CN114315021A - Full-scale treatment system and method for middle and later-period leachate of refuse landfill - Google Patents
Full-scale treatment system and method for middle and later-period leachate of refuse landfill Download PDFInfo
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- CN114315021A CN114315021A CN202111596587.3A CN202111596587A CN114315021A CN 114315021 A CN114315021 A CN 114315021A CN 202111596587 A CN202111596587 A CN 202111596587A CN 114315021 A CN114315021 A CN 114315021A
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Abstract
The invention provides a full-scale treatment system and method for middle and later-stage leachate of a refuse landfill. The system comprises a disc tube type reverse osmosis DTRO device, a primary electric flocculation device, a primary biological filter, a secondary electrolysis device, a secondary biological filter, a tertiary electrolysis device and a gas supply device; wherein, the disc tube type reverse osmosis DTRO device is respectively connected with the first-stage electric flocculation device and the third-stage electrolysis device, the first-stage biofilter is respectively connected with the first-stage electric flocculation device, the second-stage electrolysis device and the gas supply device, the second-stage electrolysis device is also connected with the first-stage electric flocculation device, and the second-stage biofilter is respectively connected with the second-stage electrolysis device and the third-stage electrolysis device; the disc tube type reverse osmosis DTRO device comprises a disc tube type DTRO membrane component and a two-stage SWRO membrane component. The invention aims at the characteristics of high ammonia nitrogen and refractory organic wastewater, firstly concentrates the wastewater, and then carries out the organic combination of electrocoagulation, electrolysis and a biological filter tank, thereby economically and effectively treating the wastewater until the effluent reaches the standard, and the invention has the advantages of high reaction speed, small occupied area and low operating cost.
Description
Technical Field
The invention relates to the technical field of sewage treatment, in particular to a full-scale treatment system and method for treating middle and later-stage leachate of a landfill with high ammonia nitrogen and refractory organic matters.
Background
In leachate at the middle and later stages of a refuse landfill and certain specific industrial wastewater, the water quality of the leachate has the characteristics of high ammonia nitrogen concentration, more refractory components, high salinity and the like, and is characterized in that the B/C ratio (BOD5 (biochemical oxygen demand) to COD (chemical oxygen demand)) is particularly low, and the C/N ratio (carbon-nitrogen ratio) is seriously unbalanced.
The existing wastewater treatment process for high ammoniA nitrogen and refractory organic matters in the market generally adopts A process route of (A/O-A/O) biochemistry, membrane concentration and evaporation, and although the process has A good pollutant removal effect, the process still has A plurality of defects: the B/C ratio is particularly low, so that the treatment effect of biochemical treatment on difficultly degraded COD is poor; the C/N ratio imbalance causes excessive carbon sources added for biochemical denitrification; the difficult-to-degrade COD is high, so that the NF or RO membrane is seriously blocked, and the water yield is reduced; the rear-section evaporation equipment cannot produce salt due to high organic matters and a heat exchange system is seriously blocked; and the problems of long process flow, complex operation, large occupied area and the like exist.
Therefore, a total treatment process with short process flow, small occupied area and low operating cost needs to be developed to solve the treatment problem of the wastewater containing high ammonia nitrogen and refractory organic matters.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a full-scale treatment process for treating high-ammonia nitrogen and refractory organic wastewater. The process integrates the advantages of various biochemical treatments and physicochemical treatments by combining membrane concentration, electrolytic advanced oxidation and biotechnology, fully utilizes the advantages of each process section to integrate into a whole, has short process flow and small occupied area, effectively reduces the operation cost of the system, and treats the middle and later-period leachate of the refuse landfill with high salt, high ammonia nitrogen and high COD (chemical oxygen demand) or other industrial wastewater to meet the discharge standard.
The invention provides a full-scale treatment system for middle and later-stage leachate of a refuse landfill, which comprises a disc tube type reverse osmosis DTRO device, a primary electric flocculation device, a primary biological filter, a secondary electrolysis device, a secondary biological filter, a tertiary electrolysis device and a gas supply device;
the disc tube type reverse osmosis DTRO device is respectively connected with the primary electric flocculation device and the tertiary electrolysis device, the primary biofilter is respectively connected with the primary electric flocculation device, the secondary electrolysis device and the gas supply device, the secondary electrolysis device is also connected with the primary electric flocculation device, and the secondary biofilter is respectively connected with the secondary electrolysis device and the tertiary electrolysis device;
the disc tube type reverse osmosis DTRO device comprises a disc tube type DTRO membrane module and a two-stage SWRO membrane module.
