Whole-process treatment and resource utilization device and method for sweet potato starch wastewater

Abstract

The invention discloses a whole-process treatment and resource utilization device and method for sweet potato starch wastewater, and the method comprises the following steps: high-concentration wastewater and low-concentration wastewater are respectively pretreated and then enter a high-wastewater adjusting tank and a low-wastewater adjusting tank, and the effluent of the low-wastewater adjusting tank enters the high-wastewater adjusting tank or directly enters an A / O tank; and the effluent of the high wastewater adjusting tank sequentially enters an EGSB anaerobic reactor, a secondary air floatation tank, an A / O tank, a biochemical sedimentation tank, a magnetic coagulation sedimentation tank and an effluent tank. According to the invention, two sets of pretreatment modules are designed, so that the tank capacity is designed more accurately, the agent adding amount is selected more accurately, and the removal efficiency is greatly improved; in the pretreatment process, the sludge is subjected to protein recovery through a protein separation system, so that resource utilization of the sweet potato starch wastewater is realized; and an alternate treatment mode of biochemical treatment, physicochemical treatment, biochemical treatment and terminal deep physicochemical treatment is adopted, so that the method has higher flexibility and impact load resistance.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a device and method for whole-process treatment and resource utilization of sweet potato starch wastewater. Background Art

[0002] With the increasing demand for sweet potato starch, a large number of small and medium-sized sweet potato starch processing enterprises have emerged, and water use and pollution problems have followed. The production of sweet potato starch wastewater is mainly concentrated in multiple stages of the starch processing process, including raw material cleaning, crushing, grinding, separation, washing, dehydration and other steps.

[0003] (1) Cleaning and washing

[0004] During production, sweet potatoes are flushed into the chute in the yard with a water gun, and then continue to be hydraulically conveyed into the weeder to remove weeds, branches, rotten raw materials, etc. mixed in the raw materials. The next step is to enter the stone remover to remove stones mixed in the raw materials. After weeding, stone removal, and sediment removal, they enter the drum cleaning machine for thorough cleaning to remove sediment and debris again. The cleaning machine adopts the countercurrent washing principle, and clean water washes the raw materials and dirty water washes the newly entered sweet potatoes. The completely washed raw materials are sent to the buffer bin. During this process, the magnetic metal debris is removed by the magnetic belt conveyor and magnetic separator, and then sent to the crusher and file grinder for filing through the screw conveyor. The flushing water and washing water can be recycled after being treated according to the water quality to save water. The main cleaning wastewater is water containing mud, sand, potato skin, etc. The wastewater generated at this stage contains a large amount of impurities such as mud, sand, and sweet potato skin, and the content of suspended solids (SS) is at a high level.

[0005] (2) Crushing and grinding

[0006] The cleaned sweet potatoes first enter the clean raw material bin. To ensure the stability of the crushing amount, the sweet potatoes in the clean sweet potato bin are continuously and evenly fed into the crusher for pre-crushing by the feeding auger controlled by the variable frequency speed regulating motor. The large sweet potato pieces are broken into small particles or small pieces, and then sent to the file grinder to be filed into mixed slurry.

[0007] (3) Slurry separation

[0008] The purpose of crushing and filing is to destroy the tissue structure of fresh potatoes, so that tiny starch particles can be smoothly disintegrated and separated from the root tubers. Fresh potato residue is a thin and long fiber, which has a larger volume and expansion coefficient than starch particles, and a lighter specific gravity than starch particles. The crushed raw pulp is used with water as the medium to further filter out the starch slurry contained in the potato residue, so as to achieve the purpose of recovering starch to the greatest extent.

[0009] (4) Starch extraction stage:

[0010] During the starch extraction process, starch is released from the cells of sweet potatoes to form starch milk. The wastewater from the extraction stage mainly includes the processing wastewater after filtration and sedimentation, which is rich in nutrients such as protein, polysaccharides, amino acids, inorganic salts, etc. Although these wastewaters do not contain toxic substances and heavy metals, due to their high organic content (such as COD values ​​are usually around 25,000 mg / L), direct discharge will seriously affect the environment.

[0011] (5) Starch purification and drying stage:

[0012] In the processing of fresh potato starch, the protein contained in the fresh potato must be separated out. This process is a purification process, including butterfly separators and cyclones, which are used to separate protein from starch slurry. The dry matter is commonly known as yellow powder. Low-temperature and high-volume airflow drying is adopted. The wet material enters the drying tube from the powder feeder. The fresh air is heated by the radiator and mixed with the wet material sent into the drying tube by the powder lifter. Due to the power of the fan, the wet material is suspended in the hot air flow to undergo heat exchange in the heat and mass transfer process and is dried.

