Energy-saving, consumption-reducing and low-carbon sewage biochemical treatment process

Abstract

The application relates to the field of sewage treatment, and particularly discloses an energy-saving, consumption-reducing and low-carbon sewage biochemical treatment process. The energy-saving, consumption-reducing and low-carbon sewage biochemical treatment process comprises the following specific steps: sequentially performing anaerobic treatment, main aerobic treatment, oxygen-eliminating treatment, main anoxic treatment, post-aerobic treatment and secondary sedimentation tank treatment on sewage to form effluent and sludge; 20-30% of the sewage is subjected to pre-anoxic treatment before the anaerobic treatment to form pre-anoxic effluent, the pre-anoxic effluent is transported to the anaerobic treatment zone for treatment to form anaerobic effluent, 10-20% of the anaerobic effluent is transported to the oxygen-eliminating treatment zone for treatment, and 80-90% of the anaerobic effluent is transported to the main aerobic treatment zone for treatment. The sewage biochemical treatment process has good biochemical treatment efficiency, replaces the traditional internal reflux process, reduces the energy consumption caused by the internal reflux, and reduces the supply of external carbon sources.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sewage treatment, more particularly, it relates to an energy-saving, consumption-reducing and low-carbon sewage biochemical treatment process. BACKGROUND

[0002] Currently, the biochemical treatment technologies applied in sewage treatment plants mainly include activated sludge method and biofilm method. The biofilm method has less application scope and weak biochemical treatment capacity, and thus is less applied. The activated sludge method has become the mainstream technology for sewage biochemical treatment. With the gradual improvement of the effluent standard of sewage treatment in China, the biochemical treatment process using the activated sludge method is also gradually developed.

[0003] At present, the multi-point water-in multi-stage AO process can better realize the removal of organic pollutants and simultaneous nitrogen and phosphorus removal, and meet the high effluent standard and high-quality development requirements of sewage treatment plants. The process has a high treatment efficiency through the pre-anoxic-anaerobic-primary anoxic-primary aerobic-secondary anoxic-secondary aerobic process. However, the denitrification process is not smooth, the internal reflux ratio and internal reflux flow are large, the internal reflux flow energy consumption is high, and an external carbon source needs to be additionally added. The overall process has high energy and material consumption. SUMMARY

[0004] In order to improve the deficiencies of the existing sewage treatment process and meet the high effluent standard requirements of sewage treatment plants, the present application provides an energy-saving, consumption-reducing and low-carbon sewage biochemical treatment process.

[0005] The present application provides an energy-saving, consumption-reducing and low-carbon sewage biochemical treatment process, which adopts the following technical solution:

[0006] An energy-saving, consumption-reducing and low-carbon sewage biochemical treatment process comprises the following specific steps:

[0007] The sewage is sequentially treated in an anaerobic zone, a main aerobic zone, an oxygen-consuming zone, a main anoxic zone, a post-aerobic zone and a secondary sedimentation tank to form effluent and sludge.

[0008] Before anaerobic treatment, 20-30% of the sewage is subjected to pre-anoxic treatment to form pre-anoxic effluent, the pre-anoxic effluent is delivered to the anaerobic zone for treatment to form anaerobic zone effluent, 10-20% of the anaerobic zone effluent is delivered to the oxygen-consuming zone for treatment, and 80-90% of the anaerobic zone effluent is delivered to the main aerobic zone for treatment.

[0009] By adopting the technical scheme, the main function of the main aerobic zone is biosynthesis, organic matter removal, nitrification reaction and aerobic phosphorus uptake, and the main function of the main anoxic zone is denitrification. The biochemical treatment of the wastewater in the application adopts an oxygen-free aerobic-oxygen-consuming-anoxic process instead of a traditional internal reflux anoxic-aerobic process. The ammoniaization of organic nitrogen and the nitrification biochemical reaction process of ammonia nitrogen are completed in the main aerobic zone. The dissolved oxygen content in the wastewater is reduced in the oxygen-consuming zone to eliminate the adverse effect of the dissolved oxygen content on the denitrification effect of the subsequent main anoxic zone. Then, the wastewater is introduced into the main anoxic zone for denitrification. The application uses a sequential and smooth denitrification process instead of an internal reflux process, reduces the energy consumption of the traditional internal reflux process, and reduces the internal reflux occupation of the biochemical treatment space, thereby improving the wastewater biochemical treatment efficiency and saving energy.

[0010] In addition, the application supplements part of the effluent from the preceding anaerobic zone to the oxygen-consuming zone, and transports the residual organic matter in the wastewater treated in the anaerobic zone to the oxygen-consuming zone to provide internal carbon sources for the oxygen-consuming zone and the main anoxic zone, reduce the supply of external carbon sources, and improve the utilization rate of internal carbon sources.