In some embodiments of the invention, the disc tube reverse osmosis DTRO device further comprises a pretreatment module comprising a raw water tank, a sand filter and a filter.
In some embodiments of the present invention, the primary electroflocculation apparatus includes an electroflocculation tank, in which a plurality of plate-shaped first anodes and first cathodes are alternately arranged, the first anodes are metallic iron or metallic titanium electrodes, and the first cathodes are metallic iron, metallic titanium or graphite electrodes.
In some embodiments of the present invention, the primary biofilter is a low-air-volume biological aerated filter, and the filter material of the primary biofilter is one or more of ceramsite, activated carbon and volcanic rock.
In some embodiments of the invention, the secondary electrolysis device comprises a first electrolysis bath, wherein a plurality of second anodes and second cathodes which are alternately arranged and are in plate shapes or net shapes are arranged in the first electrolysis bath, the second anodes are titanium-based ruthenium iridium electrodes, and the second cathodes are metallic titanium or stainless steel electrodes.
In some embodiments of the present invention, the secondary biofilter is a biological activated carbon filter or an anoxic biological aerated filter, and the filter material of the secondary biofilter is one or more of ceramsite, activated carbon and volcanic rock.
In some embodiments of the invention, the three-stage electrolysis device comprises a second electrolysis bath, wherein a plurality of plate-shaped or net-shaped third anodes and third cathodes which are alternately arranged are arranged in the second electrolysis bath, the third anodes are titanium-based ruthenium iridium electrodes, and the third cathodes are metallic titanium or stainless steel electrodes.
The method for treating the leachate in the middle and later periods of the refuse landfill by adopting the total treatment system comprises the following steps:
removing suspended matters from the leachate in the middle and later stages of the refuse landfill, and sending the leachate into the disc tube type DTRO membrane module and the two-stage SWRO membrane module to obtain first produced water and first concentrated water;
feeding the first concentrated water into the primary electric flocculation device, controlling the voltage of the primary electric flocculation device to be 3-5V, and controlling the reaction time to be 30-60 min to obtain second produced water;
feeding the second produced water into the primary biofilter, and controlling the dissolved oxygen concentration of the primary biofilter to be 0.5-1.5 mg/L, pH value to be 6.5-7.5 and the temperature to be 18-30 ℃ to obtain third produced water;
feeding the third produced water into the secondary electrolysis device, controlling the voltage of the secondary electrolysis device to be 3-7V, and controlling the reaction time to be 30-120 min to obtain fourth produced water;
returning part of the fourth produced water to the primary electric flocculation device, and feeding the rest of the fourth produced water to a secondary biological filter, and controlling the pH value of the secondary biological filter to be 6.5-7.5 and the temperature to be 18-30 ℃ to obtain fifth produced water;
feeding the fifth produced water into the third-stage electrolysis device, and controlling the voltage of the third-stage electrolysis device to be 3-7V and the reaction time to be 30-120 min to obtain sixth produced water;
combining and discharging the first produced water and the sixth produced water.
In some embodiments of the invention, acid, a sand filter and a filter are sequentially used for removing the suspended substances of the leachate in the middle and later periods of the refuse landfill.
In some embodiments of the invention, the particle size of the filter material in the primary biofilter and the secondary biofilter is 5-20 mm.
The invention aims at the characteristics of high ammonia nitrogen and refractory organic wastewater, firstly concentrates the wastewater, and then carries out the organic combination of electrocoagulation, electrolysis and a biological filter tank, thereby economically and effectively treating the wastewater until the effluent reaches the standard, and the invention has the advantages of high reaction speed, small occupied area and low operating cost.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
Fig. 1 is a schematic structural diagram of a full-scale treatment system for middle and later-stage leachate in a landfill according to an embodiment of the present invention.
Detailed Description
In the following, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention. Furthermore, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first," "second," etc. may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly above and obliquely above the second feature, or simply meaning that the first feature is at a lesser level than the second feature.
Unless otherwise indicated, the reagents, materials and instruments used in the technical scheme provided by the invention can be obtained from conventional sources or on the market.
