阅读说明：本技术 生活污水的处理系统和处理方法 (Treatment system and treatment method for domestic sewage ) 是由 周文栋 谢永新 李锐敬 陈益成 雒怀庆 徐波 黄睦凯 李小强 曾诗林 杨炜雯 于 2021-07-06 设计创作，主要内容包括：本发明提供了一种生活污水的处理系统和处理方法,涉及污水处理的技术领域,该处理系统包括磁粉-生物絮凝区、固液分离区、填料-微生物燃料电池区以及厌氧消化区。本发明的磁粉-生物絮凝区、固液分离区能强化碳源分离效果；填料-微生物燃料电池区通过设置多层不同填料的结构,并设置镁砂作为燃料电池的阳极填料,强化了对于废水中氮和磷的去除效果。本发明通过燃料电池和厌氧消化回收能源,不仅能有效降低系统的能耗,还能提高其能源利用效率。(The invention provides a treatment system and a treatment method for domestic sewage, and relates to the technical field of sewage treatment. The magnetic powder-biological flocculation area and the solid-liquid separation area can enhance the carbon source separation effect; the filler-microbial fuel cell area is provided with a structure of multiple layers of different fillers and magnesite as anode filler of the fuel cell, so that the removal effect of nitrogen and phosphorus in wastewater is enhanced. The invention recovers energy through the fuel cell and anaerobic digestion, not only can effectively reduce the energy consumption of the system, but also can improve the energy utilization efficiency.)

1. The domestic sewage treatment system is characterized by comprising a magnetic powder-biological flocculation area, a solid-liquid separation area, a filler-microbial fuel cell area and an anaerobic digestion area;

the magnetic powder-biological flocculation area contains a mixture of magnetic powder and a microbial extracellular enzyme flocculant;

the lower part of the magnetic powder-biological flocculation area is communicated with the lower part of the solid-liquid separation area;

an upper-layer water outlet of the solid-liquid separation zone is communicated with a lower-layer water inlet of the filler-microbial fuel cell zone, and a lower-layer sludge outlet of the solid-liquid separation zone is communicated with the anaerobic digestion zone;

the filler-microbial fuel cell area is sequentially provided with a crushed stone filler layer, a zeolite filler lower layer, a magnesia filler layer, a zeolite filler upper layer and an aquatic plant layer from bottom to top;

the filler-microbial fuel cell area is provided with an anode electrode and a cathode electrode, the anode electrode is arranged in the magnesia filler layer, the cathode electrode is partially arranged in the aquatic plant layer, the rest part of the cathode electrode is exposed out of the water surface and is communicated with the outside air, and the anode electrode and the cathode electrode are connected with an external energy storage component through leads.

2. The treatment system according to claim 1, wherein a dosing device is arranged at the top of the magnetic powder-biological flocculation zone and used for adding magnetic powder and a microbial extracellular enzyme flocculant;

the top of the magnetic powder-biological flocculation area is provided with flocculation stirring slurry for mixing magnetic powder and a microbial extracellular enzyme flocculant;

preferably, the stirring speed of the flocculation stirring slurry is 100-300 r/min;

preferably, the adding amount of the magnetic powder is 20-100mg/L, and the adding amount of the microbial extracellular enzyme flocculant is 1-3mL/100 mL.

3. The processing system according to claim 2, wherein the microbial extracellular enzyme flocculant is prepared by a method comprising the steps of:

A. activating the microbial bacteria to obtain activated microbial bacteria;

B. culturing the activated microbial bacteria to obtain a bacterial liquid;

C. adding the bacterial liquid into an inorganic salt culture medium for culturing to obtain a culture solution;

D. carrying out solid-liquid separation on the culture solution to obtain supernatant, and then precipitating to obtain a microbial extracellular enzyme flocculant;

preferably, the culturing time in the step B is 48-56 h;

preferably, the culturing time in the step C is 72-80 h;

preferably, the adding amount of the bacterial liquid in the step C is 5-7 mL;

preferably, the solid-liquid separation in step D comprises centrifugation;

preferably, the mode of precipitation in step D comprises ethanol precipitation.

4. The treatment system of claim 1, wherein a partition wall is provided between the magnetic particle-bioflocculation zone and the solid-liquid separation zone for separating the solid-liquid separation zone and the magnetic particle-bioflocculation zone.

5. The treatment system of claim 1, wherein the solid liquid displacement zone is provided with a solid liquid separation membrane for separating water and sludge.

6. The treatment system as claimed in claim 1, wherein the crushed stone filler layer of the filler-microbial fuel cell area has a crushed stone particle size of 20-40mm and a thickness of 800-900 mm; the zeolite grain diameter of the lower layer of the zeolite filler is 8-16mm, and the thickness of the lower layer of the zeolite filler is 600-700 mm; the particle size of the magnesia packing layer is 1-3mm, and the thickness of the magnesia packing layer is 300-400 mm; the particle size of the zeolite on the upper layer of the zeolite filler is 3-5mm, and the thickness of the upper layer of the zeolite filler is 100-200 mm;

preferably, the structure of the anode electrode and the structure of the cathode electrode of the filler-microbial fuel cell area are independent structures of activated carbon and stainless steel mesh.

