A pretreatment method for high-concentration pit bottom wastewater from liquor brewing

Abstract

The present invention provides a method for pretreating high-concentration wastewater from the bottom of a liquor brewing pit, and belongs to the field of water treatment technology. The pretreatment method provided by the present invention includes chemical treatment, solid-liquid separation, aeration, and precipitation processes. In the chemical treatment process, the present invention uses calcium hypochlorite, ferric hydroxide, and modified lime slurry as modifiers for treatment, which can greatly remove soluble organic matter and organic particulate matter in the wastewater, further reduce the difficulty of subsequent treatment, and further improve the impact load resistance of the subsequent biochemical treatment system. The method for pretreating high-concentration wastewater from the bottom of a liquor brewing pit provided by the present invention has good treatment effect, high denitrification efficiency, strong impact load resistance, low operating costs, and good application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment, and in particular to a pretreatment method for high-concentration pit bottom wastewater in liquor brewing. Background Art

[0002] High-concentration baijiu brewing pit wastewater (also known as yellow water) is a mixed wastewater collected from the bottom of boilers, fermentation pits, seepage from distillery warehouses, and cleaning equipment during the baijiu brewing process. It is characterized by high production volume, high concentrations of organic matter and total nitrogen, dark color, strong odor, and complex composition. Its COD typically ranges from 50,000 to 500,000 mg / L, BOD from 35,000 to 400,000 mg / L, SS from 600 to 3,000 mg / L, total nitrogen from 5,000 to 12,000 mg / L, and total phosphorus from 2,000 to 5,000 mg / L. It is a dark black liquid and contains large amounts of suspended solids, dissolved solids, and volatile solids. It is acidic (pH 3 to 6), making it difficult to treat. Conventional sewage treatment systems are unable to withstand such high loads. If not properly treated and discharged, this wastewater will directly cause serious environmental pollution and ecological damage.

[0003] The high-concentration pit bottom wastewater (yellow water) from liquor brewing has an extremely high concentration, and contains some difficult-to-biodegrade components and low-concentration alcohol, resulting in its biodegradability being almost zero. Its water quality, water volume, water temperature and other indicators fluctuate greatly due to the influence of factors such as the liquor brewing production process, cycle and season, and the microbial treatment system is fragile. Among them, total nitrogen, ammonia nitrogen and difficult-to-degrade components are the key points and difficulties in the treatment of high-concentration pit bottom wastewater (yellow water) from liquor brewing. The current wastewater treatment process for the liquor brewing industry mostly uses coagulation sedimentation / flotation for anaerobic pretreatment and anaerobic post-treatment, resulting in problems such as high reagent consumption; at the same time, the traditional A / O process is used for biological denitrification, but the denitrification load is low, resulting in a huge volume of the A / O reaction tank. On the other hand, the traditional A / O denitrification system has poor shock resistance and is a bottleneck in the treatment system of high-concentration bottom wastewater (yellow water) from liquor brewing. In the production wastewater discharged from the fifth to seventh rounds of the liquor brewing process, the concentrations of difficult-to-degrade organic matter and organic nitrogen increase, and the proportion of carbon sources available for denitrification by denitrifying bacteria decreases, requiring the addition of a large amount of carbon source, resulting in increased sludge production and operating costs.

[0004] The prior art CN114538711A discloses a microbial degradation treatment method, in which liquor production wastewater is sequentially subjected to sedimentation, filtration and microbial degradation treatment, wherein the composite microbial liquid is prepared by mixing lactic acid bacteria, Acinetobacter baumannii, Aquaspirillum, photosynthetic bacteria, actinomycetes and Acidovorax avenae, etc., and its resistance to shock loads still needs to be further improved.