Fig. 1 shows a full-scale treatment system 100 for middle and later-stage leachate in a landfill, which comprises a disc-tube reverse osmosis DTRO device 110, a primary electroflocculation device 120, a primary biofilter 130, a secondary electrolysis device 140, a secondary biofilter 150, a tertiary electrolysis device 160 and a gas supply device 170, according to an embodiment of the present invention.
Wherein, the disc tube type reverse osmosis DTRO device 110 is respectively connected with the first-stage electric flocculation device 120 and the third-stage electrolysis device 160, the first-stage biological filter 130 is respectively connected with the first-stage electric flocculation device 120, the second-stage electrolysis device 140 and the air supply device 170, the second-stage electrolysis device 140 is also connected with the first-stage electric flocculation device 120, and the second-stage biological filter 150 is respectively connected with the second-stage electrolysis device 140 and the third-stage electrolysis device 160.
The disc tube type reverse osmosis DTRO apparatus 110 includes a disc tube type DTRO membrane module (not shown) and a two-stage SWRO membrane module (not shown).
The disc-tube type reverse osmosis DTRO device 110 further comprises a high-pressure plunger type water inlet pump and a circulating booster pump. DTRO membranes have two major special advantages: the special open flow channel and the sufficient turbulent flow design have much lower requirements on water inlet SS and COD than the common RO membrane, can greatly reduce common dirt blockage and scaling in the reverse osmosis membrane component, and has the water yield of over 70 percent and the retention rate of over 98.8 percent. The water produced after the treatment of the DTRO membrane can meet the strict water quality discharge requirement.
Optionally, the disc-tube reverse osmosis DTRO device 110 may also include a pre-treatment component (not shown). The pretreatment component can comprise a raw water tank, a sand filter and a filter, and can remove suspended matters, a small amount of COD (chemical oxygen demand) and organic nitrogen by adopting a mode of adding acid into the raw water tank, filtering sand and mechanically filtering.
Optionally, the disc tube reverse osmosis DTRO device 110 may also include a dosing device, a cleaning device, and a product/concentrate tank.
The produced water of the disc-tube reverse osmosis DTRO device 110 is directly mixed with the effluent of the third stage electrolysis device 160 and then discharged. The concentrate from the disc-tube reverse osmosis DTRO device 110 enters the primary electroflocculation device 120.
The primary electroflocculation system 120 is an integrated machine integrating electrolysis, flocculation and air flotation. The primary electroflocculation apparatus 120 includes an electroflocculation tank (not shown in the figure), in which a plurality of plate-like first anodes and first cathodes are arranged alternately, the first anodes are metallic iron or metallic titanium electrodes, and the first cathodes are metallic iron, metallic titanium or graphite electrodes.
For example, metal iron is used as an anode, and divalent iron ions dissolved on the anode and transferred into the solution in the electrolysis process are hydrolyzed to become an effective flocculant for dispersing impurities. If metallic titanium is used as anode, iron coagulant is added to the electric flocculation tank to form suspended matter SS and animal and vegetable oil into flocs. While generating oxygen or chlorine bubbles as by-products at the anode and hydrogen bubbles at the cathode. The fine micro-bubbles generate air flotation to bring the floccules to the water surface to form a scum layer and are scraped to a slag collecting barrel by a slag scraper. Controlling the voltage of the electric flocculation system to be 3-5V, and controlling the reaction time to be 30-60 min. The electric flocculation system is also provided with a pH adjusting device and a medicament (PAM (polyacrylamide)) adding device. In order to effectively reduce the viscosity of the inlet water and prevent excessive foam generation, part of the produced water of the secondary electrolytic device 140 is returned to the front of the primary electroflocculation device 120.
The produced water of the primary electric flocculation device 120 enters a primary biological filter 130. The primary biofilter 130 is a low-air-volume aerated biofilter, and a blower of the air supply device 170 is used for supplying a proper amount of air or oxygen to the primary biofilter 130. During the treatment, the dissolved oxygen is controlled to be 0.5-1.5 mg/L. The system fully utilizes BOD (biochemical oxygen demand) increased by the primary electric flocculation device 120 as a carbon source, and forms an aerobic/anoxic environment locally through the filter material of the primary biological filter 130. The filter material can be one or more of ceramsite, activated carbon and volcanic rock, the particle size is selected from 5-20 mm, and the particle size is uniform. The microorganism on the surface of the filter material can carry out biodegradation on partial ammonia nitrogen and COD (chemical oxygen demand) with low operation cost and good treatment effect. The pH value and the temperature in the first-stage biological filter 130 can be controlled to be 6.5-7.5 and 18-30 ℃.
