Process and device for treating ship domestic sewage

Abstract

The invention relates to the technical field of sewage treatment, and discloses a ship domestic sewage treatment process and device. The process comprises the following steps: removing large garbage from the ship domestic sewage through a rotary garbage separator, and crushing the ship domestic sewage through a crushing pump to obtain to-be-treated sewage; the sewage to be treated is subjected to A / O biochemical treatment, and biochemical effluent is obtained; carrying out external MBR (Membrane Bioreactor) on the biochemical effluent to obtain a concentrated mixed solution and produced water; the concentrated mixed solution is subjected to reflux A / O biochemical treatment, produced water is subjected to ultraviolet sterilization treatment, and discharged water is obtained. According to the present invention, the ship domestic sewage is treated by using the MBBR reinforced A / O biochemical and external MBR combined technology, the process has good treatment effects of high solid-liquid separation efficiency, small sludge amount, strong nitrogen and phosphorus removal ability and the like, the quality of the produced water is significantly higher than the quality of the produced water produced by using the conventional treatment method, the activated sludge concentration is improved, the equipment volume is reduced, the sewage blocking of the external MBR membrane element is reduced, and the sewage treatment efficiency is improved. And the maintainability of the equipment is improved, and the service life is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a process and a device for treating domestic sewage from ships. Background Art

[0002] my country has a large number of ships, a wide range of activities, and strong mobility. While bringing convenience, they are also a major source of pollution in the transportation industry. With the rapid increase in the number of ships active at sea, the degree of pollution in offshore waters has deepened, posing a threat to human health. In recent years, due to the increased awareness of ecological environmental protection, the discharge of sewage from ships has begun to receive more attention and attention. Proper treatment and recycling of ship sewage is the only way for the development of my country's shipping industry, and it is also an inevitable choice for maintaining my country's ecological security and promoting the construction of ecological civilization.

[0003] Domestic sewage from ships mainly refers to sewage from showers, washing and laundry, kitchen water, discharge from any form of toilets and other waste, sewage from medical clinics, etc. discharged from the daily life of ship personnel. It can be divided into black water (higher pollution level) and gray water (relatively lighter pollution, lower pollutant content). Domestic sewage from ships has the following characteristics: large changes in water quality and quantity; high pollution load, mainly high-concentration organic pollutants, rich in nitrogen, phosphorus and other elements. The sewage is treated on board and discharged overboard after meeting the standards. The treatment processes mainly include biological methods, physical-chemical treatment methods, electrochemical treatment methods, advanced oxidation treatment methods, etc. For example, membrane bioreactor (MBR) is a new water treatment technology that combines membrane separation technology with biological treatment units. It is often used in the treatment of domestic sewage from ships and can effectively solve the above problems. MBR technology can be divided into built-in MBR and external MBR according to the installation position of the membrane assembly. The built-in MBR is more compact, occupies a smaller area, and has lower energy consumption. However, the membrane assembly is easily contaminated due to long-term immersion in activated sludge, and requires frequent cleaning, replacement and maintenance; the main advantages of the external MBR are stable and reliable operation, easy independent control, and easy cleaning, replacement and expansion of the membrane assembly. However, a larger circulating water flow rate is required to provide a higher cross-flow velocity to reduce the deposition of pollutants on the membrane surface. The moving bed biofilm reactor (MBBR), also known as the suspended filler moving bed process, is a new type of biofilm enhanced treatment technology. The principle of MBBR technology is to add fillers with a specific gravity close to that of water to the biochemical reactor for microorganisms to attach and grow, forming a mobile biofilm, on which microorganisms reproduce and grow and degrade pollutants in sewage, ultimately playing a role in water purification.

[0004] Among various methods and equipment for treating domestic sewage on ships, biochemical treatment devices are the most commonly used treatment equipment. For example, a "continuous flow anoxic / aerobic coupled anaerobic ammonia oxidation sewage treatment device and method" disclosed in Chinese patent documents, with the announcement number CN111087074A, includes: an inlet unit, which introduces sewage to be treated; a continuous flow anoxic / aerobic reactor, including an anoxic section and an aerobic section; a secondary sedimentation tank, into which the effluent of the aerobic section flows for sedimentation; an intermediate water tank, into which the effluent in the secondary sedimentation tank flows; an anaerobic ammonia oxidation reactor, in which the sewage in the intermediate water tank undergoes anaerobic ammonia oxidation denitrification reaction; and an outlet unit, into which the qualified sewage discharged from the anaerobic ammonia oxidation reactor enters the outlet unit. This invention couples an anaerobic ammonia oxidation reactor on the basis of a traditional anoxic / aerobic reactor, and increases the original process treatment capacity and improves the effluent quality through segmented water inlet and reflux. However, in this scheme, the treated sewage is directly introduced into the anoxic reactor from the water inlet tank. The garbage and solid particles in the sewage can easily clog the pump body and pipelines, causing damage to components. The overall device is not compact enough. For example, the aeration module of the aerobic reactor requires an external air compressor, and the device uses a total of 6 pumps, which are inconvenient to use and maintain.

[0005] At present, the treatment of domestic sewage on ships mainly adopts the built-in MBR technology, while the external MBR technology is rarely used. For example, the "A Ship Domestic Sewage Zero Discharge Treatment System and Activated Carbon Filter Device Therefor" disclosed in the Chinese patent literature, with the announcement number CN115159784A, adopts the technical route of pretreatment + biochemical + deep oxidation + activated carbon adsorption to treat ship domestic sewage. The effluent of the CAST system is pumped into the external MBR membrane through the process pump for filtration treatment. However, the external MBR technology in this scheme does not consider the cleaning, replacement and addition of membrane components, which may lead to irreversible fouling of the MBR membrane and reduce the service life of the membrane.

[0006] In summary, there are some problems in the existing technology that have not been well solved: the traditional physical method uses gravity sedimentation and membrane separation technology. Once the ship is in a swaying or tilting state, the solid-liquid separation effect is poor, affecting the quality of the discharged water after treatment; due to the low concentration of microorganisms, the sewage has poor resistance to the impact of organic load and hydraulic load. The above problems have caused the existing biochemical sewage equipment to be large in size, prone to sludge swelling and sedimentation sludge denitrification, and complex maintenance and operation management during actual use.

