Application method of disposal system in sewage / food waste collaborative disposal low-carbon plant station

Abstract

The application relates to sewage treatment and solid waste treatment technology, in particular to an application method of a disposal system in a sewage / kitchen garbage collaborative disposal low-carbon plant station, characterized in that the application method comprises the following steps: sewage is treated through a coarse grid, an initial sedimentation tank, a biochemical tank, a secondary sedimentation tank, an efficient sedimentation tank, a filter tank and a disinfection tank in a sewage treatment unit, and the sewage is discharged after the water quality reaches the standard; meanwhile, sludge left after sedimentation in the initial sedimentation tank, the secondary sedimentation tank and the efficient sedimentation tank enters a sludge thickening tank, and the thickened sludge enters a material mixing tank; kitchen garbage is subjected to impurity removal, crushing, pulping, heating and three-phase separation in a kitchen garbage comprehensive treatment room, oil fat is recycled through three-phase separation, the negative influence of the kitchen garbage on an anaerobic generator can be reduced, and coarse oil fat income can be increased.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sewage treatment and solid waste treatment, and more specifically relates to an application method of a disposal system in a sewage / kitchen waste collaborative disposal low-carbon plant station. BACKGROUND

[0002] With the increasingly stringent sewage discharge standards and the proposal of carbon neutralization energy saving and emission reduction requirements, the traditional environmental protection disposal system urgently needs to be improved. According to incomplete statistics, the power consumption per ton of water in China reaches about 0.3 kWh. In order to meet the level A or even more stringent local discharge standards, a large amount of carbon source is added to the sewage treatment system, and the power consumption and external carbon source become the main sources of CO2 emission. In order to reduce carbon, reduce cost, increase efficiency, improve the energy self-sufficiency rate of environmental protection facilities and replace the external carbon source, which has become the main direction of effort.

[0003] In terms of improving the energy self-sufficiency rate of the sewage plant, the domestic mainly adopts sludge anaerobic digestion cogeneration process and photovoltaic method. However, due to the high sand content and low organic matter proportion of sludge in China, there are few successful cases of sludge anaerobic digestion process. And the power generation capacity of photovoltaic is limited by the available area of sewage plant, geographical location of plant site, scale effect and other factors, which can only meet 5%-10% of the power consumption of sewage plant, and the effect is limited.

[0004] In terms of replacing the external carbon source, sludge anaerobic acidification, kitchen waste anaerobic acidification and other methods can be used, but they all have certain defects. For example, the Chinese invention patent application with publication number CN110293114A and publication date October 1, 2019 discloses a kitchen waste and domestic sewage collaborative treatment system and method. The kitchen waste is cut and broken in the fermentation reactor by a reamer, the operation mode is 15 minutes of reamer work and 45 minutes of intermittent, after three cycles, the fermentation liquid is sucked by negative pressure and mixed and added to the anaerobic tank. The disadvantage of this method is that the kitchen waste coarse residue is easy to cause equipment failure, the hydrolysis acidification time is insufficient, the VFA content in the fermentation liquid is low, the value of denitrification utilization of activated sludge is low, and the oil in the kitchen waste is not separated, which not only loses the oil income, but also easily causes suffocation death of the activated sludge in the biochemical system.

[0005] For another example, the Chinese invention patent with announcement number CN215208983U and announcement date December 17, 2021 disposes kitchen waste hydrolysis and low C / N sewage collaboratively. After the kitchen waste is sorted, broken and hydrolyzed in the acidification reaction device, the hydrolysis acidification liquid is treated by the struvite method to remove nitrogen and phosphorus, and then introduced into the biochemical system to supplement the carbon source. The disadvantage of this method is that the hydrolysis acidification device needs to maintain a high temperature of 90-150℃, and a large amount of alkali needs to be added to maintain the pH to 8-9 when the hydrolysis acidification liquid is treated by the struvite method, which greatly increases the cost of kitchen waste hydrolysis acidification and has no engineering economy. SUMMARY

[0006] In view of the problems of low operation efficiency, large power consumption, high cost of additional reagent and the like in traditional kitchen waste treatment and sewage treatment, the application provides a sewage / kitchen waste collaborative disposal low-carbon plant station system, the disposal system saves the use amount of additional carbon source of the sewage plant, improves the energy self-sufficiency rate of the system, reduces the land use of the engineering project and sludge reduction, and improves the comprehensive yield of the sewage treatment.

[0007] To achieve the above object, the application provides the following technical scheme.

[0008] The application method of the disposal system in the sewage / kitchen waste collaborative disposal low-carbon plant station comprises the following steps.

