Sewage treatment system and sewage treatment method

Abstract

The invention relates to a sewage treatment system and a sewage treatment method. The sewage treatment system comprises an aeration tank and a solid-liquid separator, the aeration tank comprises an aeration tank body, the tank body of the aeration tank is provided with an octagonal side wall, and the octagonal side wall comprises a first straight face wall, a second straight face wall, a third straight face wall, a fourth straight face wall, a fifth straight face wall, a sixth straight face wall, a seventh straight face wall and an eighth straight face wall which are sequentially connected end to end in the horizontal direction; a first water inlet and a first water outlet are formed in the first straight surface wall, and a second water inlet and a second water outlet are formed in the fifth straight surface wall; a muddy water outlet is formed in the third straight surface wall; and the muddy water outlet is in fluid communication with the water inlet of the solid-liquid separator. When the sewage treatment system disclosed by the invention is used for treating sewage, the denitrification effect is good, suspended solids in effluent are low, and the energy consumption and the cost are relatively low.

Description

Technical Field

[0001] The present application relates to a sewage treatment system and a sewage treatment method. Background Art

[0002] With the progress of industrialization and urbanization in my country, a large amount of industrial and domestic pollutants are discharged into the environment, causing increasingly serious pollution to water bodies. The deteriorating water quality not only causes water shortages in many areas and increases the cost of obtaining water resources for the entire society, but also endangers people's health. Therefore, it is necessary to treat the wastewater containing pollutants so that it can meet the discharge standards. Biochemical treatment technology has become the mainstream technology for sewage treatment because of its advantages such as good treatment effect and low treatment cost.

[0003] Biological sewage treatment is divided into biofilm method and activated sludge method according to the presence or absence of carriers. The treatment efficiency of biofilm method is usually higher than that of activated sludge method. In order to improve the treatment effect of biochemical reactions, biofilm reactors filled with solid carriers have been developed, such as biological fluidized bed reactors (MBBR). In the reactor, microorganisms attach and grow on the surface of the carrier to form microbial biofilms. Pollutants are degraded and transformed through the biochemical reactions of microorganisms in the biofilm and the adsorption and interception of the carrier layer. The fluidized bed reactor filled with carriers has a high microbial biomass. It has strong resistance to shock loads, can effectively separate the hydraulic retention time (HRT) and the sludge retention time (SRT), has low operation and maintenance costs, and is an ideal reactor form. Therefore, it has been widely studied.

[0004] For example, CN108191048B provides a sludge internal circulation MBBR sewage treatment device and its application, the device includes a tank body and a baffle; the tank body is divided into three sections by two outer baffles, the middle section is a sedimentation zone, and the two ends are aerobic MBBR reaction zones; the lower part of the outer baffle is inclined along the sedimentation zone, and the bottom of the outer baffle constitutes a sludge return port, which is arranged higher than the bottom of the tank, so that the sedimentation zone and the bottom of the aerobic MBBR reaction zone are connected; a water inlet is arranged on the upper part of the outer baffle; a group of inner baffles are arranged in parallel with the upper part of the inner baffle in the sedimentation zone; a connecting ditch is arranged between the inner baffle and the outer baffle; the aerobic MBBR reaction zone and the water inlet, the connecting ditch, the sedimentation zone and the sludge return port constitute a sludge internal circulation; the hydraulic retention time of the device is independent of the sludge age, the sludge discharge cycle and the discharge amount are easy to adjust, the device has a compact structure, good denitrification effect on township sewage with a low C / N ratio, high resistance to COD shock load, and less residual sludge.

[0005] Although the above-mentioned biological fluidized bed method has advantages over the conventional activated sludge method, the conventional biological fluidized bed method also has problems such as large area occupied by the sludge sedimentation area, need for sludge return, high energy consumption, high content of suspended solids in effluent, etc. Therefore, it is necessary to develop a reactor with good treatment effect, small area occupied, low energy consumption, and low suspended solids in effluent. Summary of the invention

[0006] The purpose of the present disclosure is to provide a sewage treatment system and a sewage treatment method. The sewage treatment system of the present disclosure has good denitrification effect when used to treat sewage, low suspended solids in effluent, and low energy consumption and cost.