[0005] Therefore, there is an urgent need to explore an efficient treatment process and control method for liquor brewing industrial wastewater with good treatment effect, high denitrification efficiency, strong resistance to shock loads and low operating costs. Summary of the Invention

[0006] In view of this, the present invention aims to provide a pretreatment method for high-concentration wastewater from liquor brewing pits. The pretreatment method provided by the present invention can effectively reduce the concentrations of organic matter, total nitrogen, ammonia nitrogen, and total phosphorus in high-concentration wastewater from liquor brewing pits, converting the high-concentration wastewater from liquor brewing pits into biodegradable wastewater of conventional concentration, thereby reducing the load impact on the sewage treatment system.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a pretreatment method for high-concentration pit bottom wastewater from liquor brewing, comprising the following steps:

[0009] Calcium hypochlorite, ferric hydroxide and modified lime slurry are sequentially added to high-concentration wastewater from liquor brewing pits and mixed, and the pH value of the resulting mixed solution is 12-13; the modified lime slurry is obtained by mixing cooled slaked lime slurry with sodium metaaluminate;

[0010] The mixed liquid is subjected to a first aeration, wherein the first aeration gas is compressed and heated hot air, to obtain chemically modified wastewater;

[0011] performing solid-liquid separation on the chemically modified wastewater to obtain separated water;

[0012] aerating the separated water for the second time, wherein the second aeration gas is air, to obtain aerated water;

[0013] The aeration effluent is subjected to sedimentation and aging treatment to separate the sediment to obtain pretreated wastewater.

[0014] Preferably, the high-concentration pit bottom wastewater from liquor brewing has a COD of 50,000-500,000 mg / L, a BOD of 35,000-400,000 mg / L, a SS of 600-3,000 mg / L, a total nitrogen of 5,000-12,000 mg / L, a total phosphorus of 2,000-5,000 mg / L, and a pH of 3-6.

[0015] Preferably, the dosage of calcium hypochlorite is 0.3-1.2% of the mass of high-concentration pit bottom wastewater from liquor brewing;

[0016] The added amount of the ferric hydroxide is 0.2-1.0% of the mass of high-concentration pit bottom wastewater from liquor brewing.

[0017] Preferably, after adding ferric hydroxide, stirring is carried out for 10 to 30 minutes.

[0018] Preferably, the modified lime slurry is obtained by mixing cooled slaked lime slurry with sodium aluminate, and the mass ratio of the slaked lime slurry to sodium aluminate is 100:5-10;

[0019] The dosage of the modified lime slurry is 1-10% of the volume of high-concentration pit bottom wastewater in liquor brewing.

[0020] Preferably, the aeration rate of the first aeration is 8-40m3 per cubic meter of water. 3 / h, aeration time is 30 to 120 minutes.

[0021] Preferably, the solid-liquid separation method is plate and frame filter press separation.

[0022] Preferably, the aeration volume of the second aeration is 5 to 20 m3 per cubic meter of water. 3 / h, aeration time is 5 to 12h.

[0023] Preferably, the pH value of the aerated effluent is ≤8.5.

[0024] Preferably, the sedimentation and aging treatment is sedimentation in an inclined plate sedimentation tank or a gravity sedimentation tank;

[0025] The precipitation aging treatment time is 12 to 24 hours.

[0026] The invention provides a pretreatment method for high-concentration pit bottom wastewater from liquor brewing. The method comprises the following steps: sequentially adding calcium hypochlorite, ferric hydroxide and modified lime slurry into the high-concentration pit bottom wastewater from liquor brewing and mixing the mixture, wherein the pH value of the obtained mixed solution is 12-13; the modified lime slurry is obtained by mixing cooled slaked lime slurry with sodium metaaluminate; performing a first aeration on the mixed solution, wherein the first aeration gas is compressed and heated hot air, to obtain chemically modified wastewater; performing solid-liquid separation on the chemically modified wastewater to obtain separated effluent; performing a second aeration on the separated effluent, wherein the second aeration gas is air, to obtain aerated effluent; and performing sedimentation and aging treatment on the aerated effluent to separate precipitates to obtain pretreated wastewater. In the chemical modification treatment stage, the present invention mainly removes small-molecule organic matter with strong reducing properties and large-molecule organic matter in a semi-dissolved state in the high-concentration pit bottom wastewater of liquor brewing. The strong oxidizing property of a large amount of hypochlorite ions contained in calcium hypochlorite is utilized. The hypochlorite ions oxidize and decompose the large-molecule organic matter into small-molecule organic matter (easy to decompose and remove), and the calcium ions form insoluble calcium salts with large-molecule organic acids, thereby removing a large amount of organic matter and protein in the wastewater, and greatly reducing the COD and organic nitrogen, phosphorus and other pollutants in the wastewater; the ferric hydroxide suspension mainly reacts with the organic acid in the wastewater and combines to form a partial complex or chelate, and adsorbs the free phosphate ions and ammonium ions in the water to form a precipitate. The role of adding modified lime is to adjust the pH value of the wastewater, increase the concentration of calcium and aluminum ions in the solution, so that the large-particle organic molecules in the wastewater combine with calcium and aluminum ions to form a precipitate, remove some of the difficult-to-degrade large-molecule organic matter, reduce the chromaticity of the wastewater, etc., and increase the OH of the solution. - Ion concentration: The present invention can decompose part of the organic nitrogen containing protein by controlling the pH value of the mixed solution to 12-13.