[0011] At the same time, part of the wastewater is first transported to the pre-anoxic zone, which can remove a small amount of dissolved oxygen content and nitrate nitrogen in the wastewater in advance, provide a good pH condition and anoxic environment for subsequent anaerobic treatment, promote the decomposition and dissolution of organic matter, improve the treatment efficiency of the anaerobic zone, and ensure the biological phosphorus release environment of the anaerobic zone.

[0012] Preferably, the sludge is divided into reflux sludge and waste sludge, 20-30% of the reflux sludge is transported to the oxygen-consuming zone for treatment, and 70-80% of the reflux sludge is transported to the pre-anoxic zone for treatment.

[0013] By adopting the technical scheme, the activated sludge generated in the secondary sedimentation tank can be used as reflux sludge, and then the reflux sludge is transported to the oxygen-consuming zone and the pre-anoxic zone, respectively, to fully exploit and utilize the external carbon source in the reflux sludge, reduce the dependence on external carbon sources, and reduce the consumption of external carbon sources. The insoluble substances and heavy metals generated in the secondary sedimentation tank are used as waste sludge and introduced into the subsequent sludge treatment process.

[0014] Preferably, the hydraulic retention time of the pre-anoxic zone is 0.5-1.5h, the hydraulic retention time of the anaerobic zone is 1-1.5h, the hydraulic retention time of the oxygen-consuming zone is 0.5-1h, and the hydraulic retention time of the post-aerobic zone is 0.5-1h.

[0015] By adopting the technical scheme, the water retention time of each process is controlled to be different, which can promote specific microbial reactions of the sewage in each stage, and efficiently remove the organic matter, nitrogen and phosphorus in the sewage, and improve the sewage biochemical treatment efficiency. The long water retention time in the anaerobic zone is mainly to sufficiently remove the organic matter and organic nitrogen in the sewage, release phosphorus in the anaerobic zone, and ensure the biological phosphorus removal effect.

[0016] Preferably, the water flow state of the pre-anoxic zone and the oxygen-free zone is complete mixing type, the water flow state of the anaerobic zone is reciprocating type, and the water flow state of the main aerobic zone, the main anoxic zone and the post-aerobic zone is plug flow type.

[0017] By adopting the technical scheme, different water flow states are provided in different stages of the sewage biochemical treatment, which can optimize the contact and mass transfer effect of the sewage, microorganisms, oxygen and suspended organic matter, and further improve the sewage biochemical treatment efficiency. The plug flow type water flow state is beneficial to increasing the mass transfer efficiency of oxygen and improving the oxidation effect of the aerobic zone. The reciprocating type water flow state is beneficial to forming small bubbles in the anaerobic zone, and can increase the contact area of microorganisms and organic matter, promote the anaerobic microbial degradation of organic matter, and improve the degradation efficiency of anaerobic microorganisms. The complete mixing type water flow state can promote the uniform mixing of wastewater and microorganisms, and improve the dissolved oxygen elimination effect of the pre-anoxic zone and the oxygen-free zone.

[0018] Preferably, the biological adsorption material is added in the main aerobic zone and the anaerobic zone, and the biological adsorption material comprises the following raw materials in parts by weight: polyurethane foam 20-40 parts, zeolite 5-8 parts, mesoporous silica 3-5 parts, and silica gel binder 8-12 parts.

[0019] By adopting the technical scheme, the polyurethane foam has a large number of pore structures and a high specific surface area, which can provide more oxygen transfer channels, increase the oxygen supply in the aerobic zone, promote the aerobic degradation activity of microorganisms, and improve the organic matter removal efficiency of wastewater in the aerobic zone. At the same time, the polyurethane foam can provide an attachment surface for microorganisms, which is beneficial to the growth and degradation of anaerobic microorganisms, and improves the degradation efficiency of the anaerobic zone. The zeolite and mesoporous silica both have porous structures, which are beneficial to the transfer of oxygen, promote better organic matter removal, nitrification reaction and aerobic phosphorus absorption reaction in the main aerobic zone, and improve the efficiency of organic matter removal in wastewater. At the same time, the pore channels and high specific surface area of the mesoporous silica are beneficial to the fixation of microorganisms, which can adsorb and aggregate more microbial communities, guarantee the biological phosphorus release environment in the anaerobic zone, maintain the activity and stability of microorganisms, promote the degradation of organic matter, and improve the wastewater treatment efficiency.

[0020] The silica gel binder has high high-temperature resistance, impact resistance and weather resistance, which can load the zeolite and mesoporous silica in the polyurethane foam, increase the roughness and strength of the polyurethane foam, and further improve the adsorption performance and stability of the polyurethane foam.