[0007] In order to achieve the above-mentioned object, the present disclosure provides a sewage treatment system in a first aspect, the sewage treatment system comprising an aeration tank and a solid-liquid separator;

[0008] The aeration tank comprises an aeration tank body, the aeration tank body has an octagonal side wall, and the octagonal side wall comprises a first straight wall, a second straight wall, a third straight wall, a fourth straight wall, a fifth straight wall, a sixth straight wall, a seventh straight wall and an eighth straight wall which are connected end to end in a horizontal direction;

[0009] The first facing wall is provided with a first water inlet and a first water outlet, the fifth facing wall is provided with a second water inlet and a second water outlet; the third facing wall is provided with a muddy water outlet; the muddy water outlet is fluidically connected to the water inlet of the solid-liquid separator.

[0010] Optionally, the width of the third straight wall is recorded as L1, the endpoint where the first straight wall connects with the top of the second straight wall is recorded as a, the endpoint where the fourth straight wall connects with the top of the fifth straight wall is recorded as b, the length of the line segment ab is recorded as L2, and the ratio of L2 to L1 is (1.5-20):1, preferably (2-10):1;

[0011] The width of the seventh straight wall is recorded as L3, the endpoint where the fifth straight wall is connected to the top of the sixth straight wall is recorded as c, the endpoint where the eighth straight wall is connected to the top of the first straight wall is recorded as d, the length of the line segment cd is recorded as L4, and the ratio of L4 to L3 is (1.5-20):1, preferably (2-10):1;

[0012] The height between the line segment ab and the line segment cd is denoted as H, and the ratio of L2, L4 and H is (2.0-10.0):(2.0-10.0):1, preferably (3.0-5.0):(3.0-5.0):1.

[0013] Optionally, the line segment ab is parallel to the top edge of the first straight wall, the line segment cd is parallel to the top edge of the seventh straight wall, and endpoints a, b, c and d form a rectangle.

[0014] Optionally, the first water inlet and the second water outlet are arranged diagonally, and the second water inlet and the first water outlet are arranged diagonally.

[0015] Optionally, an aeration device is provided on the bottom surface of the aeration tank body, and the aeration device is selected from one or more of a microporous aerator, a hose aerator and a disc-type flat plate aerator.

[0016] Optionally, fillers are further provided in the aeration tank body, and the total volume of the fillers accounts for 30-40% of the volume of the tank body;

[0017] The filler is one or more of plastic filler, sponge filler and polyurethane filler, preferably plastic filler;

[0018] The shape of the filler is one or more of a sphere, a cylinder and a cube, preferably a sphere, and the diameter of the sphere is 5-20 mm.

[0019] Optionally, the solid-liquid separator has a separation chamber, the separation chamber comprises a straight section and an inverted cone section at the lower part of the straight section, and the straight section and the cone section are fluidically connected;

[0020] A mud discharge port is arranged at the cone tip of the inverted cone section, and a supernatant outlet is arranged on the side wall of the straight cylinder section, and the supernatant outlet is fluidly connected to the first water inlet and / or the second water inlet; a water inlet pipe is arranged in the straight cylinder section, and the upper end opening of the water inlet pipe forms the water inlet of the solid-liquid separator.

[0021] A second aspect of the present disclosure provides a method for treating sewage using the sewage treatment system provided by the first aspect of the present disclosure, the method comprising:

[0022] S1, firstly introducing the sewage to be treated into the aeration tank from the first water inlet for treatment, then discharging the clean water from the second water outlet, and discharging the muddy water from the muddy water outlet and then sending it into the solid-liquid separator;

[0023] S2, switching the water inlet, introducing the sewage to be treated into the aeration tank from the second water inlet for treatment, discharging clean water from the first water outlet, and draining muddy water from the muddy water outlet and then sending it to the solid-liquid separator;

[0024] S3, step S1 and step S2 are performed alternately.

[0025] Optionally, the dissolved oxygen concentration in the aeration tank is 2-4 mg / L, the hydraulic retention time of the sewage to be treated in the aeration tank is 2-80 h, and the treatment temperature is 25-35° C.; the residence time of the muddy water in the solid-liquid separator is 0.5-16 h.

[0026] Optionally, the COD of the sewage to be treated is 200-800 mg / L, and the sludge concentration is 2500-3500 mg / L.

[0027] Through the above technical scheme, the system disclosed in the present invention has an octahedral aeration tank which can realize the division of anoxic zone and aerobic zone in the same tank, and then combine it with alternating water inlet and outlet to realize the redistribution of fillers, which can minimize the nitrogen in the effluent and remove suspended matter in the water, and has low energy consumption and cost.