7. The treatment system of claim 1, wherein the bottom of the anaerobic digestion zone is provided with sludge stirring paddle for stirring sludge;

preferably, the stirring speed of the sludge stirring slurry is 300-500 r/min;

the side wall of the anaerobic digestion area is provided with a constant temperature device for adjusting the temperature;

an emptying system is arranged outside the anaerobic digestion area and is used for emptying air;

and the top of the anaerobic digestion area is provided with a gate for controlling sludge to enter the anaerobic digestion area.

8. The treatment system of any one of claims 1-7, further comprising a disinfection tank and a water collection tank;

the filler-microbial fuel cell zone is communicated with the disinfection tank;

the disinfection tank is used for disinfecting the water after nitrogen and phosphorus removal;

the disinfection tank is communicated with the water collecting tank;

the water collecting tank is used for collecting the disinfected water.

9. The processing system according to any one of claims 1 to 7, further comprising a gas collection device;

and an upper layer gas outlet of the anaerobic digestion area is communicated with a gas inlet of the gas collecting device.

10. A method for treating domestic sewage, characterized in that the treatment is carried out by the treatment system according to any one of claims 1 to 9, comprising the steps of:

(a) the pretreated domestic sewage enters the magnetic powder-biological flocculation area for flocculation treatment to obtain wastewater and flocculated concentrated sludge;

(b) the wastewater and the flocculated and concentrated sludge obtained in the step (a) enter the solid-liquid separation zone for solid-liquid separation to obtain carbon source separation water and carbon source concentrated sludge;

(c) separating the water obtained from the carbon source in the step (b) and allowing the water to enter the filler-microbial fuel cell area for nitrogen and phosphorus removal to obtain water after nitrogen and phosphorus removal;

(d) and (c) allowing the carbon source concentrated sludge obtained in the step (b) to enter the anaerobic digestion area for anaerobic digestion to obtain methane.

Technical Field

The invention relates to the technical field of sewage treatment, in particular to a treatment system and a treatment method for domestic sewage.

Background

At present, the treatment technology of rural sewage mainly comprises a biological treatment system, an ecological treatment system and the like, wherein the biological treatment system mainly comprises anaerobic methane tank treatment, a biological membrane technology, an efficient microorganism treatment technology and the like; the ecological treatment technology mainly comprises a stabilization pond technology, an earthworm ecological filter tank, a soil infiltration technology, an artificial wetland technology and the like. The artificial wetland technology is most widely applied to rural sewage treatment, but the single artificial wetland has the problems of easy blockage, unstable treatment effect and the like, so that the development of a treatment process combining the artificial wetland technology and other biological technologies or physical and chemical technologies is urgent.

In the prior art, a combined process of pretreatment and ecological treatment is mainly used as a treatment basis, for example, in patent CN112479477A, an electric flocculation method, a sedimentation method and an artificial wetland technology are adopted to treat rural sewage, hollow aeration is adopted in an electric flocculation and sedimentation unit, the organic load of inlet water is reduced through the electric flocculation and sedimentation method, the dissolved oxygen amount of inlet water of the artificial wetland at the rear end is kept stable by adopting the hollow aeration, and the removal effect of ammonia nitrogen and phosphorus of the artificial wetland is improved. However, the above technical solutions mainly have the following disadvantages: firstly, the rural waste water containsAbundant organic matters are used as excellent biomass energy, and a corresponding energy recovery scheme is not designed in the scheme, so that the operation energy efficiency of the system is low; secondly, sludge generated by electrocoagulation is dried by a reed ecological bed, and sludge drying is realized mainly by plant transpiration and solar illumination processes, and is easily affected by plant growth state and environmental climate condition change, so that the sludge dewatering effect is unstable; third, the process of electrocoagulation and precipitation mainly removes suspended and colloidal pollutants in domestic sewage, while the main dissolved organic matters are not concentrated and separated in advance, thereby leading to a large amount of CO₂The production and discharge of organic carbon reduces the effective conversion of organic carbon and also has a negative impact on the climate environment.

In view of the above, the present invention is particularly proposed.

Disclosure of Invention

One of the purposes of the invention is to provide a domestic sewage treatment system, which not only solves the problem of poor carbon source separation efficiency in domestic sewage, but also solves the problem of poor nitrogen and phosphorus removal effect in domestic sewage, and simultaneously avoids the influence of odor generated in the sludge transfer process in the traditional process on the surrounding environment, and also solves the problem of energy recycling in domestic sewage.

The invention also aims to provide a domestic sewage treatment method which is stable in operation, efficient and flexible in control.

In order to achieve the above purpose of the present invention, the following technical solutions are adopted:

in a first aspect, the invention provides a domestic sewage treatment system, which comprises a magnetic powder-biological flocculation area, a solid-liquid separation area, a filler-microbial fuel cell area and an anaerobic digestion area;

the magnetic powder-biological flocculation area contains a mixture of magnetic powder and a microbial extracellular enzyme flocculant;

the lower part of the magnetic powder-biological flocculation area is communicated with the lower part of the solid-liquid separation area;

an upper-layer water outlet of the solid-liquid separation zone is communicated with a lower-layer water inlet of the filler-microbial fuel cell zone, and a lower-layer sludge outlet of the solid-liquid separation zone is communicated with the anaerobic digestion zone;

the filler-microbial fuel cell area is sequentially provided with a crushed stone filler layer, a zeolite filler lower layer, a magnesia filler layer, a zeolite filler upper layer and an aquatic plant layer from bottom to top;

