Process method for treating refined sugar ion exchange decoloration regeneration waste liquid

Abstract

The invention relates to the field of sewage treatment, and discloses a process method for treating refined sugar ion exchange decoloration regeneration waste liquid. The method comprises the steps of electric flocculation foam separation pretreatment and salt-tolerant activated sludge biological treatment, and the invention also discloses a system for realizing the method, and the system comprises a raw water tank, an electric coagulation tank, a flocculation tank, an air floatation tank, a salt-tolerant microorganism biochemical treatment tank and a precipitation tank. According to the method disclosed by the invention, the high-COD, high-salt and high-chroma waste liquid generated by a sugar refining process is effectively treated, so that higher emission standards are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sewage treatment, more particularly, it relates to a process for treating waste liquid of ion exchange decolorization regeneration of refined sugar. BACKGROUND

[0002] In recent years, domestic sugar companies have introduced advanced refined sugar complete equipment to provide the market with high-quality refined products that meet higher removal rates of sucrose impurities and color, more uniform crystalline particle size, and standard moisture content indicators. Among them, sugar decolorization is the most important link of refined sugar. In the current refining process, after primary lime decolorization, the sugar solution is decolorized by ion exchange resin, and the decolorization rate can reach 80-90%. The sugar syrup can be refined into 25IU (refined sugar national standard value) refined white sugar, reaching or exceeding the national refined sugar standard.

[0003] The deep purification medium ion exchange adsorption resin of the refined sugar factory is installed in a cylindrical tank container. The sugar syrup is pumped into the decolorization resin tank, and the sugar syrup is contacted with the container and the resin. The internal impurities and pigments are adsorbed by the resin, and the sugar syrup is purified, and the decolorization resin adsorbs the pigments and impurities of the sugar syrup. When the resin processes a certain amount of water, the adsorption performance gradually decreases and becomes saturated. When the adsorption performance decreases to a certain extent, the resin needs to be regenerated to perform the next cycle of purification.

[0004] Decolorization resin regeneration is to clean and regenerate the resin with a certain amount of 8-9% brine as the main regeneration liquid to restore its optimal performance. The ion exchange resin decolorization system usually also has a recovery system to recover sugar syrup and high-concentration brine. The salt-containing waste liquid that cannot be recovered needs to be treated after being discharged. However, the waste liquid has a very high pollutant concentration and is a complex waste liquid containing sugar, NaCl, a large amount of polyphenolic pigments, caramel pigments, heterocyclic organic matter, etc. The COD Cr 15000-24000 mg / L, total nitrogen 170-200 mg / L, NaCl 1.5-3%, color 2300-3500 times, pH 6.5-7.0.

[0005] Domestic high-quality refined sugar production started late, and there is not much mature water treatment experience for this waste liquid. Design and production units are troubled by the lack of mature technology that can be used in actual production. Discharging into the ordinary sewage system will damage the activated sludge system, and sugar industry is a state plan index control material. Production is intermittent, and most manufacturers can only treat this waste liquid as hazardous waste and entrust it to the local environmental protection company for hazardous waste treatment, which has a high treatment cost. Therefore, a new waste liquid treatment method is urgently needed to fill the gap. SUMMARY

[0006] The application aims to provide a new method for treating refined sugar ion exchange decolorization regenerated waste liquid, so as to effectively treat the high COD, high salt and high chroma waste liquid generated in the refined sugar process, and achieve higher discharge standards.

[0007] To achieve the above-mentioned application purposes, the application provides a process method for treating refined sugar ion exchange decolorization regenerated waste liquid, which adopts the following technical scheme:

[0008] The application provides, in the first aspect, a process method for treating refined sugar ion exchange decolorization regenerated waste liquid, which includes the steps of electric flocculation foam separation pretreatment and salt-tolerant activated sludge biological treatment.

[0009] Further, the electric flocculation foam separation pretreatment includes electric coagulation treatment and flocculation treatment.

[0010] In the electric coagulation treatment step, the pH of the refined sugar ion exchange decolorization regenerated waste liquid is adjusted to be acidic in the electric coagulation tank, the residence time is 20-40 min, the voltage is 30-40 V, the electrode plate current density is 20-30 A / m 2 , the electrode plate material is aluminum, and the electrode plate thickness is 4-6 mm.