[0028] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0030] Figure 1 It is a structural schematic diagram of a specific implementation of an aeration tank of a sewage treatment system disclosed in the present invention.

[0031] Figure 2 It is a structural schematic diagram of a specific implementation of the solid-liquid separator of the sewage treatment system disclosed in the present invention.

[0032] Description of Reference Numerals

[0033] 1. First water inlet 2. First water outlet 3. Second water inlet

[0034] 4. Second water outlet 5. Mud and water outlet 6. Water inlet

[0035] 7. Aeration device 8. Mud discharge port 9. Supernatant outlet

[0036] 10. Filler DETAILED DESCRIPTION

[0037] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0038] In the present disclosure, unless otherwise specified, directional words such as “inside” and “outside” refer to the inside and outside where the system of the present disclosure can be normally used.

[0039] like Figure 1As shown, the first aspect of the present disclosure provides a sewage treatment system, which includes an aeration tank and a solid-liquid separator; the aeration tank includes an aeration tank body, the aeration tank body has an octagonal side wall, and the octagonal side wall includes a first straight wall, a second straight wall, a third straight wall, a fourth straight wall, a fifth straight wall, a sixth straight wall, a seventh straight wall and an eighth straight wall connected in sequence end to end in the horizontal direction; the first straight wall is provided with a first water inlet 1 and a first water outlet 2, the fifth straight wall is provided with a second water inlet 3 and a second water outlet 4; the third straight wall is provided with a muddy water outlet 5; the muddy water outlet 5 is fluidically connected to the water inlet 6 of the solid-liquid separator.

[0040] The sewage treatment system disclosed in the present invention has an aeration tank body with an octahedral structure and two water inlets and two water outlets for alternate water inlet. The octagonal tank body is wider in the middle and narrower at the front and rear ends. As the water flow advances, the suspended fillers in the aeration tank gradually accumulate toward the downstream of the water flow, i.e., the end of the tank body, wherein the end of the tank body downstream of the water flow is narrower, with more accumulated fillers, a high concentration of microorganisms, and a faster oxygen consumption rate, forming a lower concentration dissolved oxygen zone; while the middle part of the tank body in the middle of the water flow has less fillers and a high dissolved oxygen concentration, forming a higher concentration dissolved oxygen zone. The above octahedral structure of the reaction tank can realize the division of anoxic zones and aerobic zones in the same reaction tank, can realize the denitrification process of nitrification and denitrification, and the phosphorus removal process of its own phosphorus release and phosphorus accumulation, thereby improving the system's ability to remove pollutants. At the same time, combined with alternating water inflow, the filler in the aeration tank is redistributed, effectively reducing the dead zone, so that the system disclosed in the present invention can remove nitrogen and suspended matter in the sewage to the maximum extent when applied in the sewage treatment process. The system disclosed in the present invention does not require backwashing and sludge return, and has the advantages of low treatment cost and energy saving.

[0041] In a specific embodiment of the present disclosure, the width of the third straight wall is recorded as L1, the endpoint where the first straight wall connects to the top of the second straight wall is recorded as a, the endpoint where the fourth straight wall connects to the top of the fifth straight wall is recorded as b, the length of the line segment ab is recorded as L2, and the ratio of L2 to L1 is (1.5-20): 1, preferably (2-10): 1. According to the present disclosure, the width L1 of the third straight wall can vary in a large range, for example, it can be 0.5-5m, preferably 1.0-2.0m.

[0042] In a specific embodiment of the present disclosure, the width of the seventh straight wall is recorded as L3, the endpoint where the fifth straight wall is connected to the top of the sixth straight wall is recorded as c, the endpoint where the eighth straight wall is connected to the top of the first straight wall is recorded as d, the length of the line segment cd is recorded as L4, and the ratio of L4 to L3 is (1.5-20): 1, preferably (2-10): 1. According to the present disclosure, the width L3 of the seventh straight wall can vary in a large range, for example, it can be 0.5-5m, preferably 1.0-2.0m.

[0043] In a specific embodiment of the present disclosure, the height between the line segment ab and the line segment cd is recorded as H, and the ratio of L2, L4 and H is (2.0-10.0): (2.0-10.0): 1, preferably (3.0-5.0): (3.0-5.0): 1. In the above embodiment, the structure of the aeration tank is more reasonable, which can improve its treatment effect on sewage, thereby further effectively removing nitrogen from sewage and reducing the content of suspended matter in water.