the filler-microbial fuel cell area is provided with an anode electrode and a cathode electrode, the anode electrode is arranged on the magnesia filler layer, the cathode electrode is partially arranged on the aquatic plant layer, the rest part of the cathode electrode is exposed out of the water surface and is communicated with the external air, and the anode electrode and the cathode electrode are connected with an external energy storage component through leads;

furthermore, a dosing device is arranged at the top of the magnetic powder-biological flocculation area and used for adding magnetic powder and a microbial extracellular enzyme flocculant;

the top of the magnetic powder-biological flocculation area is provided with flocculation stirring slurry for mixing magnetic powder and a microbial extracellular enzyme flocculant;

further preferably, the stirring speed of the flocculation stirring slurry is 100-300 r/min;

further preferably, the adding amount of the magnetic powder is 20-100mg/L, and the adding amount of the microbial extracellular enzyme flocculant is 1-3mL/100 mL.

Further, the preparation method of the microbial extracellular enzyme flocculant comprises the following steps:

A. activating the microbial bacteria to obtain activated microbial bacteria;

B. culturing the activated microbial bacteria to obtain a bacterial liquid;

C. adding the bacterial liquid into an inorganic salt culture medium for culturing to obtain a culture solution;

D. carrying out solid-liquid separation on the culture solution to obtain supernatant, and then precipitating to obtain a microbial extracellular enzyme flocculant;

preferably, the culturing time in the step B is 48-56 h;

preferably, the culturing time in the step C is 72-80 h;

preferably, the adding amount of the bacterial liquid in the step C is 5-7 mL;

preferably, the solid-liquid separation in step D comprises centrifugation;

preferably, the mode of precipitation in step D comprises ethanol precipitation.

Furthermore, a partition wall is arranged between the magnetic powder-biological flocculation area and the solid-liquid separation area and is used for separating the solid-liquid separation area and the magnetic powder-biological flocculation area.

Furthermore, the solid-liquid separation area is provided with a solid-liquid separation membrane for separating water and sludge.

Furthermore, the particle size of the crushed stone filler layer in the filler-microbial fuel cell area is 20-40mm, and the thickness of the crushed stone filler layer is 800-900 mm; the zeolite grain diameter of the lower layer of the zeolite filler is 8-16mm, and the thickness of the lower layer of the zeolite filler is 600-700 mm; the particle size of the magnesia packing layer is 1-3mm, and the thickness of the magnesia packing layer is 300-400 mm; the particle size of the zeolite on the upper layer of the zeolite filler is 3-5mm, and the thickness of the upper layer of the zeolite filler is 100-200 mm;

further preferably, the structures of the anode and the cathode of the filler-microbial fuel cell area are independent structures of activated carbon and stainless steel mesh.

Further, sludge stirring slurry is arranged at the bottom of the anaerobic digestion area and is used for stirring sludge;

further preferably, the stirring speed of the sludge stirring slurry is 300-;

the side wall of the anaerobic digestion area is provided with a constant temperature device for adjusting the temperature;

an emptying system is arranged outside the anaerobic digestion area and is used for emptying air;

and the top of the anaerobic digestion area is provided with a gate for controlling sludge to enter the anaerobic digestion area.

Further, the treatment system also comprises a disinfection pool and a water collecting pool;

the filler-microbial fuel cell zone is communicated with the disinfection tank;

the disinfection tank is used for disinfecting the water after nitrogen and phosphorus removal;

the disinfection tank is communicated with the water collecting tank;

the water collecting tank is used for collecting the disinfected water.

Further, the processing system further comprises a gas collecting device;

and an upper layer gas outlet of the anaerobic digestion area is communicated with a gas inlet of the gas collecting device.

In a second aspect, the invention provides a method for treating domestic sewage, which utilizes the treatment system to perform treatment, and comprises the following steps:

(a) the pretreated domestic sewage enters a magnetic powder-biological flocculation area for flocculation treatment to obtain wastewater and flocculated concentrated sludge;

(b) the wastewater and the flocculated and concentrated sludge obtained in the step (a) enter a solid-liquid separation zone for solid-liquid separation to obtain carbon source separation water and carbon source concentrated sludge;

(c) separating the water obtained from the carbon source in the step (b) and allowing the water to enter a filler-microbial fuel cell area for nitrogen and phosphorus removal to obtain water after nitrogen and phosphorus removal;

(d) and (c) allowing the carbon source concentrated sludge obtained in the step (b) to enter an anaerobic digestion area for anaerobic digestion to obtain methane.

Compared with the prior art, the invention has at least the following beneficial effects:

the domestic sewage treatment system comprises a magnetic powder-biological flocculation area, a solid-liquid separation area, a filler-microbial fuel cell area and an anaerobic digestion area, wherein the magnetic powder-biological flocculation area performs flocculation treatment on the wastewater by combining a biological flocculant prepared from magnetic powder and extracellular enzymes, and the magnetic powder is used as a flocculation mediator, so that the flocculation effect of organic matters of the wastewater can be enhanced, the separation efficiency of a carbon source is improved, and the solid-liquid separation effect is also enhanced; the biofuel cell system of the filler-microbial fuel cell area has the advantages that the removal effect of the system on nitrogen and phosphorus in wastewater is enhanced by arranging a structure of multiple layers of different fillers and arranging magnesia as anode filler of the fuel cell; the flocculation area and the anaerobic digestion area are in the same system, and can directly discharge flocculated sludge to the anaerobic digestion area, thereby avoiding the influence of odor generated in the sludge transfer process of the traditional process on the surrounding environment. The invention recovers energy through the fuel cell and anaerobic digestion, not only can effectively reduce the energy consumption of the system, but also can improve the energy utilization efficiency.

