High-medium temperature anaerobic digestion-concentration reflux equipment for desizing wastewater

Abstract

The utility model relates to the field of wastewater treatment equipment, in particular to high-medium temperature anaerobic digestion-concentration reflux equipment for desizing wastewater. According to the utility model, the hydrolysis acid production device, the alkalinity detection and addition system, the high-temperature methane device, the medium-temperature methane device, the sludge-water separation device, the sludge concentration and reflux system, the heating system and other matched systems and facilities are arranged; the molecular structure of refractory organic matters is changed or the concentration of pollutants in the refractory organic matters is reduced, the toxicity of the refractory organic matters is reduced, the BOD5 / COD value of the wastewater is improved, and conditions are created for the operation stability and high treatment efficiency of subsequent biological treatment.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of wastewater treatment equipment, specifically relates to high-medium temperature anaerobic digestion-concentration reflux equipment for desizing wastewater. BACKGROUND

[0002] Printing and dyeing cloth needs to be sized when weaving, and the sizing agent used is of many types, such as starch, acrylic acid, polyvinyl alcohol, etc., and the amount used is large, accounting for 5% to 10% of the weight of the fabric. The sizing agent used for warp sizing includes natural sizing agent and chemical sizing agent. Natural sizing agent and chemical sizing agent are generally used for warp sizing of cotton and polyester-cotton fabrics, and chemical sizing agent is used alone for warp sizing of polyester-cotton fabrics in some areas. Natural sizing agent includes wheat starch, corn starch, potato starch, etc., and chemical sizing agent includes polyvinyl alcohol (PVA), polyacrylamide (PAM), carboxymethyl cellulose (CMC), etc. At present, modified starch, polyvinyl alcohol (PVA) and acrylic acid are the three major types of sizing agent used at home and abroad. These sizing agents play a role in ensuring the quality of weaving, but have a great impact on printing and dyeing, and therefore must be removed before printing and dyeing. Desizing is a process in which chemical agents (enzyme preparation, acid, alkali, oxidizing agent, etc.) are used to hydrolyze the sizing agent on the fabric into soluble substances for removal. Desizing not only removes the sizing agent on the fabric, but also removes part of the natural impurities on the fabric, facilitating scouring and bleaching in the subsequent processes. In addition to the binder, desizing agent also contains appropriate amounts of other components, such as lubricant, softener, thickener, preservative, etc. The amount of desizing wastewater accounts for 15% of the total amount of printing and dyeing wastewater, the pH value is high, the organic matter content is high, the BOD accounts for about 45% of the total amount of printing and dyeing wastewater, and the COD is high.

[0003] The starch, glue and wax produced in desizing increase the BOD value of the wastewater, and the commonly used acidifying agent such as acetic acid also increases the BOD value. The COD of the wastewater mainly comes from PVA and other chemical sizing agents. Other pollutants brought into the wastewater include starch-decomposing enzyme, caustic soda, sodium hyposulfite, hydrogen peroxide, etc. Therefore, the main pollutants in desizing wastewater are starch, PVA and some additives. According to the measured data, the COD of desizing wastewater of natural sizing agent is 10,000 to 20,000 mg / L, the BOD is 5,000 to 10,000 mg / L, it is high-concentration organic wastewater with easy biodegradability, and the pH value is generally about 9; the COD of desizing wastewater of synthetic sizing agent (PVA) is 10,000 to 40,000 mg / L, the BOD is 500 to 1000 mg / L, and the pH value is generally about 6, which is high-concentration organic wastewater with difficult biodegradability.