[0009] Step 1: sewage is treated through a coarse grid, an initial sedimentation tank, a biochemical tank, a secondary sedimentation tank, a high-efficiency sedimentation tank, a filter tank and a disinfection tank in the sewage treatment unit, and the water quality meets the discharge standard, while the sludge left after the sedimentation of the initial sedimentation tank, the secondary sedimentation tank and the high-efficiency sedimentation tank enters a sludge thickening tank, and the thickened sludge enters a material mixing tank;

[0010] Step 2: kitchen waste is subjected to impurity removal, crushing, pulping, heating and three-phase separation in a kitchen waste comprehensive treatment room;

[0011] Step 3: the separated oil recovered by heating enters an oil tank;

[0012] Step 4: a part of the three-phase separation liquid separated by heating enters a hydrolysis acidification tank for hydrolysis acidification, and the hydrolysis acidification liquid is added as an additional carbon source to the sewage treatment unit;

[0013] Step 5: another part of the three-phase separation liquid enters the material mixing tank, is mixed with the sludge in the material mixing tank and then enters an anaerobic reactor for anaerobic fermentation to produce anaerobic fermentation liquid and biogas;

[0014] Step 6: the biogas is subjected to desulfurization treatment and then is used for cogeneration to be converted into steam and electric energy.

[0015] The anaerobic fermentation liquid produced in Step 5 is subjected to COD and ammonia nitrogen removal through a flow measurement pretreatment / anaerobic ammonia oxidation integrated reactor and then enters the sewage treatment unit for treatment.

[0016] The heating temperature of the kitchen waste in the kitchen waste comprehensive treatment room is 75-85 DEG C.

[0017] The hydrolysis acidification temperature of a part of the three-phase separation liquid in the hydrolysis acidification tank is 30-40 DEG C, and the hydrolysis acidification time is 1-4 days.

[0018] Another part of the three-phase separation liquid is anaerobically fermented in the anaerobic reactor at a temperature of 30-40 DEG C for 20-30 days.

[0019] In step 5, the supernatant of the hydrolytic acidification liquid flows into the carbon source storage tank of the dosing room, and then a metering pump supplements each carbon source adding point of the biochemical pool through a dosing pipeline.

[0020] Compared with the prior art, the application has the following beneficial effects:

[0021] 1. The application method of the treatment system in the sewage / kitchen garbage collaborative treatment low-carbon plant station, which comprises a sewage treatment unit and a kitchen garbage treatment unit, the sewage treatment unit needs a large amount of additional carbon source for operation, the kitchen garbage treatment unit can provide high-quality carbon source with a high C / N ratio after hydrolytic acidification of the kitchen garbage, thereby effectively improving the influent COD and the denitrification efficiency, and the collaborative plant station construction can save the sewage treatment additional carbon source cost.

[0022] 2. The oil can be recovered through three-phase separation, the negative influence of the kitchen garbage on the biochemical system can be reduced, the crude oil revenue can be increased, the kitchen garbage and the sludge are collaboratively fermented, the material heat of the three-phase separator can be fully utilized, the kitchen garbage content of the sludge can be significantly improved, the C / N can be optimized, and the energy self-sufficiency rate of the whole system can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 FIG. 1 is a structural schematic diagram of a sewage / kitchen garbage collaborative treatment low-carbon plant station system according to the application;

[0024] Figure 2 FIG. 2 is a process flow diagram of the application method of the sewage / kitchen garbage collaborative treatment low-carbon plant station system according to the application.

[0025] In the drawings:

[0026] 100, sewage treatment unit; 101, coarse grid; 102, primary sedimentation tank; 103, biochemical pool; 104, secondary sedimentation tank; 105, high-efficiency sedimentation tank; 106, filter tank; 107, disinfection tank; 110, sludge thickening tank;

[0027] 200, kitchen garbage treatment unit; 201, kitchen garbage comprehensive treatment room; 202, hydrolytic acidification tank; 203, material mixing tank; 204, anaerobic reactor; 205, solid-liquid separator; 206, sludge dewatering device; 207, oil tank; 210, dosing room; 220, side flow pretreatment / anaerobic ammonia oxidation integrated reactor;

[0028] 300, combined heat and power unit; 301, gas bag; 302, biogas purification device; 303, biogas combined heat and power equipment; 304, power distribution room. EMBODIMENT

[0029] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0030] Please refer to Figures 1-2 , the present application provides an embodiment:

[0031] As Figure 1 shown, the application method of the treatment system in the sewage / kitchen waste collaborative treatment low-carbon plant station, the sewage / kitchen waste collaborative treatment low-carbon plant station includes a sewage treatment unit 100, a kitchen waste treatment unit 200 and a cogeneration unit 300, the sewage treatment unit 100 includes a coarse grid 101, an initial sedimentation tank 102, a biochemical tank 103, a secondary sedimentation tank 104, an efficient sedimentation tank 105, a filter tank 106 and a disinfection tank 107 in sequence, pipes are connected between the above structures, and a dosing room 210 is arranged outside the biochemical tank 103 of the sewage treatment unit 100, and the dosing room 210 is connected with the biochemical tank 103 of the sewage treatment unit 100 through a pipe;

[0032] The kitchen waste treatment unit 200 includes a kitchen waste comprehensive treatment room 201, a hydrolysis acidification tank 202, a material mixing tank 203, an anaerobic reactor 204, a solid-liquid separator 205, a sludge dewatering device 206 and a grease tank 207, and a sludge concentration tank 110 is arranged on the pipe connecting the initial sedimentation tank 102, the secondary sedimentation tank 104 and the efficient sedimentation tank 105 of the sewage treatment unit 100 with the material mixing tank 203 of the kitchen waste treatment unit 200.

[0033] After the pipe network sewage is lifted once, it flows into the coarse grid 101, the initial sedimentation tank 102, the biochemical tank 103, the secondary sedimentation tank 104, the efficient sedimentation tank 105, the filter tank 106 and the disinfection tank 107 in sequence under the action of gravity, the sewage treatment is completed, and the water quality meets the discharge standard; at the same time, the residual sludge generated from the initial sedimentation tank 102, the secondary sedimentation tank 104 and the efficient sedimentation tank 105 enters the sludge concentration tank 110 through a pipe, and the concentrated sludge enters the material mixing tank 203.

[0034] The cogeneration unit 300 includes a gas bag 301, a biogas purification device 302, a biogas cogeneration device 303 and a power distribution room 304 in sequence, the anaerobic reactor 204 of the kitchen waste treatment unit 200 is connected with the cogeneration unit 300 through a pipe, and specifically connected with the gas bag 301 of the cogeneration unit 300.

[0035] The integrated food waste treatment room 201 is equipped with a three-phase separator. The integrated food waste treatment room 201 is connected to the hydrolysis acidification tank 202 and the grease tank 207 through pipelines. The hydrolysis acidification tank 202 is connected to the material mixing tank 203 and the anaerobic reactor 204 through pipelines.

[0036] like Figure 2 As shown, in the comprehensive food waste treatment room 201, the food waste passes through the receiving hopper, sorting machine, pulping and screening machine, grit chamber, filter press, three-phase separator heater, slurry mixing tank, three-phase separator and settling tank in sequence to complete the sorting and impurity removal, pulping, grit settling, heating and three-phase separation process. The food waste material is heated to 75℃-85℃, preferably 80℃ in the three-phase separator to extract the oil from the food waste to the oil tank 207. The three-phase separated liquid obtained by the food waste after the three-phase separator is heated to 30℃-40℃ (preferably 35℃) by heat exchange, and a portion of it enters the hydrolysis acidification tank 202 for hydrolysis acidification. The residence time is 1-4 days. The clear liquid on the upper layer of the hydrolysis acidification liquid enters the carbon source storage tank in the dosing room 210, and is then replenished to the carbon source addition points of the biochemical tank 103 by the metering pump through the dosing pipeline.

[0037] Another portion of the three-phase separated liquid is mixed evenly with the concentrated sludge from the wastewater treatment unit in the material mixing tank 203 and then heated to 30℃-40℃ (preferably 35℃) before entering the anaerobic reactor 204 for anaerobic fermentation. The hydraulic retention time of the material in the anaerobic reactor 204 is 20-30 days, producing anaerobic fermentation liquid and biogas. The biogas enters the gas bag 301 from the gas collection pipe at the top of the anaerobic reactor and then enters the biogas purification device 302. After purification and desulfurization, the biogas undergoes cogeneration in the biogas cogeneration equipment 303, converting it into steam and electricity. The generated steam is used to heat the materials in the three-phase separator heater, the material mixing tank 203, and the anaerobic reactor 204. The remaining biogas is converted into electricity and transported to the power distribution room 304 for material processing in other units within the treatment system of this invention.

[0038] To extract oil, kitchen waste is heated to 75°C-85°C in a three-phase separator. Before entering the subsequent anaerobic fermentation stage, the material temperature needs to be reduced to 30°C-40°C, resulting in heat loss. However, after the treatment system of this invention is constructed in conjunction with the sewage treatment unit, the high-temperature material can be directly mixed with sludge to increase the material temperature, which helps to reduce the amount of steam consumed by the material during the anaerobic process.

