Hydrolytic acidification-AO combined treatment device and method for printing and dyeing wastewater

Abstract

The invention discloses a hydrolytic acidification-AO combined treatment device and method for printing and dyeing wastewater, the device comprises a hydrolytic acidification tank, an AO tank and a sedimentation tank, the hydrolytic acidification tank is internally provided with an iron-carbon micro-electrolysis filler used for enhancing pollutant degradation and inhibiting methanogens growth, the AO tank comprises an anoxic tank and an aerobic tank, and the anoxic tank is provided with an aerobic tank. The sedimentation tank is internally provided with a conveying device for respectively refluxing mud-water mixed liquid and nitrification liquid to the hydrolysis acidification tank and the anoxic tank; the preparation method of the iron-carbon micro-electrolysis filler comprises the following steps: S1, uniformly mixing zero-valent iron powder, powdered activated carbon and kaolin; s2, sodium bicarbonate is added into the mixture, and then water is added for stirring; s3, preparing granular filler balls from the mixture, drying the filler balls, and performing anaerobic calcination; s4, manganese sulfate monohydrate is added firstly, then water is added, a mixed solution is obtained, a potassium permanganate solution is added, stirring is performed, and standing and aging are performed; and S5, drying the filler balls. The device can enhance the pollutant degradation effect and reduce carbon emission at the same time.

Description

Technical Field

[0001] The invention relates to the treatment of printing and dyeing wastewater, in particular to a hydrolysis acidification-AO combined treatment device and method for printing and dyeing wastewater. Background Art

[0002] As one of the key links in the textile industry, printing and dyeing discharges about 80% of the wastewater in the textile industry and is the main pollution emission carrier in the printing and dyeing industry. Printing and dyeing wastewater is the wastewater discharged from the processing of cotton and cotton blended fabrics, linen, silk, fiber, wool, yarn, etc. It is one of the more difficult industrial wastewaters to treat, with the characteristics of large water volume, high COD, high pH, ​​high chroma, high alkalinity, and complex composition. The nitrogen composition in printing and dyeing wastewater is complex, containing a high concentration of difficult-to-degrade organic nitrogen, mainly including nitrogen-containing dyes and various dye auxiliaries containing azo, nitro and amino groups. Excessive discharge of nitrogen is one of the important reasons for eutrophication of natural water bodies.

[0003] For the sewage treatment industry, the carbon emissions from the entire process include direct emissions of CO 2 , CH 4 and N 2 O, and indirect emissions from energy consumption and drug consumption. At present, the main ways to reduce carbon emissions in the sewage treatment industry include reducing energy consumption, reducing drug consumption, and recycling organic energy.

[0004] The number of microorganisms used for hydrolysis and acidification in the treatment of printing and dyeing wastewater determines the speed and final effect of pollutant degradation, while the number of methanogens determines carbon emissions. At present, there is no product in the waste treatment process of printing and dyeing that can simultaneously promote the growth of microorganisms used for hydrolysis and acidification and inhibit the growth of methanogens to achieve enhanced pollutant degradation while reducing carbon emissions; secondly, the sludge in the treatment process of printing and dyeing wastewater has not been effectively recycled, which has increased the sludge treatment workload and the floor space of the treatment equipment, that is, increased the operating cost, and increased the carbon source input in the wastewater process, thereby increasing carbon emissions. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a hydrolysis acidification-AO combined treatment device and method for printing and dyeing wastewater that can enhance the pollutant degradation effect while reducing carbon emissions.

[0006] Technical solution: The hydrolysis acidification-AO combined treatment device for printing and dyeing wastewater described in the present invention comprises a hydrolysis acidification tank, an AO tank and a sedimentation tank. The hydrolysis acidification tank is provided with an iron-carbon micro-electrolysis filler for enhancing the degradation of pollutants and inhibiting the growth of methanogens. The AO tank comprises an anoxic tank and an aerobic tank. The sedimentation tank is provided with a transport device for returning the precipitated sludge and supernatant to the hydrolysis acidification tank and the anoxic tank respectively.

[0007] Based on the above technical scheme, an iron-carbon micro-electrolysis filler bed for enhancing pollutant degradation and inhibiting the growth of methanogens is set in the hydrolysis acidification tank, which can not only enhance the pollutant degradation effect, but also inhibit the growth of methanogens, thereby reducing carbon emissions; the transportation device returns the sludge in the sedimentation tank to the hydrolysis acidification tank, and after hydrolysis, volatile fatty acids can be increased as the endogenous carbon source of the system, which is beneficial to denitrification, and can reduce the additional carbon source added to the system, or even no longer need to be added, achieving the effect of internal carbon source replenishment and coordinated denitrification, thereby reducing carbon source input and also reducing carbon emissions; at the same time, the returned sludge also contains some denitrifying bacteria, which can be enriched in the hydrolysis acidification tank and then flow into the anoxic tank for denitrification reaction, thereby improving the denitrification effect, which is equivalent to reducing the denitrification pressure of the anoxic tank.

