Method for treating rural domestic sewage by adopting heterotrophic nitrification-aerobic denitrification

Abstract

The invention provides a method for treating rural domestic sewage by adopting heterotrophic nitrification-aerobic denitrification, and belongs to a sewage treatment technology. According to the method, the pichia pastoris is adopted for heterotrophic nitrification-aerobic denitrification treatment, synchronous nitrification and denitrification are realized, the denitrification efficiency is improved, and the construction and operation cost is reduced. The problems of efficient treatment of rural domestic sewage and reduction of water eutrophication are solved. According to the treatment scheme provided by the invention, the effluent quality is stable and reaches the standard, the use of chemical agents can be effectively reduced, the sludge yield is reduced, energy is saved, consumption is reduced, seasonal water quality fluctuation is adapted, and the system stability and reliability are improved.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and in particular to a method for treating rural domestic sewage by adopting heterotrophic nitrification-aerobic denitrification. Background Art

[0002] Sewage treatment technology is an important branch in the field of environmental protection. Its main goal is to remove organic matter, nitrogen, phosphorus and other pollutants in sewage to reduce water pollution. Traditional sewage treatment technologies, such as activated sludge method and biological filter, can remove pollutants to a certain extent, but they have problems such as low treatment efficiency, high energy consumption and high operating costs. Especially in rural areas, due to economic and technical conditions, the application of these traditional technologies is subject to certain restrictions.

[0003] Heterotrophic Nitrification-Aerobic Denitrification (HNAD) technology is a new type of biological denitrification technology. The core of this technology is to use certain microorganisms to simultaneously carry out nitrification and denitrification reactions under aerobic conditions to achieve nitrogen removal. In 1984, Robertson et al. discovered a mixotrophic microorganism Thiosphaera Pantotropha that can use NO3-N and oxygen as electron acceptors at the same time, and named this process aerobic denitrification. This discovery broke through the traditional biological denitrification theory, and since then, scholars have successively carried out research in the field of aerobic denitrification. Currently, the aerobic denitrifying bacteria reported include Alcaligenes, Pseudomonas, Bacillus, and Rhodococcus. Summary of the invention

[0004] The purpose of the present invention is to provide a method for treating rural domestic sewage by heterotrophic nitrification-aerobic denitrification, which provides an effective means for sewage treatment.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for treating rural domestic sewage by heterotrophic nitrification-aerobic denitrification, comprising the following steps:

[0007] The sewage to be treated enters the septic tank for preliminary organic matter degradation and suspended solids removal;

[0008] Flows into the screen channel to remove solid particles;

[0009] Enter the regulating pond to balance water quality and quantity;

[0010] Pump into the aerobic reactor, adjust dissolved oxygen, sludge return ratio, pH value and temperature, and add compound preparation and Pichia jardinis bacteria agent;

[0011] It enters the sedimentation tank to remove suspended solids and complete the treatment.

[0012] Preferably, the compound preparation comprises polyferric sulfate, ferric chloride, EDTA and chitosan flocculant.

[0013] Preferably, the Pichia jardinis yeast agent uses diatomaceous earth as a carrier.

[0014] Preferably, in the aerobic reactor, the aeration system uses a blower and a microporous aerator; in the aerobic reactor, a submersible mixer or a surface aerator is used for mixing and circulation.

[0015] Preferably, the residence time of the septic tank is 10 to 15 hours.

[0016] Preferably, the dosage of the polyferric sulfate is 95-110 mg / L;

[0017] The dosage of the ferric chloride is 45-55 mg / L;

[0018] The dosage of the EDTA is 0.8-1.3 mg / L;

[0019] The dosage of the chitosan flocculant is 0.9-1.4 g / L.

[0020] Preferably, the concentration of dissolved oxygen is 2.8 to 3.25 mg / L;

[0021] The hydraulic retention time is 7.5 to 8.5 hours.

[0022] Preferably, the sludge return ratio is 55-65%.

[0023] Preferably, the pH value is 7.3 to 7.7;

[0024] The temperature is 19-22°C.

[0025] Preferably, the dosage of the Pichia jardiniflora agent is 4-6 g / L.

[0026] Technical effects and advantages of the present invention:

[0027] The present invention innovatively utilizes heterotrophic nitrification-aerobic denitrification bacteria, Pichia jardinis, a characteristic strain that has demonstrated excellent performance in the field of sewage treatment. Pichia jardinis can simultaneously carry out nitrification and denitrification reactions under aerobic conditions. This simultaneous treatment capability greatly improves the treatment efficiency of rural domestic sewage, reduces the multiple reactors and complex operations required in traditional processes, and thus reduces construction and operating costs.

