A rapid construction method of a biological denitrification system for ultra-high salt pickling wastewater

Abstract

In view of the significant inhibition of salinity on traditional autotrophic denitrification functional microorganisms, the construction of hyper-salinity biological denitrification system is difficult, and the current pickling wastewater treatment project is diluted to reduce the salinity before biological treatment, which leads to the problems of large amount of water to be treated, low denitrification efficiency, high investment and high treatment cost. The present application provides a rapid construction method of hyper-salinity pickling wastewater biological denitrification system with salinity of 7% to 15%, which directly enriches the original halophilic functional flora in hyper-salinity pickling wastewater, and couples the hydrolysis acidification and biological denitrification processes under anoxic-aerobic operating conditions, and simultaneously adds zero-valent iron particles to improve the hydrolysis acidification efficiency of organic matter in the anoxic period and the denitrification efficiency of the original halophilic heterotrophic denitrification flora in the aerobic period, so as to accelerate the dominant enrichment of the original halophilic heterotrophic denitrification functional flora, and realize the rapid construction of the hyper-salinity pickling wastewater biological denitrification system. The present application greatly shortens the construction time of the hyper-salinity biological denitrification system, significantly improves the denitrification efficiency of the system, and opens up a new way for efficient and low-cost treatment of hyper-salinity preserved vegetable pickling wastewater.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wastewater treatment, and particularly relates to a rapid construction method of a super-high-salinity pickling wastewater biological denitrification system. BACKGROUND

[0002] The pickling wastewater produced in the pickling process of preserved vegetables, pickled vegetables and fish cans has high salinity and complex pollutant composition. Taking pickled vegetable pickling wastewater as an example, the salinity of the wastewater produced in the second and third pickling processes is as high as 7% to 15%, the COD concentration is 29300 to 91000 mg / L, the NH4 + -N concentration is 263 to 910 mg / L, and the TN concentration is 1620 to 3100 mg / L. The nitrifying functional bacteria such as ammonia-oxidizing bacteria and nitrite-oxidizing bacteria in the traditional biological denitrification system are sensitive to salinity. Among them, ammonia-oxidizing bacteria can tolerate 3% salinity, while nitrite-oxidizing bacteria are completely inhibited at a salinity of 2%. For this reason, the current pickled vegetable pickling wastewater treatment project uses the method of dilution to reduce the salinity of the wastewater to below 1.5% before treatment, resulting in a substantial increase in the amount of water to be treated, and high investment and cost of wastewater treatment.

[0003] Currently, the research on biological denitrification of high-salinity wastewater mainly targets wastewater with a salinity of 3% to 7%, and usually uses the method of gradually increasing the salinity to domesticate microorganisms or adding salt-tolerant / salt-loving inoculants to construct a biological denitrification system. Chinese patent (CN102502955A) discloses a method for culturing activated sludge suitable for high-salinity wastewater. The method first increases the chloride ion load by intermittent water feeding, and then increases the hydraulic load by continuous water feeding, so as to obtain activated sludge capable of treating high-salinity wastewater. However, this method is only suitable for treating wastewater with a chloride ion concentration of less than 7000 mg / L, and has the problems of long domestication time, low denitrification efficiency and complex operation and management. Chinese patent (CN113023901A) discloses a method for constructing a salt-tolerant microbial community and its application in the field of high-salinity wastewater treatment. The method constructs a salt-tolerant microbial community by domesticating and enriching biological samples from regions with high original salinity, and uses it to treat high-salinity wastewater. However, the salt-tolerant microbial community constructed by this method can only tolerate a salinity range of 1% to 7%, and has the problems of complex construction process and unknown treatment effect on actual high-salinity wastewater. There is no report on the construction of a biological denitrification system for super-high-salinity wastewater with a salinity of 7% to 15% and the denitrification efficiency. Therefore, it is particularly necessary to develop a biological denitrification technology for super-high-salinity pickling wastewater to provide technical support for efficient and low-cost treatment of pickling wastewater.

[0004] Heterotrophic nitrifying bacteria are a kind of bacteria that grow by utilizing organic carbon sources, and at the same time convert nitrogen-containing compounds into NH2OH, NO2 - -N and NO3 -Microorganisms of -N and the like products, many heterotrophic nitrifying bacteria have the function of aerobic denitrification. Compared with autotrophic nitrifying bacteria, heterotrophic nitrifying bacteria have stronger tolerance to extreme environment, faster metabolic speed, higher growth rate, and more abundant nitrogen substrate types, and have great application prospect in biological denitrification of high-salt / ultra-high-salt wastewater.