[0013] The wastewater from the sweet potato starch production process is divided into two categories. Among them, the wastewater from the raw material cleaning stage and the pulp-residue separation stage is low-concentration wastewater, and the wastewater generated in the starch extraction stage, starch purification and drying stage is high-concentration wastewater.

[0014] The wastewater generated in the above links usually has the following characteristics: (1) High suspended matter content: The wastewater contains a large amount of suspended matter, which mainly comes from the cleaning, crushing and separation process of the raw materials, such as soil, sweet potato peels, etc., causing the wastewater to be turbid and have a high turbidity. (2) High organic matter concentration: The wastewater contains a large amount of organic pollutants, such as protein, sugar, soluble starch, fine fibers, etc. The concentration of these organic matter is usually high, resulting in a correspondingly high COD (chemical oxygen demand) value of the wastewater, generally between 2000-30000 mg / L. (3) Acidic or weakly acidic: Sweet potato starch wastewater is generally acidic or weakly acidic, with a low pH value, which is related to the chemical agents used in the processing process or the properties of the starch itself. (4) High nitrogen and phosphorus content: Sweet potato starch wastewater also contains a certain amount of nutrients such as nitrogen and phosphorus. After these substances are discharged into the water body, they are likely to cause eutrophication of the water body, triggering algae proliferation and water quality deterioration.

[0015] In the prior art, anaerobic + aerobic biochemical treatment processes are basically used for starch wastewater with high organic content. Due to the excessively high organic content in wastewater, the rapid start-up and high efficiency of biochemical treatment processes, especially anaerobic processes, become particularly important. However, the production of periodic wastewater discharge has large fluctuations in water quality and quantity, which has a greater impact on the biochemical system and affects the stability of the operation of the biochemical system. Therefore, it is necessary to seek a treatment device and method, which combines the whole process of sweet potato starch production process, strengthens the pretreatment of sweet potato starch wastewater, reduces the wastewater treatment load and treatment cost of the biochemical system, improves the start-up efficiency and stability of the biochemical system, strengthens the terminal deep treatment, stabilizes the treatment effect, and finally realizes the degradation of pollutants and the standard discharge of wastewater, and at the same time realizes the multi-stage resource utilization in the process of sweet potato starch manufacturing and wastewater treatment. Summary of the invention

[0016] In view of the deficiencies in the prior art, the present invention provides a device and method for the whole process treatment and resource utilization of sweet potato starch wastewater. Two sets of pretreatment modules are arranged for high-concentration wastewater and low-concentration wastewater to perform pretreatment respectively. After merging, an alternating treatment mode of "biochemical + physicochemical + biochemical + terminal deep physicochemical" is adopted, which has greater flexibility and ability to resist shock loads.

[0017] In order to solve the above technical problems, the first aspect of the present invention provides a method for the whole process treatment and resource utilization of sweet potato starch wastewater, comprising the following steps:

[0018] S1. The high-concentration wastewater and low-concentration wastewater from sweet potato starch production are pre-treated and then enter the high-concentration wastewater regulating tank and the low-concentration wastewater regulating tank, which specifically includes the following steps:

[0019] S11, wastewater passes through the screen to intercept the scum;

[0020] S12, the water from the grid enters the primary sedimentation tank, and PAC and PAM are added to the primary sedimentation tank to form larger alum flake particles for precipitation and separation of some organic matter, colloidal substances and suspended matter that are difficult to dissolve in water;

[0021] S13, the supernatant of the primary sedimentation tank flows into the flotation tank by gravity, PAC and PAM are added, and air is introduced into the wastewater, which precipitates from the water in the form of tiny bubbles to become carriers, adheres to the emulsified oil and tiny suspended particles in the wastewater, and then floats to the water surface as scum for separation;

[0022] S14, the effluent from the flotation tank enters the respective regulating tanks for homogenization and quantity treatment;

[0023] S2, the effluent from the low wastewater regulating tank directly enters the A / O tank, or is mixed with the effluent from the high wastewater regulating tank and then enters the EGSB anaerobic reactor to remove organic matter in the wastewater and achieve gas, liquid and solid three-phase separation;

[0024] S3, the effluent of the EGSB anaerobic reactor enters the secondary flotation tank, further removes suspended solids, and then enters the A / O tank to remove TN, NH3-N and BOD5 in the wastewater;

[0025] S4, the effluent from the A / O pool enters the radial flow biochemical sedimentation tank to further separate mud and water;

[0026] S5, the effluent from the biochemical sedimentation tank enters the magnetic coagulation sedimentation tank, PAC, PAM, alkali solution and magnetic powder are added to the magnetic coagulation sedimentation tank, and the pollutants in the wastewater form flocs and are precipitated and separated after being combined with the magnetic powder;

[0027] S6. The effluent from the magnetic coagulation sedimentation tank enters the effluent tank.