The domestic sewage treatment method is stable in operation, efficient and flexible in control.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a flow chart of a domestic sewage treatment process according to an embodiment of the present invention;

FIG. 2 is a system diagram of a domestic sewage treatment process according to an embodiment of the present invention.

The figure is as follows: 1-automatic medicine adding device; 2-flocculating and stirring the slurry; 3-partition wall; 4-solid-liquid separation membrane; 5-an electric gate; 6-sludge stirring slurry; 7-a constant temperature device; 8-evacuation system; 9-a gas collection device; 10-a stone filler; 11-a zeolite filler; 12-magnesia filler; 13-a zeolite filler; 14-aquatic plants; 15-an anode electrode; 16-a cathode electrode; 17-energy storage components.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

According to a first aspect of the present invention, a domestic sewage treatment system comprises a magnetic powder-bioflocculation zone, a solid-liquid separation zone, a filler-microbial fuel cell zone, and an anaerobic digestion zone;

the magnetic powder-biological flocculation area of the treatment system comprises a mixture of magnetic powder and a microbial extracellular enzyme flocculant; the lower part of the magnetic powder-biological flocculation area of the treatment system is communicated with the lower part of the solid-liquid separation area; the upper-layer water outlet of the solid-liquid separation zone of the treatment system is communicated with the lower-layer water inlet of the filler-microbial fuel cell zone, and the lower-layer sludge outlet of the solid-liquid separation zone is communicated with the anaerobic digestion zone; the filler-microbial fuel cell area of the treatment system is sequentially provided with a crushed stone filler layer, a zeolite filler lower layer, a magnesia filler layer, a zeolite filler upper layer and an aquatic plant layer from bottom to top, wherein a positive electrode is arranged on the magnesia filler layer, a negative electrode part is arranged on the aquatic plant layer, the rest part of the negative electrode is exposed out of the water surface and is communicated with the external air, and the positive electrode and the negative electrode are connected with an external energy storage component through leads.

The zeolite and the crushed stone of the packing layer can also be ceramsite, limestone, volcanic rock, shale and furnace slag; the magnesia of the packing layer can also be talcum powder and vermiculite; the filler crushed stone layer and the filler zeolite layer mainly filter SS (suspended pollutants) in water, provide a growth space for microorganisms and realize the nitrogen and phosphorus removal of wastewater; the filler magnesite of the invention mainly provides Mg²⁺Under the action of the fuel cell, the waste water reacts with nitrogen and phosphorus in the waste water to form struvite, and the struvite can be recycled; the aquatic plant layer decomposes and converts or enriches pollutants in water into a body through self life activities, then removes the pollutants, restores the nutrient balance in a water area, releases oxygen through the photosynthesis of the aquatic plants, increases the content of dissolved oxygen in the water, improves the water quality, and reduces or eliminates water pollution; the anode electrode is arranged on the magnesia packing layer and mainly utilizes the Mg in the magnesia packing layer²⁺Struvite is synthesized on the anode electrode, the cathode electrode is arranged on the aquatic plant layer, and part of the anode electrode is exposed out of the water surface because the anode electrode is contacted with air which is used as a cathode electrode reaction material.

The magnetic powder-biological flocculation area utilizes the microbial extracellular enzyme flocculant to carry out flocculation treatment, and simultaneously takes the magnetic powder as a flocculation mediator, so that the flocculation effect of organic matters in domestic sewage can be enhanced, and the separation efficiency of a carbon source is improved. The biofuel cell system disclosed by the invention has the advantages that the removal effect of the system on nitrogen and phosphorus in wastewater is enhanced by arranging the structure of multiple layers of different fillers and arranging the magnesia as the anode filler of the fuel cell; the magnetic powder-biological flocculation area and the anaerobic digestion area are arranged in the same system, so that carbon source concentrated sludge is directly discharged into the anaerobic digestion area for anaerobic digestion, and the influence of odor generated in the sludge transfer process in the traditional process on the surrounding environment is avoided. The treatment system of the invention recovers energy through two processes of fuel cell and anaerobic digestion, can effectively reduce the energy consumption of the system, and improves the energy utilization efficiency of the treatment process.

Magnetic powder-biological flocculation zone

In a preferred embodiment, the top of the magnetic powder-biological flocculation zone of the treatment system is provided with a dosing device, and the dosing device is used for adding the magnetic powder and the microbial extracellular enzyme flocculant.

In a preferred embodiment, the top of the magnetic particle-biological flocculation zone of the treatment system of the invention is provided with a flocculation stirring slurry, the flocculation stirring slurry is used for mixing the magnetic particles and the microbial extracellular enzyme flocculant, and the stirring rate of the flocculation stirring slurry is 100-300r/min, such as 100r/min, 150r/min, 200r/min, 250r/min, 300 r/min.