[0044] In a specific embodiment of the present disclosure, the line segment ab is parallel to the top edge of the first straight wall, the line segment cd is parallel to the top edge of the seventh straight wall, and the end points a, b, c and d form a rectangle. More preferably, L1 is equal to L3, and the width of the second straight wall, the width of the fourth straight wall, the width of the sixth straight wall and the width of the eighth straight wall are the same. In the above embodiment, the aeration tank body has a symmetrical octagonal structure, which can further improve the effect of the system of the present disclosure in removing nitrogen from sewage and removing suspended matter.

[0045] According to the present disclosure, the present disclosure does not specifically limit the height of each straight wall of the octagonal pool body, and can be selected according to actual needs. In one embodiment, the heights of the first straight wall, the second straight wall, the third straight wall, the fourth straight wall, the fifth straight wall, the sixth straight wall, the seventh straight wall and the eighth straight wall are the same or different, preferably the same, and the height of each straight wall can be independently 0.2-1.0, preferably 0.5-0.7.

[0046] In a preferred specific embodiment of the present disclosure, the first water inlet 1 is diagonally arranged with the second water outlet 4, and the second water inlet 3 is diagonally arranged with the first water outlet 2. The present disclosure does not limit the specific positions of the first water inlet and the first water outlet on the first straight wall, and the positions of the second water outlet 4 and the second water inlet 3 on the fifth straight wall, which can be selected according to actual needs.

[0047] In a preferred embodiment of the present disclosure, an aeration device 7 is provided on the bottom surface of the aeration tank. The aeration device is well known to those skilled in the art, for example, the aeration device can be selected from one or more of a microporous aerator, a hose aerator and a disc-type flat plate aerator.

[0048] In a specific embodiment of the present disclosure, a filler 10 is further provided in the aeration tank body, and the total volume of the filler accounts for 30-40% of the volume of the tank body, preferably 32-36%. According to the present disclosure, the volume of the tank body can vary within a large range, for example, it can be 0.4-180m 3 , preferably 4.0-20m 3 .

[0049] According to the present disclosure, the type of filler in the aeration tank can be conventionally used by those skilled in the art. In one embodiment, the filler is one or more of a plastic filler, a sponge filler and a polyurethane filler, preferably a plastic filler. The present disclosure does not specifically limit the form of the filler, and the shape of the filler can be, for example, one or more of a sphere, a cylinder and a cube, preferably a sphere, and the diameter of the sphere can vary in a large range, for example, it can be 5-20 mm, preferably 8-12 mm.

[0050] like Figure 2 As shown, in a specific embodiment of the present disclosure, the solid-liquid separator has a separation chamber, and the separation chamber includes a straight section and an inverted cone section at the lower part of the straight section, and the straight section and the cone section are fluidically connected; a mud discharge port 8 is provided at the cone tip of the inverted cone section, and a supernatant outlet 9 is provided on the side wall of the straight section, and the supernatant outlet 9 is fluidically connected to the first water inlet 1 and / or the second water inlet 3; a water inlet pipe is provided in the straight section, and the upper end opening of the water inlet pipe forms the water inlet 6 of the solid-liquid separator. The solid-liquid separator in the system of the present disclosure can realize mud and water separation, and return the separated water to the aeration tank for further treatment without backwashing and sludge reflux, and has the advantages of low treatment cost and energy saving.

[0051] The second aspect of the present disclosure provides a method for treating sewage by using the sewage treatment system provided by the first aspect of the present disclosure, the method comprising: S1, first introducing the sewage to be treated from the first water inlet 1 into the aeration tank for treatment, then discharging clean water from the second water outlet 4, and leading muddy water from the muddy water outlet 5 and then sending it to the solid-liquid separator; S2, switching the water inlet, introducing the sewage to be treated from the second water inlet 3 into the aeration tank for treatment, then discharging clean water from the first water outlet 2, and leading muddy water from the muddy water outlet 5 and then sending it to the solid-liquid separator; S3, alternately performing step S1 and step S2.

[0052] According to the present disclosure, there is no specific limitation on the time of water inletting in step S1 and step S2. In one embodiment, the water inletting time in each step S1 is 60-2400 min, preferably 120-720 min, and the water inletting time in each step S2 is 60-2400 min, preferably 120-720 min.

[0053] The method disclosed in the present invention uses an alternating water inlet method to treat the sewage to be treated in the sewage treatment system, which can achieve maximum removal of nitrogen and suspended matter in the sewage to be treated, with a small footprint and low energy consumption.