[0028] The present invention sets two sets of pretreatment modules for high-concentration wastewater and low-concentration wastewater. The effluent of the low-concentration pretreatment system can be directly connected to the biochemical A / O section, or it can be connected to the anaerobic EGSB for comprehensive anaerobic treatment from the high-concentration wastewater regulating tank according to the water quality. This wastewater method can better adapt to the fluctuation of water quality and water volume, and the process adjustment and dosage adjustment are simpler and more efficient, and the process adaptability is strong and more flexible. At the same time, in order to achieve the stability of the wastewater treatment effect, reduce the impact load on the biochemical system, and obtain the maximum protein recovery rate, a two-stage physical and chemical pretreatment is designed, namely the primary sedimentation tank and the flotation tank.

[0029] Furthermore, perforated aeration and stirring equipment is provided in both the high wastewater regulating tank and the low wastewater regulating tank to pre-aerate the wastewater.

[0030] Furthermore, the sediment in the primary sedimentation tank and the scum in the flotation tank enter the protein separation system to extract and recover protein.

[0031] Further, in S12, the dosage of PAC in the primary sedimentation tank is 280-350 mg / L, and the dosage of PAM is 8-10 mg / L;

[0032] And / or, the pH of the primary sedimentation tank is 2.9-4.4.

[0033] The primary sedimentation tank adopts a drug-added coagulation sedimentation primary sedimentation process. After the flocculant is added, whether it is aluminum salt or iron salt, the multi-nuclear hydroxyl complex generated after hydrolysis has a strong positive charge, which can neutralize the negative charge on the surface of suspended particles such as starch and protein, compress the double electric layer, reduce the charge repulsion between particles, and promote their coagulation. The high bridging ability of PAM can make the coagulation and adsorption faster, and the flocs can be condensed into flocs to form more stable large flocs, thereby achieving a better flocculation effect.

[0034] Among the same type of aluminum or iron flocculants, the flocculation effect of PAC is better than that of AS, and that of PFS is better than that of FC. The reason is that AS and FC are inorganic low molecular weight flocculants, while PAC and PFS are inorganic high molecular weight flocculants. Under acidic conditions, both can neutralize the negative charge on the surface of suspended particles, compress the double electric layer, and reduce the repulsive force between colloid particles. However, the degree of polymerization of inorganic high molecular weight flocculants is higher, and they have the bridge connection of colloidal particles and the web capture effect of long-chain macromolecules, and have stronger cohesion ability. The flocculation effect of aluminum-based high molecular weight PAC is better than that of iron-based high molecular weight PFS. The reason is that when the pH is 4.4, PAC presents multi-core high-polymerization hydroxyl complexes such as poly(hexa-aluminum), poly(hepta-aluminum), poly(octa-aluminum) and poly(trideca-aluminum), while PFS is a low-polymerization hydroxyl complex such as poly(di-iron) and poly(tri-iron). PAC with a high degree of polymerization has stronger adsorption, bridging, adhesion, web capture and other effects than PFS. In the primary sedimentation process, sludge needs to be recycled, so the type of reagent added is particularly important. The effects of three different flocculants, PAC, chitosan, and MBF, on the recovery of useful components such as protein from sweet potato starch wastewater were studied. The results showed that the recoverable precipitate per ton of sweet potato starch wastewater was 4.0kg, 3.5kg, and 2.5kg, respectively, and the protein content per 100g of precipitate reached 17.5g, 34.3g, and 36.8g, respectively. It can be seen that PAC has the highest protein recovery rate, and the protein obtained can be used as animal feed.