[0005] However, the ultra-high-salt pickling wastewater often has complex water quality composition, and there are some macromolecular organic matters and refractory substances, which are not conducive to the utilization of carbon sources by heterotrophic denitrifying bacteria, thereby affecting the denitrification efficiency and organic matter degradation efficiency of the ultra-high-salt biological denitrification system. Hydrolysis acidification is usually used as a pretreatment process for industrial wastewater, which can convert refractory macromolecular organic matters into easily degradable small molecular organic matters, and improve the biodegradability of wastewater. In addition, the addition of conductive materials can strengthen the hydrolysis acidification efficiency of the system, and zero-valent iron is a cheap and environmentally friendly reducing agent, which can reduce the redox potential of the system and has strong reducing capacity. However, there is no report on the construction of a hydrolysis acidification and biological denitrification coupled system for ultra-high-salt pickling wastewater, and the use of zero-valent iron to strengthen the hydrolysis acidification and denitrification efficiency of ultra-high-salt wastewater. SUMMARY

[0006] The purpose of the present application is to provide a method for rapidly constructing an ultra-high-salt pickling wastewater biological denitrification system. The method enriches the original halophilic functional flora in the ultra-high-salt pickling wastewater, and couples the hydrolysis acidification and heterotrophic biological denitrification processes under anoxic-aerobic operating conditions. At the same time, zero-valent iron particles are added to improve the hydrolysis acidification efficiency of organic matter during the anoxic period and the denitrification efficiency of the original halophilic heterotrophic denitrifying bacterial flora during the aerobic period, so as to accelerate the enrichment of the original halophilic heterotrophic denitrification functional flora, realize the rapid construction of the ultra-high-salt pickling wastewater biological denitrification system with a salinity of 7% to 15%, and solve the problems of difficult construction, long construction time, low treatment efficiency, high treatment cost, etc. of the ultra-high-salt pickling wastewater biological treatment system caused by the inhibition of salinity on denitrifying microorganisms.

[0007] The specific technical solutions of the present application include:

[0008] The construction method includes two stages, the first stage is enrichment of the original halophilic functional flora in the pickling wastewater, and the second stage is construction of a hydrolysis acidification and heterotrophic denitrification system. The process of the two stages is as follows:

[0009] The first stage includes: adding a pickling wastewater stock solution with a salinity of 7% to 15% to a sequencing batch biofilm reactor, and continuously aeration at a preset temperature and aeration rate to enrich the original halophilic functional flora carried by the pickling wastewater; the biofilm is formed on the filler in the sequencing batch biofilm reactor by continuous aeration, and the removal rates of organic matter and nitrogen both reach the preset requirements;

[0010] The second stage comprises: after the first stage is completed, adjusting the operation condition of the sequencing batch biofilm reactor to influent-anoxic-aerobic-settling-drainage, and adding a preset amount of zero-valent iron particles into the sequencing batch biofilm reactor; adding the pickling wastewater stock solution with a salinity of 7% to 15% into the sequencing batch biofilm reactor, and operating the sequencing batch biofilm reactor under the conditions of a preset temperature, a preset organic load and a preset aeration rate; the sequencing batch biofilm reactor undergoes the hydrolysis and acidification process of organic matter in the anoxic period, and undergoes the heterotrophic denitrification process in the aerobic period; continuously operating until the removal rates of the sequencing batch biofilm reactor for organic matter and nitrogen both reach preset requirements, and the biological denitrification system for the hypersaline pickling wastewater is constructed.

[0011] Further, the pickling wastewater stock solution with a salinity of 7% to 15% comprises wastewater formed in a food production and processing process, and the C / N of the wastewater is 10 to 20.

[0012] The food production and processing process is a process of salt pickling preserved vegetables, pickles, pickled vegetables and / or meat.

[0013] Further, the sequencing batch biofilm reactor is internally provided with fillers, preferably rope-shaped fillers, combined fillers and suspended ball fillers, and the filler filling ratio is 50%.

[0014] The combined fillers comprise polypropylene plastic discs and synthetic fiber bundles of 6 g / piece.