[0008] Preferably, the iron-carbon micro-electrolysis filler can move up and down in the hydrolysis acidification tank.

[0009] The pollutant concentration, sludge concentration and dissolved oxygen concentration at different heights in the hydrolysis acidification tank are all different. Moving the iron-carbon micro-electrolysis filler to a suitable height according to the conditions of the printing and dyeing wastewater can achieve better hydrolysis effects.

[0010] Preferably, a vertical partition is provided in the middle of the aerobic pool, and a through groove communicating with both sides is provided at the bottom of the partition; an aeration device for supplying oxygen is provided in the aerobic pool.

[0011] A partition is set in the middle of the aerobic pool, and a through groove is set at the bottom of the partition to connect the two sides. In this way, the wastewater will flow from the side where the wastewater is first poured in, from top to bottom and then into the other side, which increases the residence time of the wastewater in the aerobic pool and the length of the flow path, so that it can more fully carry out nitrification reaction; the setting of an aeration device can ensure that there is sufficient dissolved oxygen concentration in the aerobic pool.

[0012] Preferably, the hydrolysis acidification tank, the anoxic tank and the aerobic tank are all provided with a stirrer.

[0013] Setting up a stirrer can make the wastewater and various bacteria come into full contact so as to better complete the corresponding reaction.

[0014] The preparation method of the iron-carbon micro-electrolysis filler of the present invention comprises the following steps:

[0015] S1, mixing zero-valent iron powder, powdered activated carbon and kaolin in a mass ratio of 2:1:2 to obtain a mixture;

[0016] S2, adding sodium bicarbonate to the mixture in step S1, the mass ratio of sodium bicarbonate to the mixture is 1:20; then adding water and stirring, the mass ratio of the added water to the solid is 1:5 to 2:5;

[0017] S3, preparing the mixture obtained in step S2 into granular filler balls, drying the filler balls and then performing anaerobically calcining;

[0018] S4, adding manganese sulfate monohydrate to the calcined filler balls at a mass ratio of 1:10 to 1:5 to the filler balls, then adding water thereto at a solid-liquid mass ratio of 1:4 to 1:5 to obtain a mixed solution, and then adding potassium permanganate solution to the mixed solution at a mass ratio of 1:6 to 1:5, wherein the mass ratio of manganese sulfate monohydrate to potassium permanganate is 3:2 to 2:1; stirring for 0.5 to 1 hour and then aging for 24 to 48 hours;

[0019] S5. Drying the aged filler balls in step S4 to obtain iron-carbon micro-electrolysis filler.

[0020] The iron-carbon micro-electrolysis filler prepared by the above method has a higher porosity and a larger specific surface area, which provides favorable attachment sites and reproductive space for microorganisms. When treating wastewater, it will produce various processes such as galvanic cell reaction, redox reaction, physical and chemical adsorption, microbial attachment and degradation. The combined effect of these processes enhances the degradation of pollutants. At the same time, through step S4, the filler is modified by metal Mn, so that the filler can enrich heterogeneous metal-reducing bacteria in the hydrolysis tank. Through the heterogeneous metal reduction process, the valence cycle of Fe2+ / Fe3+ and Mn2+ / Mn4+ is realized; the relative abundance of methanogens is significantly reduced, achieving the effect of reducing methane emissions.

[0021] Preferably, the ratio of water to solid added in step S2 is 1:5.

[0022] Preferably, in step S3, the drying temperature is 95°C to 115°C, and the drying time is 1 to 2 hours; the calcination temperature is 800°C to 1000°C, and the calcination time is 1 to 2 hours, and the heating rate is 10°C / min.

[0023] Preferably, in step S4, the mass ratio of manganese sulfate monohydrate to filler balls is 3:20; the solid-liquid mass ratio in the mixed solution is 23:100; the mass ratio of potassium permanganate solution to the mixed solution is 109:615; the mass ratio of manganese sulfate monohydrate to potassium manganate is 5:3; the stirring time after adding the potassium permanganate solution is 0.5h, and the static aging time is 24h.