[0011] In the flocculation treatment step, a flocculating agent is added in the flocculation tank, and the residence time is 10-20 min.

[0012] Further, in the step of adjusting the pH of the refined sugar ion exchange decolorization regenerated waste liquid to be acidic, 10% sulfuric acid is used to adjust the pH of the refined sugar ion exchange decolorization regenerated waste liquid to be 3-3.5.

[0013] Further, in the flocculation treatment step, the flocculating agent is anionic polyacrylamide, and the addition amount is 3 mg / L.

[0014] Further, after the electric flocculation foam separation pretreatment, a flotation treatment step is further included, the residence time is 1-2 h, and the surface load is 1-2 m 3 / m 2 .h.

[0015] Further, the salt-tolerant activated sludge biological treatment step,

[0016] the residence time is 25-30 d;

[0017] the system oxygen supply amount is 1.8-2.2 kgO / kgCOD;

[0018] the nutrient modulation ratio is C:N:P=100:10:1;

[0019] The salt-tolerant activated sludge mixed liquid concentration MLSS is 4000-5000 mg / L, the settling ratio is 30-45%, and the sludge age is 20-30 d.

[0020] Further, the inoculation and domestication step of the salt-tolerant activated sludge is as follows: 400-600 mg / L of salt-tolerant bacteria is added at the beginning, 2800-3200 mg / L of ordinary activated sludge is added, and the sludge is exposed for 3-5 d; the design load is 0.25 times for 10 days, then 0.5 times for 10 days, then 0.75 times for 10 days, and finally the wastewater amount is gradually increased to 1.0 times, and after 45 days, the activated sludge is basically domesticated successfully.

[0021] Further, the salt-tolerant bacteria is a "salt-tolerant bacteria agent" (powder, mainly composed of bacilli and cocci capable of forming endospores, and the viable bacterial content is ≥200 billion / g), which is a commercially available product purchased from Nanjing Sailai Biological Technology Co., Ltd. The ordinary activated sludge is the activated sludge in the secondary sedimentation tank of Shanghai Zhuyuan Sewage Treatment Plant, and the MLSS concentration is 10000 mg / L.

[0022] Further, in the beginning of the sludge domestication stage, in order to accelerate the salt tolerance of ordinary microorganisms, an organic nitrogen source nutrient needs to be added, and amino acids (50-100 mg / L in terms of nitrogen content) are added to increase the thickness of the cell membrane of the activated sludge and improve the ability of the bacterial outer membrane to resist external salt water osmotic pressure, so as to accelerate the speed of sludge domestication.

[0023] The application provides a system for implementing any of the above methods in a second aspect, comprising:

[0024] A raw water tank is used to store refined sugar ion exchange decolorization regeneration waste liquid;

[0025] An electrocoagulation tank is used to perform electrocoagulation treatment;

[0026] A flocculation tank is used to perform flocculation treatment;

[0027] An air flotation tank is used to perform air flotation treatment;

[0028] A salt-tolerant microbial biochemical treatment tank is used to perform salt-tolerant activated sludge biological treatment; and

[0029] A sedimentation tank is used to perform sedimentation treatment.

[0030] In summary, the application has the following beneficial effects:

[0031] The process method of the application recovers high-COD caramel substances through efficient electrocoagulation pretreatment as a carbon resource, regenerates the tail sewage, removes most of the difficult-biodegradable COD, color, and colloidal impurities, and achieves higher discharge standards.

[0032] The organic foam separated by electroflocculation is changed into waste liquid by adding a small amount of defoaming agent and stirring, the recovery rate of organic carbon source waste liquid is >60%, and COD Cr The removal rate is 65%-70%, the color removal rate is 88%-92%, and the removal rate is increased by about 50% compared with the traditional method.

[0033] The waste liquid separated by foam in the electric coagulation tank has a COD Cr 150000-200000mg / L, T-N 200-600mg / L, and salt content 300-700mg / L, which can be recycled as carbon source nutrients for denitrification in other wastewater treatment plants.

[0034] The tail sewage after pretreatment is treated by subsequent specific salt-tolerant activated sludge biological method, and the effluent COD Cr 100-180mg / L, the removal rate is greater than 95%, total nitrogen is 40mg / L, greater than 75%, color is <50 times, removal rate is greater than 85%, and it can completely meet the standard of discharge into urban sewer.