[0035] With the increase of PAC dosage, the COD and turbidity removal rates of wastewater show an increasing trend. When the PAC dosage is 280 mg / L, the COD and turbidity removal rates of the supernatant after flocculation reach the maximum, which are 26.6% and 67.8% respectively; further increasing the PAC dosage to more than 350 mg / L will lead to a decrease in COD removal rate. Similarly, with the increase of PAM dosage, the COD and turbidity removal rates of wastewater increase, showing a trend of first increasing and then decreasing. When the PAM dosage is 8 mg / L, the flocculation effect is best, and the COD and turbidity removal rates are 28.9% and 66.7% respectively; when the PAM dosage is greater than 10 mg / L, the COD and turbidity removal rates are reduced.

[0036] In the primary sedimentation stage, no liquid alkali is added to adjust the pH value of the wastewater. The change in the pH value of the solution will affect the solubility of the protein. The protein precipitates at the isoelectric point, and adjusting the pH value of the solution will also affect the chromaticity of the wastewater. When pH <4.4, the solution is clear and transparent; when pH >4.4, the solution changes from milky yellow to dark brown. The higher the pH, the darker the solution color. This is because amino compounds (proteins, amino acids) and carbonyl compounds (starch, monosaccharides) in starch wastewater undergo a Maillard reaction to produce soluble melanin. The increase in wastewater chromaticity will cause difficulties for subsequent treatment processes. Therefore, the pH value of the wastewater should not be higher than 4.4. At pH = 2.9, the COD and turbidity removal rates are the highest, but the upper layer of the precipitate obtained is a fluffy light yellow impurity, which affects the purity of the recovered starch; at pH = 4.4, there are fewer impurities in the precipitate obtained by centrifugation, so the pH value of the wastewater is preferably 4.4.

[0037] Furthermore, in S13, the air is introduced into the wastewater by means of reflux pressurized dissolved air, and 20% of the effluent from the flotation tank is pressurized and dissolved in air and then refluxed to the flotation tank. Compared with the sedimentation method, the flotation method can not only maintain a high removal rate for sediments, but also has an effect on suspended matter. In addition, by adding flocculants, flocculation is first performed and then flotation is performed, which also has a good effect on colloidal substances.

[0038] Furthermore, in S13, the PAC and PAM are added in the form of aqueous solutions, the amount of the PAC aqueous solution added is 1%-2% of the total volume of the flotation tank wastewater, and the amount of the PAM aqueous solution added is 2%-4% of the total volume of the flotation tank wastewater.

[0039] Since the solid suspended matter content of the wastewater is very high and contains a large amount of protein, an air flotation tank is added to further separate and extract the protein, improve economic benefits, and reduce the pressure of subsequent treatment structures. This process uses a pressure reflux dissolved air method. Part of the effluent from the air flotation tank is refluxed and pressurized to dissolve the air and then mixed with the inlet water to enter the air flotation tank. The reflux dissolved air flotation has the advantages of small dissolved air tank volume, high and relatively uniform bubble dispersion, but the volume of the air flotation tank is large. The air flotation tank uses a TSV type dissolved air releaser and a TR type pressure dissolved air tank.

[0040] After pretreatment, low-concentration wastewater is directly pumped into the A / O section and reserved for the EGSB anaerobic reactor pipeline. In special cases, it can be combined with high-concentration pretreated wastewater for comprehensive anaerobic treatment. The process can be flexibly adjusted according to the water quality.

[0041] Furthermore, in S2, the pH of the EGSB anaerobic reactor is 7.5-7.8, the rising flow rate is 1.4-1.5 m / h, and the volume load is 4-5 kgCOD / (m 3 ·d), the residence time of the reactor is 2.5-3 days. The biogas produced by the EGSB anaerobic reactor is purified and then enters the biogas tank for recycling.

[0042] Compared with traditional anaerobic sedimentation tanks, the effluent from the EGSB anaerobic reactor enters the secondary flotation tank. With the assistance of tiny bubbles and high molecular weight flocculants, it can more efficiently capture sludge particles and prevent the loss of anaerobic sludge to the greatest extent.

[0043] Further, in S3, the dissolved oxygen concentration in the A pool of the A / O pool is 0.4-0.6 mg / L, the dissolved oxygen concentration in the O pool is 2.8-3.2 mg / L, the residence time of the A / O pool is 3-3.5 days, and the volume load is 0.8-1COD / (m 3 ·d).

[0044] Further, in S5, the pH in the magnetic coagulation sedimentation tank is 10±0.5, the dosage of PAC is 100-150 mg / L, the dosage of PAM is 4-6 mg / L, the dosage of magnetic powder is 9-11 mg / L, the stirring rate is 100-150 r / min, and the flocculation sedimentation time is 50-70 min.