[0024] The hydrolysis acidification-AO combined treatment method of the present invention comprises the following steps:

[0025] S1. Input printing and dyeing wastewater into the hydrolysis acidification tank for stirring, and control the dissolved oxygen concentration in the hydrolysis acidification tank at 0-0.3 mg / L;

[0026] S2. The printing and dyeing wastewater in the hydrolysis and acidification tank overflows into the anoxic tank for stirring, and the dissolved oxygen concentration in the anoxic tank is controlled at 0-0.5 mg / L;

[0027] S3. The printing and dyeing wastewater overflowing from the anoxic tank enters the aerobic tank, and the dissolved oxygen concentration in the aerobic tank is controlled at 2-4 mg / L;

[0028] S4. The printing and dyeing wastewater in the aerobic tank overflows into the sedimentation tank, the supernatant in the sedimentation tank flows back to the anoxic tank according to the set ratio, and the precipitated sludge flows back to the hydrolysis acidification tank according to the set ratio;

[0029] Preferably, the sludge precipitated in the sedimentation tank is returned at 5% to 35% of the total sludge amount, and the supernatant is returned at 150% to 200% of the influent amount of printing and dyeing wastewater.

[0030] Beneficial effects: Compared with the prior art, the present invention has the following significant effects: by setting the iron-carbon micro-electrolysis filler prepared according to the method provided by the present invention in the hydrolysis acidification tank, it can not only enhance the degradation of pollutants but also reduce carbon emissions; at the same time, the reflux of the mud-water mixture in the aerobic tank can provide an internal carbon source supply, reduce the carbon source input, and further reduce carbon emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of the device;

[0032] Figure 2 This is a physical picture of the device;

[0033] Figure 3 This is a physical picture of the iron-carbon micro-electrolysis material;

[0034] Figure 4 The concentration of various pollutants after the iron-carbon micro-electrolysis filler prepared with different zero-valent iron powder activated carbon ratios was placed in printing and dyeing wastewater for 8 hours;

[0035] Figure 5 The concentration of various pollutants after the iron-carbon micro-electrolysis filler prepared with different zero-valent iron powder dosage was placed in the printing and dyeing wastewater for 8 hours;

[0036] Figure 6 FTIR spectra of the prior art and the present invention's iron-carbon micro-electrolysis filler metal;

[0037] Figure 7 The following are scanning electron microscope photos of the surface of iron-carbon micro-electrolytic fillers, wherein (a) is the existing iron-carbon micro-electrolytic filler; (b) is the iron-carbon micro-electrolytic filler of the present invention;

[0038] Figure 8 The mapping diagrams of iron-carbon micro-electrolytic fillers under a scanning electron microscope are shown in FIG. 1 , wherein (a) is the existing iron-carbon micro-electrolytic filler; and (b) is the iron-carbon micro-electrolytic filler of the present invention. DETAILED DESCRIPTION

[0039] As shown in the figure, a hydrolysis acidification-AO combined treatment device for printing and dyeing wastewater described in the present invention includes a hydrolysis acidification tank 1, an AO tank 2 and a sedimentation tank 3. The hydrolysis acidification tank 1 is provided with an iron-carbon micro-electrolysis filler 4 for enhancing pollutant degradation and inhibiting the growth of methanogens. The AO tank 2 includes an anoxic tank 2-1 and an aerobic tank 2-2. The sedimentation tank 3 is provided with a conveying device for returning the mud-water mixture and the nitrification liquid to the hydrolysis acidification tank 1 and the anoxic tank 2-1 respectively.

[0040] The bottom of the hydrolysis and acidification tank 1 is provided with an inlet for printing and dyeing wastewater and a reflux port for mud and water mixture. The hydrolysis and acidification tank 1 also has an agitator. The agitator can adopt a conventional blade-type stirring device driven by a motor. An iron-carbon micro-electrolysis filler 4 is provided above the agitator. A support frame or a support bed can be set for the iron-carbon micro-electrolysis filler 4, and the iron-carbon micro-electrolysis filler 4 is evenly arranged on the support frame. The support frame is provided with a plurality of hollow through holes for increasing the contact area between the iron-carbon micro-electrolysis filler 4 and the wastewater; the support frame is slidably connected in the hydrolysis and acidification tank 1 and can move up and down. Its up and down movement can be carried out by manual pulling or driven by mechanical connection methods such as a motor and a rack; an overflow port is provided on the side wall above the hydrolysis and acidification tank 1, and the overflow port is connected to the anoxic tank 2-1. With the continuous addition of printing and dyeing wastewater, the wastewater after hydrolysis and acidification overflows into the anoxic tank 2-1 through the overflow port.