The produced water of the primary biofilter 130 enters the secondary electrolysis device 140. The secondary electrolysis device 140 comprises a first electrolysis bath (not shown in the figure) in which a plurality of second anodes and second cathodes are alternately arranged, wherein the second anodes are titanium-based ruthenium iridium electrodes, and the second cathodes are metallic titanium or stainless steel electrodes.
Controlling the voltage of an electrolysis system to be 3-7V and the reaction time to be 30-120 min. Through the electrocatalytic oxidation reaction of electrolysis, strong oxidizing substances such as hydroxyl radicals and hypochlorite radicals can be formed at the anode, nitrate nitrogen, nitrite nitrogen and the like can be reduced at the cathode, so that ammonia nitrogen and COD which are difficult to degrade can be effectively removed, the B/C ratio and the C/N ratio are improved, and conditions are created for the secondary biofilter 150.
Part of the water produced by the secondary electrolytic device 140 flows back to the primary electric flocculation device 120, and the rest enters the secondary biological filter 150. The secondary biological filter 150 is a biological activated carbon filter or an anoxic aeration biological filter, and the filter material can be one or more of activated carbon, ceramsite and volcanic rock, the particle size is selected from 5-20 mm, and the particle size is uniform. The secondary biofilter 150 makes full use of BOD increased by the secondary electrolysis device 140 as a carbon source, further reduces total nitrogen and COD in an anoxic environment, and has low operation cost and good treatment effect. The pH value and the temperature in the secondary biofilter 150 need to be controlled between 6.5 and 7.5 and between 18 and 30 ℃.
The produced water of the secondary biofilter 150 enters the tertiary electrolysis device 160. The three-stage electrolyzer 160 comprises a second electrolyzer (not shown in the figure), wherein a plurality of plate-shaped or net-shaped third anodes and third cathodes are alternately arranged in the second electrolyzer, the third anodes are titanium-based ruthenium iridium electrodes, and the third cathodes are metallic titanium or stainless steel electrodes.
Controlling the voltage of an electrolysis system to be 3-7V and the reaction time to be 30-120 min. By means of the electrocatalytic oxidation reaction of electrolysis, strong oxidizing substances such as hydroxyl radicals and hypochlorite can be formed at the anode, nitrate nitrogen, nitrite nitrogen and the like can be reduced at the cathode, and therefore total nitrogen and COD which is difficult to degrade can be further removed. In order to further improve the reaction efficiency, electrolytic catalytic fillers can be filled between the adjacent anode plate/net and cathode plate/net, and the electrolytic catalytic fillers can be formed by high-temperature sintering of alumina or activated carbon loaded noble metal.
In the invention, the disc tube type reverse osmosis DTRO device can further concentrate raw water, so that the salinity of the post-stage electric flocculation and electrolysis is improved, the removal efficiency of ammonia nitrogen and difficultly degraded COD by the electric flocculation and electrolysis is improved, and membrane produced water is mixed with three-stage electrolysis effluent to ensure that the effluent is discharged after reaching the standard. The primary electroflocculation device can effectively remove suspended matters and colloid substances, preliminarily remove a part of ammonia nitrogen and difficultly degraded COD, improve the B/C ratio and create conditions for a primary biofilter system. In order to effectively reduce the viscosity of inlet water and prevent excessive foam generation, part of produced water of the secondary electrolysis is returned to the front of the primary electroflocculation device. The primary biofilter adopts a low-air-volume aeration biofilter, the BOD improved by the primary electroflocculation system is fully utilized as a carbon source, the ammonia nitrogen and the COD are further reduced through a local aerobic/anoxic environment, and the effect of reducing the operation cost is achieved. The anode of the secondary electrolysis device adopts a titanium-based ruthenium iridium electrode, so that ammonia nitrogen and difficultly degraded COD can be effectively removed, the B/C ratio is improved, and conditions are created for a secondary biological filter system. The secondary biological filter adopts biological activated carbon or an anoxic aeration biological filter, fully utilizes BOD improved by a secondary electrolysis system as a carbon source, further reduces total nitrogen and COD in an anoxic environment, and achieves the effect of reducing the operation cost. The anode of the three-stage electrolysis device adopts a titanium-based ruthenium iridium electrode, so that total nitrogen and difficultly-degraded COD can be further removed. The invention aims at the characteristics of high ammonia nitrogen and refractory organic wastewater, firstly concentrates the wastewater, and then carries out the organic combination of electrocoagulation, electrolysis and a biological filter tank, thereby economically and effectively treating the wastewater until the effluent reaches the standard, and the invention has the advantages of high reaction speed, small occupied area and low operating cost.