[0007] It should be noted that the statements herein merely provide background information related to the present application and do not necessarily constitute prior art. Summary of the invention

[0008] To this end, the present invention proposes a process and device for treating domestic sewage from ships that can solve at least part of the above-mentioned problems.

[0009] This application adopts the following technical solutions:

[0010] In the first aspect, the present application provides a process for treating domestic sewage from ships, the process comprising: removing large pieces of garbage from the domestic sewage from the ships through a rotating garbage separator, and then crushing it through a pulverizing pump to obtain sewage to be treated; subjecting the sewage to be treated to A / O biochemical treatment to obtain biochemical effluent; subjecting the biochemical effluent to an external MBR to obtain a concentrated mixed liquor and produced water; returning the concentrated mixed liquor to A / O biochemical treatment, and subjecting the produced water to ultraviolet sterilization treatment to obtain discharge water.

[0011] Preferably, the crushed particles obtained by the crushing pump crushing process are less than or equal to 5 mm, which is used to improve the efficiency of subsequent biochemical treatment.

[0012] Preferably, the A / O biochemical treatment is enhanced by MBBR, and the A / O biochemical treatment includes anoxic MBBR treatment and aerobic MBBR treatment; the anoxic MBBR treatment HRT is 3.5-9 h; the aerobic MBBR treatment HRT is 6-10 h, DO is 2-5 mg / L, and the nitrification solution reflux ratio is 200-400%.

[0013] Preferably, the external MBR adopts a tubular SiC ceramic membrane, the operating pressure of the tubular SiC ceramic membrane is 0.05~0.25 MPa, and the membrane surface flow rate ranges from 2~4.5 m / s.

[0014] Preferably, the external MBR further includes a backwashing process, in which the backwashing pressure is provided by compressed air, and air intake is maintained for a period of time after the backwashing water is flushed to perform air washing.

[0015] Preferably, the concentrated mixed liquor is membrane-returned to A / O biochemical treatment, the concentrated mixed liquor can be returned to aerobic MBBR treatment and / or anoxic MBBR treatment, and the concentrated mixed liquor returned to anoxic MBBR treatment can be used as nitrification liquid to provide nitrate nitrogen for denitrifying bacteria.

[0016] In the second aspect, the present application also provides a device for treating domestic sewage from ships, the device comprising: a sewage inlet, a regulating water tank, a pulverizing pump, anoxic MBBR, aerobic MBBR, an MBR circulation pump, an ultrafiltration ceramic membrane, a jet aerator, a backwash tank, a qualified water discharge port and a medicine washing tank; a rotating garbage separator for automatically compressing and packing filtered particles is provided between the sewage inlet and the regulating water tank; the rotating garbage separator is fixed on the regulating water tank; the regulating water tank, pulverizing pump, anoxic MBBR, aerobic MBBR, an MBR circulation pump and an ultrafiltration ceramic membrane are connected in sequence along the direction of water flow; the outlet of the ultrafiltration ceramic membrane is respectively connected to the jet aerator and the backwash tank; the jet aerator is connected to the aerobic MBBR; the backwash tank is connected to the qualified water discharge port. A water tank level gauge is provided in the regulating water tank; the water tank level gauge adopts a float type level gauge with adjustable upper and lower limits. A pulverizing direct discharge port with a three-way valve is provided between the pulverizing pump and the anoxic MBBR. The anoxic MBBR includes an exhaust port 1 and a bacterial agent addition port 1, an interception net for promoting fluidization is provided at the bottom, and an anoxic circulation pump is provided outside. The aerobic MBBR includes an exhaust port 2 and a bacterial agent addition port 2, an interception net for promoting fluidization is provided at the bottom, and an aerobic liquid level gauge is provided inside. The ultrafiltration ceramic membrane is a tubular SiC ceramic membrane. The backwash tank is provided with a compressed air interface; the drug washing box is provided with a drug washing waste liquid discharge port, and the drug washing box is connected to the ultrafiltration ceramic membrane. An ultraviolet sterilization lamp is provided between the backwash tank and the qualified water discharge port.

[0017] Preferably, the device is used to treat domestic sewage from ships. Domestic sewage from ships enters the regulating water tank through the sewage inlet after the rotary garbage separator, enters the anoxic MBBR after being crushed by the crushing pump, and enters the anoxic MBBR through the switching of the valve. The crushing pump can also be used as a discharge pump. After a certain hydrolysis, the sewage enters the aerobic MBBR through the connecting hole, and a stainless steel grid is installed on the connecting hole to prevent the loss of fillers in the pool. The MBR circulation pump takes water from the middle height of the aerobic MBBR, and the mixed liquid enters the membrane assembly after pressurization. The filtrate is discharged through the membrane assembly of the ultrafiltration ceramic membrane, and the concentrated mixed liquid flows back to the biochemical pool. Most of the mixed liquid passes through the ejector and flows back to the aerobic pool, and a small part of the mixed liquid flows back to the anoxic pool as the nitrification liquid in the A / O process. The water produced by the ultrafiltration ceramic membrane is first stored in the backwash tank for standby use. After the backwash tank overflows, it is sterilized by the ultraviolet sterilization lamp and then discharged. The backwash pressure is provided by the compressed air on board, and the air intake is maintained for a period of time after the backwash water is flushed for air washing.

[0018] Preferably, the anoxic MBBR is provided with a bacterial agent addition port and an exhaust port on the top, and an inlet hole on the side; the box is filled with polyurethane filler accounting for 30% of the box volume, and the anoxic circulation pump is used to provide fluidization power for the filler; the MBR circulation pump simultaneously returns part of the sludge in the aerobic MBBR to the fluidized anoxic tank; the structure is optimized to facilitate the flow of sewage, reduce dead water areas, and make the filler in a good fluidized state in the box; an emptying port is provided at the bottom, and an interception net is installed to prevent the filler from being discharged from the emptying port.