[0004] For organic wastewater that is difficult to biodegrade, chemical, physical, or biological pretreatment is required first to change the molecular structure of difficult-to-degrade organic matter or reduce the concentration of certain pollutants therein, reduce their toxicity, and improve the BOD5 / COD value of the wastewater, creating conditions for the operational stability and high treatment efficiency of subsequent biological treatment. The choice of pretreatment method is related to the nature and concentration of difficult-to-degrade organic matter. The main methods are: ① Advanced oxidation method, such as ozone oxidation, catalytic oxidation, and wet oxidation, which use oxidants to remove toxic and harmful groups of organic matter, improve its biodegradability and reduce the COD concentration of wastewater; ② Chemical hydrolysis method, such as alkaline hydrolysis and acid hydrolysis. Chemical hydrolysis method requires hydrolysis with alkali or acid according to the characteristics of organic matter to change the chemical structure of difficult-to-degrade organic matter, reduce its toxicity and improve the biodegradability of wastewater; ③ Anaerobic hydrolysis acidification method. Summary of the Invention

[0005] The utility model hopes to provide a high-medium temperature anaerobic digestion-concentration reflux equipment for desizing wastewater, the specific scheme is as follows:

[0006] The high-medium temperature anaerobic digestion-concentration reflux equipment for desizing wastewater includes a hydrolysis acid production device, a high temperature methane device, a medium temperature methane device and a mud-water separation device which are arranged in sequence and are connected to each other through a desizing wastewater pipeline.

[0007] It also includes a heating boiler, a high-pressure gas storage tank, an air compressor and a low-pressure gas storage tank, which are connected to each other through a biogas pipeline, and the low-pressure gas storage tank is connected to a hydrolysis acid production device, a high-temperature methane device and a medium-temperature methane device through a biogas pipeline.

[0008] A heat exchanger is provided between the heating boiler and the hydrolysis acid generating device.

[0009] An alkalinity detection and dosing system and a heat exchanger are provided between the hydrolysis acid production device and the high-temperature methane device.

[0010] It also includes a sludge thickening device and a sludge return pump.

[0011] Anaerobic biological treatment involves the decomposition of complex carbon-containing organic matter into simpler organic and inorganic compounds by facultative and obligate anaerobic microorganisms in the absence of oxygen and nitrates. The final products are CH₄, CO₂, and small amounts of H₂S, NH₃, and H₂, thereby stabilizing the wastewater treatment process. Anaerobic biodegradation, also known as anaerobic digestion, consists of three stages: hydrolysis and fermentation, acid-dehydrogenation, and methanogenesis.

[0012] The first stage, the hydrolysis fermentation stage, is to hydrolyze the macromolecular insoluble complex organic matter into small molecular soluble organic matter under the action of extracellular enzymes, and then the small molecular soluble organic matter penetrates into cells to participate in the microorganism, the main microorganism is facultative bacteria and specific anaerobic bacteria, the byproduct of the facultative bacteria is to consume the dissolved oxygen in the wastewater to create favorable conditions for the growth of specific anaerobic bacteria. In addition, fungi and protozoa, etc. can be collectively referred to as hydrolysis fermentation bacteria.

[0013] The second stage, the acid production and dehydrogenation stage, is to degrade the product of the first stage into simple fatty acids and dehydrogenate. The odd carbon organic matter also produces CO2. The microorganism participating in the action is facultative and specific anaerobic bacteria. Therefore, the main product of the second stage is fatty acid, CO2, etc. The speed of this stage is faster.

[0014] The third stage, the methane production stage, is to reduce the product of the second stage into CH4, and the microorganism participating in the action is absolute anaerobic bacteria (methanogens). The reaction rate of this stage is slow, and it is the control stage of anaerobic digestion.

[0015] The final product of anaerobic digestion is carbon dioxide and methane gas. Compared with aerobic oxidation, the energy produced by anaerobic digestion is very small, and most of the energy is used for the life activities of the bacteria, only a small amount is used for the synthesis of new cells, so the sludge produced by anaerobic biological treatment is much less than that produced by aerobic oxidation. For the same substrate, the energy produced by anaerobic digestion is only 1 / 20-1 / 30 of that produced by aerobic oxidation.

[0016] The utility model has the following advantages:

[0017] 1. According to the anaerobic digestion mechanism, anaerobic digestion is divided into three stages of hydrolysis fermentation, acid production and dehydrogenation, and methane production. The bacteria, digestion speed and digestion product of each stage are different. If they are mixed in one digestion tank, there are many unsuitable, so the first stage and the second stage of digestion are completed in the hydrolysis acid production phase, and the third stage is completed in the methane phase, so each has the best environmental conditions. Two-phase digestion has the advantages of small total volume, low heating and stirring energy consumption, easy operation and management, high removal rate of organic matter and high gas production rate.