[0015] The suspended ball fillers comprise polypropylene spherical shells and polyurethane foam fillers.

[0016] Further, in the first stage, the sequencing batch biofilm reactor takes the indigenous halophilic functional bacterial flora carried in the pickling wastewater stock solution as a seed source, and does not inoculate a seed source additionally.

[0017] Further, the preset temperature of the sequencing batch biofilm reactor is 20 ℃ to 30 ℃, and the preset aeration rate is controlled at 3 to 5 L / min.

[0018] Further, in the second stage, the zero-valent iron particle addition amount in the sequencing batch biofilm reactor is 5 to 20 g / L, and the particle size is 150 to 500 μm.

[0019] Further, in the second stage, the operation cycle of the sequencing batch biofilm reactor is controlled at 18 to 24 h, and in each operation cycle, the ratio of the anoxic operation period to the aerobic operation period is controlled at 1 to 1.5:0.5 to 1.

[0020] Further, in the second stage, the sequencing batch biofilm reactor undergoes the hydrolysis and acidification process of organic matter in the anoxic period, and undergoes the heterotrophic denitrification process in the aerobic period, which is a one-stage process.

[0021] Further, in the second stage, the organic load of the sequencing batch biofilm reactor is 1-2 kg COD / (m 3 ·d).

[0022] The technical principle of the method is:

[0023] In the enrichment stage of the native halophilic functional bacteria group in the pickling wastewater, the method directly enriches the native halophilic functional bacteria group in the pickling wastewater with a salinity of 7%-15% to construct an ultra-high-salinity biological denitrification reactor without additional inoculation of a seed source. The native halophilic functional bacteria group does not need to be acclimated to the salinity, and can be accelerated in the proliferation and enrichment in the ultra-high-salinity environment through aeration oxygen supply, thereby greatly saving the construction time of the system. Compared with the method of additional inoculation of a halophilic bacteria agent, the native microorganism has more advantages in metabolic kinetics, microbial diversity, and operation stability.

[0024] In the second stage of construction of the hydrolysis acidification coupled heterotrophic biological denitrification system, the operating conditions of the sequencing batch biofilm reactor are adjusted to an anoxic-aerobic operation to couple the hydrolysis acidification process and the heterotrophic biological denitrification process. In the anoxic period, the native halophilic hydrolysis acidification bacteria enriched in the system convert the refractory and macromolecular organic matters in the pickling wastewater into easily utilized small-molecular organic matters, such as volatile fatty acids. In the aerobic period, the native halophilic heterotrophic denitrification bacteria group, such as heterotrophic nitrification-aerobic denitrification bacteria, aerobic denitrification bacteria, and anoxic denitrification bacteria, can quickly utilize the small-molecular organic matters produced in the anoxic period for heterotrophic denitrification, thereby improving the denitrification rate and the organic matter utilization efficiency of the system. In addition, in the anoxic period, the zero-valent iron particles can be used as an electron donor to promote the breakage of unsaturated chemical bonds of the organic matters, thereby strengthening the hydrolysis acidification process and improving the biodegradability of the pickling wastewater. In the aerobic period, the zero-valent iron particles can also be used as an electron donor and an electron transfer intermediate to participate in the denitrification process, thereby improving the electron transfer activity and transfer efficiency in the denitrification process of the system and enhancing the enzyme activity of the native halophilic heterotrophic denitrification bacteria group, and further strengthening the enrichment of the native halophilic heterotrophic denitrification bacteria group, thereby shortening the construction time of the system and improving the denitrification efficiency of the system. Meanwhile, in the second stage, the zero-valent iron particles can also promote the production of extracellular polymeric substances by the microorganisms in the system, accelerate the formation of the biofilm, improve the stability of the biofilm, and further accelerate the construction of the ultra-high-salinity biological denitrification system.

[0025] The main advantages of the method are:

[0026] (1) The native halophilic functional bacteria group in the pickling wastewater is used as a seed source, and the system is constructed quickly without acclimation and with high salt tolerance.