[0019] Preferably, the aerobic MBBR is provided with a bacterial agent addition port and an exhaust port at the top, and an inlet hole at the side; the box is filled with polyurethane filler accounting for 30% of the box volume, and the MBR circulation pump is used to provide fluidization power for the filler; a jet aerator is used to oxygenate the sewage, and the water inlet of the jet aerator is provided by the MBR circulation pump; the MBR circulation pump works in conjunction with the float-type liquid level gauge, that is, the "high start and low stop" working mode. When the water level in the aerobic MBBR reaches the set high liquid level, the MBR circulation pump is turned on to supply water to the MBR system, and when the water level in the aerobic MBBR reaches the set low liquid level, the MBR circulation pump is turned off; the structure is optimized to facilitate the flow of sewage, reduce dead water areas, and make the filler in a good fluidized state in the box; an emptying port is provided at the bottom, and an interception net is installed to prevent the filler from being discharged from the emptying port.

[0020] At least one of the above technical solutions adopted in the embodiments of the present application can achieve the following beneficial effects:

[0021] In view of the current situation that the effluent water quality of domestic sewage treatment in existing ships is poor, the equipment volume is too large and the repair and maintenance are difficult, this application provides a process and equipment for domestic sewage treatment in ships. By adopting the A / O MBBR-MBR biochemical process, good treatment effects such as high solid-liquid separation efficiency, small sludge volume, and strong denitrification and phosphorus removal capabilities are achieved. The water quality of the produced water is significantly higher than that of conventional treatment methods. While increasing the concentration of activated sludge and reducing the volume of the equipment, the fouling of the external MBR membrane elements is reduced, and the maintainability of the equipment is improved. While ensuring that the effluent water quality meets the latest MEPC.227.(64) regulatory requirements, it can adapt to the harsh environment of the ship in the navigation environment.

[0022] The above description of the technical solution of the present application is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Also, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0024] Figure 1 This is a schematic diagram of the steps of the ship domestic sewage treatment process in the embodiment of the present application;

[0025] Figure 2 This is a flow chart of the ship domestic sewage treatment process in the embodiment of the present application;

[0026] Figure 3 This is a schematic diagram of the structure of a ship domestic sewage treatment device in an embodiment of the present application;

[0027] Figure 4 The effects of different HRT, reflux ratio and DO on COD in A / O biochemical treatment in Examples 1 to 15 of this application Cr Remove the renderings;

[0028] Figure 5 This is a diagram showing the effect of different HRT, reflux ratio and DO on NH3-N removal in A / O biochemical treatment in Examples 1 to 15 of the present application;

[0029] Figure 6 This is a diagram showing the effect of different HRT, reflux ratio and DO on TN removal in A / O biochemical treatment in Examples 1 to 15 of the present application;

[0030] Figure 7 This is a diagram showing the effect of different HRT, reflux ratio and DO on TP removal in A / O biochemical treatment in Examples 1 to 15 of the present application;

[0031] Figure 8 This is a graph showing changes in MLSS, MLVSS and MLSS / MLVSS concentrations of A / O biochemical treatment sludge in Example 13 of the present application;

[0032] Fig. 9 This is a graph showing how the stable membrane flux changes with sludge concentration, operating pressure and membrane surface flow rate in Example 16 of the present application.

[0033] In the figure: 1-sewage inlet, 2-regulating water tank, 21-water tank level gauge, 3-rotating garbage separator, 4-crushing pump, 41-crushing direct discharge port, 5-anoxic MBBR, 51-exhaust port one, 52-microorganism agent addition port one, 53-anoxic circulation pump, 6-aerobic MBBR, 61-exhaust port two, 62-microorganism agent addition port two, 63-aerobic level gauge, 7-MBR circulation pump, 8-ultrafiltration ceramic membrane, 9-jet aerator, 10-backwash tank, 101-compressed air interface, 11-ultraviolet sterilization lamp, 12-standard water discharge port, 13-medicine washing box, 131-medicine washing waste liquid discharge port. DETAILED DESCRIPTION

[0034] The exemplary embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present application and to fully convey the scope of the present application to those skilled in the art.

[0035] The technical concept of this application is to propose a process and device for treating domestic sewage from ships, aiming at the characteristics of high pollution level of domestic sewage from ships, large fluctuations in water quality and quantity, and limited installation environment of treatment equipment. This application strengthens the A / O-MBR biological treatment-ultraviolet sterilization process through pulverization-MBBR, and designs and optimizes the process operation parameters, so as to achieve good treatment effects such as high solid-liquid separation efficiency, small sludge volume, and strong denitrification and phosphorus removal capabilities. The water quality of the produced water is significantly higher than that of conventional treatment methods. While increasing the concentration of activated sludge and reducing the volume of the equipment, the fouling of the membrane elements is reduced, and the maintainability of the equipment is greatly improved. The technical solutions provided by each embodiment of this application are described in detail below in conjunction with the accompanying drawings.

[0036] The present application embodiment provides a process for treating domestic sewage of a ship, such as Figure 1 As shown, a schematic diagram of the steps of a ship sewage treatment process is provided, and the process at least includes the following steps S1 to S4:

[0037] Step S1, the ship's domestic sewage is passed through a rotating garbage separator to remove large pieces of garbage, and then is crushed by a crushing pump to obtain sewage to be treated.

[0038] Specifically, the crushed particles obtained by the crushing pump are less than or equal to 5 mm, which are used to improve the efficiency of subsequent biochemical treatment.

[0039] Step S2, subjecting the wastewater to be treated to A / O biochemical treatment to obtain biochemical effluent.

[0040] Specifically, the A / O biochemical treatment is enhanced by MBBR, and the A / O biochemical treatment includes anoxic MBBR treatment and aerobic MBBR treatment; the anoxic MBBR treatment HRT is 3.5-9 h; the aerobic MBBR treatment HRT is 6-10 h, DO is 2-5 mg / L, and the nitrification liquid reflux ratio is 200-400%.

[0041] Step S3, subjecting the biochemical effluent to external MBR treatment to obtain concentrated mixed liquor and produced water.

[0042] Specifically, the external MBR treatment uses a tubular SiC ceramic membrane, the operating pressure of the tubular SiC ceramic membrane is 0.05~0.25 MPa, and the membrane surface flow rate range is 2~4.5 m / s. The external MBR treatment also includes a backwashing process, the backwashing pressure of the backwashing process is provided by compressed air, and the air intake is maintained for a period of time after the backwashing water is flushed to perform air washing.