[0035] The carbon reduction, emission reduction and economic efficiency are particularly remarkable. By using the new method for treating refined sugar ion exchange decolorization regeneration waste liquid, the carbon source resource recycling reduces carbon emission by >60%, and the water treatment cost is 120 yuan / m 3 At present, 30m 3 / d, the daily treatment cost is 3600 yuan / d, and the current waste liquid disposal cost is 1000 yuan / m 3 , the daily treatment cost is 30000 yuan / d, and the treatment cost is saved by 88% (Guangming Dafeng Yingmao Sugar Industry Co., Ltd.). BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 : a schematic diagram of a system for implementing the method of the present application;

[0037] Figure 2 : process and results of electric coagulation treatment;

[0038] Figure 3 : pretreatment experiment process and results;

[0039] Figure 4 : subsequent biochemical treatment verification process;

[0040] Figure 5 : treatment results of refined sugar ion exchange decolorization regeneration waste liquid. DETAILED DESCRIPTION

[0041] The technical solutions and effects of the present application are further described in detail below in combination with the embodiments and drawings. It can be understood that the specific embodiments described herein are merely intended to explain the present application and are not intended to limit the present application. In addition, it should be noted that only the parts related to the present application are shown in the drawings for the convenience of description.

[0042] The waste liquid of the regenerated decolorizing resin of the refined sugar is stored in a raw water tank, is delivered by a pump to an electric coagulation tank, and is adjusted to be acidic by adding acid before entering the electric coagulation tank. After the waste liquid enters the electric coagulation tank, an electrochemical reaction is performed, and the waste liquid passes between aluminum electrode plates to which a direct current power source is added. The electrode plates generate ion pairs to act on the waste water, and under the action of micro-bubbles generated at the cathode, 60-70% of the carbon source organic matter in the waste liquid is separated into bubbles and is separated from the waste liquid. The bubbles rise to the surface of the electric coagulation tank, and are scraped by a moving foam scraper to a collection tank for recycling, which can be used as carbon source nutrients for nitrogen removal in a sewage treatment plant.

[0043] After the waste liquid separated by the electric coagulation tank, the waste liquid is further subjected to a flocculation tank. Aluminum ions generated in the waste liquid by electrifying the aluminum electrode of the electric coagulation tank are flocculated to form large flocs, and then enter a gas floatation tank. In the gas floatation tank, the flocs are separated from the waste liquid under the action of micro-bubbles and are scraped by a rotating scraper at the upper surface of the tank.

[0044] After the waste liquid separated by the gas floatation tank, the waste liquid enters a salt-tolerant microbial biochemical treatment tank. A large amount of salt-tolerant microorganisms are cultured in the tank, which have exclusive decomposition ability for the refined sugar waste liquid. There is sufficient oxygen supply in the tank. The microorganisms oxidize and decompose the pollutants in the waste liquid into carbon dioxide and water under the action of their own enzymes. After about 20-25 days of decomposition, the waste liquid is biodegradable or is converted into biodegradable organic matter in the process, and most of the waste liquid is completely decomposed. The waste liquid further passes through a sedimentation tank, and the biological activated sludge in the mixed liquid of the effluent from the biological reaction tank is precipitated to the bottom of the tank. The supernatant after purification is discharged up to the standard.

[0045] Embodiment

[0046] The method comprises the following steps:

[0047] Step 1, electric coagulation treatment

[0048] The refined sugar decolorization resin regeneration waste liquid is pumped to the electrocoagulation tank. Acid is added to adjust the waste liquid to acidity before entering the electrocoagulation tank. Sulfuric acid with a mass concentration of 10% is used to adjust the pH of the refined sugar ion exchange decolorization regeneration waste liquid to 3-3.5. After entering the electrocoagulation tank, the waste liquid undergoes an electrochemical reaction and passes between aluminum electrode plates with a DC power supply. The charged ions generated by the electrode plates act on the waste water, and under the action of tiny bubbles generated at the cathode, 60-70% of the carbon source organic matter in the waste liquid is transferred to the bubbles and separated from the waste liquid. The bubbles rise to the surface of the electrocoagulation tank and the foam is scraped to the collection tank by a mobile scraper (existing technology) for recovery. It can be reused as a carbon source nutrient for denitrification in sewage treatment plants. The parameters are: residence time 30 minutes, DC voltage 36V, and plate current density 20-30A / m 2 The plate material is aluminum, the plate thickness is 5mm, and the waste liquid power supply index q = 200A.h / t waste water. The foam separation process of electrocoagulation, such as Figure 2 shown.