[0045] Using magnetic powder as flocculation nucleus, the flocs formed under the action of magnetic force are tight and firm, and the flocs are not easily broken up under the action of vibration. The turbidity removal effect is very good, which reduces the subsequent processing load. As a highly efficient and easily available material, the flocs after magnetic flocculation are stirred at high speed to achieve the separation and recovery of magnetic powder, thereby reducing the project cost and improving the technical and economic efficiency of the project.

[0046] The process of the present invention realizes multi-stage resource utilization. The sludge protein separated from the wastewater pretreatment process is sold as animal feed, and the EGSB anaerobically produces biogas as energy for boilers; a part of the treated wastewater that meets the standards is reused to supplement the water in the sweet potato washing workshop. The possibility of resource utilization is developed from multiple angles, the operating cost is reduced, and energy saving, efficiency improvement and revenue generation are achieved for the enterprise.

[0047] The second aspect of the present invention provides a whole-process treatment and resource utilization device for sweet potato starch wastewater, which is used to implement the method described in the first aspect, comprising:

[0048] Two sets of pretreatment modules are used to pretreat high-concentration wastewater and low-concentration wastewater from sweet potato starch production, respectively, and the ends of the two sets of pretreatment modules are connected to the low-concentration wastewater regulating tank and the high-concentration wastewater regulating tank; wherein the pretreatment module includes a grid, a primary sedimentation tank, and a flotation tank connected in sequence;

[0049] The low wastewater regulating tank is connected to the high wastewater regulating tank and the A / O tank, and the high wastewater regulating tank is connected to the EGSB anaerobic reactor for removing organic matter in the wastewater and achieving gas, liquid and solid three-phase separation;

[0050] The EGSB anaerobic reactor is connected to a secondary flotation tank for further removing suspended matter;

[0051] The secondary flotation tank is connected to the A / O tank to remove TN, NH3-N and BOD5 from the wastewater;

[0052] The A / O tank is connected to a radial flow biochemical sedimentation tank for further separation of mud and water;

[0053] The biochemical sedimentation tank is connected to the magnetic coagulation sedimentation tank, which is used to separate the pollutants in the wastewater in the form of flocs combined with magnetic powder;

[0054] The magnetic coagulation sedimentation tank is connected to the water outlet tank.

[0055] Furthermore, the primary sedimentation tank and the flotation tank are connected to a protein separation system via a sediment recovery module;

[0056] And / or, the gas outlet of the EGSB anaerobic reactor is connected to a biogas tank after passing through a biogas purification device.

[0057] Beneficial effects of the present invention:

[0058] The present invention designs two sets of pretreatment modules for pretreatment of low-concentration wastewater and high-concentration wastewater generated in the sweet potato production process, respectively, and more accurately designs the pool capacity and selects the dosage of the reagent, thereby greatly improving the removal efficiency; the precipitation and scum in the primary sedimentation tank and the flotation tank in the pretreatment process are recovered by the protein separation system, which can also realize the resource utilization of sweet potato starch wastewater to the greatest extent.

[0059] The comprehensive treatment of the present invention adopts an alternating treatment mode of "biochemical + physicochemical + biochemical + terminal deep physicochemical", which is more flexible and resistant to shock loads than traditional biochemical processes. The whole set of treatment processes ensures the stability of the treatment effect with a more flexible operation mode and strong resistance to shock loads. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0061] Figure 1 The present invention is a flow chart of the whole process treatment and resource utilization method of sweet potato starch wastewater. DETAILED DESCRIPTION

[0062] The technical solution of the present invention will be described clearly and completely below in conjunction with the specific embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0063] Reference Figure 1 As shown, this embodiment relates to a method for the whole process treatment and resource utilization of sweet potato starch wastewater, and the process flow chart is as follows Figure 1 As shown, the wastewater to be treated is mainly divided into low-concentration wastewater generated in the raw material washing stage and the pulp-slag separation stage, and high-concentration wastewater generated in the starch extraction stage, starch purification and drying stage. The water quality and water quantity are shown in Table 1 below:

[0064] Table 1

[0065]

[0066] This embodiment provides a method for the whole process treatment and resource utilization of sweet potato starch wastewater, comprising the following steps:

[0067] (1) After cleaning, the sweet potatoes are sent to the crusher and filer for crushing and filing. The sweet potato mixed slurry after filing is pumped to the horizontal centrifugal screen group and the cylindrical screen group for screening. After the high and low concentration wastewater is generated, it flows into the respective collection pools for wastewater treatment. The potato residue is sent out of the workshop by the screw pump, and after dehydration and drying, it is sold to local farmers or farms as feed. The crude starch extracted from the slurry is sent to the starch refining section. After concentration, dehydration and drying, it is packaged as sweet potato starch products for external sale.