[0043] Step S4, returning the concentrated mixed solution to A / O biochemical treatment, and subjecting the produced water to UV sterilization treatment to obtain discharge water.

[0044] Specifically, the concentrated mixed liquor can be returned to the aerobic MBBR for treatment and / or the anoxic MBBR for treatment. The concentrated mixed liquor returned to the anoxic MBBR for treatment can be used as a nitrification liquid to provide nitrate nitrogen for denitrifying bacteria.

[0045] like Figure 2 As shown, in some embodiments of the present application, the domestic sewage of the ship enters the regulating tank after being treated by the spiral filter (rotating garbage separator) through the sewage inlet, and enters the fluidized anoxic bioreactor (anoxic MBBR) after being crushed by the crushing pump. Through the switching of the valve, the crushing pump can also be used as a discharge pump. After a certain hydrolysis, the sewage enters the fluidized aerobic bioreactor (aerobic MBBR) through the connecting hole, and a stainless steel grid is installed on the connecting hole to prevent the loss of fillers in the pool. The MBR circulation pump takes water from the middle height of the fluidized aerobic bioreactor (aerobic MBBR), and the A / O biochemical effluent mixed liquid is pressurized and enters the membrane assembly. The filtrate is discharged through the membrane assembly of the ultrafiltration ceramic membrane, and the concentrated mixed liquid is returned to the A / O biochemical treatment. Most of the concentrated mixed liquid is returned to the aerobic tank (aerobic MBBR) through the ejector, and a small part of the mixed liquid is returned to the anoxic tank (anoxic MBBR) as the nitrification liquid in the A / O process. The water produced by MBR is first stored in the backwash tank for standby use. When the backwash tank overflows, it is sterilized by the UV sterilizer and then discharged. The backwash pressure is provided by the compressed air on board, and the air intake is maintained for a period of time after the backwash water is flushed to perform air washing. Chemical washing can also be performed. The chemical washing process is powered by the MBR circulation pump, and the water inlet switching of the chemical washing tank is achieved by switching the valve.

[0046] like Figure 3As shown, the present application involves a device for treating domestic sewage from a ship, comprising a sewage inlet 1, a regulating water tank 2 with an automatic garbage separation function, a rotating garbage separator 3, a pulverizing pump 4, anoxic MBBR 5, aerobic MBBR 6, an MBR circulation pump 7, an ultrafiltration ceramic membrane 8, a jet aerator 9, a backwash tank 10, an ultraviolet sterilization lamp 11, a qualified water discharge port 12, a drug washing tank 13, a drug washing waste liquid discharge port 131, a pulverizing direct discharge port 41 and an electrical control system; the sewage inlet is connected to the rotating garbage separator 3; the regulating water tank 2 is connected to the anoxic MBBR 5 and the aerobic MBBR 6, and as a whole serves as a part of the main treatment device; the fluidized biological treatment system is obtained by the jet aerator 9 obtain the oxygen required for the growth and reproduction of microorganisms; the filler of the fluidized biological treatment system is always in a fluidized state during operation and can be turned over freely; the ultrafiltration ceramic membrane 8 is connected to the MBR circulation pump 7 and the backwash tank 10 respectively; the drug washing water tank 13 is connected to the MBR ceramic membrane 8 and the MBR circulation pump 7, and can be switched between the sewage filtration and the cleaning circuit through a three-way valve; the ultraviolet sterilization lamp 11 is connected to the backwash tank 10; the treated water standard discharge port 12 is connected to the ultraviolet sterilization lamp 11; the pulverization direct discharge port 41 is connected to the pulverization pump 4; the electrical control system coordinates the equipment operation of the entire device; the regulating water tank 2, the anoxic MBBR5, the aerobic MBBR6, and the drug washing tank 13 are all provided with emptying pipelines.

[0047] Specifically, the regulating water tank also includes a rotating garbage separator 3 , a crushing pump 4 , and a water tank level gauge 21 .

[0048] Specifically, the pulverizing pump 4 switches the pulverizing and discharging to the outside or delivering the untreated sewage to the anoxic MBBR 5 through a three-way valve, and the flow rate can be further controlled by a manual ball valve.

[0049] Specifically, the anoxic MBBR 5 further includes an anoxic MBBR circulation pump 53 , and the aerobic MBBR 6 further includes a jet aerator 9 , a biochemical water tank float level gauge 63 and an MBR circulation pump 7 .

[0050] Specifically, the top of the anoxic MBBR5 is provided with a bacterial agent addition port 52 and an exhaust port 51, and an inlet hole is provided on the side; the box is filled with MBBR filler with a dosing rate of 30% of the effective tank volume, and the filler uses a 50*50*25 mm polyurethane filler as a carrier and is wrapped with a PE ball with a diameter of 150 mm. The anoxic MBBR circulation pump 53 provides fluidization power for the filler; the MBR circulation pump 7 simultaneously returns part of the sludge in the aerobic MBBR6 to the anoxic MBBR5; the structure of the anoxic MBBR5 is optimized to facilitate the flow of sewage, reduce dead water areas, and make the filler in a good fluidized state in the box; an emptying port is provided at the bottom, and an interception net is installed to prevent the filler from being discharged from the emptying port.

[0051] Specifically, the aerobic MBBR 6 is provided with a bacterial agent addition port 62 and an exhaust port 61 at the top, and an inlet hole at the side; the box is filled with polyurethane filler accounting for 30% of the box volume, and the MBR circulation pump 7 is used to provide fluidization power for the filler; a jet aerator 9 is used to oxygenate the sewage, and the water inlet of the jet aerator 9 is provided by the MBR circulation pump 7. The use of the jet aerator fully utilizes the residual power of the MBR circulation pump while providing fluidization power for the fluidization tank; the MBR circulation pump 7 works in coordination with the float level gauge 63 of the biochemical water tank, that is, a "high start and low stop" working mode. When the water level in the aerobic MBBR8 reaches the set high liquid level, the MBR circulation pump 7 is turned on to supply water to the ultrafiltration ceramic membrane 8. When the water level in the aerobic MBBR6 reaches the set low liquid level, the MBR circulation pump 7 is turned off. The structure of the aerobic MBBR6 is optimized to facilitate the flow of sewage, reduce dead water areas, and make the filler in a good fluidized state in the box. An emptying port is provided at the bottom, and an interception net is installed to prevent the filler from being discharged from the emptying port.