In a preferred embodiment, the magnetic powder of the present invention is added in an amount of 20-100mg/L, for example, 20mg/L, 40mg/L, 80mg/L, 100 mg/L; the addition amount of the microbial extracellular enzyme flocculant of the invention is 1-3mL/100mL, and typical but non-limiting addition amounts thereof are, for example, 1mL/100mL, 2mL/100mL, 3mL/100 mL.

The microbial extracellular enzyme flocculant is a flocculant prepared from extracellular enzyme substances generated by microbial metabolism, and is prepared by culturing microbial bacteria in a culture medium to metabolize the microbial bacteria to generate the extracellular enzyme substances, and collecting and purifying the extracellular enzyme substances as the flocculant by centrifugal separation, ethanol precipitation and other methods.

In a preferred embodiment, the preparation method of the microbial extracellular enzyme flocculant comprises the following steps:

A. activating the microbial bacteria to obtain activated microbial bacteria;

B. culturing the activated microorganism strain to obtain a bacterium solution;

C. adding the bacterial liquid into an inorganic salt culture medium for culturing to obtain a culture solution;

D. separating the culture solution from solid and liquid to obtain supernatant, and precipitating to obtain microbial extracellular enzyme flocculant;

wherein, the culture time in the step B is 48h-56h, and typical but non-limiting culture time is 48h, 50h, 52h and 56 h; the culture time in the step C is 72h-80h, and typical but non-limiting culture time is 72h, 74h, 76h and 80 h; the adding amount of the bacterial liquid in the step C is 5mL-7mL, and the adding amount of typical but non-limiting bacterial liquid is 5mL, 6mL, 7mL for example; the solid-liquid separation in step D includes but is not limited to centrifugation; the manner of precipitation in step D includes, but is not limited to, ethanol precipitation.

In a preferred embodiment, a partition wall is arranged between the magnetic particle-bioflocculation zone and the solid-liquid separation zone of the treatment system of the invention, and the partition wall is used for separating the solid-liquid separation zone and the magnetic particle-bioflocculation zone.

Solid-liquid separation zone

In a preferred embodiment, the solid-liquid separation zone of the treatment system of the present invention is provided with a solid-liquid separation membrane for separating wastewater and flocculation-concentrated sludge to obtain carbon source separated water and carbon source-concentrated sludge.

Filler-microbial fuel cell region

In a preferred embodiment, the crushed stone packing layer of the packing-microbial fuel cell zone of the treatment system of the present invention has a crushed stone particle size of 20-40mm, with typical but non-limiting particle sizes being, for example, 20mm, 25mm, 30mm, 35mm, 40 mm; the thickness of the gravel packing layer is 800-900mm, and the typical thickness of the gravel packing layer is 800mm and 900 mm; the zeolite particle size of the lower layer of zeolite filler is 8-16mm, with typical but non-limiting particle sizes such as 8mm, 10mm, 12mm, 14mm, 16 mm; the thickness of the lower layer of zeolite filler is 600-700mm, with typical but non-limiting thicknesses such as 600mm, 650mm, 700 mm; the magnesia particle size of the magnesia packing layer is 1-3mm, and the typical but non-limiting particle size is 1mm, 2mm and 3 mm; the thickness of the magnesia filler layer is 300-400mm, and typical but non-limiting thicknesses of the magnesia filler layer are 300mm, 350mm and 400 mm; the zeolite particle size of the upper layer of zeolite filler is 3-5mm, with typical but non-limiting particle sizes such as 3mm, 4mm, 5 mm; the thickness of the upper layer of zeolite filler is 100-200mm, with typical but non-limiting thicknesses such as 100mm, 150mm, 200 mm.

The specific filler and the thickness of the filler layer strengthen the removal effect of the system on nitrogen and phosphorus in the wastewater.

In a preferred embodiment, the positive electrode and the negative electrode of the filler-microbial fuel cell zone of the treatment system of the invention are respectively and independently an activated carbon and stainless steel net structure, and the activated carbon is coated on the stainless steel net structure which is used as a framework.

Anaerobic digestion zone

In a preferred embodiment, the bottom of the anaerobic digestion zone of the treatment system of the invention is provided with a sludge stirring slurry, the sludge stirring slurry is used for stirring the carbon source concentrated sludge, the stirring rate of the sludge stirring slurry is 300-500r/min, and typical but non-limiting stirring rates are 300r/min, 350r/min, 400r/min, 450r/min, 500 r/min;

wherein, the side wall of the anaerobic digestion area is provided with a constant temperature device which is used for adjusting the temperature; the outside of the anaerobic digestion area is provided with an emptying system which is used for emptying air; the top of the anaerobic digestion area is provided with a gate which is used for controlling the carbon source concentrated sludge to enter the anaerobic digestion area.

The anaerobic digestion area is provided with the constant temperature device, the emptying system and the plurality of sludge stirring paddles, so that the anaerobic digestion effect of the system on carbon source concentrated sludge can be effectively improved, and higher gas production rate can be maintained.

The treatment system also comprises a disinfection tank and a water collecting tank, specifically, the filler-microbial fuel cell area is communicated with the disinfection tank, and the disinfection tank is used for disinfecting water subjected to nitrogen and phosphorus removal; the disinfection tank of the invention is communicated with the water collecting tank, and the water collecting tank collects the disinfected water.