[0028] Through the application of Pichia jadinii, the present invention has achieved a number of technological breakthroughs in rural domestic sewage treatment. First, the strain's efficient denitrification ability ensures that the effluent water quality can stably meet or even exceed the current emission standards, which is of great significance for protecting the water environment in rural areas and preventing eutrophication of water bodies. Secondly, the rapid growth rate and strong environmental adaptability of Pichia jadinii enable the technology to cope with seasonal fluctuations in rural sewage and different water quality challenges, enhancing the stability and reliability of the system.

[0029] In addition, the present invention maximizes the activity of the strain by optimizing the preparation method and dosage of the Pichia jardinis inoculant, further improving the sewage treatment effect. This refined process control not only improves the treatment efficiency, but also reduces the use of chemical agents and reduces the sludge production, thereby alleviating the pressure of subsequent sludge treatment. This environmentally friendly treatment method is in line with the current trend of sustainable development and has a positive effect on promoting green rural construction.

[0030] The sewage treatment technology of the present invention effectively improves the removal efficiency of organic matter and nutrients in sewage by using a compound preparation and Pichia jardinis inoculum, ensuring that the effluent water quality meets strict emission standards. This technology integrates multiple treatment methods, including physical, chemical and biological means, to form an efficient, economical and environmentally friendly sewage treatment system. Compared with traditional treatment methods, the present invention simplifies the process flow, reduces the floor space and infrastructure costs, and reduces human intervention through automated operations, thereby improving treatment efficiency and stability.

[0031] In terms of energy saving and consumption reduction, the present invention achieves energy saving and carbon emission reduction in the sewage treatment process, which is of great significance for coping with global climate change and promoting green and sustainable development. In addition, the present invention exhibits good shock load resistance during operation and can adapt to sewage of different flow rates and concentrations, making the treatment effect more stable and reliable.

[0032] In general, the sewage treatment technology of the present invention is not only innovative in terms of technology, but also has important application value and broad market prospects in terms of environmental protection, resource utilization and economic benefits. Through the scheme provided by the present invention, we can more effectively protect water resources, promote sustainable development, and bring economic benefits to related industries. DETAILED DESCRIPTION

[0033] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0034] Biological sources in the specific embodiments of the present invention:

[0035] Heterotrophic nitrification-aerobic denitrification strain: Pichia jadinii, purchased from China General Microbiological Culture Collection Center, with the collection number of CGMCC 2.1201.

[0036] Rural domestic sewage parameters in the specific implementation mode of the present invention:

[0037] Chemical oxygen demand (COD): 253.75 mg / L, biochemical oxygen demand (BOD5): 152.34 mg / L, ammonia nitrogen (NH3-N): 41.28 mg / L, total phosphorus (TP): 3.12 mg / L, suspended solids (SS): 201.57 mg / L.

[0038] Example 1

[0039] Preprocessing stage:

[0040] Sewage first enters the septic tank from the collection system for preliminary organic matter degradation and suspended solids removal, with a retention time of 12 hours.

[0041] Pre-treated sewage flows from the septic tank into the screen channel to remove solid particles larger than 5mm.

[0042] Adjustment phase:

[0043] The sewage treated by the screen channel enters the regulating tank to balance the water quality and quantity, and the retention time is 12 hours.

[0044] Aerobic treatment stage:

[0045] The conditioned sewage is pumped from the regulating tank into an aerobic reactor (aeration tank), where the dissolved oxygen (DO) is maintained at 3 mg / L and the hydraulic retention time (HRT) is controlled at 8 hours.

[0046] In the aerobic reactor, the sludge recycle ratio was 60%, the pH value was controlled at 7.5, and the temperature was maintained at 20°C.

[0047] The following compound preparations were added to the aerobic reactor:

[0048] Polyferric sulfate: dosage is 100 mg / L;

[0049] Ferric chloride: dosage is 50mg / L;

[0050] EDTA: dosage is 1 mg / L;

[0051] Chitosan flocculant: the dosage is 1.0 g / L. The chitosan flocculant of the present invention is purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., item number: C105799, deacetylation degree ≥95%, viscosity 100-200 mPa.s.