[0052] Specifically, the device uses ultrafiltration ceramic membrane 8 as the filtration membrane element and is equipped with a special membrane shell. In the example, the material is pure silicon carbide, the filtration accuracy is 0.1 μm, the clean water flux is 3 m³ / h, the designed domestic sewage treatment flux is 120~150 L / h, and a total of 9 membrane cores with three 3-core membrane shells with a diameter of 6 mm are selected, and three membrane components are used in series.

[0053] Specifically, the external MBR ceramic membrane cleaning system includes a backwash tank 10 , a chemical washing box 13 , a compressed air interface 101 , and a chemical washing waste liquid discharge port 131 .

[0054] Specifically, in the example, the backwash pressure is 2 bar, the time is usually set to 6-8 seconds, the required backwash water volume is 5L, and after the hydraulic backwash, the air is ventilated for 10 seconds for air scrubbing. According to the backwash requirements, the compressed air pressure is required to be 5 bar and the exhaust volume is 40 L / min.

[0055] Specifically, in this example, the device is configured with a flow rate of 1 m 3 / h ultraviolet sterilization lamp to ensure that the number of E. coli in the effluent can be kept below 100. If the water quality of the MBR produced water is good during the actual treatment process, the ultraviolet sterilizer can be used as an optional device in subsequent products.

[0056] In specific implementation, the working process of sewage treatment by this ship sewage treatment process and device is as follows:

[0057] The domestic sewage of the ship enters the regulating water tank 2 after passing through the rotating garbage separator, and the large pieces of garbage are automatically separated, compressed and transported out. The sewage in the regulating water tank 2 is circulated and crushed by the crushing pump 4, and the water is discharged in two ways. Part of the sewage enters the anoxic MBBR5, and the remaining sewage flows back to the regulating water tank 2. By manually adjusting the valve opening, the sewage flow entering the anoxic MBBR5 can be adjusted, and the HRT of the biochemical part can be adjusted. The crushing pump 4 is also used as a discharge pump to crush the domestic sewage of the ship in non-restricted sea areas and discharge it outside, or empty the entire equipment. The regulating tank is equipped with a float-type liquid level transmitter, which can start the crushing pump at a high liquid level and automatically shut it down at a low liquid level; and the device will emit an audible and visual alarm at the alarm level.

[0058] After the sewage is hydrolyzed by the anoxic MBBR5, it flows into the aerobic MBBR6 by gravity. The anoxic MBBR5 is equipped with a low-lift anoxic circulation pump 53 to provide fluidization power for the anoxic MBBR. The aerobic MBBR is equipped with a float-type liquid level transmitter, which can start the MBR circulation pump 7 at a high liquid level and automatically shut it down at a low liquid level; and the device will sound an audible and visual alarm at the alarm liquid level. After each shutdown, a backwashing procedure is automatically performed, and then all equipment returns to the initial state until the next time the liquid level returns to a high level, the MBR circulation pump 7 starts working again.

[0059] The MBR circulation pump 7 takes water directly from the aerobic MBBR 6, and a double-layer filter (sheet grid + 2 mm stainless steel filter) is set at the inlet to prevent MBBR fillers, fiber hair and hard particles from entering the external MBR membrane system. When the flow in the external MBR system is stable, the MBR circulation pump 7 is turned on, and the pressure in the membrane is increased to the value required by the process by adjusting the brine flow. Part of the brine is returned to the anoxic MBBR 5, and the denitrification return ratio is adjusted by a manual regulating valve. The effluent can meet the latest standards in MPEC.227. (64) and the "Ship Water Pollutant Emission Control Standard" of the People's Republic of China (GB 3552-2018).

[0060] The water produced by the external MBR first enters the backwash tank 10 for standby. After the backwash tank 10 is full, it continues to overflow and is sterilized by the ultraviolet sterilizer before being discharged. Backwashing is mainly performed based on the fluidized aerobic tank level gauge 63, the MBR concentrated water pressure and the produced water flow rate. The backwash procedure will be executed only when and only when the aerobic fluidized tank is not in a high liquid level alarm state, and the concentrated mixed liquid pressure produced by the external MBR is greater than the set value or the produced water flow rate is less than the set value. In addition, a backwash procedure will be automatically executed when the continuous operation time exceeds the set time.

[0061] The backwash pressure is provided by the compressed air on board. At that time, the backwash electric ball valve will be closed, the backwash tank 10 will be in a closed state, the compressed air valve (solenoid valve) will be opened, and the air source will provide pressure to press the backwash water into the MBR membrane from the water inlet, and keep the air intake for a period of time after the backwash water is flushed to perform air washing. The backwash process will be completed within 10 minutes, so the regulating tank does not need to stop the water intake, and then the equipment will resume normal operation.

[0062] The following provides specific embodiments of the present invention:

[0063] Examples 1 to 15 use the process and device of the present application for ship sewage treatment. The average concentrations of influent COD, NH3-N, TN, and TP are 856 mg / L, 73 mg / L, 93 mg / L, and 5.3 mg / L, respectively. For the key parameters in the process, HRT regulation is achieved by controlling the influent flow rate. The HRT corresponding to the aerobic MBBR section is regulated to 6 h, 7 h, 8 h, and 10 h, respectively, and the HRT corresponding to the anoxic MBBR section is 3.5 h, 4 h, 5 h, and 6 h, respectively; the reflux volume of nitrification liquid and the aeration volume are adjusted by controlling the opening of the air duct valve.

[0064] The operating conditions of Examples 1 to 15 differ in the parameters shown in Table 1.