[0027] Due to the inhibition of salinity on nitrifying functional bacteria of traditional biological nitrogen removal, it is difficult to construct a biological nitrogen removal system for 7%-15% ultra-high salinity pickling wastewater. The method enriches the indigenous halophilic functional bacteria in 7%-15% salinity pickling wastewater, without long-term salinity acclimation or screening suitable commercial salt-tolerant / inhabiting bacteria agents. The enrichment culture can be directly carried out in the original salinity of pickling wastewater, which greatly shortens the system construction time. The indigenous halophilic functional bacteria in pickling wastewater have greater advantages in metabolic kinetics, microbial diversity and running stability compared with the functional microorganisms acclimated or inoculated from other systems.

[0028] (2) Zero-valent iron particles strengthen the hydrolysis acidification and biological nitrogen removal process of organic matter, and the system has high organic matter removal efficiency and high nitrogen removal efficiency.

[0029] By adding zero-valent iron particles, on the one hand, the zero-valent iron particles can act as an electron donor to promote the breakage of unsaturated chemical bonds of organic matter, strengthen the hydrolysis acidification process, and thus improve the biodegradability of pickling wastewater and the utilization efficiency of organic matter, providing more easily available small molecular organic matter for the indigenous halophilic heterotrophic denitrifying bacteria in the system; on the other hand, the zero-valent iron particles can act as an electron donor and electron transfer intermediate to participate in the heterotrophic denitrification process, enhance the electron transfer activity and transfer efficiency in the heterotrophic denitrification process, and also enhance the enzyme activity of the indigenous halophilic heterotrophic denitrifying functional bacteria, thereby strengthening the enrichment of the indigenous halophilic heterotrophic denitrifying functional bacteria, shortening the construction time of the system, and improving the nitrogen removal efficiency of the system; in addition, the zero-valent iron particles can also promote the production of extracellular polymeric substances by microorganisms in the system, accelerate the formation of biofilm, improve the stability of biofilm, and further accelerate the construction of the ultra-high salinity biological nitrogen removal system.

[0030] (3) Hydrolysis acidification and biological nitrogen removal are coupled, the process flow is short, the operation and management are simple, the energy consumption is low, and the investment and operation cost is low.

[0031] Hydrolysis acidification is typically used as a pretreatment process before biological treatment units to improve the biodegradability of wastewater. This method utilizes the facultative anaerobic nature of hydrolytic acidifying bacteria, coupling the hydrolysis acidification process with the biological denitrification process through alternating anoxic and aerobic operation. In the coupled reactor, organic matter is hydrolyzed and acidified during the anoxic phase, while during the aerobic phase, the native halophilic heterotrophic denitrifying bacteria within the reactor rapidly utilize the small-molecule organic matter produced during the anoxic phase for denitrification. This method not only shortens the process flow, reduces the complexity of operation and management, and decreases tank volume, but also improves the utilization efficiency of organic matter by the native halophilic heterotrophic denitrifying bacteria within the system, thereby increasing the denitrification rate, reducing aeration time, and lowering the reactor's operating energy consumption. Furthermore, this method is applicable to the construction of a biological denitrification system for ultra-high salinity pickling wastewater with a salinity of 7% to 15%. Once successfully constructed, the system can directly treat the raw ultra-high salinity pickling wastewater without dilution. This solves the prominent problem in current pickled mustard tuber wastewater treatment projects where salinity inhibits traditional denitrification microorganisms, leading to a significant increase in the amount of water to be treated and high investment and treatment costs due to dilution to reduce wastewater salinity. Attached Figure Description

[0032] Figure 1 This is a graph showing the periodic changes of TN and COD in the reactor of the experimental group in the embodiment of the present invention under steady-state conditions.

[0033] Figure 2 This is a graph showing the periodic changes of TN and COD in the control group reactor of this embodiment under steady-state conditions. Detailed Implementation

[0034] The following detailed description is provided in conjunction with specific examples:

[0035] This embodiment uses ultra-high salinity wastewater generated from pickling mustard tubers as an example to describe the construction process of a biological denitrification system for ultra-high salinity pickling wastewater, which can be implemented according to the following steps:

[0036] (1) Enrichment stage of native halophilic functional bacteria in pickling wastewater: The raw pickling wastewater with a salinity of more than 7% (specifically between 7% and 15% in this embodiment) is added to a sequencing batch biofilm reactor (SBBR, the structure of which is existing technology). The reactor is equipped with any one of rope packing, combined packing and suspended ball packing, with a packing ratio of 50%. The reactor is aerated at an operating temperature of 20 ℃ to 30 ℃ to rapidly enrich the native halophilic functional bacteria in the pickling wastewater. The aeration rate is controlled at 3 to 5 L / min. Aeration continues until a biofilm is formed on the packing in the reactor and the removal rates of carbon and nitrogen both reach more than 15%. This is considered to be the stage where the halophilic native heterotrophic denitrifying bacteria can be enhanced and enriched.