[0052] The Jading Pichia yeast agent is added to the sewage treatment biochemical pool in the aerobic stage at a dosage of 5g / L (based on the volume of the sewage to be treated). The preparation method of the Jading Pichia yeast agent is as follows: take an appropriate amount of diatomaceous earth raw soil, scrub it with deionized water to make pulp, and the obtained slurry is passed through an 80-mesh sieve to remove impurities, and the sieve under the sieve is collected as the first slurry. The first slurry is sieved again using a 120-mesh sieve, and the sieve under the sieve is collected as the second slurry. Subsequently, the second slurry is subjected to sedimentation, filter pressing and drying to obtain a diatomaceous earth-based microbial carrier. When activating Jading Pichia yeast, 1% of the yeast agent is mixed with 9% sterile water and 0.5% glucose, and cultured at 25°C for 12 hours to activate the strain. Then the activated yeast is mixed with the diatomaceous earth carrier under sterile conditions at a weight ratio of 1:10, and continues to be cultured at 25°C for 24 hours to achieve yeast loading.

[0053] The aeration system uses blowers and microporous aerators to ensure adequate oxygen supply, while submersible mixers are used for mixing and circulation to keep the sludge suspended and mixed evenly.

[0054] Sedimentation stage:

[0055] The aerobically treated sewage enters the sedimentation tank from the aerobic reactor to precipitate and remove suspended solids.

[0056] Emissions that meet standards:

[0057] Sewage after treatment in sedimentation tank:

[0058] Chemical oxygen demand (COD): 48.76 mg / L, biochemical oxygen demand (BOD5): 17.45 mg / L, ammonia nitrogen (NH3-N): 4.32 mg / L, total phosphorus (TP): 0.47 mg / L, suspended solids (SS): 28.59 mg / L, which meet the discharge standards and can be discharged from the sedimentation tank.

[0059] Example 2

[0060] Preprocessing stage:

[0061] Sewage first enters the septic tank from the collection system for preliminary organic matter degradation and suspended solids removal, with a retention time of 12 hours.

[0062] Pre-treated sewage flows from the septic tank into the screen channel to remove solid particles larger than 5mm.

[0063] Adjustment phase:

[0064] The sewage treated by the screen channel enters the regulating tank to balance the water quality and quantity, and the retention time is 12 hours.

[0065] Aerobic treatment stage:

[0066] The conditioned sewage is pumped from the regulating tank into the aerobic reactor (aeration tank), where the dissolved oxygen (DO) is maintained at 2.8 mg / L and the hydraulic retention time (HRT) is controlled at 7.5 hours.

[0067] In the aerobic reactor, the sludge recycle ratio was 55%, the pH value was controlled at 7.6, and the temperature was maintained at 21°C.

[0068] The following compound preparations were added to the aerobic reactor:

[0069] Polyferric sulfate: dosage is 95 mg / L;

[0070] Ferric chloride: dosage is 48 mg / L;

[0071] EDTA: dosage is 1.2 mg / L;

[0072] Chitosan flocculant: the dosage is 1.1 g / L. The chitosan flocculant of the present invention is purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., item number: C105799, deacetylation degree ≥95%, viscosity 100-200 mPa.s.

[0073] The Pichia jardinis inoculant was added into the sewage treatment biochemical pool in the aerobic stage at a dosage of 5 g / L (based on the volume of the sewage to be treated). The preparation method of the Pichia jardinis inoculant was the same as that in Example 1.

[0074] The aeration system uses blowers and microporous aerators to ensure adequate oxygen supply, while submersible mixers are used for mixing and circulation to keep the sludge suspended and mixed evenly.

[0075] Sedimentation stage:

[0076] The aerobically treated sewage enters the sedimentation tank from the aerobic reactor to precipitate and remove suspended solids.

[0077] Emissions that meet standards:

[0078] Sewage after treatment in sedimentation tank:

[0079] Chemical oxygen demand (COD): 47.58 mg / L, biochemical oxygen demand (BOD5): 16.89 mg / L, ammonia nitrogen (NH3-N): 4.15 mg / L, total phosphorus (TP): 0.48 mg / L, suspended solids (SS): 27.96 mg / L, which meet the discharge standards and can be discharged from the sedimentation tank.

[0080] Example 3

[0081] Preprocessing stage:

[0082] Sewage first enters the septic tank from the collection system for preliminary organic matter degradation and suspended solids removal, with a retention time of 12 hours.