[0065] Table 1

[0066]

[0067] The effluent COD under different working conditions Cr The removal rate was analyzed by taking the average value. Figure 4 It can be seen that changing the mixed liquor reflow ratio has little effect on the COD removal rate. Under the same HRT conditions, the COD removal rates under the three reflow ratios of 200%, 300% and 400% are basically the same. The average COD removal rate of the reactor increases with the increase of HRT. When the A pool HRT=3.5 h and the O pool HRT=6 h, the average COD removal rate is 86%, when the A pool HRT=4 h and the O pool HRT=7 h, the average COD removal rate is 90%, when the A pool HRT=5 h and the O pool HRT=8 h, the average COD removal rate reaches 93%, but when the A pool HRT=6 h and the O pool HRT=10 h, the average COD removal rate does not increase further, but the removal rate fluctuates. The dissolved oxygen concentration that maintains the normal life activities of aerobic activated sludge is generally not less than 2 mg / L. When the dissolved oxygen concentration in the aerobic tank increases from about 2 mg / L to about 3 mg / L, the COD Cr The average removal rate of COD has been improved to a certain extent, from about 93% to about 96%, but further increasing the aeration volume cannot crThe removal rate continued to increase. When the DO in the aerobic pool was 4 mg / L and 5 mg / L, the COD cr The removal rate is about 97%.

[0068] The average value of NH3-N effluent quality under different working conditions is analyzed. Figure 5 It can be seen that the removal rate of NH3-N in the reactor increases with the increase of HRT. In particular, when the HRT of pool A is increased from 3.5 h to 5 h, the average removal rate of NH3-N increases from 83% to 88%, and the average concentration of NH3-N in the effluent is 13 mg / L; however, when the HRT continues to increase, the removal rate of NH3-N does not increase significantly. The effluent NH3-N in the reactor tends to increase with the increase of the nitrification solution reflux ratio. When the HRT of pool A is 5 h and the HRT of pool O is 8 h, as the reflux ratio increases from 200% to 400%, the average removal rate of NH3-N increases from 90% to 95%. After increasing the DO concentration, the removal rate of NH3-N in the reactor is further improved. When the DO of O pool is about 3 mg / L, the average removal rate of NH3-N increases to 92%, when the DO of O pool is about 4 mg / L, the average removal rate of NH3-N increases to 95%, when the DO of O pool is about 4 mg / L, the average removal rate of NH3-N further increases to 97%, and the average concentration of NH3-N in the effluent is less than 3 mg / L. Therefore, properly increasing the aeration volume can fully oxidize the nitrogen-containing organic matter in the mixed solution and improve the removal rate of NH3-N.

[0069] Take the average value of TN outlet water quality under different working conditions for analysis, such as Figure 6 As shown. Under the condition of a reflow ratio of 200%, with the increase of HRT, the removal rate of TN shows a trend of first increasing and then decreasing. When HRT of pool A is 3.5h and HRT of pool O is 6h, the average removal rate of TN is 66%; when HRT of pool A is 4h and HRT of pool O is 7h, the average removal rate of TN is 71%; when HRT of pool A is 5h and HRT of pool O is 8h, the average removal rate of TN is about 76%, but when HRT of pool A is 6h and HRT of pool O is 10h, the removal rate of TN decreases instead, and the average removal rate is 71%. This is because at a shorter HRT, denitrification is not complete, but at a longer HRT, the organic load of the system is reduced and the denitrifying bacteria cannot obtain sufficient carbon source.

[0070] When the HRT of pool A=5, the HRT of pool O=8, and the nitrification liquid recycle rate is 200%, the total nitrogen in the effluent is about 25 mg / L, and the average removal rate is about 72%. After increasing the recycle ratio to 300%, the TN removal rate increases to about 81%, and the effluent TN concentration is about 13 mg / L. As the influent TN or the total nitrogen removal rate required by the system increases, the recycle rate should be increased accordingly to return more nitrates and nitrites to the anoxic zone for denitrification and denitrification. However, when the recycle rate increases to 400%, increasing the recycle rate will make the denitrification effect worse. This is because there is only a small amount of soluble COD (bsBOD) in the recirculated mixed liquor. When the recycle rate increases, the sufficient concentration of bsBOD required for denitrification is diluted.

[100] The nitrification process in the aerobic pool can only be carried out in large quantities after the degradation of organic carbon. Both processes require a certain reaction time to be fully completed. Too large a reflux ratio will prevent the denitrification process from being completed in time.

[0071] When HRT of pool A is 5 h, HRT of pool O is 8 h, and the reflow ratio is 300%, the removal rate of TN increases first and then decreases with the increase of DO concentration. When DO of pool O is about 2 mg / L, the average removal rate of TN is 81%. When DO of pool O is about 3 mg / L, the removal rate of TN increases to 86%. However, when DO of pool O exceeds 4 mg / L, the removal rate of TN decreases. This is because the increase of DO concentration in pool O also drives the increase of DO in pool A. It is found that when DO in pool O reaches about 5 mg / L, DO in pool A increases to about 1.17 mg / L, which is not conducive to the denitrification process that requires strict control of DO less than 0.5 mg / L. The denitrification in pool A will mainly occur on the biofilm on the surface of the filler, and the denitrification of the activated sludge will be affected. Therefore, the concentration of DO must ensure nitrification without affecting the denitrification process.

[0072] The average value of TP effluent quality under different working conditions is analyzed, such as Figure 7 shown.

[0073] When DO=2 mg / L and the reflow ratio is 200%, the removal rate of TP increases with the increase of hydraulic retention time. When HRT of pool A=3.5 h and HRT of pool O=6 h, the average removal rate of TP is 48%, and when HRT of pool A=5 h and HRT of pool O=8 h, the removal rate of TP is 57%, but after further increasing HRT, the removal rate of TP does not increase further. When the hydraulic retention time is constant, the removal efficiency of TP shows a trend of increasing first and then decreasing with the change of reflow ratio. When DO=2 mg / L, HRT of pool A=5 h, HRT of pool O=8 h, and reflow ratio of 300%, the average removal rate of TP is 65%, which is higher than the average removal rate of 57% when the reflow ratio is 200%, and the average removal rate of 53% when the reflow ratio is 400%. The reason is that when the reflow ratio is low, the amount of activated sludge recycle in the mixed liquor is small, and some polyphosphate bacteria do not participate in the anaerobic phosphorus release process. When the reflow rate is high, the backflow of dissolved oxygen and nitrate in the mixed liquor destroys the anaerobic environment, which is more obvious at high DO concentrations.