[0039] In addition, the application also comprises a side flow pretreatment / anaerobic ammonia oxidation integrated reactor 220, one end of the side flow pretreatment / anaerobic ammonia oxidation integrated reactor 220 is connected with the solid-liquid separator 205 of the kitchen waste treatment unit 200 through a pipeline, the other end of the side flow pretreatment / anaerobic ammonia oxidation integrated reactor 220 is connected with the front end of the primary sedimentation tank 102 through a pipeline, the residual material at the bottom of the anaerobic reactor 204 is transported to the solid-liquid separator 205 through a pipeline, the biogas residue after solid-liquid separation is transported to the sludge dewatering device 206 for deep dewatering and then is transported out for disposal, the biogas liquid is pumped into the side flow pretreatment / anaerobic ammonia oxidation integrated reactor 220, after COD and ammonia nitrogen removal, the biogas liquid enters the primary sedimentation tank 102 through a pipeline, and subsequent sewage treatment is carried out.

[0040] The working principle of the application method of the application is that the kitchen waste and the sewage treatment plant are integrated, the kitchen waste is removed of impurities, crushed and pulped in the comprehensive treatment room, and after being heated to high temperature in the three-phase separator, the oil is recovered to the oil tank; part of the three-phase separation liquid is hydrolyzed and acidified, and the hydrolyzed and acidified liquid is added as an external carbon source to the sewage treatment unit, and the other part of the three-phase separation liquid is mixed with the sludge in the sewage treatment unit and then enters the medium-temperature anaerobic reactor to produce biogas; the biogas is desulfurized and then is used for cogeneration, the steam is used for anaerobic digestion and material heating of the three-phase separator, and the remaining biogas is used for power generation to supplement the system power consumption. In addition, the anaerobic fermentation liquid first enters the side flow pretreatment / anaerobic ammonia oxidation integrated reactor, removes most of the COD and ammonia nitrogen, and then flows into the sewage treatment unit for treatment. Embodiment

[0041] This embodiment is the application method of a 50000 m 3 / d sewage and 100 t / d kitchen waste in a low-carbon plant, and the specific steps are as follows:

[0042] The sewage station removes the sand with a particle size of less than 75 microns by 95% through a high-efficiency vortex sand removal device, and the inorganic sand gravel inflow into the biochemical pool is reduced by 0.56-1.12 tons per day, which can effectively improve the VSS / TSS of sludge from the traditional 40-50% to 45-55%. During the sewage treatment process, primary sludge and residual sludge flow into the sludge thickening tank, and the thickened sludge is about 400 t / d (4DS%), the total amount of absolute dry matter (DS) is about 16 t / d, the VSS / TSS is about 0.55, and the C / N is about 5.

[0043] 100 t / d (20 DS%) kitchen waste is pretreated to remove 5.5 DSt / d impurities, and 2.7 DSt / d oil can be recovered in the three-phase separator. 26.6 t / d three-phase separation mixed liquid (11.94 DS%) is left in the hydrolysis acidification tank for 2 days, and then 26.6 t / d hydrolysis acidification liquid (COD = 50-100 thousand mg / L) is pumped into the sewage biochemical tank, which can increase COD by about 40 mg / L and increase TN removal of the biochemical system by 5-8 mg / L, effectively ensuring that the sewage meets the first level A discharge standard.

[0044] 70 t / d (11.94 DS%, t = 80°C) three-phase separation mixed liquid and 3.4 t / d (25 DS%) kitchen three-phase separation solid residue flow into the homogenizing tank, the total amount of dry matter (DS) is about 9.25 t / d, VSS / TSS is about 0.9, and C / N is about 25. Mixed with the residual sludge of the sewage treatment system, the three-phase separation mixed liquid at 80°C can provide about 4.84 t / d of equivalent heat of heating steam, saving about 1000 yuan of steam cost per day.

[0045] After the sludge and kitchen waste mixed liquid are mixed in the homogenizing tank, the material flow is 550 t / d (5.0 DS%), VSS / TSS is about 0.66, and C / N is about 7.39. The mixed liquid enters the anaerobic fermentation tank and stays for about 30 days, producing about 8400 m 3 / d of biogas per day, of which about 30% is used for material heating. The net annual biogas production is about 6000 m 3 / d, and the net annual power generation is about 3.945 million kWh / year.