The treatment system further comprises a gas collecting device, specifically, an upper layer gas outlet of the anaerobic digestion area is communicated with a gas inlet of the gas collecting device, and the gas collecting device collects methane obtained by anaerobic digestion.

According to a second aspect of the present invention, a method for treating domestic sewage by using the above treatment system comprises the following steps:

(a) the pretreated domestic sewage enters a magnetic powder-biological flocculation area for flocculation treatment to obtain wastewater and flocculated concentrated sludge;

(b) the wastewater and the flocculated and concentrated sludge obtained in the step (a) enter a solid-liquid separation zone for solid-liquid separation to obtain carbon source separation water and carbon source concentrated sludge;

(c) separating the water obtained from the carbon source in the step (b) and allowing the water to enter a filler-microbial fuel cell area for nitrogen and phosphorus removal to obtain water after nitrogen and phosphorus removal;

(d) and (c) allowing the carbon source concentrated sludge obtained in the step (b) to enter an anaerobic digestion area for anaerobic digestion to obtain methane.

According to the treatment method of the domestic sewage, the domestic sewage is pretreated and then sequentially enters a magnetic powder-biological flocculation area for treatment and a solid-liquid separation area for treatment, so that carbon source separation water and carbon source concentrated sludge are obtained; discharging carbon source separated water obtained in the solid-liquid separation zone into a filler-biofuel cell zone for nitrogen and phosphorus removal treatment to obtain water subjected to nitrogen and phosphorus removal, then discharging the water into a disinfection tank, and discharging the water into a water collecting tank after disinfection to obtain purified water; and the residual flocculated sludge in the solid-liquid separation zone enters an anaerobic digestion zone at the lower part, methane is generated after anaerobic digestion, and the methane is recovered by a gas collection device, so that the resource application is realized. The domestic sewage treatment method is stable in operation, efficient and flexible in control.

The system and the method of the invention are specific to rural domestic sewage, and specifically, a system and a method for treating rural sewage by a typical reinforced carbon source separation-fuel cell wetland system are shown in figures 1-2:

mainly comprises the following steps:

1. the sewage is pretreated and then sequentially enters a magnetic powder biological flocculation area and a solid-liquid separation area;

2. the effluent from the solid-liquid separation zone enters a filler-biofuel cell zone through an upper layer water outlet, is discharged into a disinfection tank after denitrification and dephosphorization treatment, and is discharged into a water collecting tank after disinfection;

3. and the residual flocculated sludge in the solid-liquid separation zone enters a lower anaerobic digestion zone, is subjected to anaerobic digestion to generate methane, and is recovered through a gas collection device, so that the resource application is realized.

The treatment system comprises a magnetic powder-biological flocculation area, a solid-liquid separation area, a filler-microbial fuel cell area and an anaerobic digestion area. The magnetic powder biological flocculation area is provided with an automatic dosing device 1 and a flocculation stirring slurry 2, the dosing amount of the magnetic powder and microbial extracellular enzyme flocculant is determined according to the water inflow rate of domestic sewage, the magnetic powder and the microbial extracellular enzyme flocculant are added into the magnetic powder-biological flocculation area through the automatic dosing device 1, the flocculation stirring slurry 2 is used for mixing, the stirring speed of the flocculation stirring slurry 2 is 100-300r/min, and the dosing amount of the magnetic powder is as follows: 20-100mg/L (based on domestic sewage), and the adding amount of the microbial extracellular enzyme flocculant is 0.5-3mL/100mL (based on domestic sewage), wherein the preparation method of the microbial extracellular enzyme flocculant comprises the following steps: activating the microbial bacteria to obtain activated microbial bacteria; culturing the activated microorganism strains for 48 hours to obtain a bacterial liquid; adding 5mL of bacterial liquid into an inorganic salt culture medium, and culturing for 72h to obtain a culture solution; centrifuging the culture solution, taking the supernatant, precipitating with ethanol, precipitating extracellular polymers in the supernatant, transferring the precipitate into a centrifuge tube, and sealing with a sealant with small holes to obtain the microbial extracellular enzyme flocculant; a partition wall 3 is arranged between a magnetic powder-biological flocculation area and a solid-liquid separation area for separation, wastewater and flocculation concentrated sludge obtained from the magnetic powder-biological flocculation area enter the solid-liquid separation area through the lower part of the partition wall 3, a solid-liquid separation membrane 4 is arranged in the solid-liquid separation area, carbon source separation effluent and carbon source concentrated sludge are obtained by separating the wastewater and the flocculation concentrated sludge through the selective permeability of the membrane, and the carbon source separation effluent obtained from the solid-liquid separation area is discharged into a filler-biofuel cell area through an upper water outlet; the filler-biofuel cell area of the invention is sequentially provided with a gravel filler 10 (the particle size is 20-40mm, the thickness is 800-900mm), a zeolite filler 11 (the particle size is 8-16mm, the thickness is 600-700mm), a magnesia filler 12 (the particle size is 1-3mm, the thickness is 300-400mm) and a zeolite filler 13 (the particle size is 3-5mm, the thickness is 100-200mm), meanwhile, the surface layer of the filler-biofuel cell area is planted with aquatic plants 14, the aquatic plants 14 are fixed by the zeolite filler 13, the filler-biofuel cell area is respectively provided with an anode electrode 15 and a cathode electrode 16 and is respectively connected to an external energy storage component 17 by a copper lead, wherein the anode electrode 15 and the cathode electrode 16 both adopt an active carbon and stainless steel mesh structure, the anode electrode 15 is arranged on magnesia, the cathode electrode 16 is arranged on the aquatic plant layer, and part of the cathode electrode is exposed out of the water surface and communicated with the external air; the water separated from the carbon source is discharged after denitrification and dephosphorization treatment in the filler-biofuel cell area, and is discharged into a water collecting tank after being disinfected in a disinfection tank; an electric gate 5 is arranged between a solid-liquid separation area and an anaerobic digestion area, the electric gate 5 is controlled by a control system, when the settled sludge in the solid-liquid separation area reaches a certain weight, the electric gate 5 is opened, carbon source concentrated sludge obtained in the solid-liquid separation area is discharged into the anaerobic digestion area for anaerobic digestion to obtain methane, a plurality of sludge stirring slurries 6 are arranged inside the anaerobic digestion area, the sludge stirring slurries 6 are used for fully stirring the carbon source concentrated sludge, the stirring speed is 300-500r/min, a constant temperature device 7 is arranged inside the anaerobic digestion area, the constant temperature device 7 is used for adjusting the temperature, an emptying system 8 is arranged outside the anaerobic digestion area, the emptying system 8 is used for emptying air, a gas collecting device 9 is connected outside the anaerobic digestion area, and the gas collecting device 9 is used for collecting the methane obtained by anaerobic digestion.