[0074] When HRT of pool A was 5 h, HRT of pool O was 8 h, and the reflow ratio was 300%, the average removal rate of TP reached 71% at DO=3 mg / L, which was higher than the average removal rate of TP in the effluent at DO=2 mg / L. However, as DO continued to increase, the removal rate of TP in the effluent continued to decrease. At DO=4 mg / L, the average removal rate of TP was 63%, while at DO=5 mg / L, the average removal rate of TP was only 41%. Too low dissolved oxygen concentration in the O pool will lead to insufficient power of polyphosphate bacteria in the aerobic phosphorus absorption process, but too high dissolved oxygen concentration will lead to incomplete phosphorus release of polyphosphate bacteria in the anaerobic process. Therefore, it is necessary to select a suitable dissolved oxygen concentration to coordinate the balance between the anaerobic environment and the physiological requirements of polyphosphate bacteria.

[0075] The results of Examples 1 to 15 show that when HRT of pool A is 5 h, HRT of pool O is 8 h, DO of pool O is 3.0 mg / L, and reflux ratio of nitrification solution is 300%, the average removal rates of COD, NH3-N, TN, and TP in the reactor effluent are increased to 96.3%, 98.5%, 85.7%, and 91%, respectively. The average effluent concentrations are 34.24 mg / L, 1.12 mg / L, 12.81 mg / L, and 0.477 mg / L, respectively, which meet the latest emission standards in MPEC 227. (64) and the Discharge Standard for Domestic Sewage from Ships (GB3112-2018).

[0076] Example 13 The changes in sludge concentrations MLSS, MLVSS and MLSS / MLVSS are as follows Figure 8As shown in the figure, the reactor operated without discharging excess sludge and maintained a certain stability at a higher sludge concentration. In the stable operation stage, the biomass of the filler surface film reached 4.18 g / L, the MLSS of the A pool and the O pool in the reactor were stabilized at about 5.9 g / L and 10.8 g / L respectively; the MLVSS were stabilized at about 4.1 g / L and 7.5 g / L respectively, the SV30 was maintained at about 47% and 79% respectively, and the SVI was maintained at about 63 and 86 respectively; the MLVSS / MLSS ratio was maintained at about 0.68, the F / M in the O pool was stabilized at a lower range of 0.09-0.12, and the sludge production was less.

[0077] Example 16

[0078] The flux characteristics, operating conditions, filtration effect, pollution characteristics, cleaning methods, etc. of tubular SiC ceramic membranes filtering biochemical pool mixed liquid were experimentally investigated. The choice of operating conditions determines whether the membrane element can operate stably for a long time.

[0079] Depend on Fig. 9It can be seen that within the range of MLSS=3-10 g / L, the flux value is stable between 120-130 L / (h·㎡), which can meet the expected design requirements. When the sludge concentration exceeds 10g / L, the membrane flux decreases with the increase of sludge concentration, and the fluctuation range increases. In the range of MLSS=11-13 g / L, the flux value is stable between 110-120 L / (h·㎡), and in the range of MLSS=14-16 g / L, the flux value is stable between 95-110 L / (h·㎡). When other conditions remain unchanged, the stable membrane flux increases with the increase of operating pressure. When the operating pressure is 0.2 Mpa and 0.25 Mpa, the stable flux is the largest and remains at about 130 L / h·㎡. When the operating pressure increases from 0.05 MPa to 0.2 MPa, the increase in membrane flux is linearly related to the increase in operating pressure, which can be regarded as the pressure control area of ​​the tubular SiC ceramic MBR membrane; when the operating pressure continues to increase, the membrane flux does not increase significantly, and it can be regarded as having reached the critical membrane flux. Therefore, when selecting the design flow rate of the membrane element, sufficient safety margin should be reserved, and it should not be operated near the critical membrane flux for a long time in order to save the number of membrane cores. When membrane fouling occurs, the decrease in flux can be alleviated to a certain extent by adjusting the operating pressure, but the corresponding operating pressure must be limited before the critical membrane flux. Therefore, 0.15 MPa is selected as the operating pressure in the subsequent design, and the corresponding membrane flux is about 110-120 L / h·㎡. In the membrane surface velocity range of 2-4m / s, the membrane flux at stability increases with the increase of membrane surface velocity. When v=2.0m / s, the membrane flux is 80~90L / h·㎡, and the rate of decrease of membrane flux tends to accelerate. When v=4.0m / s, the membrane flux remains at 115~125L / h·㎡ for a long time. Although too low membrane surface velocity will accelerate the process of membrane fouling, the effect of increasing membrane surface velocity on the alleviation of membrane fouling is also limited. The membrane flux at membrane surface velocity of 4.0m / s and 4.5m / s is basically the same in the stable stage. At this time, continuing to increase the membrane surface velocity will increase energy consumption. Therefore, in the subsequent design, it is optimal to use 4.0m / s as the membrane surface velocity.

[0080] The experimental study of tubular SiC ceramic MBR membrane showed that at a temperature of 21°C, MLSS = 9-11 g / L, and an operating pressure of 0.15MPa, the membrane flux was 120-130 L / h, and the membrane surface velocity was 4.0 m / s, which could achieve a good pollution control effect. In the backwash test, a good flux recovery effect was achieved with 3 times the backwash water volume and 30 s backwash gas volume. When the backwash cycle was 60 min, the membrane flux recovery after backwashing was optimal.

[0081] The parameters in the design of tubular SiC ceramic MBR membrane elements are summarized as follows: (1) sludge concentration operating range: 9~11g / L; (2) operating conditions: operating pressure 0.15 MPa, membrane surface flow rate 4.0 m / s; (3) critical membrane flux: 110~120 L / h; (4) backwashing method: clean water backwashing, followed by air backwashing.

[0082] Embodiment 17

[0083] According to the process flow chart and structural schematic diagram of this application, the equipment selection and structural design of the device are carried out. The dry weight of the device is 1.92t, the maximum size of the equipment is 2.6×2.2×2.1 m (length×width×height), and the effective volume is 5.34 m³. The design of the ship domestic sewage treatment device with a rated user population of 80 and a maximum user population of 83 is based on the discharge of 70 L of domestic sewage per person per day, and the maximum daily treatment capacity is 7.5 m³. The mixed liquid of factory domestic sewage and artificial water with a mixing ratio of 9:1 is used as the treatment object to simulate the water quality of ship domestic sewage (according to the provisions on the water quantity and water quality of raw sewage during the onshore test of the ship domestic sewage treatment device in the "Technical Conditions for Ship Domestic Sewage Treatment Equipment"), the water quality of the inlet water, the water quality after treatment by the process of the present invention, and the water quality of the discharge standard are shown in Table 2 below.