The invention further provides a method for treating middle and later-period leachate of a refuse landfill by adopting the full-scale treatment system, which comprises the following steps:
removing suspended matters from the leachate in the middle and later stages of the refuse landfill, and sending the leachate into a disc tube type DTRO membrane module and a second-stage SWRO membrane module to obtain first produced water and first concentrated water;
feeding the first concentrated water into a first-stage electric flocculation device, controlling the voltage of the first-stage electric flocculation device to be 3-5V, and reacting for 30-60 min to obtain second produced water;
feeding the second produced water into a first-stage biological filter, and controlling the dissolved oxygen concentration of the first-stage biological filter to be 0.5-1.5 mg/L, pH value to be 6.5-7.5 and the temperature to be 18-30 ℃ to obtain third produced water;
feeding the third produced water into a secondary electrolysis device, controlling the voltage of the secondary electrolysis device to be 3-7V, and controlling the reaction time to be 30-120 min to obtain fourth produced water;
returning the fourth produced water part to the first-stage electric flocculation device, and feeding the rest into the second-stage biological filter, and controlling the pH value of the second-stage biological filter to be 6.5-7.5 and the temperature to be 18-30 ℃ to obtain fifth produced water;
feeding the fifth produced water into a third-stage electrolysis device, controlling the voltage of the third-stage electrolysis device to be 3-7V, and controlling the reaction time to be 30-120 min to obtain sixth produced water;
and combining and discharging the first produced water and the sixth produced water.
The technical scheme of the invention has the following beneficial effects:
(1) the invention provides a full-scale treatment process for treating high-ammonia nitrogen and refractory organic wastewater. The membrane concentration, the electrolysis advanced oxidation and the biotechnology are combined, the advantages of various biochemical treatment and physicochemical treatment are integrated, the advantages of each process section are fully utilized and integrated into a whole, the process flow is short, the occupied area is small, the system operation cost is effectively reduced, and the middle and later-period leachate or other industrial wastewater of the high-salt high-ammonia nitrogen and high-degradation-resistant COD landfill is treated to meet the discharge standard.
(2) The disc tube type reverse osmosis DTRO system provided by the invention has lower requirements on inlet water SS and COD than those of a common RO membrane, can greatly reduce common dirt blockage and scaling in a reverse osmosis membrane component, and can reach the strict water quality discharge requirement on the water yield.
(3) The invention adopts a first-stage electric flocculation system, a second-stage electrolysis system and a third-stage electrolysis system, can form strong oxidizing substances such as hydroxyl radicals, hypochlorite and the like at the anode, can reduce nitrate nitrogen, nitrite nitrogen and the like at the cathode, and gradually increases the oxidation reduction capability, thereby gradually removing total nitrogen (ammonia nitrogen) and nondegradable COD.
(4) The invention adopts the primary biological filter system and the secondary biological filter system after the primary electric flocculation and the secondary electrolysis, fully utilizes BOD improved by the electric flocculation and the electrolysis as a carbon source to carry out anoxic denitrification, and can further reduce the total nitrogen and COD at lower operating cost.
(5) In order to effectively reduce the viscosity of inlet water and prevent excessive foam generation, part of produced water of the secondary electrolysis is refluxed to the front of the primary electric flocculation system, so that the foam generated by the primary electric flocculation system is greatly reduced.
The present invention will be described below with reference to specific examples. The values of the process conditions taken in the following examples are exemplary and ranges of values are provided as indicated in the foregoing summary, and reference may be made to conventional techniques for process parameters not specifically noted. The detection methods used in the following examples are all conventional in the industry. Unless otherwise indicated, the reagents and instruments used in the technical scheme provided by the invention can be purchased from conventional channels or markets.