[0054] In a specific embodiment of the present disclosure, the dissolved oxygen concentration in the aeration tank is 2-4 mg / L, preferably 2.5-3.5 mg / L, the treatment temperature is 25-35°C, preferably 28-32°C, the hydraulic retention time of the sewage to be treated in the aeration tank is 2-80h, preferably 4-12h; the retention time of the muddy water in the solid-liquid separator is 0.5-16h, preferably 1-3h. Under the above conditions, nitrogen in the sewage can be effectively removed and suspended matter can be removed.

[0055] In a specific embodiment of the present disclosure, the COD of the sewage to be treated is 200-800 mg / L, and the sludge concentration is 2500-3500 mg / L.

[0056] The present disclosure is further illustrated below by way of examples, but the present disclosure is not limited thereby.

[0057] Example 1

[0058] like Figure 1 and Figure 2 As shown, the sewage treatment system adopted in this embodiment includes an aeration tank and a solid-liquid separator. The aeration tank includes an aeration tank body, the aeration tank body has an octagonal side wall, the effective volume is 1.5L, and the octagonal side wall includes a first straight wall, a second straight wall, a third straight wall, a fourth straight wall, a fifth straight wall, a sixth straight wall, a seventh straight wall and an eighth straight wall in the horizontal direction, which are connected end to end and have the same height; the first straight wall is provided with a first water inlet 1 and a first water outlet 2, and the fifth straight wall is provided with a second water inlet 3 and a second water outlet 4; the third straight wall is provided with a muddy water outlet 5; the muddy water outlet 5 is fluidically connected with the water inlet 6 of the solid-liquid separator; a microporous aerator and a plastic spherical filler with a diameter of 10.0mm are provided on the bottom surface of the aeration tank body, and the total volume of the filler accounts for 35% of the tank body volume.

[0059] Among them, the width of the third straight wall is recorded as L1, the endpoint connecting the top of the first straight wall and the second straight wall is recorded as a, the endpoint connecting the top of the fourth straight wall and the fifth straight wall is recorded as b, the length of the line segment ab is recorded as L2, and the ratio of L2 to L1 is 2.0:1, the width of the seventh straight wall is recorded as L3, the endpoint connecting the top of the fifth straight wall and the sixth straight wall is recorded as c, the endpoint connecting the top of the eighth straight wall and the first straight wall is recorded as d, the length of the line segment cd is recorded as L4, and the ratio of L4 to L3 is 2.0:1, the height between the line segment ab and the line segment cd is recorded as H, and the ratio of L2, L4 to H is 3.0:3.0:1. The line segment ab is parallel to the top edge of the first straight wall, the line segment cd is parallel to the top edge of the seventh straight wall, and the endpoints a, b, c and d form a rectangle.

[0060] The solid-liquid separator has a separation chamber, which includes a straight section and an inverted cone section at the lower part of the straight section, and the straight section and the cone section are fluidically connected; a mud discharge port 8 is provided at the cone tip of the inverted cone section, and a supernatant outlet 9 is provided on the side wall of the straight section, and the supernatant outlet 9 is fluidically connected to the first water inlet 1 and / or the second water inlet 3; a water inlet pipe is provided in the straight section, and the upper end opening of the water inlet pipe forms a water inlet 6 of the solid-liquid separator.

[0061] The method of treating sewage using the above system is as follows:

[0062] S1. First, the sewage to be treated is introduced into the aeration tank from the first water inlet for treatment, and the clean water is discharged from the second water outlet. The muddy water is introduced from the muddy water outlet and sent to the solid-liquid separator for mud-water separation. The residence time of the muddy water in the solid-liquid separator is 2 hours. The separated supernatant is introduced from the supernatant outlet and then circulated into the first water inlet, and the mud is discharged from the mud outlet. The water intake time of this step is 8 hours;

[0063] S2, switch the water inlet, introduce the treated sewage into the aeration tank from the second water inlet for treatment, discharge the clean water from the first water outlet, and send the muddy water from the muddy water outlet to the solid-liquid separator for mud-water separation. The residence time of the muddy water in the solid-liquid separator is 2 hours. The separated supernatant is introduced from the supernatant outlet and then circulated into the second water inlet, and the mud is discharged from the mud outlet. The water intake time of this step is 8 hours;

[0064] S3, step S1 and step S2 are performed alternately, wherein the hydraulic retention time of the sewage in the aeration tank is 24h, the sludge concentration is 3320mg / L, the temperature is 30±1°C, and the dissolved oxygen is controlled at 2.5mg / L.