[0083] Pre-treated sewage flows from the septic tank into the screen channel to remove solid particles larger than 5mm.

[0084] Adjustment phase:

[0085] The sewage treated by the screen channel enters the regulating tank to balance the water quality and quantity, and the retention time is 12 hours.

[0086] Aerobic treatment stage:

[0087] The conditioned sewage is pumped from the regulating tank into the aerobic reactor (aeration tank), where the dissolved oxygen (DO) is maintained at 3.2 mg / L and the hydraulic retention time (HRT) is controlled at 8.5 hours.

[0088] In the aerobic reactor, the sludge recycle ratio was 65%, the pH value was controlled at 7.4, and the temperature was maintained at 19°C.

[0089] The following compound preparations were added to the aerobic reactor:

[0090] Polyferric sulfate: dosage is 105 mg / L;

[0091] Ferric chloride: dosage is 52mg / L;

[0092] EDTA: dosage is 0.9 mg / L;

[0093] Chitosan flocculant: the dosage is 0.9 g / L. The chitosan flocculant of the present invention is purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., item number: C105799, deacetylation degree ≥95%, viscosity 100-200 mPa.s.

[0094] The Pichia jardinis inoculant was added into the sewage treatment biochemical pool in the aerobic stage at a dosage of 5 g / L (based on the volume of the sewage to be treated). The preparation method of the Pichia jardinis inoculant was the same as that in Example 1.

[0095] The aeration system uses blowers and microporous aerators to ensure adequate oxygen supply, while submersible mixers are used for mixing and circulation to keep the sludge suspended and mixed evenly.

[0096] Sedimentation stage:

[0097] The aerobically treated sewage enters the sedimentation tank from the aerobic reactor to precipitate and remove suspended solids.

[0098] Emissions that meet standards:

[0099] Sewage after treatment in sedimentation tank:

[0100] Chemical oxygen demand (COD): 50.12 mg / L, biochemical oxygen demand (BOD5): 18.23 mg / L, ammonia nitrogen (NH3-N): 4.47 mg / L, total phosphorus (TP): 0.45 mg / L, suspended solids (SS): 29.01 mg / L, which meet the discharge standards and can be discharged from the sedimentation tank.

[0101] Example 4

[0102] Preprocessing stage:

[0103] Sewage first enters the septic tank from the collection system for preliminary organic matter degradation and suspended solids removal, with a retention time of 12 hours.

[0104] Pre-treated sewage flows from the septic tank into the screen channel to remove solid particles larger than 5mm.

[0105] Adjustment phase:

[0106] The sewage treated by the screen channel enters the regulating tank to balance the water quality and quantity, and the retention time is 12 hours.

[0107] Aerobic treatment stage:

[0108] The conditioned sewage is pumped from the regulating tank into the aerobic reactor (aeration tank), where the dissolved oxygen (DO) is maintained at 3.0 mg / L and the hydraulic retention time (HRT) is controlled at 8 hours.

[0109] In the aerobic reactor, the sludge recycle ratio was 60%, the pH value was controlled at 7.7, and the temperature was maintained at 20°C.

[0110] The following compound preparations were added to the aerobic reactor:

[0111] Polyferric sulfate: dosage is 110 mg / L;

[0112] Ferric chloride: dosage is 45 mg / L;

[0113] EDTA: dosage is 1.1 mg / L;

[0114] Chitosan flocculant: the dosage is 1.2 g / L. The chitosan flocculant of the present invention is purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., item number: C105799, deacetylation degree ≥95%, viscosity 100-200 mPa.s.

[0115] The Pichia jardinis inoculant was added into the sewage treatment biochemical pool in the aerobic stage at a dosage of 5 g / L (based on the volume of the sewage to be treated). The preparation method of the Pichia jardinis inoculant was the same as that in Example 1.

[0116] The aeration system uses blowers and microporous aerators to ensure adequate oxygen supply, while submersible mixers are used for mixing and circulation to keep the sludge suspended and mixed evenly.

[0117] Sedimentation stage:

[0118] The aerobically treated sewage enters the sedimentation tank from the aerobic reactor to precipitate and remove suspended solids.