[0021] Preferably, the zeolite is modified by rare earth in advance, and the modification method comprises the following specific steps: adjusting a rare earth solution to be alkaline, then adding the zeolite for impregnation, washing, drying, and calcining at 450-500℃ to obtain the rare earth modified zeolite.

[0022] By using the above technical scheme, the zeolite is modified by rare earth elements, ion exchange is carried out with the zeolite, and after drying and calcining, the rare earth ions can enter the interior of the zeolite crystal, interact with the zeolite, form a complex, enhance the stability of the zeolite framework structure, and improve the adsorption performance of the zeolite.

[0023] Preferably, the polyurethane foam is compounded with lignin.

[0024] By using the above technical scheme, the addition of lignin in the polyurethane foam can enhance the reticular effect of the polyurethane foam, expand the pore size and opening rate of the polyurethane foam. Meanwhile, the active groups such as phenolic and alcoholic hydroxyl groups on the lignin molecules can crosslink with the polyurethane molecules, thereby improving the tensile strength and elongation at break of the polyurethane foam, and prolonging the service life of the bio-adsorption material.

[0025] Preferably, the method for compounding lignin with polyurethane foam comprises the following specific steps: mixing a catalyst, a stabilizer, a foaming agent, and a polyol in advance to form a polyol mixed solution, dissolving the lignin in the polyol mixed solution, then mixing the polyol mixed solution with the lignin, and then adding isocyanate and uniformly mixing to form the polyurethane foam after foaming and demolding.

[0026] In summary, the present application has the following beneficial effects:

[0027] 1. Since the present application uses the oxygenation-anaerobic-oxygenation process without internal reflux instead of the traditional internal reflux anoxic-aerobic process, the consumption of internal reflux can be reduced, and the biochemical treatment efficiency of wastewater is improved. At the same time, the effluent from the anaerobic zone is supplemented to the anaerobic zone to provide internal carbon sources for the anaerobic zone and the main anoxic zone, thereby reducing the supply of external carbon sources and improving the recycling efficiency of internal carbon sources.

[0028] 2. In the present application, the bio-adsorption material is added in the main aerobic zone and the anaerobic zone, and the large number of pore structures of the polyurethane foam, the zeolite, and the mesoporous silica can provide more oxygen transfer channels, improve the aerobic degradation activity of microorganisms in the aerobic zone, and improve the organic matter removal efficiency of the aerobic zone. At the same time, the high specific surface area of the polyurethane foam and the mesoporous silica provides an attachment surface for microorganisms, which is conducive to the growth and degradation of anaerobic microorganisms and improves the degradation efficiency of the anaerobic zone. DETAILED DESCRIPTION

[0029] The present application will be further described in detail below in combination with examples.

[0030] Silica gel adhesive was purchased from Ningbo Haishu Ruiguang Adhesive Co., Ltd.

[0031] The polyether polyol was selected as polyether polyol TMN3050.

[0032] Preparation example of biosorption material

[0033] Preparation example 1

[0034] The biosorption material comprises the following raw materials by weight: polyurethane foam 30 kg, zeolite 7 kg, mesoporous silica 4 kg, and silica gel adhesive 10 kg. The average pore size of the mesoporous silica is 10-20 nm.

[0035] The preparation method of the biosorption material comprises the following specific steps:

[0036] The polyurethane foam, zeolite, mesoporous silica, and silica gel adhesive are mixed in advance to form a biosorption mixture, water is then added to the biosorption mixture at a mass ratio of 1:1, and the mixture is stirred and granulated uniformly, and then calcined at 400°C for 1h to form the biosorption material.

[0037] Preparation example 2

[0038] The difference between preparation example 2 and preparation example 1 is that the use amount of polyurethane foam in the raw materials of the biosorption material is 20 kg, the use amount of zeolite is 5 kg, the use amount of mesoporous silica is 5 kg, and the use amount of silica gel adhesive is 8 kg.

[0039] Preparation example 3

[0040] The difference between preparation example 3 and preparation example 1 is that the use amount of polyurethane foam in the raw materials of the biosorption material is 40 kg, the use amount of zeolite is 8 kg, the use amount of mesoporous silica is 3 kg, and the use amount of silica gel adhesive is 12 kg.

[0041] Preparation example 4

[0042] The difference between preparation example 4 and preparation example 1 is that the zeolite in the raw materials of the biosorption material is modified by rare earth. The rare earth is lanthanum chloride.

[0043] The preparation method of the biosorption material comprises the following specific steps:

[0044] S1: Mix ammonia water with rare earth to form a rare earth mixed solution, adjust the pH value of the rare earth mixed solution to 10, then add zeolite at a solid-liquid ratio of 1:50 and soak for 24h, wash with distilled water until neutral, dry, then calcine at 500°C for 1h, cool, and pass through a 100 mesh sieve to obtain the rare earth modified zeolite.