[0027] The invention introduces compressed hot air. The oxygen in the hot compressed air has high activity. The highly active oxygen reacts with small molecules in high-concentration wastewater to easily decompose organic matter into inorganic substances such as carbon dioxide and water, thereby reducing the COD content in the wastewater.

[0028] The reaction mechanism of the chemical modification treatment stage of the present invention is as follows:

[0029]

[0030] Small molecule organic matter + oxygen → carbon dioxide + water and other inorganic substances.

[0031] The present invention separates the suspended solids in the high-concentration wastewater from the bottom of the cellar from liquor brewing and the insoluble solid particles produced after the wastewater is chemically modified by performing solid-liquid separation. The organic sludge cake formed is processed for resource recovery, and the separated filtrate enters the next treatment process. The present invention neutralizes the pH value of the water effluent from the solid-liquid separation through a second aeration, and utilizes the carbon dioxide gas in the air to neutralize the hydroxide ions in the wastewater. At the same time, the calcium ions and carbon dioxide are converted into calcium carbonate and precipitated, thereby reducing the hardness of the effluent and lowering the pH value of the effluent to about 8.5. The present invention can separate the calcium-containing precipitate produced by aeration from the water through subsequent precipitation and aging treatment, and further consume the dissolved oxygen in the wastewater, thereby improving the biodegradability of the pretreated wastewater.

[0032] The results show that the pretreatment method provided by the present invention can achieve a COD removal rate of up to 85% in high-concentration pit bottom wastewater (yellow water) from liquor brewing, a NH3-N removal rate of up to 70%, a TN removal rate of up to 85%, and a TP removal rate of more than 99.9%.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) The present invention provides a method for pretreating high-concentration pit bottom wastewater (yellow water) from liquor brewing. The wastewater is pretreated by adopting physical and chemical methods. The first step is to chemically modify the high-concentration pit bottom wastewater (yellow water) from liquor brewing. The specific chemical modification treatment is to add calcium hypochlorite, ferric hydroxide and modified lime slurry to the wastewater in sequence to convert various soluble organic pollutants and nitrogen-containing compounds in the wastewater into water-insoluble solids and precipitate them out; the second step is to perform solid-liquid separation physical treatment on the chemically modified high-concentration pit bottom wastewater to remove the pollutants formed by the modification of the high-concentration pit bottom wastewater to reduce the various pollutants in the wastewater. concentration; the third step is to aerate the strongly alkaline waste liquid that has undergone solid-liquid separation, neutralize the alkalinity in the wastewater with carbon dioxide in the air, and at the same time remove a large amount of calcium and magnesium ions in the wastewater, reduce the hardness of the effluent, and make full preparations for subsequent biochemical treatment; the pretreatment method provided by the present invention has a simple process, a fast chemical reaction speed, high and stable treatment efficiency, a small amount of reagent addition and a low price, thereby reducing the cost of wastewater treatment. At the same time, the strongly alkaline effluent can remove most of the odor and other problems of high-concentration wastewater. On the premise of ensuring the removal of pollutants in the wastewater, it can withstand larger and more variable wastewater impact loads, thereby realizing continuous and stable operation of the process.