[0018] 2. High-temperature anaerobic digestion is adopted, which solves the problems of high energy consumption of high-temperature digestion and low COD removal rate of medium-temperature digestion compared with high-temperature digestion. The combination of the two can ensure a high COD removal rate while improving the utilization rate of heat and reducing energy consumption.

[0019] 3. The sludge concentration and reflux technology is adopted, which improves the concentration of high-temperature methane device digestion sludge, increases the biomass and activity of anaerobic bacteria, and solves the problems of high-temperature methane bacteria endogenous respiration consumption, high bacterial aging and mortality, and low bacterial yield in the high-temperature digestion process. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 This is a structural schematic diagram of a high-medium temperature anaerobic digestion-concentration reflux device for desizing wastewater according to the present invention;

[0021] 1. Hydrolysis acid production unit; 2. High-temperature methane unit; 3. Medium-temperature methane unit; 4. Mud-water separation unit; 5. Low-pressure gas storage tank; 6. Air compressor; 7. High-pressure gas storage tank; 8. Heating boiler; 9. Heat exchanger; 10. Sludge concentration unit; 11. Sludge return pump; 12. Alkalinity detection and dosing system. DETAILED DESCRIPTION

[0022] The following combination Figure 1 For further explanation:

[0023] The high-medium temperature anaerobic digestion-concentration reflux equipment for desizing wastewater comprises a hydrolysis acid production device 1, a high temperature methane device 2, a medium temperature methane device 3 and a mud-water separation device 4 which are arranged in sequence and are connected to each other through a desizing wastewater pipeline.

[0024] It also includes a heating boiler 8, a high-pressure gas storage tank 7, an air compressor 6 and a low-pressure gas storage tank 5, which are connected to each other through a biogas pipeline, and the low-pressure gas storage tank 5 is connected to the hydrolysis acid production device 1, the high-temperature methane device 2 and the medium-temperature methane device 3 through the biogas pipeline.

[0025] A heat exchanger 9 is provided between the heating boiler 8 and the hydrolysis acid generating device 1 .

[0026] An alkalinity detection and dosing system 12 and a heat exchanger 9 are provided between the hydrolysis acid production device 1 and the high-temperature methane device 2 .

[0027] It also includes a sludge concentrating device 10 and a sludge return pump 11.

[0028] Specifically,

[0029] 1. Hydrolysis acid production device 1

[0030] The main bacteria are hydrolytic fermentation bacteria and acid-producing dehydrogenation bacteria. The optimum pH range is 5.0 to 6.5. The large molecular insoluble complex organic matter is hydrolyzed into small molecular soluble simple organic matter.

[0031] 2. Alkalinity detection and dosing system 12

[0032] During the digestion process, organic acids will accumulate in the hydrolysis and fermentation stage and the acid-producing and dehydrogenation stage, which will reduce the pH of the effluent from the hydrolysis and acid-producing phase and inhibit the growth of subsequent methanogens. Therefore, an alkalinity detection and addition system 12 is set at the front end of the high-temperature methane device 2 to buffer the pH of the wastewater and ensure that the pH of the effluent from the hydrolysis and acid-producing phase meets the water inlet requirements of the high-temperature methane device 2.

[0033] 3. High temperature methane device 2

[0034] The high-temperature methanogen is mainly used, the temperature is 50-55℃, the volume load design is 6-7kgBOD5 / (m3·d), the suitable range of pH is 6.6-7.5, and the stirring intensity in the high-temperature methane device 2 is not more than 0.5m / s. The removal rate of COD in the high-temperature digestion of the high-temperature methane device 2 is about 25%-50% higher than that in the mesophilic methane device 3, but during the high-temperature digestion, the endogenous respiration consumption of the high-temperature methanogen is large, the aging and mortality of bacteria are also high, so the yield of bacteria is reduced, therefore, the sludge concentration and reflux system (i.e. the sludge concentration device 10 and the sludge reflux pump 11) is arranged, the sludge in the sludge-water separation tank is concentrated and then refluxed to the front end of the high-temperature methane device 2, so as to increase the concentration of the digested sludge in the high-temperature methane device 2, and increase the biomass and activity of the anaerobic bacteria.