[0045] S2: mixing polyurethane foam, rare earth modified zeolite, mesoporous silica and silica gel binder in advance to form a biosorption mixture, adding water to the biosorption mixture, the mass ratio of water to the biosorption mixture being 1:1, stirring uniformly to granulate, then calcining at 400℃ for 1h to form the biosorption material.

[0046] Preparation Example 5

[0047] Preparation Example 5 is different from Preparation Example 4 in that the polyurethane foam is compounded with lignin in the raw materials of the biosorption material. The use amount of the catalyst, stabilizer, foaming agent, polyol and isocyanate in the polyurethane raw materials is the use amount of each component of the conventional polyurethane foam. In this preparation example, the polyurethane foam includes the following raw materials by weight: polyol 50kg, isocyanate 80kg, catalyst 1.5kg, foaming agent 8kg, stabilizer 1.5kg, the mass ratio of lignin to polyol being 1:5; wherein the catalyst is dibutyltin dilaurate, the stabilizer is dimethyl silicone oil, the foaming agent is water, the isocyanate is toluene diisocyanate, and the polyol is polyether polyol.

[0048] The preparation method of the biosorption material includes the following specific steps:

[0049] S1: mixing the catalyst, foaming agent, stabilizer and polyol in advance to form a polyol mixed solution, then mixing lignin with 1,4-dioxane, the mass ratio of 1,4-dioxane to lignin being 2:1, stirring uniformly to form a lignin solution, then mixing the lignin solution with the polyol solution, stirring uniformly, then adding isocyanate and stirring for 10s to start foaming, demolding after room temperature curing for 24h to obtain lignin composite polyurethane foam.

[0050] S2: mixing ammonia water with rare earth to form a rare earth mixed solution, adjusting the pH value of the rare earth mixed solution to 10, then adding zeolite according to a solid-liquid ratio of 1:50, soaking for 24h, washing with distilled water until neutral, drying, then calcining at 500℃ for 1h, cooling, and passing through a 100 mesh sieve to obtain rare earth modified zeolite.

[0051] S3: mixing lignin composite polyurethane foam, rare earth modified zeolite, mesoporous silica and silica gel binder in advance to form a biosorption mixture, adding water to the biosorption mixture, the mass ratio of water to the biosorption mixture being 1:1, stirring uniformly to granulate, then calcining at 400℃ for 1h to form the biosorption material.

[0052] Embodiment

[0053] Embodiment 1

[0054] The embodiment provides an energy-saving, consumption-reducing and low-carbon sewage biochemical treatment process, which includes the following specific steps:

[0055] S1 pre-anoxic and anaerobic treatment: 25% of the wastewater by mass is transported to the pre-anoxic zone for treatment, the hydraulic retention time in the pre-anoxic zone is 0.5-1.5h, until the dissolved oxygen DO content in the anaerobic zone is less than 0.2mg / L, the nitrate nitrogen content is less than 1.5mg / L, and the hydraulic flow pattern is completely mixed, the pre-anoxic effluent is transported to the anaerobic zone to obtain the anaerobic zone effluent; 75% of the wastewater by mass is transported to the anaerobic zone for anaerobic treatment, the hydraulic retention time in the anaerobic zone is 1-1.5h, until the dissolved oxygen DO content in the anaerobic zone is less than 0.2mg / L, the nitrate nitrogen content is less than 1.5mg / L, and the hydraulic flow pattern is reciprocating.

[0056] S2 main aerobic and oxygen-consuming treatment: 15% of the anaerobic zone effluent by mass is transported to the oxygen-consuming zone for treatment; 85% of the anaerobic zone effluent by mass is transported to the main aerobic zone for treatment, the main aerobic zone uses a blower for aeration to form a main aerobic effluent with a dissolved oxygen DO content greater than 2mg / L, the main aerobic zone effluent is transported to the oxygen-consuming zone for treatment to form an oxygen-consuming zone effluent, the hydraulic retention time in the oxygen-consuming zone is 0.5-1h, until the dissolved oxygen content in the oxygen-consuming zone effluent is less than 1mg / L, and the hydraulic flow pattern is completely mixed.

[0057] S3 main anoxic and post-aerobic treatment: the oxygen-consuming zone effluent is sequentially transported to the main anoxic zone for treatment, the post-aerobic zone for treatment, and the secondary sedimentation tank for treatment, the dissolved oxygen content of the main anoxic zone effluent is controlled to be less than 1mg / L, the hydraulic retention time in the post-aerobic zone is 0.5-1h, until the dissolved oxygen DO content in the post-aerobic zone effluent is on average 2mg / L, the hydraulic flow pattern is plug flow, the post-aerobic zone uses a blower for aeration, and the retention time in the secondary sedimentation tank is 3-4h; after the secondary sedimentation tank treatment, the final effluent, the return sludge, and the waste sludge are formed.