[0035] (2) The physical and chemical pretreatment method of high-concentration liquor cellar wastewater (yellow water) provided by the present invention uses a specific modifier (calcium hypochlorite, ferric hydroxide, modified lime slurry) for chemical treatment during the simultaneous denitrification and phosphorus removal and COD reduction process, which can maximize the adsorption of polar organic matter, non-polar organic matter and particulate matter in the polymerized wastewater, achieving multiple functions, specifically: 1) The modifier can serve as a crystal nucleus or micro-filler for macromolecular organic pollutants, and adsorb suspended matter in the polymerized water, so that the macromolecular organic matter continues to grow under the action of the modifier, and further forms charged large-particle flocculent pollutants. 1) The first step is to remove the large flocculent sludge by solid-liquid separation, thereby reducing the concentration of organic pollutants in the wastewater; 2) The modifier, as a chemical modification material, can not only change the water solubility of organic pollutants, but also adsorb and fix polar or non-polar organic matter, thereby minimizing the concentration of organic pollutants in high-concentration liquor cellar wastewater and further improving the treatment efficiency and effect of sewage; 3) The modifier can improve the sludge settling performance, greatly shorten the solid-liquid separation time, and make the solid-liquid separation more thorough, so as to achieve the effect of uniform stirring and sufficient reaction in the lower part of the reactor and natural clarification of the water in the upper part of the reactor.

[0036] (3) The modifier used in the present invention is specifically: calcium hypochlorite is a widely used inorganic chemical modification material, especially with obvious chemical oxidation effect on difficult-to-degrade organic compounds; the trivalent iron in ferric hydroxide has extremely strong oxidizing properties and is easily reduced to divalent iron in high-concentration liquor cellar wastewater. The divalent iron forms a complex with amino groups, acyl groups and other groups in the water, thereby losing its flocculation ability; in the present invention, after ferric hydroxide is added to the wastewater and fully reacted, modified lime slurry is added and continuously stirred to complete the wastewater modification, and then the liquid obtained after solid-liquid separation of the modified wastewater is introduced into the aeration tank for large-volume aeration. After aeration, the pH of the wastewater drops to below 8.5, completing the entire physical and chemical treatment process of chemical modification and physical separation. The obtained pretreated wastewater has good biodegradability and can be transferred to an anaerobic reactor for anaerobic reaction, and then undergoes subsequent biochemical deep treatment, thereby achieving standard discharge.

[0037] In summary, the pretreatment method for high-concentration liquor brewing wastewater provided by the present invention has high treatment efficiency and good results, a high removal rate of various organic pollutants and a rapid response, strong shock load resistance, low operating costs, and promising application prospects. It provides a stable and reliable chemical pretreatment method for high-concentration liquor wastewater that cannot be directly biochemically treated (the wastewater concentration is too high for bacteria to survive). DETAILED DESCRIPTION

[0038] The present invention provides a pretreatment method for high-concentration pit bottom wastewater from liquor brewing, comprising the following steps:

[0039] Calcium hypochlorite, ferric hydroxide and modified lime slurry were added to high-concentration wastewater from liquor brewing pits in sequence and mixed, and the pH value of the resulting mixture was 12-13.

[0040] The mixed liquid is subjected to a first aeration, wherein the first aeration gas is compressed and heated hot air, to obtain chemically modified wastewater;

[0041] performing solid-liquid separation on the chemically modified wastewater to obtain separated water;

[0042] aerating the separated water for the second time, wherein the second aeration gas is air, to obtain aerated water;

[0043] The aeration effluent is subjected to sedimentation and aging treatment to separate the sediment to obtain pretreated wastewater.

