention, but these modifications and replacements all fall within the protection scope of the present invention.

Claims

1. A method for synergistically removing perchlorate and nitrate in wastewater, characterized in that, It includes the following steps: S1. The wastewater and denitrifying sludge undergo a denitrification reaction; S2. The effluent after the denitrification reaction and the reducing sludge undergo a reduction reaction; S3. The effluent after the reduction reaction is subjected to aerobic biochemical treatment, and that's it; The viable count of Pseudomonas in each milliliter of denitrifying sludge in step S1 is 1×10 9 CFU or more, the viable count of Arcobacter nitrogenifigens is 5×10 8 CFU or more, and the viable count of Thauera is 3×10 8 CFU or more; The viable cell count of Dechloromonas per milliliter of the reduced sludge in step S2 is 1.2×10 9 CFU or more, and the viable cell count of Azospirillum is 7×10 8 CFU or more.

2. The method according to claim 1, wherein In step S1, the addition amount of the denitrifying sludge is 1% - 10% of the volume of the wastewater.

3. The method according to claim 1, wherein The conditions for the denitrification reaction in step S1 are: C / N is 4 - 5, dissolved oxygen is 0.3 - 0.5 mg / L, temperature is 25 - 35 °C, pH is 6 - 9, and hydraulic retention time is 0.5 - 2 h.

4. The method according to claim 1, characterized in that, In step S2, the addition amount of the reducing sludge is 1% - 10% of the volume of the wastewater.

5. The method according to claim 1, wherein The conditions for the reduction reaction in step S2 are as follows: CH3COOH - / ClO 4- The molar ratio is 1.5 - 3, the dissolved oxygen is 0.01 - 0.2 mg / L, the temperature is 25 - 35 °C, the pH is 7 - 9, and the hydraulic retention time is 6 - 12 h.

6. The method according to claim 1, characterized in that, The conditions for the aerobic biochemical treatment in step S3 are: dissolved oxygen is 0.5 - 1.0 mg / L, and hydraulic retention time is 3 - 6 h.

7. The method according to claim 6, characterized in that The aerobic biochemical treatment is at least one of oxidation ditch, SBR, CASS, biological filter, biological rotating disk, biological contact oxidation method, biological fluidized bed, MBR or MBBR.

8. The method according to any one of claims 1 to 7, characterized in that The carbon sources for the denitrification reaction, reduction reaction and aerobic biochemical treatment are all at least one of sodium acetate, citric acid, methanol, ethanol and glucose.

9. Use of the method according to any one of claims 1-8 in wastewater treatment, characterized in that, The wastewater is at least one of fireworks wastewater, wastewater from surrounding mountain ponds and reservoirs polluted by fireworks wastewater, and groundwater polluted by fireworks wastewater.

10. The application according to claim 9, wherein, The ClO4 of the wastewater - has a concentration of 180 μg / L - 1000 mg / L, and the NO3 - -N concentration is 5.0 - 462 mg / L.

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