[0049] Step 2, flocculation treatment

[0050] The waste liquid after foam separation in the electrocoagulation tank then passes through the flocculation tank. Flocculant is added into the flocculation tank. The flocculant is anionic polyacrylamide with a dosage of 3 mg / L. The aluminum electrodes of the electrocoagulation tank are energized to generate aluminum ions in the waste liquid, which condense and form large flocs.

[0051] Step 3: Flotation treatment

[0052] Entering the flotation tank, the flocs rise to the upper surface of the tank under the action of micro bubbles and are scraped off by the rotating scraper on the upper part and separated from the waste liquid. The residence time is 1 to 2 hours and the surface load is 1 to 2 m 3 / m 2 .h.

[0053] Step 4, salt-tolerant activated sludge biological treatment

[0054] After separation in the flotation tank, the wastewater enters the salt-tolerant microbial biochemical treatment tank. This tank houses a large number of salt-tolerant microorganisms with specialized decomposition capabilities for refined sugar wastewater. With sufficient oxygen supply, the microorganisms, under the action of their own enzymes, use the pollutants in the wastewater as food, oxidizing and decomposing them into carbon dioxide and water. After approximately 20 to 25 days of decomposition, the wastewater can be biodegraded or converted into biodegradable organic matter during this process, with most of the decomposition being complete. Filler: A fixed, suspended bio-rope is installed inside, with a filling volume of 60%. Parameters include: a residence time of 25 to 30 days; a system oxygen supply of 2 kgO / kg COD; a nutrient modulation ratio of C:N:P = 100:10:1; a salt-tolerant activated sludge mixed liquor concentration of MLSS = 4,000 to 5,000 mg / L, a settling ratio of 30 to 45%, and a sludge age of 20 to 30 days.

[0055] The inoculation and acclimation of the salt-tolerant activated sludge is as follows: 400-600 mg / L of the salt-tolerant bacteria is added to the normal activated sludge, and the sludge is exposed to the atmosphere for 3-5 days, and then the amount of the wastewater is gradually increased to 0.25 times of the design load for 10 days, to 0.5 times for 10 days, to 0.75 times for 10 days, and finally to 1.0 times, and the acclimation of the activated sludge is basically successful after 45 days.

[0056] The salt-tolerant bacteria is a commercially available product, which is a powder mainly composed of bacilli and coccobacilli capable of forming endospores, and the content of the live bacteria is ≥200 billion / g. The normal activated sludge is obtained from the secondary sedimentation tank of Shanghai Zhuyuan Wastewater Treatment Plant, and the MLSS concentration is 10000 mg / L.

[0057] In the initial acclimation stage, the organic nitrogen source is added to accelerate the salt tolerance of the normal microorganisms, and the amino acid is added at a content of 50-100 mg / L to increase the thickness of the cell membrane of the activated sludge and improve the resistance of the bacterial outer membrane to the external salt water osmotic pressure, so as to accelerate the acclimation speed of the sludge.

[0058] Step 5, sedimentation treatment

[0059] The biological activated sludge in the effluent from the biological reaction tank is precipitated to the bottom of the tank through the sedimentation tank, and the supernatant after purification is discharged.

[0060] Performance test

[0061] (1) Raw water sample

[0062]

[0063]

[0064] (2) Pretreatment test results

[0065] The wastewater is electrolyzed in the electrolytic tank, and the high-valence metal ions are ionized and coagulated (as shown in Figure 3 ).

[0066]

[0067] Unit: mg / L

[0068] (3) Verification of subsequent biochemical treatment

[0069] The salt-tolerant activated sludge is inoculated and acclimated, and the COD and color in the wastewater are oxidized and decomposed by the microorganisms (the experimental process is shown in Figure 4 , and the treatment results are shown in Figure 5 ).

[0070] Item PH COD TDS T-N Color Before biochemical treatment 8 7000 27500 165 300 After biochemical treatment 8.5 100～260 21800 65 80 Removal rate / 98.5～96.2％ 20.73％ 60.61％ 73.3％

[0071] The embodiments are only illustrative of the present application, and are not intended to limit the present application. Those skilled in the art can make modifications to the embodiments according to the present application without creative contribution, as long as the modifications are within the scope of the present application.