[0044] The present invention sequentially adds calcium hypochlorite, ferric hydroxide and modified lime slurry to high-concentration wastewater from liquor brewing pits, and mixes them, and the pH value of the resulting mixed solution is 12 to 13. In the present invention, the chemical oxygen demand (COD) of the high-concentration wastewater from liquor brewing pits is preferably 50,000 to 500,000 mg / L, the biochemical oxygen demand (BOD) is preferably 35,000 to 400,000 mg / L, the suspended solids concentration (SS) is preferably 600 to 3,000 mg / L, the total nitrogen is preferably 5,000 to 12,000 mg / L, the total phosphorus is preferably 2,000 to 5,000 mg / L, and the pH value is preferably 3 to 6.

[0045] In the present invention, the dosage of calcium hypochlorite is preferably 0.3-1.2% of the mass of the wastewater, more preferably 0.4-0.7%, and further preferably 0.5-0.6%.

[0046] In the present invention, the ferric hydroxide is preferably freshly prepared. The amount of ferric hydroxide added is preferably 0.2-1.0% of the wastewater mass, more preferably 0.4-0.7%. After adding the ferric hydroxide, the mixture is preferably stirred for 10-30 minutes, more preferably 20-30 minutes.

[0047] In the present invention, the modified lime slurry is obtained by mixing cooled slaked lime slurry with sodium metaaluminate. In the present invention, the concentration of the slaked lime slurry is preferably such that a thick slurry pump can pump it. In the present invention, the density of the slaked lime slurry is preferably 1.05 to 1.2 g / mL. In the present invention, the mass ratio of the slaked lime slurry to sodium metaaluminate is preferably 100:5 to 10, more preferably 100:6 to 8. In the present invention, the amount of the modified lime slurry added is preferably 1 to 10% of the wastewater volume, more preferably 3 to 8%.

[0048] In the present invention, the mixing method is preferably stirring. In the present invention, the pH value of the obtained mixed solution is 12-13.

[0049] After obtaining the mixed liquid, the present invention performs a first aeration on the mixed liquid, wherein the first aeration gas is compressed hot air, and the temperature of the compressed hot air is preferably 35-60° C., to obtain chemically modified wastewater.

[0050] In the present invention, the first aeration is preferably performed at an aeration rate of 8 to 40 m3 of water per cubic meter. 3 / h, more preferably 20 to 30 m 3 / h, and the aeration time is preferably 30 to 120 minutes, more preferably 60 to 90 minutes. In the present invention, after the first aeration, the chemically modified wastewater is grayish yellow.

[0051] After obtaining the chemically modified wastewater, the present invention performs solid-liquid separation on the chemically modified wastewater to obtain separated water. The present invention preferably uses a high-pressure pump to transport the chemically modified wastewater to the solid-liquid separation process. In the present invention, the delivery pressure of the high-pressure pump is preferably 0.4 to 1.2 MPa, more preferably 0.6 to 1.0 MPa.

[0052] In the present invention, the solid-liquid separation method is preferably a plate-frame filter press. The present invention has no special requirements for the plate-frame filter press, and a plate-frame filter press well known in the art can be used.

[0053] After obtaining the separated water, the present invention performs a second aeration on the separated water, and the second aeration gas is air to obtain aerated water. In the present invention, the aeration volume of the second aeration is preferably 5 to 20 m3 per cubic meter of water. 3 / h, more preferably 10 to 15m 3 / h, and the aeration time is preferably 5 to 12 hours, more preferably 8 to 10 hours. In the present invention, the pH value of the aerated effluent is preferably ≤8.5, more preferably 8 to 8.5.

[0054] After obtaining the aerated effluent, the present invention performs a sedimentation and aging treatment on the aerated effluent to separate the precipitate to obtain pretreated wastewater. In the present invention, the sedimentation and aging treatment is preferably carried out in an inclined plate sedimentation tank or a gravity sedimentation tank; in the present invention, the sedimentation and aging treatment is preferably carried out for 12 to 24 hours, more preferably 16 to 20 hours.

[0055] The pretreatment method provided by the present invention can achieve a COD removal rate of up to 85% in high-concentration pit bottom wastewater (yellow water) from liquor brewing, a NH3-N removal rate of up to 70%, a TN removal rate of up to 85%, and a TP removal rate of more than 99.9%.