[0084] Table 2

[0085]

[0086] As shown in Table 2, when HRT of pool A is 5 h, HRT of pool O is 8 h, DO of pool O is 3.0 mg / L, and reflux ratio of nitrification liquid is 300%, COD in the effluent water quality is Cr , NH3-N, TN and TP indicators meet the effluent standard requirements.

[0087] Specifically, in the material and equipment costs other than labor costs, the main expenditure of the device is SiC ceramic membrane core and membrane assembly, accounting for 30% of the total equipment cost, followed by profile standard parts and automatic control equipment, accounting for 22% and 13% of the total equipment cost respectively. Although the cost of instruments and sensors accounts for 8% of the total cost. Due to the highly automated control method of the equipment and the long chemical washing cycle, the cost of manual operation and cleaning agents can be ignored when calculating the operating cost, and the equipment's transportation cost is mainly the consumption of electricity. Since the compressed air source will be provided on board at that time, the actual power-consuming devices are only the MBR circulation pump and the water inlet crushing pump. It can be calculated that when the device is turned on all day, it costs 14.59 yuan to treat each ton of water.

[0088] The above embodiments are only used to further illustrate a ship domestic sewage treatment process and device of the present invention, but the present invention is not limited to the embodiments. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention should be included in the scope of the claims of this application.

Claims

1. A process for treating domestic sewage from a ship, characterized in that: include: The domestic sewage of the ship is passed through a rotating garbage separator to remove large pieces of garbage, and then crushed by a crushing pump to obtain sewage to be treated; The sewage to be treated is subjected to A / O biochemical treatment to obtain biochemical effluent; The biochemical effluent is treated by an external MBR to obtain a concentrated mixed liquid and produced water; The concentrated mixed liquor is returned to A / O biochemical treatment, and the produced water is sterilized by ultraviolet light to obtain the discharge water.

2. The process according to claim 1, characterized in that: The crushing pump crushing process obtains crushed particles less than or equal to 5 mm, which are used to improve the efficiency of subsequent biochemical treatment.

3. The process according to claim 1, characterized in that: The A / O biochemical treatment is enhanced by MBBR, and the A / O biochemical treatment includes anoxic MBBR treatment and aerobic MBBR treatment; The anoxic MBBR treatment HRT is 3.5-9 h; The aerobic MBBR treatment has an HRT of 6-10 h, a DO of 2-5 mg / L, and a nitrification solution reflux ratio of 200-400%.

4. The process according to claim 1, characterized in that: The external MBR treatment adopts a tubular SiC ceramic membrane, the tubular SiC ceramic membrane has an operating pressure of 0.05-0.25 MPa and a membrane surface flow rate range of 2-4.5 m / s.

5. The process according to claim 4, characterized in that: The external MBR also includes a backwashing process, in which the backwashing pressure is provided by compressed air, and air intake is maintained for a period of time after the backwashing water is flushed to perform air washing.

6. The process according to claim 1, characterized in that: The concentrated mixed liquor is returned to A / O biochemical treatment, the concentrated mixed liquor can be returned to aerobic MBBR treatment and / or anoxic MBBR treatment, and the concentrated mixed liquor returned to anoxic MBBR treatment can be used as nitrification liquid to provide nitrate nitrogen for denitrifying bacteria.

7. A device for treating domestic sewage from a ship, characterized in that: include: A sewage inlet (1), a regulating water tank (2), a pulverizing pump (4), anoxic MBBR (5), aerobic MBBR (6), an MBR circulation pump (7), an ultrafiltration ceramic membrane (8), a jet aerator (9), a backwash tank (10), a qualified water discharge port (12) and a chemical washing tank (13); a rotating garbage separator (3) for automatically compressing and packing filtered particles is provided between the sewage inlet (1) and the regulating water tank (2); the rotating garbage separator (3) is fixed on the regulating water tank (2); the regulating water tank (2), the pulverizing pump (4), the anoxic MBBR (5), the aerobic MBBR (6), the MBR circulation pump (7) and the ultrafiltration ceramic membrane (8) are connected in sequence along the water flow direction; the outlet of the ultrafiltration ceramic membrane (8) is respectively connected to the jet aerator (9) and the backwash tank (10); the jet aerator (9) is connected to the aerobic MBBR (6); and the backwash tank (10) is connected to the qualified water discharge port (12).

8. The device according to claim 7, characterized in that: A water tank liquid level gauge (21) is provided in the regulating water tank (2); the water tank liquid level gauge (21) is a float type liquid level gauge with adjustable upper and lower limits.

9. The device according to claim 7, characterized in that: A pulverizing direct discharge port (41) with a three-way valve is provided between the pulverizing pump (4) and the anoxic MBBR (5).

10. The device according to claim 7, characterized in that: The anoxic MBBR (5) comprises an exhaust port (51) and a bacterial agent addition port (52), an interception net for promoting fluidization is provided at the bottom, and an anoxic circulation pump (53) is provided outside.

11. The device according to claim 7, characterized in that: The aerobic MBBR (6) comprises a second exhaust port (61) and a second bacterial agent addition port (62), an interception net for promoting fluidization is provided at the bottom, and an aerobic liquid level meter (63) is provided inside.

12. The device according to claim 7, characterized in that: The ultrafiltration ceramic membrane (8) is a tubular SiC ceramic membrane.

13. The device according to claim 7, characterized in that: The backwash tank (10) is provided with a compressed air interface (101); the drug washing box (13) is provided with a drug washing waste liquid discharge port (131); and the drug washing box (13) is connected to the ultrafiltration ceramic membrane (8).

14. The device according to claim 7, characterized in that: An ultraviolet sterilization lamp (11) is provided between the backwash tank (10) and the qualified water discharge port (12).

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