[0037] (2) Hydrolysis acidification coupled with heterotrophic denitrification system construction phase: 5-20 g / L of zero-valent iron particles with a particle size of 150-500 μm were added to the constructed sequencing batch biofilm reactor in the enrichment culture phase of the indigenous halophilic bacteria group; the reactor operating conditions were adjusted to influent-anoxic-aerobic-settling-drainage, and the operating cycle was controlled at 18-24 h. In each operating cycle, the ratio of anoxic operating period to aerobic operating period was controlled at 1-1.5:0.5-1; the salted mustard pickle wastewater stock with a salinity of 7%-15% was added to the reactor, and the reactor was operated at a temperature of 20 ℃-30 ℃, an organic load of 1-2 kg COD / (m 3 ·d) and an aeration rate of 3-5 L / min during the aerobic period. After continuous operation until the removal rates of carbon and nitrogen in the system both reached more than 80%, the ultra-high-salinity pickle wastewater biological denitrification system was constructed.

[0038] The actual third-stage pickle wastewater was used in the examples, and the relevant water quality characteristics of the third-stage pickle wastewater were as follows: COD concentration 34,000 ± 1,000 mg / L, NH4 + -N concentration 740 ± 50 mg / L, NO3 - -N concentration 220 ± 20 mg / L, TN concentration 2,350 ± 100 mg / L, salinity 15% ± 0.5%, and pH 4.5 ± 0.2.

[0039] Example 1

[0040] In the first-stage pickle wastewater indigenous halophilic functional bacteria group enrichment phase, a sequencing batch biofilm reactor was used, and a rope-shaped filler was arranged in the reactor with a filler filling ratio of 50%; the pickle wastewater stock with a salinity of 15% was added to the reactor, and the reactor was sealed and exposed at a temperature of 30 ± 2 ℃ to quickly enrich the indigenous halophilic functional bacteria group in the pickle wastewater, and the aeration rate was 3 L / min; on the 4th day of reactor operation, a thin biofilm was observed to form on the filler in the reactor, and the removal rates of TN and COD in the reactor were 20.34% and 30.94%, respectively, which was considered as the completion of the first stage.

[0041] In the second stage of the hydrolysis acidification coupled heterotrophic denitrification system construction phase, the experimental group sequencing batch biofilm reactor was added with 10 g / L of zero-valent iron particles with a particle size of 150-500 μm, the operation cycle was 24 h, and the operation condition was anoxic-aerobic: influent 0.1 h-anoxic 12 h-aerobic 11.5 h-settlement 0.3 h-drainage 0.1 h; the control group reactor was not added with zero-valent iron particles, the operation cycle was 24 h, and the operation condition was full aerobic: influent 0.1 h-aerobic 23.5 h-settlement 0.3 h-drainage 0.1 h; the salinity of 15% pickling wastewater was added to the reactor, and the experimental group and the control group reactor were operated under the conditions of temperature 30 ± 2 ℃, organic load 1 kg COD / (m 3 ·d), and aerobic period aeration rate 3 L / min.

[0042] When the experimental group sequencing batch biofilm reactor was operated to the 18th day-22nd day, the average concentrations of TN and COD in the effluent of the experimental group reactor were 429 mg / L and 4120 mg / L respectively, and the average removal rates of TN and COD were 81.74% and 87.88% respectively, which was considered as the success of the biological denitrification system construction of the ultra-high salt pickling wastewater; the experimental group reactor was continuously operated to the 44th day-48th day, and the system was gradually stabilized, the average concentrations of TN and COD in the effluent of the experimental group reactor were 37 mg / L and 680 mg / L respectively, and the average removal rates of TN and COD were 98.43% and 98.00% respectively.

[0043] When the control group sequencing batch biofilm reactor was operated to the 44th day-48th day, the average concentrations of TN and COD in the effluent of the control group reactor were 463 mg / L and 6730 mg / L respectively, and the average removal rates of TN and COD were 80.30% and 80.21% respectively, which was considered as the success of the biological denitrification system construction of the ultra-high salt pickling wastewater; the control group reactor was continuously operated to the 80th day-86th day, and the system was gradually stabilized, the average concentrations of TN and COD in the effluent of the control group reactor were 206 mg / L and 5025 mg / L respectively, and the average removal rates of TN and COD were 91.23% and 85.22% respectively.