[0056] After obtaining the pretreated wastewater, the present invention preferably transfers the obtained pretreated wastewater to an anaerobic reactor for anaerobic reaction, and then performs subsequent biochemical deep treatment to meet the wastewater discharge standards.

[0057] The following is a detailed description of the pretreatment method for high-concentration wastewater from the bottom of a pit in the liquor brewing process provided by the present invention in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0058] Example 1

[0059] The pretreatment method for the wastewater from the Danquan liquor brewing pit is as follows:

[0060] (1) Add calcium hypochlorite at a mass ratio of 0.8% to the wastewater from the liquor brewing pit and stir it evenly. Add freshly made ferric hydroxide solid at a mass ratio of 0.5% and stir for 20 minutes. Then add modified lime slurry to make it strongly alkaline. The addition amount is 3.0% and the pH value is 13. The modified lime slurry is made by mixing cooled slaked lime slurry and sodium aluminate at a mass ratio of 100:7. Then, the wastewater is aerated with compressed heated air for 60 minutes, with an aeration rate of 20m3 per cubic meter of water. 3 , stirring continuously, the obtained pre-treated waste liquid turns grayish yellow and enters the next solid-liquid separation process.

[0061] (2) The pre-treated waste liquid obtained in step (1) is passed through a plate and frame filter press for solid-liquid separation, and the obtained solid is recycled.

[0062] (3) The water obtained in step (2) is aerated with air, and the aeration rate per cubic meter of wastewater is 96m 3 The aeration time was 8 hours, and the pH value of the effluent after aeration was 8.5.

[0063] (4) The aerated effluent obtained in step (3) is flowed to the inclined plate sedimentation tank by gravity and retained for 20 hours to separate the calcium-containing precipitate produced by aeration from the water to obtain pretreated wastewater.

[0064] The pretreatment effect of Danquan liquor brewing pit bottom wastewater is shown in Table 1.

[0065] Table 1 Pretreatment effect of Danquan liquor brewing pit bottom wastewater

[0066] pollutants Influent concentration Outlet concentration Removal rate / % COD / mg / L 179500 46600 74.04 <![CDATA[NH3-N / mg / L]]> 2145 832 61.21 TN / mg / L 7393 2237 69.74 TP / mg / L 2565 2.65 99.90

[0067] Example 2

[0068] The pretreatment method for Junfeng Hanke liquor brewing pit bottom wastewater is as follows:

[0069] (1) Add calcium hypochlorite at a mass ratio of 0.6% to the wastewater from the liquor brewing pit and stir it evenly. Add freshly made ferric hydroxide solid at a mass ratio of 0.5% and stir for 20 minutes. Then add modified lime slurry to make it strongly alkaline. The addition amount is 4.0% and the pH is 13. The modified lime slurry is made by mixing cooled slaked lime slurry and sodium aluminate at a mass ratio of 100:5. Then, the wastewater is aerated with compressed heated air for 60 minutes. The aeration volume is 25m3 / m3 of wastewater. 3 , stirring continuously, the obtained pre-treated waste liquid turns grayish yellow and enters the next solid-liquid separation process.

[0070] (2) The pre-treated waste liquid obtained in step (1) is passed through a plate and frame filter press for solid-liquid separation, and the obtained solid is recycled.

[0071] (3) The water obtained in step (2) is aerated with air, and the aeration rate per cubic meter of wastewater is 80m 3 The aeration time was 8 hours, and the pH value of the effluent after aeration was 8.5.

[0072] (4) The aerated effluent obtained in step (3) is flowed to the inclined plate sedimentation tank by gravity and retained for 18 hours to separate the calcium-containing precipitate produced by aeration from the water to obtain pretreated wastewater.

[0073] The pretreatment effect of Junfeng Hangke liquor brewing pit bottom wastewater is shown in Table 2.