[0035] 4. Mesophilic methane device 3

[0036] The mesophilic methanogen is mainly used, the temperature is 30-36℃, the volume load design is 2-3kgBOD5 / (m3·d), the suitable range of pH is 6.6-7.5, and the stirring intensity in the high-temperature methane device 2 is not more than 0.5m / s. The mesophilic methane device 3 uses the residual heat to perform mesophilic digestion treatment, further degrades the residual organic matter in the effluent of the high-temperature methane device 2, removes the COD, and reduces the effluent temperature.

[0037] 5. Sludge-water separation device 4

[0038] The digestion mixed liquor is divided into supernatant effluent and sludge sediment, the supernatant effluent enters the subsequent aerobic biological treatment system, and the sludge enters the sludge concentration device for concentration.

[0039] 6. Sludge concentration and reflux system

[0040] The sludge concentration and reflux system is used for refluxing the mixed liquor in the sludge-water separation tank to the high-temperature methane device 2 after concentration, so as to increase the concentration of the digested sludge in the high-temperature methane device 2, and increase the biomass and activity of the anaerobic bacteria. The sludge concentration device 10 can adopt a centrifugal thickener, a neutral belt thickener or a gas floatation thickener.

[0041] 7. Heating system

[0042] The biogas generated by the hydrolysis acid production device 1, the high-temperature methane device 2 and the mesophilic methane device 3 is collected, stored and desulfurized, then the heating system of the heating boiler 8 is used for chemical energy and heat energy conversion, and the heat exchanger 9 is used for heating and warming the desizing wastewater, so that the temperature requirement of the anaerobic digestion is met.

[0043] 8. Other supporting systems and facilities

[0044] The system mainly comprises a sludge and overflow system, a stirring system, a biogas collection and desulfurization system and the like; and the instruments and meters mainly comprise a biogas meter, a thermometer, a pH tester, a liquid level meter and a sludge discharge meter and the like.

[0045] The utility model discloses a hydrolysis acid device, alkalinity detection and adding system, high temperature methane device, medium temperature methane device, sludge and water separation device, sludge concentration and reflux system, heating system and other supporting system and facility are set up, aiming at this kind of difficult biodegradable organic wastewater of synthetic sizing material (PVA) desizing wastewater, change the molecular structure of difficult degradation organic matter or reduce the concentration of pollutant in it, reduce its toxicity, improve the BOD5 / COD value of wastewater, create conditions for the operation stability and high processing efficiency of subsequent biological treatment.

[0046] Although the embodiments of the utility model have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the utility model, and the scope of the utility model is defined by the appended claims and their equivalents.

Claims

1. A high-medium temperature anaerobic digestion-concentration reflux apparatus for desizing wastewater, characterized by: It comprises hydrolytic acid production device, high temperature methane device, medium temperature methane device and sludge water separation device which are arranged in sequence and connected by desizing wastewater pipeline; it also comprises heating boiler, high pressure gas storage tank, air compressor and low pressure gas storage tank which are connected by biogas pipeline; the low pressure gas storage tank is connected with hydrolytic acid production device, high temperature methane device and medium temperature methane device by biogas pipeline; it also comprises sludge concentration device and sludge backflow pump.

2. The high-medium temperature anaerobic digestion-concentration reflux apparatus for desizing wastewater according to claim 1, characterized by: A heat exchanger is arranged between the heating boiler and the hydrolytic acid production device.

3. The high-medium temperature anaerobic digestion-concentration reflux apparatus for desizing wastewater according to claim 1, characterized by: An alkalinity detection and adding system and a heat exchanger are arranged between the hydrolytic acid production device and the high temperature methane device.

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