[0041] The anoxic pool 2-1 is also provided with a stirrer, and an overflow port connected to the aerobic pool 2-2 is provided on the upper side wall of the anoxic pool 2-1, and a denitrification reaction is carried out in the anoxic pool 2-1.

[0042] A vertical partition is provided in the middle of the aerobic tank 2-2 to divide it into two independent left and right tanks. A through groove connecting the two sides is provided at the bottom of the partition. Wastewater is first poured into the left tank, and then gradually flows into the right tank from the bottom through groove. An overflow port connecting the sedimentation tank 3 is provided on the side wall above the right tank; an aeration device 5 for supplying oxygen is provided in the aerobic tank 2-2, and an existing device such as an aeration disk can be used; a stirrer can also be provided in the aerobic tank 2-2.

[0043] A liquid pump is provided above the sedimentation tank 3 for pumping the supernatant in the sedimentation tank 3 back to the anoxic tank 2-2; the bottom of the sedimentation tank 3 is connected to a sludge pump, which is also connected to the reflux port of the mud-water mixture at the bottom of the hydrolysis acidification tank 1, and the mud-water mixture at the bottom of the aerobic tank 2-2 is pumped back to the hydrolysis acidification tank 1 through the sludge pump.

[0044] The structural diagram of the processing device can be referred to Figure 1 and Figure 2 , Figure 2 In the real picture and Figure 1 The left and right directions are reversed, that is, Figure 2 The middle glass shell includes, from right to left, a hydrolysis acidification tank 1, anoxic tank 2-1, aerobic tank 2-2 and sedimentation tank 3.

[0045] The preparation method of the iron-carbon micro-electrolysis filler of the present invention comprises the following steps:

[0046] S1. Mix zero-valent iron powder, powdered activated carbon and kaolin in a mass ratio of 2:1:2 to obtain a mixture;

[0047] S2. Add sodium bicarbonate in a set mass ratio to the mixture in step S1, wherein the mass ratio of sodium bicarbonate to the mixture is 1:20; then add a set proportion of water and stir until it becomes viscous, wherein the content ratio of water added to the solid is 1:5 to 2:5, and the ratio can be 1:5, 3:10 or 2:5.

[0048] S3. Prepare the mixture obtained in step S2 into granular filler balls, place the filler balls in an oven for drying, and then place them in a tubular furnace for high-temperature anaerobic calcination; the drying temperature is 95°C to 115°C, and 95°C, 105°C and 115°C can be selected; the drying time is 1 to 2h, and 1h and 2h can be selected; the calcination temperature is 800°C to 1000°C, and 800°C, 900°C and 1000°C can be selected; the calcination time is 1 to 2h, and 1h and 2h can be selected; the calcination heating rate is 10°C / min.

[0049] S4. Add manganese sulfate monohydrate to the calcined filler balls according to a set mass ratio. The mass ratio of filler balls to manganese sulfate monohydrate is 5:1-10:1. You can choose to weigh 200g of seasoning balls, and then add 20g, 30g or 40g of manganese sulfate monohydrate MnSO4·H2O; then add water in a set proportion to obtain a mixed solution. The solid-liquid mass ratio in the mixed solution is 1:4-1:5. If the solid mass is 230g, then 920ml, 1000ml or 1150ml of ultrapure water can be added and stirred for 1h to obtain a mixed solution.

[0050] A potassium permanganate solution of a set ratio and concentration is added to the mixed solution, stirred for a set time, and then allowed to stand for aging; wherein the mass ratio of the mixed solution to the potassium permanganate solution is 5:1-6:1. If the mass of the mixed solution is 1230 g, then 205 g, 218 g, or 246 g of potassium permanganate solution can be added, wherein the mass ratio of manganese sulfate monohydrate to potassium permanganate is 3:2-2:1, that is, if 30 g of manganese sulfate monohydrate is removed, then 15 g, 20 g, or a mass therebetween can be taken from potassium permanganate. In this embodiment, 18 g is taken, and the total mass of the potassium permanganate solution is 218 g; the stirring time is 0.5-1 h, and the standing aging time is 24-48 h. It can be selected to stir for 0.5 h and then stand for aging for 24 h.

[0051] S5. Drying the aged filler balls in step S4 to obtain iron-carbon micro-electrolysis filler.