[0074] Table 2 Pretreatment effect of Junfeng Hangke liquor brewing pit bottom wastewater

[0075] pollutants Influent concentration Outlet concentration Removal rate / % COD / mg / L 132039 37887 71.31 <![CDATA[NH3-N / mg / L]]> 1477 562 61.95 TN / mg / L 6089 1967 67.69 TP / mg / L 2265 1.46 99.94

[0076] Example 3

[0077] The comprehensive wastewater from the liquor industrial park is pretreated as follows:

[0078] (1) Add calcium hypochlorite at a mass ratio of 0.7% to the wastewater from the liquor brewing pit and stir it evenly. Add freshly made ferric hydroxide solid at a mass ratio of 0.6% and stir for 30 minutes. Then add modified lime slurry to make it strongly alkaline. The addition amount is 4.0% and the pH range is 13. The modified lime slurry is made by mixing cooled slaked lime slurry and sodium aluminate at a mass ratio of 100:7. Then, the wastewater is aerated with compressed heated air for 60 minutes. The aeration volume is 22m3 / m3 of wastewater. 3 , stirring continuously, the obtained pre-treated waste liquid turns grayish yellow and enters the next solid-liquid separation process.

[0079] (2) The pre-treated waste liquid obtained in step (1) is passed through a plate and frame filter press for solid-liquid separation, and the obtained solid is recycled.

[0080] (3) The water obtained in step (2) is aerated with air, and the aeration rate per cubic meter of wastewater is 104m 3 The aeration time was 8 hours, and the pH value of the effluent after aeration was 8.5.

[0081] (4) The aerated effluent obtained in step (3) is flowed to the inclined plate sedimentation tank by gravity and retained for 24 hours to separate the calcium-containing precipitate produced by aeration from the water to obtain pretreated wastewater.

[0082] The pretreatment effect of comprehensive wastewater from the liquor industrial park is shown in Table 3.

[0083] Table 3 Pretreatment effect of comprehensive wastewater from liquor industrial park

[0084] pollutants Influent concentration Outlet concentration Removal rate / % COD / mg / L 50394 10268 79.62 <![CDATA[NH3-N / mg / L]]> 706.8 250.3 64.59 TN / mg / L 2877 899 68.75 TP / mg / L 1246 1.27 99.90

[0085] Comparative Example 1

[0086] The comprehensive wastewater from the liquor industrial park is pretreated as follows:

[0087] (1) Add freshly made ferric hydroxide solid to the wastewater from liquor brewing pit at a mass ratio of 0.6%, stir for 30 minutes, and then add modified lime slurry to make it strongly alkaline, with a dosage of 4.0% and a pH of 13. The modified lime slurry is made by mixing cooled slaked lime slurry with sodium metaaluminate at a mass ratio of 100:6. Then, the wastewater is aerated with compressed hot air for 60 minutes, with an aeration rate of 22m3 / m3 of wastewater. 3 , stirring continuously, the obtained pre-treated waste liquid turns grayish yellow and enters the next solid-liquid separation process.

[0088] (2) The pre-treated waste liquid obtained in step (1) is passed through a plate and frame filter press for solid-liquid separation, and the obtained solid is recycled.

[0089] (3) The water obtained in step (2) is aerated with air at a rate of 104m 3 The aeration time was 8 hours, and the pH value of the effluent after aeration was 8.5.

[0090] (4) The aerated effluent obtained in step (3) is flowed to the inclined plate sedimentation tank by gravity and retained for 24 hours to separate the calcium-containing precipitate produced by aeration from the water to obtain pretreated wastewater.

[0091] The pretreatment effect of comprehensive wastewater from the liquor industrial park is shown in Table 4.

[0092] Table 4 Pretreatment effect of comprehensive wastewater from liquor industrial park

[0093] pollutants Influent concentration Outlet concentration Removal rate / % COD 179500 124500 30.64 <![CDATA[NH3-N]]> 2145 1485 30.77 TN 7739 4895 36.75 TP 2565 1.02 99.95

[0094] Comparative Example 2

[0095] The comprehensive wastewater from the liquor industrial park is pretreated as follows:

[0096] (1) Calcium hypochlorite was added to the wastewater from the liquor brewing pit at a mass ratio of 0.7% and stirred evenly. Modified lime slurry was then added to the liquor brewing pit until it became strongly alkaline at a dosage of 4.0% and a pH of 13. The modified lime slurry was prepared by mixing cooled slaked lime slurry with sodium metaaluminate at a mass ratio of 100:6. The wastewater was then aerated with compressed heated air for 60 minutes at an aeration rate of 22 cubic meters per cubic meter of wastewater. The wastewater was stirred continuously. After the pre-treated wastewater turned grayish yellow, it entered the next solid-liquid separation process.