[0119] Emissions that meet standards:

[0120] Sewage after treatment in sedimentation tank:

[0121] Chemical oxygen demand (COD): 49.34 mg / L, biochemical oxygen demand (BOD5): 17.67 mg / L, ammonia nitrogen (NH3-N): 4.09 mg / L, total phosphorus (TP): 0.49 mg / L, suspended solids (SS): 28.34 mg / L, which meet the discharge standards and can be discharged from the sedimentation tank.

[0122] Example 5

[0123] Preprocessing stage:

[0124] Sewage first enters the septic tank from the collection system for preliminary organic matter degradation and suspended solids removal, with a retention time of 12 hours.

[0125] Pre-treated sewage flows from the septic tank into the screen channel to remove solid particles larger than 5mm.

[0126] Adjustment phase:

[0127] The sewage treated by the screen channel enters the regulating tank to balance the water quality and quantity, and the retention time is 12 hours.

[0128] Aerobic treatment stage:

[0129] The conditioned sewage is pumped from the regulating tank into the aerobic reactor (aeration tank), where the dissolved oxygen (DO) is maintained at 2.9 mg / L and the hydraulic retention time (HRT) is controlled at 7.8 hours.

[0130] In the aerobic reactor, the sludge recycle ratio was 58%, the pH value was controlled at 7.5, and the temperature was maintained at 22°C.

[0131] The following compound preparations were added to the aerobic reactor:

[0132] Polyferric sulfate: dosage is 100 mg / L;

[0133] Ferric chloride: dosage is 50mg / L;

[0134] EDTA: dosage is 1.0 mg / L;

[0135] Chitosan flocculant: the dosage is 1.0 g / L. The chitosan flocculant of the present invention is purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., item number: C105799, deacetylation degree ≥95%, viscosity 100-200 mPa.s.

[0136] The Pichia jardinis inoculant was added into the sewage treatment biochemical pool in the aerobic stage at a dosage of 5 g / L (based on the volume of the sewage to be treated). The preparation method of the Pichia jardinis inoculant was the same as that in Example 1.

[0137] The aeration system uses blowers and microporous aerators to ensure adequate oxygen supply, while submersible mixers are used for mixing and circulation to keep the sludge suspended and mixed evenly.

[0138] Sedimentation stage:

[0139] The aerobically treated sewage enters the sedimentation tank from the aerobic reactor to precipitate and remove suspended solids.

[0140] Emissions that meet standards:

[0141] Sewage after treatment in sedimentation tank:

[0142] Chemical oxygen demand (COD): 46.91 mg / L, biochemical oxygen demand (BOD5): 16.45 mg / L, ammonia nitrogen (NH3-N): 4.21 mg / L, total phosphorus (TP): 0.44 mg / L, suspended solids (SS): 27.58 mg / L, which meet the discharge standards and can be discharged from the sedimentation tank.

[0143] Example 6

[0144] Preprocessing stage:

[0145] Sewage first enters the septic tank from the collection system for preliminary organic matter degradation and suspended solids removal, with a retention time of 12 hours.

[0146] Pre-treated sewage flows from the septic tank into the screen channel to remove solid particles larger than 5mm.

[0147] Adjustment phase:

[0148] The sewage treated by the screen channel enters the regulating tank to balance the water quality and quantity, and the retention time is 12 hours.

[0149] Aerobic treatment stage:

[0150] The conditioned sewage is pumped from the regulating tank into the aerobic reactor (aeration tank), where the dissolved oxygen (DO) is maintained at 3.1 mg / L and the hydraulic retention time (HRT) is controlled at 8.2 hours.

[0151] In the aerobic reactor, the sludge return ratio was 62%, the pH value was controlled at 7.4, and the temperature was maintained at 19°C.

[0152] The following compound preparations were added to the aerobic reactor:

[0153] Polyferric sulfate: dosage is 98 mg / L;

[0154] Ferric chloride: dosage is 55 mg / L;

[0155] EDTA: dosage is 0.8 mg / L;

[0156] Chitosan flocculant: the dosage is 1.3 g / L. The chitosan flocculant of the present invention is purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., item number: C105799, deacetylation degree ≥95%, viscosity 100-200 mPa.s.

[0157] The Pichia jardinis inoculant was added into the sewage treatment biochemical pool in the aerobic stage at a dosage of 5 g / L (based on the volume of the sewage to be treated). The preparation method of the Pichia jardinis inoculant was the same as that in Example 1.

[0158] The aeration system uses blowers and microporous aerators to ensure adequate oxygen supply, while submersible mixers are used for mixing and circulation to keep the sludge suspended and mixed evenly.