[0065] The wastewater to be treated in this method is 50% diluted coal gasification ash water, the pH of the ash water is 8.25, the ammonia nitrogen content is 525mg / L, the COD is 205mg / L, and the initial water inlet ratio is 40 volume% coal gasification ash water + 60 volume% distribution water (only part of the alkalinity is supplemented, and the pH is adjusted to 8.3 to facilitate the start-up of the process), and then the water inlet ratio is gradually increased. Specifically: after 40 days of continuous operation, the initial water inlet is 40 volume% ash water, the ammonia nitrogen content of the inlet water is 220-230mg / L, and the ammonia nitrogen content of the effluent is gradually reduced from 112.6mg / L to below 20mg / L through acclimation and adjustment of operating conditions, and the denitrification load is 0.17kgN / m 3 / d; from the 15th day, the gray water ratio of the influent was increased to 50% by volume, and the effluent fluctuated slightly. The effluent ammonia nitrogen increased to 56mg / L, and then slowly decreased to 20mg / L, and the denitrification load increased to 0.20kgN / m 3 / d; On the 25th day, the proportion of gray water in the influent continued to increase to 60% volume, the ammonia nitrogen content of the influent reached 300-320 mg / L, and the ammonia nitrogen content of the effluent was raised to 68 mg / L in the early stage. By adjusting the aeration control, there was no obvious accumulation of nitrite nitrogen, and the ammonia nitrogen content of the effluent dropped to a minimum of 13.8 mg / L. The total nitrogen content of the effluent was 53.5 mg / L, the ammonia nitrogen removal rate reached 95.4%, and the total nitrogen removal rate reached 82.3%.

[0066] Example 2

[0067] The device and method in Example 1 are used to treat sewage, except that the sewage is the effluent from a one-piece anaerobic ammonia oxidation reactor in this laboratory that treats nitrogen-containing petrochemical wastewater, and the ammonia nitrogen content in the sewage is 10-20 mg / L, the nitrate nitrogen concentration is 30-40 mg / L, and the COD is 110-150 mg / L.

[0068] On the basis of Example 1, denitrifying bacteria were inoculated, the sludge concentration was controlled at 3000-4000 mg / L, sodium acetate was added as a carbon source, the influent COD was increased to about 250 mg / L, the dissolved oxygen was controlled at 0.5-1.0 mg / L by reducing aeration, and the simultaneous nitrification and denitrification process was gradually started.

[0069] After 10 days of continuous operation, the effluent ammonia nitrogen was reduced to below 1.0 mg / L, the nitrate nitrogen was reduced to below 10 mg / L, there was no accumulation of nitrite nitrogen, the effluent COD was 80-120 mg / L, the effluent total nitrogen was as low as 5.6 mg / L, and the denitrification rate was 88.6%.

[0070] Example 3

[0071] In the system of Example 1, the same method as in Example 1 is used to treat sewage, except that the structural parameters of the aeration tank are different from those in Example 1, the ratio of L2 to L1 is 1.2:1, the ratio of L4 to L3 is 1.2:1, the height between line segment ab and line segment cd is denoted as H, the ratio of L2, L4 to H is 4.0:4.0:1, and the effective volume of the aeration tank is 560L.

[0072] The lowest ammonia nitrogen content in the effluent dropped to 12.2 mg / L, and the total nitrogen content in the effluent reached 77 mg / L. The removal rate of ammonia nitrogen reached 95.9%, and the removal rate of total nitrogen was 74.3%.

[0073] Example 4

[0074] In the system of Example 1, the same method as in Example 1 is used to treat sewage, the only difference being that the total volume of the filler in the aeration tank accounts for 25% of the tank volume, the dissolved oxygen concentration in the aeration tank is 1.5 mg / L, the hydraulic retention time of the sewage to be treated in the aeration tank is 8 h, and the treatment temperature is 20°C.

[0075] The lowest ammonia nitrogen content in the effluent dropped to 89.9 mg / L, and the total nitrogen content in the effluent was 102.4 mg / L. The removal rate of ammonia nitrogen reached 70.3%, and the removal rate of total nitrogen reached 65.6%.

[0076] It can be seen from the above that the system disclosed in the present invention can effectively remove nitrogen-containing compounds in sewage.