[0097] (2) The pre-treated waste liquid obtained in step (1) is passed through a plate and frame filter press for solid-liquid separation, and the obtained solid is recycled.

[0098] (3) The water obtained in step (2) is aerated with air at a rate of 104m 3 The aeration time was 8 hours, and the pH value of the effluent after aeration was 8.5.

[0099] (4) The aerated effluent obtained in step (3) is flowed to the inclined plate sedimentation tank by gravity and retained for 24 hours to separate the calcium-containing precipitate produced by aeration from the water to obtain pretreated wastewater.

[0100] The pretreatment effect of comprehensive wastewater from the liquor industrial park is shown in Table 5.

[0101] Table 5 Pretreatment effect of comprehensive wastewater from liquor industrial park

[0102] pollutants Influent concentration Outlet concentration Removal rate / % COD 231762 189311 18.32 <![CDATA[NH3-N]]> 1424 1333 6.39 TN 6229 5245 15.80 TP 1899 0.67 99.96

[0103] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for pretreating high-concentration wastewater from liquor brewing pits, comprising the following steps: Calcium hypochlorite, ferric hydroxide and modified lime slurry are sequentially added to high-concentration wastewater from liquor brewing pits and mixed, and the pH value of the resulting mixed solution is 12-13; the modified lime slurry is obtained by mixing cooled slaked lime slurry with sodium metaaluminate; The mixed liquid is subjected to a first aeration, wherein the first aeration gas is compressed and heated hot air, to obtain chemically modified wastewater; performing solid-liquid separation on the chemically modified wastewater to obtain separated water; aerating the separated water for the second time, wherein the second aeration gas is air, to obtain aerated water; The aeration effluent is subjected to sedimentation and aging treatment to separate the sediment to obtain pretreated wastewater.

2. The method according to claim 1, characterized in that The high-concentration liquor brewing pit bottom wastewater has a COD of 50,000-500,000 mg / L, a BOD of 35,000-400,000 mg / L, a SS of 600-3,000 mg / L, a total nitrogen of 5,000-12,000 mg / L, a total phosphorus of 2,000-5,000 mg / L, and a pH of 3-6.

3. The method according to claim 1, characterized in that The dosage of calcium hypochlorite is 0.3-1.2% of the mass of high-concentration pit bottom wastewater from liquor brewing; The added amount of the ferric hydroxide is 0.2-1.0% of the mass of high-concentration pit bottom wastewater from liquor brewing.

4. The method according to claim 1 or 3, characterized in that After adding ferric hydroxide, stir for 10 to 30 minutes.

5. The method according to claim 1 or 3, characterized in that The mass ratio of slaked lime slurry to sodium metaaluminate in the modified lime slurry is 100:5-10; The dosage of the modified lime slurry is 1-10% of the volume of high-concentration pit bottom wastewater in liquor brewing.

6. The method according to claim 1, wherein The temperature of the first aeration gas is 35-60°C; The aeration volume of the first aeration is 8-40m3 per cubic water. 3 / h, aeration time is 30 to 120 minutes.

7. The method according to claim 1, characterized in that The solid-liquid separation method is plate and frame filter press separation.

8. The method according to claim 1, characterized in that The aeration volume of the second aeration is 5 to 20 m3 per cubic meter of water. 3 / h, aeration time is 5 to 12h.

9. The method according to claim 1 or 8, characterized in that The pH value of the aerated effluent is ≤8.

5.

10. The method according to claim 1, characterized in that The sedimentation and aging treatment is carried out by using an inclined plate sedimentation tank or a gravity sedimentation tank; The precipitation aging treatment time is 12 to 24 hours.

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