[0058] S4 return sludge distribution: 25% of the return sludge by mass is transported to the oxygen-consuming zone for treatment, and 75% of the return sludge by mass is transported to the pre-anoxic zone for treatment, which completes the energy-saving, consumption-reducing, and low-carbon wastewater biochemical treatment process.

[0059] Example 2

[0060] The difference between Example 2 and Example 1 is that in the energy-saving, consumption-reducing, and low-carbon wastewater biochemical treatment process, in step S1, 20% of the wastewater by mass is transported to the pre-anoxic zone for treatment, and 80% of the wastewater by mass is transported to the anaerobic zone for anaerobic treatment.

[0061] Example 3

[0062] The difference between Example 3 and Example 1 is that in the energy-saving, consumption-reducing, and low-carbon wastewater biochemical treatment process, in step S1, 30% of the wastewater by mass is transported to the pre-anoxic zone for treatment, and 70% of the wastewater by mass is transported to the anaerobic zone for anaerobic treatment.

[0063] Example 4

[0064] Example 4 differs from Example 1 in that in the energy-saving, consumption-reducing, and low-carbon biochemical treatment process for wastewater, in step S2, 10% by mass of the effluent from the anaerobic zone is transported to the oxygen-consuming zone for treatment, and 90% by mass of the effluent from the anaerobic zone is transported to the main aerobic zone for treatment.

[0065] Example 5

[0066] Example 5 differs from Example 1 in that in the energy-saving, consumption-reducing, and low-carbon biochemical treatment process for wastewater, in step S2, 20% by mass of the effluent from the anaerobic zone is transported to the oxygen-consuming zone for treatment, and 80% by mass of the effluent from the anaerobic zone is transported to the main aerobic zone for treatment.

[0067] Example 6

[0068] Example 6 differs from Example 1 in that in the energy-saving, consumption-reducing, and low-carbon biochemical treatment process for wastewater, in step S4, 20% by mass of the return sludge is transported to the oxygen-consuming zone for treatment, and 80% by mass of the return sludge is transported to the pre-anoxic zone for treatment.

[0069] Example 7

[0070] Example 7 differs from Example 1 in that in the energy-saving, consumption-reducing, and low-carbon biochemical treatment process for wastewater, in step S4, 30% by mass of the return sludge is transported to the oxygen-consuming zone for treatment, and 70% by mass of the return sludge is transported to the pre-anoxic zone for treatment.

[0071] Example 8

[0072] Example 8 differs from Example 1 in that in the energy-saving, consumption-reducing, and low-carbon biochemical treatment process for wastewater, a biological adsorption material is added to the main aerobic zone and the anaerobic zone, and the addition amount of the biological adsorption material is 5% of the wastewater flow, wherein the biological adsorption material is derived from Preparation Example 1.

[0073] Example 9

[0074] Example 9 differs from Example 8 in that in the energy-saving, consumption-reducing, and low-carbon biochemical treatment process for wastewater, a biological adsorption material is added to the main aerobic zone and the anaerobic zone, and the addition amount of the biological adsorption material is 5% of the wastewater flow, wherein the biological adsorption material is derived from Preparation Example 2.

[0075] Example 10

[0076] Example 10 differs from Example 8 in that in the energy-saving, consumption-reducing, and low-carbon biochemical treatment process for wastewater, a biological adsorption material is added to the main aerobic zone and the anaerobic zone, and the addition amount of the biological adsorption material is 5% of the wastewater flow, wherein the biological adsorption material is derived from Preparation Example 3.

[0077] Example 11

[0078] Example 11 differs from Example 8 in that the energy-saving, consumption-reducing, and low-carbon biochemical treatment process for wastewater includes adding a biological adsorption material to the main aerobic zone and the anaerobic zone, the amount of the biological adsorption material added is 5% of the wastewater flow, and the biological adsorption material is derived from Preparation Example 4.

[0079] Example 12

[0080] Example 12 differs from Example 8 in that the energy-saving, consumption-reducing, and low-carbon biochemical treatment process for wastewater includes adding a biological adsorption material to the main aerobic zone and the anaerobic zone, the amount of the biological adsorption material added is 5% of the wastewater flow, and the biological adsorption material is derived from Preparation Example 5.

[0081] Example 13

[0082] Example 13 differs from Example 1 in that the energy-saving, consumption-reducing, and low-carbon biochemical treatment process for wastewater directly discharges sludge generated by the secondary sedimentation tank without backflow.