[0068] (2) Low-concentration wastewater and high-concentration wastewater flow into their respective collection tanks for pretreatment. After the scum is intercepted by the grille, it enters the primary sedimentation tank + flotation tank for physical and chemical pretreatment. Among them, the dosage of PAC and PAM in the primary sedimentation tank is 350 mg / L and 10 mg / L, and the pH is 4.4; in the flotation tank, PAC is prepared into a 5% aqueous solution with a dosage of 2% of the wastewater volume; PAM is prepared into a 0.05% aqueous solution with a dosage of 4% of the wastewater volume.

[0069] Preferably, the sludge from the primary sedimentation tank and the flotation tank is recycled, and the protein is separated by a protein separation system and sold as animal feed.

[0070] (3) The effluent from the flotation tank flows into the respective regulating tanks (high wastewater regulating tank and low wastewater regulating tank). The water quality and quantity are comprehensively collected in the respective regulating tanks, and the quality and quantity are evenly distributed.

[0071] (4) The effluents from each regulating tank are mixed and pumped into the biochemical treatment section as comprehensive biochemical wastewater. The biochemical treatment process adopts medium-temperature anaerobic + A / O + secondary sedimentation process, and the anaerobic process adopts the third-generation EGSB anaerobic reactor.

[0072] Specifically, in the EGSB anaerobic reactor, the wastewater is in an anaerobic state, and the organic matter in the wastewater is decomposed, metabolized, and digested by anaerobic bacteria, which greatly reduces the organic matter content in the wastewater. The pH of the EGSB anaerobic reactor is 7.5-7.8, the rising flow rate is 1.45m / h, and the volume load is 4-5kgCOD / (m 3 ·d), the residence time of the reactor is 3 days. The biogas produced by the EGSB anaerobic reactor is dehydrated and desulfurized, then stored in an independent double-membrane biogas tank and finally sent to the biogas boiler for combustion.

[0073] Specifically, the effluent from the EGSB anaerobic reactor flows by gravity to the secondary flotation tank to further remove fine suspended matter and reduce anaerobic SS carryover, and the flotation clarified effluent flows by gravity into the A / O tank. The A / O tank process is a pre-denitrification biological denitrification process with reflux, which consists of an anoxic tank and an aerobic tank. The process mainly removes TN, NH3-N, and BOD5 from the wastewater. Among them, the dissolved oxygen concentration of the A pool of the A / O pool is 0.5 mg / L, the dissolved oxygen concentration of the O pool is 3 mg / L, and the residence time of the A / O pool is 3 days.

[0074] Specifically, the effluent from the A / O tank enters the secondary sedimentation tank, i.e., the biochemical sedimentation tank. The function of the biochemical sedimentation tank is to separate mud and water and clarify the effluent. The secondary sedimentation tank adopts radial flow, which is simple to operate, reliable in operation, and thorough in sludge discharge. Part of the sludge in the biochemical sedimentation tank is returned to the A / O tank, and part is returned to the anaerobic tank for further anaerobic digestion, so as to achieve the purpose of sludge reduction.

[0075] (5) The effluent from the secondary sedimentation tank enters the magnetic flocculation sedimentation tank. The pH of the magnetic flocculation sedimentation tank is 10, the dosage of PAC is 100 mg / L, the dosage of PAM is 5 mg / L, the dosage of magnetic powder is 10 mg / L, the stirring rate is 100 r / min, and the flocculation sedimentation time is 60 min. It consists of a coagulation unit, a sedimentation unit, a magnetic medium recovery unit, and a detection control unit. It uses the effect of an external magnetic load to enhance flocculation to achieve high-speed sedimentation. The sedimentation part adopts a combination of a vertical flow sedimentation tank and a high-density sedimentation tank: the tank type is a vertical flow sedimentation tank, and an inclined tube sedimentation area and sludge return are set in the tank. An efficient magnetic powder recovery system is set to ensure the temperature operation of the magnetic flocculation sedimentation system.

[0076] (6) The effluent from the magnetic flocculation sedimentation tank is collected and temporarily stored in the effluent tank, and then discharged into the downstream secondary sewage treatment plant. Part of it is reused as supplementary water in the sweet potato washing workshop.