[0052] The preparation method of iron-carbon micro-electrolysis filler is the best solution finally obtained through multiple tests and verifications. The specific verification process is as follows:

[0053] Depend on Figure 4 It can be seen that with the increase of iron-carbon ratio (zero-valent iron powder / activated carbon), NO 3 - -N concentration showed a trend of first decreasing and then slowly increasing. As the mass of activated carbon decreased, the number of primary cells formed by the contact between zero-valent iron powder and activated carbon increased or the reaction activity was higher, making the electrochemical reaction easier and promoting the reaction of iron-carbon micro-electrolysis filler. When the ratio of zero-valent iron powder to activated carbon was 2:1, NO 3 - -N concentration was the lowest, at 26.8 mg / L, with a removal rate of 32.06%, but excessive zero-valent iron powder could not always increase NO 3 - -N and TN removal rates.

[0054] like Figure 5 As shown in the figure, the amount of iron added and the reaction effect are not completely positively correlated. As the amount of iron added increases, NO 3 - -N residual concentration first decreased and then increased. When the dosage of zero-valent iron powder was low, the number of primary cells formed was too small, and the effect of iron-carbon micro-electrolysis filler was weak, so NO 3 - -N reduction effect is not good; when the iron dosage is too high, it may cause polarization, which in turn affects the dissolution of iron ions. In addition, if the iron ions are dissolved too much, it may cause the filler to compact. When the dosage of zero-valent iron powder is 5g / L, the residual NO 3 - -N concentration was the lowest, at 7.0 mg / L, and the denitrification effect was the best. In subsequent experiments, the ratio of zero-valent iron powder to activated carbon was 2:1, and the dosage of zero-valent iron powder was 5 g / L.

[0055] Depend on Figure 6 The surface functional groups of the filler particles can be known, and the molecular structure and vibration state of the material surface substances can be understood in detail. The functional group absorption peaks of the iron-carbon micro-electrolysis filler provided by the present invention and the existing ones before and after modification are slightly changed, indicating that the MnO2 loading does not have a significant effect on the functional groups of the initial materials. The two materials have a peak absorption peak at 3440cm -1 There are large absorption peaks at 1638cm. The characteristic peak here represents the -OH stretching vibration, which is formed by the -OH stretching vibration peak and the interlayer free water molecule stretching vibration band, indicating that there is residual water in the sample. -1The peak at 980cm represents C=C stretching vibration, indicating the skeleton bending vibration absorption peak of water molecules in the sample, which comes from the coordinated water molecules of the Al-OH complex. -1 870cm -1 The absorption peak of Fe-O bond is at 670cm -1 Appear at 480cm -1 The peak at represents the elastic vibration of Si-O bond.

[0056] Depend on Figure 7 From the scanning electron microscope photograph, it can be seen that the iron-carbon material in the iron-carbon micro-electrolysis filler provided by the present invention is well dispersed, and the surface is rougher and more uneven, which is conducive to the attachment of microorganisms.

[0057] Depend on Figure 8 From the mapping diagram, it can be seen that the color of the Mn element in the iron-carbon micro-electrolysis filler provided by the present invention is darker, indicating that the modification is successful and the Mn element is successfully loaded on the filler.

[0058] The hydrolysis acidification-AO combined treatment method for printing and dyeing wastewater of the present invention comprises the following steps:

[0059] S1. Input printing and dyeing wastewater into the hydrolysis acidification tank 1 for stirring; the dissolved oxygen concentration in the hydrolysis acidification tank 1 is 0-0.3 mg / L, specifically 0 mg / L, 0.15 mg / L or 0.3 mg / L.

[0060] S2. The printing and dyeing wastewater in the hydrolysis acidification tank 1 overflows into the anoxic tank 2-1 for stirring; the dissolved oxygen concentration in the anoxic tank 2-1 is 0-0.5 mg / L, specifically 0 mg / L, 0.25 mg / L or 0.5 mg / L.

[0061] S3. The printing and dyeing wastewater overflowing from the anoxic tank 2-1 enters the aerobic tank 2-2. The dissolved oxygen concentration in the aerobic tank is 2-4 mg / L, which can be 2 mg / L, 3 mg / L or 4 mg / L.

[0062] S4. The printing and dyeing wastewater in the aerobic tank 2-2 overflows into the sedimentation tank 3, and the supernatant in the sedimentation tank 3 is returned to the anoxic tank 2-1 according to 150% to 200% of the inflow of the printing and dyeing wastewater in the hydrolysis acidification tank 1, and the return ratio can be 150%, 180% or 200%; the sludge precipitated in the sedimentation tank 3 is returned to the hydrolysis acidification tank 1 according to 5% to 35% of the total sludge, and the return ratio can be 5%, 20% or 35%.