[0083] The energy-saving, consumption-reducing, and low-carbon biochemical treatment process for wastewater includes the following specific steps:

[0084] S1 Pre-anoxic and anaerobic treatment: 25% of the wastewater by mass is transported to the pre-anoxic zone for treatment, the hydraulic retention time in the pre-anoxic zone is 0.5-1.5 h, until the dissolved oxygen DO content in the anaerobic zone is less than 0.2 mg / L, the nitrate nitrogen content is less than 1.5 mg / L, and the hydraulic flow pattern is completely mixed, the pre-anoxic effluent is transported to the anaerobic zone to obtain the anaerobic zone effluent; 75% of the wastewater by mass is transported to the anaerobic zone for anaerobic treatment, the hydraulic retention time in the anaerobic zone is 1-1.5 h, until the dissolved oxygen DO content in the anaerobic zone effluent is less than 0.2 mg / L, the nitrate nitrogen content is less than 1.5 mg / L, and the hydraulic flow pattern is cyclic.

[0085] S2 Main aerobic and deoxygenation treatment: 15% of the anaerobic zone effluent by mass is transported to the deoxygenation zone for treatment; 85% of the anaerobic zone effluent by mass is transported to the main aerobic zone for treatment, the main aerobic zone uses a blower for aeration to form main aerobic effluent with a dissolved oxygen DO content greater than 2 mg / L, the main aerobic zone effluent is transported to the deoxygenation zone for treatment to form deoxygenation zone effluent, the hydraulic retention time in the deoxygenation zone is 0.5-1 h, until the dissolved oxygen content in the deoxygenation zone effluent is less than 1 mg / L, and the hydraulic flow pattern is completely mixed.

[0086] S3 main anoxic and post- aerobic treatment: the effluent from the oxygen depletion zone is sequentially delivered to the main anoxic zone, the post- aerobic zone, and the secondary sedimentation tank for treatment, the dissolved oxygen content of the effluent from the main anoxic zone is controlled to be less than 1 mg / L, the hydraulic retention time in the post- aerobic zone is 0.5-1 h, until the average dissolved oxygen content of the effluent from the post- aerobic zone is 2 mg / L, the hydraulic flow state is plug flow, the post- aerobic zone uses a blower for aeration, the retention time in the secondary sedimentation tank is 3-4 h; after the treatment in the secondary sedimentation tank, the final effluent, the return sludge, and the waste sludge are formed, that is, the energy-saving, consumption-reducing, and low-carbon biochemical treatment process for wastewater is completed.

[0087] Comparative example

[0088] Comparative example 1

[0089] The difference between comparative example 1 and example 1 is that in the energy-saving, consumption-reducing, and low-carbon biochemical treatment process for wastewater, all the wastewater is directly subjected to pre- anoxic treatment first.

[0090] An energy-saving, consumption-reducing, and low-carbon biochemical treatment process for wastewater, comprising the following specific steps:

[0091] S1 pre- anoxic and anaerobic treatment: the wastewater is delivered to the pre- anoxic zone for treatment, the hydraulic retention time in the pre- anoxic zone is 0.5-1.5 h, until the dissolved oxygen content in the anaerobic zone is less than 0.2 mg / L, the nitrate content is less than 1.5 mg / L, and the hydraulic flow state is complete mixing; the pre- anoxic effluent is delivered to the anaerobic zone, to obtain the anaerobic zone effluent, the hydraulic retention time in the anaerobic zone is 1-1.5 h, until the dissolved oxygen content in the anaerobic zone is less than 0.2 mg / L, the nitrate content is less than 1.5 mg / L, and the hydraulic flow state is cyclic.

[0092] S2 main aerobic and oxygen depletion treatment: 15% by mass of the anaerobic zone effluent is delivered to the oxygen depletion zone for treatment; 85% by mass of the anaerobic zone effluent is delivered to the main aerobic zone for treatment, the main aerobic zone uses a blower for aeration, to form the main aerobic effluent with a dissolved oxygen content greater than 2 mg / L, the main aerobic zone effluent is delivered to the oxygen depletion zone for treatment, to form the oxygen depletion zone effluent, the hydraulic retention time in the oxygen depletion zone is 0.5-1 h, until the dissolved oxygen content of the oxygen depletion zone effluent is less than 1 mg / L, and the hydraulic flow state is complete mixing.