[0077] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0078] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0079] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A sewage treatment system, comprising an aeration tank and a solid-liquid separator; The aeration tank comprises an aeration tank body, the aeration tank body has an octagonal side wall, and the octagonal side wall comprises a first straight wall, a second straight wall, a third straight wall, a fourth straight wall, a fifth straight wall, a sixth straight wall, a seventh straight wall and an eighth straight wall which are connected end to end in a horizontal direction; The first straight wall is provided with a first water inlet (1) and a first water outlet (2), the fifth straight wall is provided with a second water inlet (3) and a second water outlet (4); the third straight wall is provided with a muddy water outlet (5); the muddy water outlet (5) is fluidically connected to the water inlet (6) of the solid-liquid separator.

2. The system according to claim 1, wherein: The width of the third straight wall is recorded as L1, the endpoint where the first straight wall and the top of the second straight wall are connected is recorded as a, the endpoint where the fourth straight wall and the top of the fifth straight wall are connected is recorded as b, the length of the line segment ab is recorded as L2, and the ratio of L2 to L1 is (1.5-20):1, preferably (2-10):1; The width of the seventh straight wall is recorded as L3, the endpoint where the fifth straight wall is connected to the top of the sixth straight wall is recorded as c, the endpoint where the eighth straight wall is connected to the top of the first straight wall is recorded as d, the length of the line segment cd is recorded as L4, and the ratio of L4 to L3 is (1.5-20):1, preferably (2-10):1; The height between the line segment ab and the line segment cd is denoted as H, and the ratio of L2, L4 and H is (2.0-10.0):(2.0-10.0):1, preferably (3.0-5.0):(3.0-5.0):

1.

3. The system according to claim 2, wherein: The line segment ab is parallel to the top edge of the first straight wall, the line segment cd is parallel to the top edge of the seventh straight wall, and a rectangle is formed between endpoints a, endpoint b, endpoint c and endpoint d.

4. The system according to claim 1, wherein: The first water inlet (1) and the second water outlet (4) are arranged diagonally, and the second water inlet (3) and the first water outlet (2) are arranged diagonally.

5. The system according to claim 1, wherein: An aeration device (7) is arranged on the bottom surface of the aeration tank body, and the aeration device is selected from one or more of a microporous aerator, a hose aerator and a disc-type flat plate aerator.

6. The system according to claim 1, wherein: The aeration tank body is also provided with fillers (10), and the total volume of the fillers accounts for 30-40% of the volume of the tank body; The filler is one or more of plastic filler, sponge filler and polyurethane filler, preferably plastic filler; The shape of the filler is one or more of a sphere, a cylinder and a cube, preferably a sphere, and the diameter of the sphere is 5-20 mm.

7. The system according to claim 1, wherein: The solid-liquid separator has a separation chamber, which includes a straight section and an inverted cone section at the lower part of the straight section, and the straight section and the cone section are fluidically connected; A mud discharge port (8) is provided at the cone tip of the inverted cone section, and a supernatant outlet (9) is provided on the side wall of the straight cylinder section, and the supernatant outlet (9) is fluidically connected to the first water inlet (1) and / or the second water inlet (3); a water inlet pipe is provided in the straight cylinder section, and the upper end opening of the water inlet pipe forms the water inlet (6) of the solid-liquid separator.

8. A method for treating sewage using the sewage treatment system according to any one of claims 1 to 7, the method comprising: S1, firstly introducing the sewage to be treated into the aeration tank from the first water inlet (1) for treatment, then discharging the clean water from the second water outlet (4), and discharging the muddy water from the muddy water outlet (5) and then sending it into the solid-liquid separator; S2, switching the water inlet, introducing the sewage to be treated into the aeration tank from the second water inlet (3) for treatment, and then discharging the clean water from the first water outlet (2), and the muddy water from the muddy water outlet (5) and then feeding it into the solid-liquid separator; S3, step S1 and step S2 are performed alternately.

9. The method according to claim 8, wherein: The dissolved oxygen concentration in the aeration tank is 2-4 mg / L, the hydraulic retention time of the sewage to be treated in the aeration tank is 2-80 hours, and the treatment temperature is 25-35° C.; the retention time of the muddy water in the solid-liquid separator is 0.5-16 hours.

10. The method according to claim 8, wherein: The COD of the sewage to be treated is 200-800 mg / L, and the sludge concentration is 2500-3500 mg / L.

Images