[0077] In this embodiment, the primary sedimentation tank and the flotation tank pretreatment stage, the secondary flotation tank, and the magnetic coagulation sedimentation tank produce physicochemical sludge and the biochemical stage produces residual sludge, wherein the pretreated sludge is recycled, and the remaining sludge is pumped into the sludge tank, and a filter press is set to dehydrate the sludge to a moisture content of about 60%, and then dried to a moisture content of less than 30% by sludge drying equipment before being transported out, and the supernatant and filtrate of the sludge tank are returned to the low wastewater regulating tank for further treatment.

[0078] The removal of various substances by each processing unit in this embodiment is shown in Table 2 below:

[0079] Table 2

[0080]

[0081] As can be seen from Table 2, the present invention designs two sets of pretreatment modules for low-concentration wastewater and high-concentration wastewater generated in the sweet potato production process to perform pretreatment respectively, designs the tank capacity and selects the dosage of the reagent more accurately, and greatly improves the removal efficiency; the precipitation and scum in the primary sedimentation tank and the flotation tank in the pretreatment process are recovered by the protein separation system, and the resource utilization of sweet potato starch wastewater can be realized to the greatest extent; the alternating treatment mode of "biochemical + physicochemical + biochemical + terminal deep physicochemical" is adopted in the comprehensive treatment, which is more flexible and resistant to shock loads than the traditional biochemical process. The whole set of treatment processes ensures the stability of the treatment effect with a more flexible operation mode and strong resistance to shock loads.

[0082] Another embodiment of the present invention provides a whole process treatment and resource utilization device for sweet potato starch wastewater, the device framework diagram is referenced Figure 1 , including: two sets of pretreatment modules, respectively used to pretreat high-concentration wastewater and low-concentration wastewater from sweet potato starch production, and the ends of the two sets of pretreatment modules are connected to a low-concentration wastewater regulating tank and a high-concentration wastewater regulating tank; wherein the pretreatment module includes a grid, a primary sedimentation tank, and a flotation tank connected in sequence; the low-concentration wastewater regulating tank is connected to a high-concentration wastewater regulating tank and an A / O tank, and the high-concentration wastewater regulating tank is connected to an EGSB anaerobic reactor for removing organic matter in the wastewater and realizing gas, liquid, and solid three-phase separation; the EGSB anaerobic reactor is connected to a secondary flotation tank for further removing suspended matter; the secondary flotation tank is connected to an A / O tank for removing TN, NH3-N, and BOD5 from the wastewater; the A / O tank is connected to a radial flow biochemical sedimentation tank for further mud and water separation; the biochemical sedimentation tank is connected to a magnetic coagulation sedimentation tank for separating pollutants in the wastewater in the form of flocs combined with magnetic powder; the magnetic coagulation sedimentation tank is connected to an outlet tank.

[0083] Preferably, the primary sedimentation tank and the flotation tank are connected to the protein separation system via a sediment recovery module, and the gas outlet of the EGSB anaerobic reactor is connected to the biogas tank after passing through a biogas purification device.

[0084] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A method for the whole process treatment and resource utilization of sweet potato starch wastewater, characterized in that: The steps include: S1. The high-concentration wastewater and low-concentration wastewater from sweet potato starch production are pre-treated and then enter the high-concentration wastewater regulating tank and the low-concentration wastewater regulating tank, which specifically includes the following steps: S11, wastewater passes through the screen to intercept the scum; S12, the water from the grid enters the primary sedimentation tank, and PAC and PAM are added to the primary sedimentation tank to form larger alum flake particles for precipitation and separation of some organic matter, colloidal substances and suspended matter that are difficult to dissolve in water; S13, the supernatant of the primary sedimentation tank flows into the flotation tank by gravity, PAC and PAM are added, and air is introduced into the wastewater, which precipitates from the water in the form of tiny bubbles to become carriers, adheres to the emulsified oil and tiny suspended particles in the wastewater, and then floats to the water surface as scum for separation; S14, the effluent from the flotation tank enters the respective regulating tanks for homogenization and quantity treatment; S2, the effluent from the low wastewater regulating tank directly enters the A / O tank, or is mixed with the effluent from the high wastewater regulating tank and then enters the EGSB anaerobic reactor to remove organic matter in the wastewater and achieve gas, liquid and solid three-phase separation; S3, the effluent of the EGSB anaerobic reactor enters the secondary flotation tank, further removes suspended solids, and then enters the A / O tank to remove TN, NH3-N and BOD5 in the wastewater; S4, the effluent from the A / O pool enters the radial flow biochemical sedimentation tank to further separate mud and water; S5, the effluent from the biochemical sedimentation tank enters the magnetic coagulation sedimentation tank, PAC, PAM, alkali solution and magnetic powder are added to the magnetic coagulation sedimentation tank, and the pollutants in the wastewater form flocs and are precipitated and separated after being combined with the magnetic powder; S6. The effluent from the magnetic coagulation sedimentation tank enters the effluent tank.