[0093] S3 main anoxic and post- aerobic treatment: the effluent from the oxygen depletion zone is sequentially delivered to the main anoxic zone, the post- aerobic zone, and the secondary sedimentation tank for treatment, the dissolved oxygen content of the effluent from the main anoxic zone is controlled to be less than 1 mg / L, the hydraulic retention time in the post- aerobic zone is 0.5-1 h, until the average dissolved oxygen content of the effluent from the post- aerobic zone is 2 mg / L, the hydraulic flow state is plug flow, the post- aerobic zone uses a blower for aeration, the retention time in the secondary sedimentation tank is 3-4 h; after the treatment in the secondary sedimentation tank, the final effluent, the return sludge, and the waste sludge are formed.

[0094] S4 reflux sludge distribution: 25% of the reflux sludge is transported to the oxygen depletion zone for treatment, and 75% of the reflux sludge is transported to the pre-anoxic zone for treatment, that is, the energy-saving, consumption-reducing and low-carbon biochemical treatment process of wastewater is completed.

[0095] Comparative Example 2

[0096] Comparative Example 2 and Example 1 differ in that in the energy-saving, consumption-reducing and low-carbon biochemical treatment process of wastewater, all wastewater is directly subjected to pre-anoxic treatment, and the effluent from the anaerobic zone is all transported to the main aerobic zone for treatment.

[0097] The energy-saving, consumption-reducing and low-carbon biochemical treatment process of wastewater comprises the following specific steps:

[0098] S1 pre-anoxic and anaerobic treatment: the wastewater is transported to the pre-anoxic zone for treatment, the hydraulic retention time in the pre-anoxic zone is 0.5-1.5 h, until the dissolved oxygen DO content in the effluent from the anaerobic zone is less than 0.2 mg / L, the nitrate nitrogen content is less than 1.5 mg / L, and the hydraulic flow pattern is completely mixed, the effluent from the pre-anoxic zone is transported to the anaerobic zone, and the anaerobic zone is obtained, the hydraulic retention time in the anaerobic zone is 1-1.5 h, until the dissolved oxygen DO content in the effluent from the anaerobic zone is less than 0.2 mg / L, the nitrate nitrogen content is less than 1.5 mg / L, and the hydraulic flow pattern is cyclic.

[0099] S2 main aerobic and oxygen depletion treatment: the effluent from the anaerobic zone is transported to the main aerobic zone for treatment, the main aerobic zone uses a blower for aeration to form main aerobic effluent with a dissolved oxygen DO content greater than 2 mg / L, and the main aerobic zone effluent is transported to the oxygen depletion zone for treatment to form oxygen depletion zone effluent, the hydraulic retention time in the oxygen depletion zone is 0.5-1 h, until the dissolved oxygen content in the oxygen depletion zone effluent is less than 1 mg / L, and the hydraulic flow pattern is completely mixed.

[0100] S3 main anoxic and post-aerobic treatment: the oxygen depletion zone effluent is sequentially transported to the main anoxic zone for treatment, the post-aerobic zone for treatment, and the secondary sedimentation tank for treatment, the dissolved oxygen content of the main anoxic zone effluent is controlled to be less than 1 mg / L, the hydraulic retention time in the post-aerobic zone is 0.5-1 h, until the average dissolved oxygen DO content in the post-aerobic zone effluent is 2 mg / L, the hydraulic flow pattern is plug flow, the post-aerobic zone uses a blower for aeration, and the secondary sedimentation tank has a retention time of 3-4 h; after the secondary sedimentation tank treatment, the final effluent, the reflux sludge and the waste sludge are formed.

[0101] S4 reflux sludge distribution: 25% of the reflux sludge is transported to the oxygen depletion zone for treatment, and 75% of the reflux sludge is transported to the pre-anoxic zone for treatment, that is, the energy-saving, consumption-reducing and low-carbon biochemical treatment process of wastewater is completed.

[0102] Performance test

[0103] The final effluent provided by the energy-saving, consumption-reducing and low-carbon sewage biochemical treatment process according to the embodiments 1-13 and the comparative examples 1-2 is subjected to the following water quality detection, and the specific detection results are shown in Table 1.

[0104] Detection method

[0105] COD determination: GB11914-89 "Determination of Chemical Oxygen Demand in Water by Dichromate Method" is adopted.

[0106] NH3-N determination: Nash reagent spectrophotometry is adopted for determination.

[0107] TN determination: Alkaline potassium persulfate digestion ultraviolet spectrophotometry is adopted for determination.

[0108] TP determination: Ammonium molybdate spectrophotometry for determination of total phosphorus is adopted.

[0109] SS determination: GB11901-89 gravimetric method is adopted for determination.

[0110] Table 1: Water quality detection results

[0111]

[0112]

[0113] It can be known from the performance detection results that the energy-saving, consumption-reducing and low-carbon sewage biochemical treatment process can meet the wastewater treatment standard IV effluent standard requirements, and can reduce the consumption of internal reflux and improve the sewage biochemical treatment efficiency by combining various processes and replacing the anoxic-oxygen process for internal reflux.