[0159] Sedimentation stage:

[0160] The aerobically treated sewage enters the sedimentation tank from the aerobic reactor to precipitate and remove suspended solids.

[0161] Emissions that meet standards:

[0162] Sewage after treatment in sedimentation tank:

[0163] Chemical oxygen demand (COD): 48.26 mg / L, biochemical oxygen demand (BOD5): 17.89 mg / L, ammonia nitrogen (NH3-N): 4.56 mg / L, total phosphorus (TP): 0.46 mg / L, suspended solids (SS): 28.79 mg / L, which meet the discharge standards and can be discharged from the sedimentation tank.

[0164] Example 7

[0165] Preprocessing stage:

[0166] Sewage first enters the septic tank from the collection system for preliminary organic matter degradation and suspended solids removal, with a retention time of 12 hours.

[0167] Pre-treated sewage flows from the septic tank into the screen channel to remove solid particles larger than 5mm.

[0168] Adjustment phase:

[0169] The sewage treated by the screen channel enters the regulating tank to balance the water quality and quantity, and the retention time is 12 hours.

[0170] Aerobic treatment stage:

[0171] The conditioned sewage is pumped from the regulating tank into the aerobic reactor (aeration tank), where the dissolved oxygen (DO) is maintained at 2.85 mg / L and the hydraulic retention time (HRT) is controlled at 7.7 hours.

[0172] In the aerobic reactor, the sludge recycle ratio was 59%, the pH value was controlled at 7.6, and the temperature was maintained at 21°C.

[0173] The following compound preparations were added to the aerobic reactor:

[0174] Polyferric sulfate: dosage is 102 mg / L;

[0175] Ferric chloride: dosage is 47 mg / L;

[0176] EDTA: dosage is 1.3 mg / L;

[0177] Chitosan flocculant: the dosage is 1.1 g / L. The chitosan flocculant of the present invention is purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., item number: C105799, deacetylation degree ≥95%, viscosity 100-200 mPa.s.

[0178] The Pichia jardinis inoculant was added into the sewage treatment biochemical pool in the aerobic stage at a dosage of 5 g / L (based on the volume of the sewage to be treated). The preparation method of the Pichia jardinis inoculant was the same as that in Example 1.

[0179] The aeration system uses blowers and microporous aerators to ensure adequate oxygen supply, while surface aerators are used for mixing and circulation to keep the sludge suspended and mixed evenly.

[0180] Sedimentation stage:

[0181] The aerobically treated sewage enters the sedimentation tank from the aerobic reactor to precipitate and remove suspended solids.

[0182] Emissions that meet standards:

[0183] Sewage after treatment in sedimentation tank:

[0184] Chemical oxygen demand (COD): 47.45 mg / L, biochemical oxygen demand (BOD5): 16.78 mg / L, ammonia nitrogen (NH3-N): 4.02 mg / L, total phosphorus (TP): 0.47 mg / L, suspended solids (SS): 27.86 mg / L, which meet the discharge standards and can be discharged from the sedimentation tank.

[0185] Example 8

[0186] Preprocessing stage:

[0187] Sewage first enters the septic tank from the collection system for preliminary organic matter degradation and suspended solids removal, with a retention time of 12 hours.

[0188] Pre-treated sewage flows from the septic tank into the screen channel to remove solid particles larger than 5mm.

[0189] Adjustment phase:

[0190] The sewage treated by the screen channel enters the regulating tank to balance the water quality and quantity, and the retention time is 12 hours.

[0191] Aerobic treatment stage:

[0192] The conditioned sewage is pumped from the regulating tank into the aerobic reactor (aeration tank), where the dissolved oxygen (DO) is maintained at 3.25 mg / L and the hydraulic retention time (HRT) is controlled at 8.3 hours.

[0193] In the aerobic reactor, the sludge recycle ratio was 61%, the pH value was controlled at 7.3, and the temperature was maintained at 20°C.

[0194] The following compound preparations were added to the aerobic reactor:

[0195] Polyferric sulfate: dosage is 97 mg / L;

[0196] Ferric chloride: dosage is 53 mg / L;

[0197] EDTA: dosage is 0.9 mg / L;

[0198] Chitosan flocculant: the dosage is 1.4 g / L. The chitosan flocculant of the present invention is purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., item number: C105799, deacetylation degree ≥95%, viscosity 100-200 mPa.s.