[0063] In order to better illustrate the implementation mode and beneficial effects of the present invention, the following is further described with specific experiments.

[0064] Experiment 1:

[0065] The experimental equipment used is Figure 2 As shown, the devices are all made of organic glass (PMMA). The hydrolysis acidification tank 1 is a vertically arranged cylinder with a size of Φ2000×2500mm and an effective volume of about 3.8L in the tank. An overflow pipe is arranged at a height of 1500mm in the tank body. An iron-carbon micro-electrolysis filler bed is arranged on the upper part of the hydrolysis acidification tank 1. In order to detect the greenhouse gas emissions of hydrolysis, a static glass gas box is arranged on the top of the hydrolysis acidification tank 1, and an air hole is arranged on the top of the static gas box and a 250ml air bag is connected to balance the air pressure in the gas box. Water seals are arranged at the bottom and outlet of the static gas box to prevent gas leakage. For the convenience of sampling, sampling ports are arranged at different heights in the pool. The anoxic tank 2-1 and the aerobic tank 2-2 are an integrated device, wherein the anoxic tank 2-1 is a square column with a width of 1000mm and a height of 2500mm; the aerobic tank 2-2 is divided into two grids, each of which is the same size as the anoxic tank 2-1, and the bottom is connected by a slit wall. The effluent enters the sedimentation tank 3 and is discharged after sedimentation.

[0066] The hydraulic retention time of hydrolysis acidification tank 1 is 16h, and it has been operating for more than 40 days to treat artificially configured printing and dyeing wastewater. The composition of the wastewater is shown in Table 1. The average COD value of the simulated printing and dyeing wastewater is 1280mg / L, the average TN value is 57mg / L, the average TP value is 8.2mg / L, and the average pH value is 8.5.

[0067] Table 1 Composition and concentration of simulated printing and dyeing wastewater and trace elements

[0068]

[0069] The printing and dyeing wastewater to be treated is pumped into the system constructed by the process of the present invention through a peristaltic pump. The wastewater to be degraded enters from the bottom of the hydrolysis acidification tank 1, then passes through the anoxic tank 2-1 and the aerobic tank 2-2 in sequence, and finally passes through the sedimentation tank 3 for precipitation before being discharged.

[0070] Among them, the dissolved oxygen concentration of the hydrolysis acidification tank 1 is 0-0.3 mg / L; the hydrolysis acidification tank 1 is built with an iron-carbon micro-electrolysis filler bed, which provides a favorable attachment site and reproductive space for microorganisms. When treating wastewater, the filler itself can generate a potential difference to electrochemically degrade organic pollutants; the sludge precipitated in the sedimentation tank 3 is returned to the hydrolysis acidification tank 1 at 5%-35% of the total sludge; the trace dissolved oxygen in the return nitrification liquid is not only conducive to increasing the species abundance of hydrolysis acidification bacteria and the relative activity of hydrolytic enzymes, but also can reduce the activity of methanogens and reduce methane emissions; the return nitrification liquid can produce a partial denitrification effect in the hydrolysis acidification tank, reducing the pressure of subsequent anoxic tank denitrification. On the other hand, the return residual sludge can be used as an organic substrate for hydrolysis, and through the hydrolysis and acidification of facultative anaerobic bacteria extracellular enzymes, macromolecular organic matter is converted into easily degradable small molecular organic matter, generating organic matter such as volatile fatty acids, providing a carbon source for denitrification, and achieving the effect of internal carbon source replenishment.

[0071] Controlling the dissolved oxygen concentration of the anoxic pool 2-1 at 0.5 mg / L can enrich nitrifying and denitrifying microorganisms. The effluent from the aerobic pool 2-2 flows back to the anoxic pool 2-1, and pre-denitrification and denitrification are carried out in the anoxic section. Denitrifying bacteria use the organic carbon source in the sewage to convert nitrate nitrogen into nitrogen gas and release it into the air, achieving the purpose of denitrification;

[0072] An aeration plate is set at the bottom of the aerobic pool 2-2, and air is introduced into the aerobic pool through an air pump to control the dissolved oxygen concentration at 2-4 mg / L, which is conducive to the rapid enrichment of autotrophic nitrifying bacteria.

[0073] After a period of microbial enrichment and domestication, when the system is stable, the treatment effect of the process of the present invention is as follows: the average COD value of the effluent from sedimentation tank 3 is 65 mg / L, and the COD removal rate is greater than 94.8%; the average TN value is 8.9 mg / L, and the TN removal rate is greater than 84.3%.