2. The whole process treatment and resource utilization method of sweet potato starch wastewater as claimed in claim 1, characterized in that, In S12, the dosage of PAC in the primary sedimentation tank is 280-350 mg / L, and the dosage of PAM is 8-10 mg / L; And / or, the pH of the primary sedimentation tank is 2.9-4.

4.

3. The whole process treatment and resource utilization method of sweet potato starch wastewater as claimed in claim 1, characterized in that, In S13, air is introduced into the wastewater by means of reflux pressurized dissolved air, so that 20% of the effluent from the flotation tank is pressurized and dissolved in air and then refluxed to the flotation tank.

4. The whole process treatment and resource utilization method of sweet potato starch wastewater as claimed in claim 1, characterized in that, In S13, the PAC and PAM are added in the form of aqueous solutions, the amount of the PAC aqueous solution added is 1%-2% of the total volume of the flotation tank wastewater, and the amount of the PAM aqueous solution added is 2%-4% of the total volume of the flotation tank wastewater.

5. The whole process treatment and resource utilization method of sweet potato starch wastewater as claimed in claim 1, characterized in that, In S2, the pH of the EGSB anaerobic reactor is 7.5-7.8, the rising flow rate is 1.4-1.5 m / h, and the volume load is 4-5 kgCOD / (m 3 ·d), the residence time of the reactor is 2.5-3d.

6. The whole process treatment and resource utilization method of sweet potato starch wastewater as claimed in claim 1, characterized in that, In S3, the dissolved oxygen concentration of the A / O pool is 0.4-0.6 mg / L, the dissolved oxygen concentration of the O pool is 2.8-3.2 mg / L, the residence time of the A / O pool is 3-3.5 days, and the volume load is 0.8-1COD / (m 3 ·d).

7. The whole process treatment and resource utilization method of sweet potato starch wastewater as claimed in claim 1, characterized in that: In S5, the pH in the magnetic coagulation sedimentation tank is 10±0.5, the dosage of PAC is 100-150 mg / L, the dosage of PAM is 4-6 mg / L, the dosage of magnetic powder is 9-11 mg / L, the stirring rate is 100-150 r / min, and the flocculation sedimentation time is 50-70 min.

8. The whole process treatment and resource utilization method of sweet potato starch wastewater as claimed in claim 1, characterized in that, The sedimentation in the primary sedimentation tank and the scum in the flotation tank enter the protein separation system to extract and recover protein.

9. A whole-process treatment and resource utilization device for sweet potato starch wastewater, used to implement the method according to any one of claims 1 to 8, characterized in that: include: Two sets of pretreatment modules are used to pretreat high-concentration wastewater and low-concentration wastewater from sweet potato starch production, respectively, and the ends of the two sets of pretreatment modules are connected to the low-concentration wastewater regulating tank and the high-concentration wastewater regulating tank; wherein the pretreatment module includes a grid, a primary sedimentation tank, and a flotation tank connected in sequence; The low wastewater regulating tank is connected to the high wastewater regulating tank and the A / O tank, and the high wastewater regulating tank is connected to the EGSB anaerobic reactor for removing organic matter in the wastewater and achieving gas, liquid and solid three-phase separation; The EGSB anaerobic reactor is connected to a secondary flotation tank for further removing suspended matter; The secondary flotation tank is connected to the A / O tank to remove TN, NH3-N and BOD5 from the wastewater; The A / O tank is connected to a radial flow biochemical sedimentation tank for further separation of mud and water; The biochemical sedimentation tank is connected to the magnetic coagulation sedimentation tank, which is used to separate the pollutants in the wastewater in the form of flocs combined with magnetic powder; The magnetic coagulation sedimentation tank is connected to the water outlet tank.

10. The whole process treatment and resource utilization device of sweet potato starch wastewater according to claim 9, characterized in that: The primary sedimentation tank and the flotation tank are connected to the protein separation system via a sediment recovery module; And / or, the gas outlet of the EGSB anaerobic reactor is connected to a biogas tank after passing through a biogas purification device.

Images