[0199] The Pichia jardinis inoculant was added into the sewage treatment biochemical pool in the aerobic stage at a dosage of 5 g / L (based on the volume of the sewage to be treated). The preparation method of the Pichia jardinis inoculant was the same as that in Example 1.

[0200] The aeration system uses blowers and microporous aerators to ensure adequate oxygen supply, while submersible mixers are used for mixing and circulation to keep the sludge suspended and mixed evenly.

[0201] Sedimentation stage:

[0202] The aerobically treated sewage enters the sedimentation tank from the aerobic reactor to precipitate and remove suspended solids.

[0203] Emissions that meet standards:

[0204] Sewage after treatment in sedimentation tank:

[0205] Chemical oxygen demand (COD): 49.56 mg / L, biochemical oxygen demand (BOD5): 18.12 mg / L, ammonia nitrogen (NH3-N): 4.38 mg / L, total phosphorus (TP): 0.43 mg / L, suspended solids (SS): 29.23 mg / L, which meet the discharge standards and can be discharged from the sedimentation tank.

[0206] Example 9

[0207] Preprocessing stage:

[0208] Sewage first enters the septic tank from the collection system for preliminary organic matter degradation and suspended solids removal, with a retention time of 12 hours.

[0209] Pre-treated sewage flows from the septic tank into the screen channel to remove solid particles larger than 5mm.

[0210] Adjustment phase:

[0211] The sewage treated by the screen channel enters the regulating tank to balance the water quality and quantity, and the retention time is 12 hours.

[0212] Aerobic treatment stage:

[0213] The conditioned sewage is pumped from the regulating tank into the aerobic reactor (aeration tank), where the dissolved oxygen (DO) is maintained at 3.0 mg / L and the hydraulic retention time (HRT) is controlled at 8.1 hours.

[0214] In the aerobic reactor, the sludge return ratio was 63%, the pH value was controlled at 7.5, and the temperature was maintained at 19°C.

[0215] The following compound preparations were added to the aerobic reactor:

[0216] Polyferric sulfate: dosage is 103 mg / L;

[0217] Ferric chloride: dosage is 49 mg / L;

[0218] EDTA: dosage is 1.2 mg / L;

[0219] Chitosan flocculant: the dosage is 1.2 g / L. The chitosan flocculant of the present invention is purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., item number: C105799, deacetylation degree ≥95%, viscosity 100-200 mPa.s.

[0220] The Pichia jardinis inoculant was added into the sewage treatment biochemical pool in the aerobic stage at a dosage of 5 g / L (based on the volume of the sewage to be treated). The preparation method of the Pichia jardinis inoculant was the same as that in Example 1.

[0221] The aeration system uses blowers and microporous aerators to ensure adequate oxygen supply, while submersible mixers are used for mixing and circulation to keep the sludge suspended and mixed evenly.

[0222] Sedimentation stage:

[0223] The aerobically treated sewage enters the sedimentation tank from the aerobic reactor to precipitate and remove suspended solids.

[0224] Emissions that meet standards:

[0225] Sewage after treatment in sedimentation tank:

[0226] Chemical oxygen demand (COD): 48.89 mg / L, biochemical oxygen demand (BOD5): 17.34 mg / L, ammonia nitrogen (NH3-N): 4.29 mg / L, total phosphorus (TP): 0.48 mg / L, suspended solids (SS): 28.47 mg / L, which meet the discharge standards and can be discharged from the sedimentation tank.

[0227] Example 10

[0228] Preprocessing stage:

[0229] Sewage first enters the septic tank from the collection system for preliminary organic matter degradation and suspended solids removal, with a retention time of 12 hours.

[0230] Pre-treated sewage flows from the septic tank into the screen channel to remove solid particles larger than 5mm.

[0231] Adjustment phase:

[0232] The sewage treated by the screen channel enters the regulating tank to balance the water quality and quantity, and the retention time is 12 hours.

[0233] Aerobic treatment stage:

[0234] The conditioned sewage is pumped from the regulating tank into the aerobic reactor (aeration tank), where the dissolved oxygen (DO) is maintained at 2.95 mg / L and the hydraulic retention time (HRT) is controlled at 7.9 hours.

[0235] In the aerobic reactor, the sludge recycle ratio was 57%, the pH value was controlled at 7.4, and the temperature was maintained at 22°C.