[0074] The CO of the device was monitored by the static gas box method. 2 and CH 4 The addition of iron-carbon micro-electrolysis filler reduced the methane emission of the hydrolysis system. Under different reflux ratios, carbon emissions also showed obvious differences, but CH 4 Carbon emissions are greater than CO 2 Carbon emission; control group (reflux 0%) CO 2 Emission is 7.65g / m 2 / d,CH 4 Emission is 21.99g / m 2 / d, after the nitration mixture is refluxed, the system CO 2 Emission less than 5.89g / m 2 / d; CH4 emission is less than 18.97g / m 2 / d, minimum 4.25g / m 2 / d.

[0075] Experiment 2:

[0076] The wastewater from a printing and dyeing factory is used as raw water, and the water quality is shown in the following table:

[0077] Table 2 Water quality indicators of printing and dyeing wastewater

[0078]

[0079] The raw water to be treated is introduced into the pilot system constructed by the present invention, with a scale of 5m 3 / d. The wastewater to be treated is discharged after passing through the hydrolysis acidification tank 1, the anoxic tank 2-1, the aerobic tank 2-2 and the sedimentation tank 3 in sequence. According to the characteristics of the water quality, the proportion of the nitrification liquid returned to the anoxic tank is adjusted to 150% to 200% of the inflow of the printing and dyeing wastewater. The muddy water mixture formed by the nitrification liquid and the residual sludge is returned to the hydrolysis acidification tank at 5% to 35% as a hydrolysis substrate, and partial denitrification can also be constructed in the hydrolysis tank. By subjecting the returned sludge to hydrolysis and acidification, a high-quality carbon source is provided for the denitrification, and the carbon source in the system is supplemented.

[0080] The test operation results show that after the system is stably running, the water quality indicators of the present invention are as follows: CODcr of sedimentation tank effluent: average value is 132 mg / L; total nitrogen: 4.6 mg / L, CODcr removal rate is greater than 90.5%, and total nitrogen removal rate is greater than 89.7%.

[0081] Experiment 3

[0082] Under the same experimental conditions, the treatment device is provided with no iron-carbon micro-electrolysis filler, the existing iron-carbon micro-electrolysis seasoning and the micro-electrolysis filler provided by the present invention, respectively, and the treatment results of printing and dyeing wastewater in Table 3 can be obtained. It can be seen that the addition of filler is beneficial to the hydrolysis reaction and enhances the removal effect of pollutants. The COD degradation rate is increased from 60.33% to 69.42% and 64.80%, and the chroma removal rate is increased from 46.87% to 57.20% and 62.42%. At the same time, the acid production of hydrolysis and acidification increased from 298.27 mg COD / L to 335.31 mg COD / L and 348.34 mg COD / L, and the CO2 production was greatly reduced after the addition of iron-carbon micro-electrolysis filler. The modified iron-carbon micro-electrolysis filler provided by the present invention makes the CO2 production lower; although the methane production is also improved to a certain extent, this is because the larger specific surface area of ​​the iron-carbon micro-electrolysis filler is conducive to the attachment of microorganisms, and the addition of the filler is conducive to electron transport, regulating the interspecies direct electron transfer (DIET) mechanism, and promoting the performance of anaerobic digestion. The CH4 emission (21.32 g / m2 / d) of the modified iron-carbon micro-electrolysis filler system provided by the present invention is significantly lower than that of the existing iron-carbon micro-electrolysis filler before modification (45.87 g / m2 / d), which is because the load of manganese element strengthens the metal-driven anaerobic oxidation process of methane; in summary, adding the iron-carbon micro-electrolysis filler provided by the present invention to the treatment device can better degrade pollutants in printing and dyeing wastewater from multiple indicators, while reducing carbon emissions.

[0083] Table 3 Water quality index analysis items

[0084]

[0085] The present invention adopts a combined process of hydrolysis acidification-anoxic-aerobic, which has good treatment effects on various water quality indicators, and has the advantages of good water effluent effect, small footprint, low operating cost, etc. While efficiently treating printing and dyeing wastewater, it reduces residual sludge and reduces methane emissions. The effect of synergistic carbon reduction by degrading multiple pollutants is achieved.