[0046] Anaerobic fermentation can digest about 50% of VSS, and sludge reduction is about 30%. After sludge dewatering, 74.4 t / d of sludge with a moisture content of 75% is formed and transported for treatment, and about 550 m 3 / d of anaerobic digestion liquid is returned to the main stream of the sewage treatment system after being treated by the side stream biochemical pretreatment / anaerobic ammonia oxidation unit.

[0047] Compared with the sewage plant station and the kitchen waste treatment plant station independently constructed, the sewage / kitchen waste collaborative treatment low-carbon plant station has the following benefits: 33.36 million kWh of electricity is saved per year, the net power generation capacity is increased by 36.79 million kWh, the self-sufficiency rate of the power generation capacity of the anaerobic digestion to the system power consumption is increased from 36.3% to 41.4%, 25% of the NaAc external carbon source is reduced by 4,380 tons per year, 7,785.5 tons of sludge (80% moisture content) is reduced per year, the fermentation liquid treatment cost is reduced by 0.8415 million per year, in addition, 0.365 million of steam expenses is saved per year, and the direct benefits are increased by 7.9626 million per year. In addition, the cumulative carbon emission reduction amount of the carbon source, sludge reduction and green electricity can reach 9,373.2 tons per year. Compared with the independent station construction, the collaborative low-carbon station construction needs to increase the investment by about 15.2589 million, the payback period is about 2 years, the engineering land can be reduced by 10-15%, about 20 mu. In addition, compared with the single anaerobic fermentation of kitchen waste, the sludge / kitchen waste coupled fermentation can reach about 60% of the total dry matter, and the stable sludge can effectively make up for the insufficient incoming materials of the current single kitchen project, and improve the overall benefit rate.

[0048] The embodiment shows that when the technical solution of the application is adopted, the effluent quality can fully meet the first-level A and above discharge standard, the kitchen waste hydrolysis acidification liquid can save the use amount of the external carbon source of the sewage plant, the collaborative fermentation of the sludge and the kitchen waste can effectively make up for the insufficient production capacity of the single kitchen project, increase the anaerobic fermentation gas production, promote the sludge reduction and carbon emission reduction, and effectively increase the economic and social benefits of the project.

Claims

1. A method for applying a treatment system in a low-carbon plant for the co-treatment of sewage / kitchen waste, characterized in that: This application method includes the following steps: Step 1: Wastewater is treated through the coarse screen, primary sedimentation tank, biological treatment tank, secondary sedimentation tank, high-efficiency sedimentation tank, filter tank and disinfection tank in the wastewater treatment unit. The water quality meets the standards and is discharged. At the same time, the sludge left after sedimentation in the primary sedimentation tank, secondary sedimentation tank and high-efficiency sedimentation tank enters the sludge thickening tank. The thickened sludge enters the material mixing tank. Step 2: Food waste undergoes impurity removal, crushing, pulping, heating, and three-phase separation in the integrated food waste treatment room; Step 3: The separated grease is heated and recycled into the grease tank; Step 4: A portion of the three-phase separated liquid is heated and then fed into a hydrolysis acidification tank for hydrolysis acidification. The hydrolyzed acidified liquid is then added to the wastewater treatment unit as an external carbon source. Step 5: Another portion of the three-phase separated liquid enters the material mixing tank, mixes with the sludge inside, and then enters the anaerobic reactor for anaerobic fermentation to produce anaerobic fermentation liquid and biogas. Step 6: After desulfurization treatment, biogas is used for combined heat and power generation to convert it into steam and electricity; The anaerobic fermentation broth generated in step 5 is treated by removing COD and ammonia nitrogen in a flow pretreatment / anaerobic ammonia oxidation integrated reactor before entering the wastewater treatment unit for further treatment. In step 5, the supernatant of the hydrolyzed acidified liquid flows into the carbon source storage tank in the dosing room, and then is replenished to each carbon source dosing point in the biochemical tank by a metering pump through the dosing pipeline.

2. The application method of the treatment system according to claim 1 in a low-carbon plant for co-processing sewage / kitchen waste, characterized in that: The food waste is heated to a temperature of 75-85℃ in the integrated food waste treatment room.

3. The application method of the treatment system according to claim 1 in a low-carbon plant for co-processing sewage / kitchen waste, characterized in that: A portion of the three-phase separated liquid undergoes hydrolysis and acidification in a hydrolysis and acidification tank at a temperature of 30-40℃ for 1-4 days.

4. The application method of the treatment system according to claim 1 in a low-carbon plant for co-processing sewage / kitchen waste, characterized in that: The other part of the three-phase separated liquid undergoes anaerobic fermentation in an anaerobic reactor at a temperature of 30-40℃ for 20-30 days.

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