The invention is further illustrated by the following examples. The materials in the examples are prepared according to known methods or are directly commercially available, unless otherwise specified.

Example 1

Domestic sewage (COD 203 mg/L; ammonia nitrogen 76 mg/L; TP 31mg/L) is discharged into a magnetic powder-biological flocculation area for flocculation treatment, wherein the stirring speed of the flocculation area is 150r/min, and the adding amount of the magnetic powder is as follows: 40mg/L, and the adding amount of the microbial extracellular enzyme flocculant is 0.5mL/100mL, so that the wastewater and the flocculated and concentrated sludge are obtained;

discharging the wastewater and the flocculation concentrated sludge obtained in the magnetic powder-biological flocculation area into a solid-liquid separation area, and separating by the solid-liquid separation area to obtain carbon source separation water and carbon source concentrated sludge;

the carbon source separated water obtained in the solid-liquid separation zone is discharged into a filler-biofuel cell zone for denitrification and desulfurization treatment to obtain water after denitrification and dephosphorization, and then the water is disinfected to obtain purified water, wherein the filler-biofuel cell zone is sequentially provided with a rubble layer, a zeolite filler layer, a magnesia filler layer and the zeolite filler layer from bottom to top;

and (3) discharging the carbon source concentrated sludge obtained in the solid-liquid separation zone into an anaerobic digestion zone for anaerobic digestion treatment to obtain methane, and then discharging the methane into a gas collection device.

Example 2

Domestic sewage (COD 194mg/L, ammonia nitrogen 80mg/L and TP 27mg/L) is discharged into a magnetic powder-biological flocculation area for flocculation treatment, wherein the stirring speed of the flocculation area is 150r/min, and the adding amount of the magnetic powder is as follows: 70mg/L, and the adding amount of the microbial extracellular enzyme flocculant is 0.5mL/100mL, so as to obtain wastewater and flocculated and concentrated sludge;

discharging the wastewater and the flocculation concentrated sludge obtained in the magnetic powder-biological flocculation area into a solid-liquid separation area, and separating by the solid-liquid separation area to obtain carbon source separation water and carbon source concentrated sludge;

the carbon source separated water obtained in the solid-liquid separation zone is discharged into a filler-biofuel cell zone for denitrification and desulfurization treatment to obtain water after denitrification and dephosphorization, and then the water is disinfected to obtain purified water, wherein the filler-biofuel cell zone is sequentially provided with a rubble layer, a zeolite filler layer, a magnesia filler layer and the zeolite filler layer from bottom to top;

and (3) discharging the carbon source concentrated sludge obtained in the solid-liquid separation zone into an anaerobic digestion zone for anaerobic digestion treatment to obtain methane, and then discharging the methane into a gas collection device.

Example 3

Domestic sewage (COD 231 mg/L; ammonia nitrogen 65 mg/L; TP 17mg/L) is discharged into a magnetic powder-biological flocculation area for flocculation treatment, wherein the stirring speed of the flocculation area is 150r/min, and the adding amount of the magnetic powder is as follows: 100mg/L, and the adding amount of the microbial extracellular enzyme flocculant is 0.5mL/100mL, so as to obtain wastewater and flocculated and concentrated sludge;

discharging the wastewater and the flocculation concentrated sludge obtained in the magnetic powder-biological flocculation area into a solid-liquid separation area, and separating by the solid-liquid separation area to obtain carbon source separation water and carbon source concentrated sludge;

the carbon source separated water obtained in the solid-liquid separation zone is discharged into a filler-biofuel cell zone for denitrification and desulfurization treatment to obtain water after denitrification and dephosphorization, and then the water is disinfected to obtain purified water, wherein the filler-biofuel cell zone is sequentially provided with a rubble layer, a zeolite filler layer, a magnesia filler layer and the zeolite filler layer from bottom to top;

and (3) discharging the carbon source concentrated sludge obtained in the solid-liquid separation zone into an anaerobic digestion zone for anaerobic digestion treatment to obtain methane, and then discharging the methane into a gas collection device.