Claims

1. A combined hydrolysis and acidification-AO treatment device for printing and dyeing wastewater, comprising a hydrolysis and acidification tank (1), an AO tank (2) and a sedimentation tank (3), characterized in that: The hydrolysis acidification tank (1) is provided with an iron-carbon micro-electrolysis filler (4) for enhancing the degradation of pollutants and inhibiting the growth of methanogens; the AO tank (2) comprises an anoxic tank (2-1) and an aerobic tank (2-2); and the sedimentation tank (3) is provided with a transport device for returning the precipitated sludge and the supernatant to the hydrolysis acidification tank (1) and the anoxic tank (2-1), respectively.

2. The hydrolysis acidification-AO combined treatment device for printing and dyeing wastewater according to claim 1 is characterized in that: The iron-carbon micro-electrolysis filler (4) can move up and down in the hydrolysis acidification tank (1).

3. The hydrolysis acidification-AO combined treatment device for printing and dyeing wastewater according to claim 1 is characterized in that: A vertical partition is provided in the middle of the aerobic pool (2-2), and a through groove communicating with both sides is provided at the bottom of the partition; an aeration device (5) for supplying oxygen is provided in the aerobic pool (2-2).

4. The hydrolysis acidification-AO combined treatment device for printing and dyeing wastewater according to claim 1 is characterized in that: Agitators are provided in the hydrolysis acidification tank (1), the anoxic tank (2-1) and the aerobic tank (2-2).

5. A method for preparing the iron-carbon micro-electrolysis filler used in the hydrolysis acidification-AO combined treatment device according to claim 1, characterized in that: The following steps are involved: S1, mixing zero-valent iron powder, powdered activated carbon and kaolin in a mass ratio of 2:1:2 to obtain a mixture; S2, adding sodium bicarbonate to the mixture in step S1, the mass ratio of sodium bicarbonate to the mixture is 1:20; then adding water and stirring, the mass ratio of the added water to the solid is 1:5~2:5; S3, preparing the mixture obtained in step S2 into granular filler balls, drying the filler balls and then performing anaerobically calcining; S4, adding manganese sulfate monohydrate to the calcined filler balls at a mass ratio of 1:10 to 1:5 to the filler balls, then adding water thereto at a solid-liquid mass ratio of 1:4 to 1:5 to obtain a mixed solution, and then adding potassium permanganate solution to the mixed solution at a mass ratio of 1:6 to 1:5, wherein the mass ratio of manganese sulfate monohydrate to potassium permanganate is 3:2 to 2:1; stirring for 0.5 to 1 hour and then standing for aging for 24 to 48 hours; S5. Drying the aged filler balls in step S4 to obtain iron-carbon micro-electrolysis filler.

6. The preparation method according to claim 5, characterized in that: The content ratio of water to solid added in step S2 is 1:

5.

7. The preparation method according to claim 5, characterized in that: In step S3, the drying temperature is 95°C-115°C, and the drying time is 1-2 hours; the calcination temperature is 800°C-1000°C, and the calcination time is 1-2 hours, and the heating rate is 10°C / min.

8. The preparation method according to claim 5, characterized in that: In step S4, the mass ratio of manganese sulfate monohydrate to filler balls is 3:20; the solid-liquid mass ratio in the mixed solution is 23:100; the mass ratio of potassium permanganate solution to the mixed solution is 109:615; the mass ratio of manganese sulfate monohydrate to potassium manganate is 5:3; the stirring time after adding the potassium permanganate solution is 0.5h, and the static aging time is 24h.

9. A method for treating printing and dyeing wastewater using the device according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, inputting printing and dyeing wastewater into the hydrolysis acidification tank (1) for stirring, and controlling the dissolved oxygen concentration in the hydrolysis acidification tank (1) to be 0-0.3 mg / L; S2, the printing and dyeing wastewater in the hydrolysis acidification tank (1) overflows into the anoxic tank (2-1) for stirring, and the dissolved oxygen concentration in the anoxic tank (2-1) is controlled at 0~0.5mg / L; S3, the printing and dyeing wastewater overflowing from the anoxic tank (2-1) enters the aerobic tank (2-2), and the dissolved oxygen concentration in the aerobic tank is controlled at 2~4mg / L; S4. The printing and dyeing wastewater in the aerobic tank (2-2) overflows into the sedimentation tank (3), the supernatant in the sedimentation tank (3) flows back to the anoxic tank (2-1) according to a set ratio, and the precipitated sludge flows back to the hydrolysis acidification tank (1) according to a set ratio.

10. The method for treating printing and dyeing wastewater according to claim 9, characterized in that: The sludge precipitated in the sedimentation tank (3) is returned at 5% to 35% of the total sludge volume, and the supernatant is returned at 150% to 200% of the influent volume of the printing and dyeing wastewater.

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