[0044] The results showed that compared with the control group reactor without adding zero-valent iron particles and full aerobic operation, the construction time of the experimental group reactor was greatly reduced, and the denitrification efficiency and organic matter removal efficiency were significantly improved, which indicated that the zero-valent iron particles could effectively enhance the hydrolysis acidification efficiency and heterotrophic denitrification efficiency of the system, thereby improving the utilization rate and removal efficiency of organic matter, accelerating the enrichment of the indigenous halophilic heterotrophic denitrifying bacteria, and shortening the construction time of the system.

[0045] After the construction of the two reactors, the changes of water quality indexes in a typical cycle under stable state were tested, and the results are shown in the following table and the following figures:Figure 1 and attached Figure 2 It can be seen from the figure that the TN concentration in the experimental reactor decreases rapidly within 1.5 h before the start of the aerobic period, with a removal rate of 35.11 mg / (L·h), and about 80% of the periodic net reduction of TN is removed within 6 h before the aerobic period. The TN removal rate in the control reactor without zero-valent iron particles and running in the whole aerobic period is relatively flat, with a TN removal rate of 8.94 mg / (L·h) within the first 1.5 h, and only about 58% of the periodic net reduction of TN is removed within 6 h before the aerobic period. The results show that the addition of zero-valent iron in the experimental reactor effectively enhances the hydrolysis and acidification of organic matter in the anoxic period, so that the indigenous halophilic heterotrophic denitrifying bacteria in the reactor can perform efficient denitrification in the aerobic period. At the same time, compared with the control reactor running in the whole aerobic period, the experimental reactor greatly shortens the aeration time, which is beneficial to reduce the operating energy consumption.

[0046] Example 2:

[0047] In the first stage of the pickling wastewater indigenous halophilic functional bacteria enrichment stage, a sequencing batch biofilm reactor was used, and rope-shaped fillers were arranged in the reactor with a filler filling ratio of 50%. The salinity of 15% pickling wastewater stock solution was added to the reactor, and the reactor was exposed to temperature at 30 ± 2 ℃ to quickly enrich the indigenous halophilic functional bacteria in the pickling wastewater, and the aeration rate was 3 L / min. Four groups of reactors were set up, and by the 4th day of operation, it was observed that a thin biofilm gradually formed on the fillers in the reactor, and the TN and COD removal rates of the four groups of reactors were 19.35-21.09% and 28.76%-32.25%, respectively, which was considered as the completion of the first stage.

[0048] In the second stage of the hydrolysis and acidification coupled heterotrophic denitrification system construction stage, four groups of reactors were added with 0 g / L, 5 g / L, 10 g / L, and 20 g / L of zero-valent iron particles with a particle size of 150-500 μm, respectively, and the operation cycle was 24 h. The operation condition was anoxic-aerobic: 0.1 h of influent-12 h of anoxic-11.5 h of aerobic-0.3 h of sedimentation-0.1 h of effluent. The salinity of 15% pickling wastewater stock solution was added to the reactor, and the experimental and control reactors were operated at a temperature of 30 ± 2 ℃, an organic load of 1 kg COD / (m 3 ·d), and an aerobic period aeration rate of 3 L / min.

[0049] The biological denitrification system of hypersaline pickling wastewater was constructed by operating the reactors with zero-valent iron particle dosage of 0 g / L, 5 g / L, 10 g / L and 20 g / L to the 67th-71st day, 30th-34th day, 18th-22nd day and 16th-20th day, respectively. The average concentration of effluent TN was 462 mg / L, 451 mg / L, 429 mg / L and 402 mg / L, respectively, and the average removal rate of TN was 80.34%, 80.80%, 81.74% and 82.89%, respectively. The average concentration of effluent COD was 6514 mg / L, 5870 mg / L, 4120 mg / L and 4262 mg / L, respectively, and the average removal rate of COD was 80.84%, 82.74%, 87.88% and 87.46%, respectively. The reactors were continuously operated to the 104th-108th day, 52th-56th day, 44th-48th day and 40th-44th day, respectively. The system gradually stabilized, and the average concentration of effluent TN was 153 mg / L, 106 mg / L, 37 mg / L and 32 mg / L, respectively, and the average removal rate of TN was 93.49%, 95.49%, 98.43% and 98.64%, respectively. The average concentration of effluent COD was 4375 mg / L, 1498 mg / L, 680 mg / L and 635 mg / L, respectively, and the average removal rate of COD was 87.13%, 95.59%, 98.00% and 98.13%, respectively. The results showed that the optimal dosage of zero-valent iron particles for the system construction was 5-20 g / L.