Example 4

Domestic sewage (COD 210mg/L, ammonia nitrogen 73mg/L and TP 21mg/L) is discharged into a magnetic powder-biological flocculation area for flocculation treatment, wherein the stirring speed of the flocculation area is 150r/min, and the adding amount of the magnetic powder is as follows: 70mg/L, and the adding amount of the microbial extracellular enzyme flocculant is 1.5mL/100mL, so as to obtain wastewater and flocculated and concentrated sludge;

discharging the wastewater and the flocculation concentrated sludge obtained in the magnetic powder-biological flocculation area into a solid-liquid separation area, and separating by the solid-liquid separation area to obtain carbon source separation water and carbon source concentrated sludge;

the carbon source separated water obtained in the solid-liquid separation zone is discharged into a filler-biofuel cell zone for denitrification and desulfurization treatment to obtain water after denitrification and dephosphorization, and then the water is disinfected to obtain purified water, wherein the filler-biofuel cell zone is sequentially provided with a rubble layer, a zeolite filler layer, a magnesia filler layer and the zeolite filler layer from bottom to top;

and (3) discharging the carbon source concentrated sludge obtained in the solid-liquid separation zone into an anaerobic digestion zone for anaerobic digestion treatment to obtain methane, and then discharging the methane into a gas collection device.

Example 5

Domestic sewage (COD 207mg/L, ammonia nitrogen 86mg/L and TP 27mg/L) is discharged into a magnetic powder-biological flocculation area for flocculation treatment, wherein the stirring speed of the flocculation area is 150r/min, and the adding amount of the magnetic powder is as follows: 70mg/L, and the adding amount of the microbial extracellular enzyme flocculant is 3mL/100mL, so that the wastewater and the flocculated and concentrated sludge are obtained;

discharging the wastewater and the flocculation concentrated sludge obtained in the magnetic powder-biological flocculation area into a solid-liquid separation area, and separating by the solid-liquid separation area to obtain carbon source separation water and carbon source concentrated sludge;

the carbon source separated water obtained in the solid-liquid separation zone is discharged into a filler-biofuel cell zone for denitrification and desulfurization treatment to obtain water after denitrification and dephosphorization, and then the water is disinfected to obtain purified water, wherein the filler-biofuel cell zone is sequentially provided with a rubble layer, a zeolite filler layer, a magnesia filler layer and the zeolite filler layer from bottom to top;

and (3) discharging the carbon source concentrated sludge obtained in the solid-liquid separation zone into an anaerobic digestion zone for anaerobic digestion treatment to obtain methane, and then discharging the methane into a gas collection device.

Comparative example 1

Discharging domestic sewage (COD is 243mg/L, ammonia nitrogen is 82mg/L, TP is 19mg/L) into a flocculation area for flocculation treatment, wherein the stirring speed of the flocculation area is 150r/min, magnetic powder is not added, the adding amount of a microbial extracellular enzyme flocculant is 1.5mL/100mL, and wastewater and flocculated concentrated sludge are obtained;

discharging the wastewater and the flocculation concentrated sludge obtained in the flocculation area into a solid-liquid separation area, and separating by the solid-liquid separation area to obtain carbon source separation water and carbon source concentrated sludge;

the carbon source separated water obtained in the solid-liquid separation zone is discharged into a filler-biofuel cell zone for denitrification and desulfurization treatment to obtain water after denitrification and dephosphorization, and then the water is disinfected to obtain purified water, wherein the filler-biofuel cell zone is sequentially provided with a rubble layer, a zeolite filler layer, a magnesia filler layer and the zeolite filler layer from bottom to top;

and (3) discharging the carbon source concentrated sludge obtained in the solid-liquid separation zone into an anaerobic digestion zone for anaerobic digestion treatment to obtain methane, and then discharging the methane into a gas collection device.

Comparative example 2

The comparative example is different from example 1 in that the comparative example is not provided with the magnetic powder-bioflocculation zone, and the rest is the same as example 1.

Comparative example 3

The comparative example is different from example 1 in that the comparative example is not provided with a filler-microbial fuel cell region, and the rest is the same as example 1.

Test examples

The purified water obtained in examples 1 to 5 and comparative examples 1 to 3 was measured by the COD measuring method: the dichromate method GB 11914-89; the ammonia nitrogen determination method comprises the following steps: salicylic acid spectrophotometry HJ 536-2009; the method for measuring total phosphorus TP: ammonium molybdate spectrophotometry GB 11893-891. The results are shown in Table 1.

Results of measurement of examples 1 to 5 and comparative examples 1 to 3 Table 1

	Example 1	Example 2	Example 3	Example 4	Example 5	Comparative example 1	Comparative example 2	Comparative example 3
									COD removal Rate (%)	79.3	78.4	80.1	83.7	86.4	72.4	58.4	64.2
Ammonia nitrogen removal (%)	87.2	88.1	90.3	93.1	95.7	81.3	73.2	68.1
									TP removal Rate (%)	88.7	90.1	91.9	94.8	97.3	83.2	74.3	70.2

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.