[0114] In the embodiments 8-12, a proper amount of biological adsorption material is added in the energy-saving, consumption-reducing and low-carbon sewage biochemical treatment process, more oxygen transfer channels are provided in the aerobic zone, and the organic matter removal efficiency of the aerobic zone is improved. At the same time, the modification of zeolite by rare earth can improve the adsorption performance of zeolite, the use of lignin composite polyurethane foam can enhance the tensile strength of polyurethane foam and prolong the service life of polyurethane foam, thereby improving the adsorption effect of polyurethane foam and improving the promoting effect of biological adsorption material on sewage biochemical treatment.

[0115] It can be known by comparing the embodiment 13 with the embodiment 1 that the treatment effect of sewage is reduced without sludge reflux in the embodiment 13, and each process needs to supplement additional carbon source to meet the effluent standard.

[0116] It can be known by comparing the comparative example 1, the comparative example 2 and the example 1 that the comparative example 1 does not use all the sewage to directly perform the pre-anoxic treatment first, the comparative example 1 directly performs the pre-anoxic treatment first on all the sewage, and the effluent of the anaerobic zone is all transported to the main aerobic zone for treatment. It can be known from the water quality detection result that the effluent quality obviously decreases, and at the same time, a proper amount of carbon source needs to be additionally supplemented in the sewage biochemical treatment stage to reach the effluent standard of each process. It is further illustrated that the present application can fully recycle the internal carbon source, reduce the supply of external carbon source, and improve the sewage biochemical treatment efficiency through the cooperation of each process.

[0117] The specific embodiments are only an explanation of the present application, and are not a limitation of the present application, and the person skilled in the art can make a modification of the present embodiment without a creative contribution according to the need after reading the present specification, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. An energy-saving, cost-reducing and low-carbon sewage biochemical treatment process, characterized in that, The method comprises the following specific steps: The sewage is sequentially treated in an anaerobic zone, a main aerobic zone, an oxygen elimination zone, a main anoxic zone, a post-aerobic zone and a secondary sedimentation tank to form effluent and sludge; Before the anaerobic treatment, 20-30% of the sewage is transported to a pre-anoxic zone for pre-anoxic treatment, and the effluent of the pre-anoxic zone is transported to the anaerobic zone for treatment to form anaerobic zone effluent, 10-20% of the anaerobic zone effluent is transported to the oxygen elimination zone for treatment, and 80-90% of the anaerobic zone effluent is transported to the main aerobic zone for treatment; The hydraulic flow state of the pre-anoxic zone and the oxygen elimination zone is complete mixing, the hydraulic flow state of the anaerobic zone is reciprocating circulation, and the hydraulic flow state of the main aerobic zone, the main anoxic zone and the post-aerobic zone is plug flow; The main aerobic zone and the anaerobic zone are both added with a biological adsorption material, and the biological adsorption material comprises the following raw materials in parts by weight: 20-40 parts of polyurethane foam, 5-8 parts of zeolite, 3-5 parts of mesoporous silica and 8-12 parts of silica gel binder; The zeolite is pre-modified with rare earth, and the modification method comprises the following specific steps: adjusting a rare earth solution to be alkaline, then adding the zeolite for impregnation, washing, drying, calcining at 450-500 DEG C and cooling to obtain the rare earth modified zeolite.

2. The energy-saving, cost-reducing and low-carbon biochemical wastewater treatment process according to claim 1, characterized in that, The sludge is divided into reflux sludge and waste sludge, 20-30% of the reflux sludge is transported to the oxygen elimination zone for treatment, and 70-80% of the reflux sludge is transported to the pre-anoxic zone for treatment.

3. The energy-saving, cost-reducing and low-carbon biochemical wastewater treatment process according to claim 1, characterized in that, The hydraulic retention time of the pre-anoxic zone is 0.5-1.5 h, the hydraulic retention time of the anaerobic zone is 1-1.5 h, the hydraulic retention time of the oxygen elimination zone is 0.5-1 h, and the hydraulic retention time of the post-aerobic zone is 0.5-1 h.

4. The energy-saving, cost-reducing and low-carbon biochemical wastewater treatment process according to claim 1, characterized in that, The polyurethane foam is compounded with lignin.

5. The energy-saving, cost-reducing and low-carbon biochemical wastewater treatment process according to claim 4, characterized in that, A method for compounding lignin with polyurethane foam comprises the following specific steps: mixing a catalyst, a stabilizer and a foaming agent with a polyol in advance to form a polyol mixed solution, dissolving lignin and mixing the lignin with the polyol mixed solution, then adding isocyanate and mixing uniformly, foaming, demolding and forming polyurethane foam.

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