Claims

1. A rapid construction method for a biological denitrification system for ultra-high salinity pickling wastewater, characterized in that, The construction method includes two stages. The first stage is the enrichment of native halophilic functional bacteria in pickling wastewater. The second stage: Construction of a hydrolysis-acidification coupled heterotrophic denitrification system; the process of the second stage is as follows. The first stage includes: adding raw pickling wastewater with a salinity of 7% to 15% into a sequencing batch reactor (SBR); continuously aerating the SBR at a preset temperature and a preset aeration rate to enrich the native halophilic functional bacteria in the pickling wastewater; and continuously aerating until a biofilm forms on the packing material inside the SBR, and the removal rates of organic matter and nitrogen both meet the preset requirements. The second stage includes: after the completion of the first stage, adjusting the operating conditions of the sequencing batch reactor (SBR) to influent-anoxic-aerobic-sedimentation-discharge, and adding a preset amount of zero-valent iron particles into the SBR; adding raw pickling wastewater with a salinity of 7%~15% into the SBR, and operating the SBR under preset organic load, preset temperature, and preset aeration rate; the SBR undergoes a hydrolysis and acidification of organic matter during the anoxic period and a heterotrophic biological denitrification process during the aerobic period; and continuing operation until the removal rates of organic matter and nitrogen by the SBR reach the preset requirements, thus completing the construction of the ultra-high salinity pickling wastewater biological denitrification system. The sequencing batch biofilm reactor uses the native halophilic functional bacteria carried in the raw pickling wastewater as the seed source, without additional inoculation.

2. The rapid construction method for a biological denitrification system for ultra-high salinity pickling wastewater according to claim 1, characterized in that, The raw pickling wastewater with a salinity of 7% to 15% includes wastewater with a salinity of 7% to 15% and a C / N ratio of 10 to 20 generated during food production and processing. The food production and processing process is the process of salting and pickling pickled vegetables, salted vegetables, kimchi, and / or meat.

3. The rapid construction method for a biological denitrification system for ultra-high salinity pickling wastewater according to claim 1, characterized in that, The sequencing batch reactor (SBR) is filled with rope packing, combined packing, and suspended ball packing, with a packing ratio of 50%. The composite filler consists of polypropylene plastic discs and 6 g / disc synthetic fiber bundles; Suspended ball packing includes a polypropylene spherical shell and polyurethane foam packing.

4. The rapid construction method of the biological denitrification system for ultra-high salinity pickling wastewater according to claim 1, characterized in that, In the first stage, the sequencing batch biofilm reactor uses the native halophilic functional bacteria carried in the raw pickling wastewater as the seed source, without additional inoculation.

5. The rapid construction method for a biological denitrification system for ultra-high salinity pickling wastewater according to claim 1, characterized in that, The preset temperature of the sequencing batch biofilm reactor is 20 ℃~30 ℃, and the preset aeration rate is controlled at 3~5 L / min.

6. The rapid construction method for a biological denitrification system for ultra-high salinity pickling wastewater according to claim 1, characterized in that, In the second stage, the amount of zero-valent iron particles added to the sequencing batch reactor is 5~20 g / L, and the particle size is 150~500 μm.

7. The rapid construction method for a biological denitrification system for ultra-high salinity pickling wastewater according to claim 1, characterized in that, In the second stage, the operating cycle of the sequencing batch reactor is controlled at 18-24 h, and the ratio of the anoxic operation period to the aerobic operation period in each operating cycle is controlled at 1-1.5:0.5-1.

8. The rapid construction method for a biological denitrification system for ultra-high salinity pickling wastewater according to claim 1, characterized in that, In the second stage, the organic loading of the sequencing batch reactor was 1-2 kg COD / (m³). 3 ·d).

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