Claims

1. A process for treating wastewater from ion exchange decolorization and regeneration of refined sugar, characterized in that: The method comprises the steps of electro-flocculation foam separation pretreatment and salt-tolerant activated sludge biological treatment.

2. The process for treating refined sugar ion exchange decolorization and regeneration wastewater according to claim 1, characterized in that: The electro-flocculation foam separation pretreatment includes electro-coagulation treatment and flocculation treatment; The electrocoagulation treatment step is to adjust the pH of the refined sugar ion exchange decolorization regeneration wastewater to acidic in the electrocoagulation tank, with a residence time of 20 to 40 minutes, a voltage of 30 to 40V, and a plate current density of 20 to 30A / m 2 , the plate material is aluminum, the plate thickness is 4 to 6 mm; The flocculation treatment step comprises adding a flocculant into the flocculation tank and retaining the flocculant for 10 to 20 minutes.

3. The process for treating refined sugar ion exchange decolorization and regeneration wastewater according to claim 2, characterized in that: The step of adjusting the pH of the refined sugar ion exchange decolorization regeneration waste liquid to acidic: using sulfuric acid with a mass concentration of 10% to adjust the pH of the refined sugar ion exchange decolorization regeneration waste liquid to 3-3.

5.

4. The process for treating refined sugar ion exchange decolorization and regeneration wastewater according to claim 2, characterized in that: The flocculation treatment step: the flocculant is anionic polyacrylamide, and the addition amount is 3 mg / L.

5. The process for treating refined sugar ion exchange decolorization and regeneration wastewater according to claim 2, characterized in that: After the electro-flocculation foam separation pretreatment is completed, an air flotation treatment step is also included: a residence time of 1 to 2 hours, a surface load of 1 to 2 m 3 / m 2 .h.

6. The process for treating refined sugar ion exchange decolorization and regeneration wastewater according to claim 1, characterized in that: The salt-tolerant activated sludge biological treatment step, Residence time: 25-30 days; The system oxygen supply is 1.8-2.2 kgO / kgCOD; The nutritional modulation ratio is C:N:P=100:10:1; The concentration of salt-tolerant activated sludge mixed liquor is MLSS = 4000-5000 mg / L, the sedimentation ratio is 30-45%, and the sludge age is 20-30 days.

7. The process for treating refined sugar ion exchange decolorization and regeneration wastewater according to claim 6, characterized in that: The salt-tolerant activated sludge inoculation and acclimation steps are as follows: initially adding 400-600 mg / L of salt-tolerant bacteria and 2800-3200 mg / L of ordinary activated sludge, exposing for 3-5 days, continuing at 0.25 times the design load for 10 days, then continuing at 0.5 times for 10 days, then continuing at 0.75 times for 10 days, and finally gradually increasing the amount of wastewater added by 1.0 times. After 45 days, the activated sludge is basically successfully acclimated.

8. The process for treating refined sugar ion exchange decolorization and regeneration wastewater according to claim 7, characterized in that: The salt-tolerant bacteria are salt-tolerant bacteria agents, which are commercially available; the MLSS concentration of ordinary activated sludge is 10,000 mg / L.

9. The process for treating refined sugar ion exchange decolorization and regeneration wastewater according to claim 7, characterized in that: At the beginning of the sludge acclimation stage, in order to accelerate the salt tolerance of common microorganisms, it is necessary to add organic nitrogen source nutrients and amino acids (50-100 mg / L in terms of nitrogen content) to increase the thickness of the activated sludge cell membrane and improve the ability of the bacterial outer membrane to resist the external salt water osmotic pressure, so as to accelerate the speed of sludge acclimation.

10. A system for implementing the method according to any one of claims 1 to 9, characterized in that: include: Raw water tank, used to store refined sugar ion exchange decolorization regeneration wastewater; An electrocoagulation tank, used for performing electrocoagulation treatment; Flocculation tank, used for flocculation treatment; An air flotation tank, used for air flotation treatment; Salt-tolerant microbial biochemical treatment tank, used for biological treatment of salt-tolerant activated sludge; as well as Sedimentation tank, used for sedimentation treatment.

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