[0236] The following compound preparations were added to the aerobic reactor:

[0237] Polyferric sulfate: dosage is 101 mg / L;

[0238] Ferric chloride: dosage is 51 mg / L;

[0239] EDTA: dosage is 1.1 mg / L;

[0240] Chitosan flocculant: the dosage is 1.3 g / L. The chitosan flocculant of the present invention is purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., item number: C105799, deacetylation degree ≥95%, viscosity 100-200 mPa.s.

[0241] The Pichia jardinis inoculant was added into the sewage treatment biochemical pool in the aerobic stage at a dosage of 5 g / L (based on the volume of the sewage to be treated). The preparation method of the Pichia jardinis inoculant was the same as that in Example 1.

[0242] The aeration system uses blowers and microporous aerators to ensure adequate oxygen supply, while submersible mixers are used for mixing and circulation to keep the sludge suspended and mixed evenly.

[0243] Sedimentation stage:

[0244] The aerobically treated sewage enters the sedimentation tank from the aerobic reactor to precipitate and remove suspended solids.

[0245] Emissions that meet standards:

[0246] Sewage after treatment in sedimentation tank:

[0247] Chemical oxygen demand (COD): 47.23 mg / L, biochemical oxygen demand (BOD5): 16.56 mg / L, ammonia nitrogen (NH3-N): 4.11 mg / L, total phosphorus (TP): 0.45 mg / L, suspended solids (SS): 27.68 mg / L, which meet the discharge standards and can be discharged from the sedimentation tank.

[0248] As can be seen from the above examples, the present invention provides an efficient and stable method for treating rural domestic sewage. The method uses heterotrophic nitrification-aerobic denitrification technology, combined with specific chemical agents and microbial agents, to effectively remove pollutants such as organic matter, nitrogen, and phosphorus in sewage, ensuring that the treated water quality meets national emission standards.

[0249] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for treating rural domestic sewage by heterotrophic nitrification-aerobic denitrification, characterized in that: The following steps are involved: The sewage to be treated enters the septic tank for preliminary organic matter degradation and suspended solids removal; Flows into the screen channel to remove solid particles; Enter the regulating pond to balance water quality and quantity; Pump into the aerobic reactor, adjust dissolved oxygen, sludge return ratio, pH value and temperature, and add compound preparation and Pichia jardinis bacteria agent; It enters the sedimentation tank to remove suspended solids and complete the treatment.

2. The method for treating rural domestic sewage by heterotrophic nitrification-aerobic denitrification according to claim 1, characterized in that: The compound preparation comprises polymerized ferric sulfate, ferric chloride, EDTA and chitosan flocculant.

3. The method for treating rural domestic sewage by heterotrophic nitrification-aerobic denitrification according to claim 1, characterized in that: The Pichia jardinis yeast agent uses diatomaceous earth as a carrier.

4. The method for treating rural domestic sewage by heterotrophic nitrification-aerobic denitrification according to claim 1, characterized in that: In the aerobic reactor, the aeration system adopts a blower and a microporous aerator; in the aerobic reactor, a submersible mixer or a surface aerator is used for mixing and circulation.

5. The method for treating rural domestic sewage by heterotrophic nitrification-aerobic denitrification according to claim 1, characterized in that: The residence time of the septic tank is 10 to 15 hours.

6. The method for treating rural domestic sewage by heterotrophic nitrification-aerobic denitrification according to claim 2, characterized in that: The dosage of the polyferric sulfate is 95-110 mg / L; The dosage of the ferric chloride is 45-55 mg / L; The dosage of the EDTA is 0.8-1.3 mg / L; The dosage of the chitosan flocculant is 0.9-1.4 g / L.

7. The method for treating rural domestic sewage by heterotrophic nitrification-aerobic denitrification according to claim 1, characterized in that: The concentration of dissolved oxygen is 2.8-3.25 mg / L; The hydraulic retention time is 7.5 to 8.5 hours.

8. The method for treating rural domestic sewage by heterotrophic nitrification-aerobic denitrification according to claim 1, characterized in that: The sludge return ratio is 55-65%.

9. The method for treating rural domestic sewage by heterotrophic nitrification-aerobic denitrification according to claim 8, characterized in that: The pH value is 7.3 to 7.7; The temperature is 19-22°C.

10. The method for treating rural domestic sewage by heterotrophic nitrification-aerobic denitrification according to any one of claims 1 to 9, characterized in that: The dosage of the Pichia jardinis yeast agent is 4-6 g / L.