Examples
In this example, the system shown in FIG. 1 is used to treat leachate in the middle and later stages of a landfill, the leachate has a COD of 5500mg/L and a B/C ratio of 0.24 and contains NH3N2860mg/L, TN3010mg/L, TDS23500mg/L, C/N ratio 2.
The method comprises the following specific steps:
(1) and (3) removing suspended matters from the leachate in the middle and later stages of the refuse landfill in a raw water tank, a sand filter and a filter, and sending the leachate into a disc tube type DTRO membrane module and a second-stage SWRO membrane module to obtain first produced water and first concentrated water.
And removing suspended substances, a small amount of COD (chemical oxygen demand) and organic nitrogen in the percolate through acid and sand filtration and mechanical filtration. Wherein the acid used in the raw water tank is concentrated sulfuric acid, the pH of the raw water tank is adjusted to 6.0-7.0, and the water inlet pressure of the disc-tube type DTRO membrane component is 60-120 bar.
The recovery rate in this step was 60%. The COD of the first produced water is 35mg/L, -NH3N is 12mg/L, TN is 12mg/L, TDS is 280 mg/L.
The COD of the first concentrated water is 13700mg/L, the B/C ratio is 0.24, and the NH content3N is 7150mg/L, TN is 7500mg/L, TDS is 58000mg/L, and C/N ratio is 2.
(2) And (3) feeding the first concentrated water into a first-stage electric flocculation device, controlling the voltage of the first-stage electric flocculation device to be 3V, and reacting for 60min to obtain second produced water.
Wherein, the anode of the first-stage electric flocculation device is a pure iron anode, and the cathode of the first-stage electric flocculation device is a pure iron anode. The distance between the adjacent anode plate and cathode plate is 2cm, and the current density is 350mA/cm2。
The COD of the second produced water is 7560mg/L, the B/C ratio is 0.31, and NH3N is 6510mg/L, TN is 6850 mg/L.
(3) And (3) feeding the second produced water into the first-stage biological filter, controlling the dissolved oxygen concentration of the first-stage biological filter to be 1-1.5mg/L, pH, the value to be 7-7.5 and the temperature to be 25-30 ℃, and obtaining third produced water.
The used filter materials are ceramsite and active carbon, and the particle size of the filter materials is 10 mm.
COD of the third product water is 5500mg/L, NH3N is 3200mg/L, and TN is 3500 mg/L.
(4) And (4) feeding the third produced water into a secondary electrolysis device, and controlling the voltage of the secondary electrolysis device to be 6.5V and the reaction time to be 120min to obtain fourth produced water.
Wherein, the anode of the secondary electrolysis device is a titanium-based ruthenium-iridium anode, and the cathode is a metal titanium cathode. The distance between the adjacent anode plate and cathode plate is 2cm, and the current density is 3500mA/cm2。
The fourth produced water has COD of 2560mg/L, B/C ratio of 0.42 and NH3N is 580mg/L, TN is 650mg/L, and the C/N ratio is 4.5.
(5) And refluxing the fourth produced water part to the first-stage electric flocculation device, and feeding the rest into the second-stage biological filter, and controlling the pH value of the second-stage biological filter to be 6.5-7 and the temperature to be 25-30 ℃ to obtain fifth produced water.
The used filter material is activated carbon, and the particle size of the filter material is 7 mm.
The COD of the fifth produced water is 600mg/L and NH3N is 50mg/L, TN is 72 mg/L.
(6) And (4) delivering the fifth produced water into a third-stage electrolytic device, controlling the voltage of the third-stage electrolytic device to be 6.5V, and controlling the reaction time to be 30min to obtain sixth produced water.
Wherein, the anode of the three-stage electrolysis device is a titanium-based ruthenium-iridium anode, and the cathode is a stainless steel cathode. The distance between the adjacent anode plate and cathode plate is 2cm, and the current density is 1000mA/cm2。
The COD of the sixth produced water is 46mg/L, NH3N is 0.3mg/L, TN is 18 mg/L.
(7) The first produced water and the sixth produced water are combined and discharged, the total produced water COD is 40mg/L, NH37.5mg/L of-N and 15mg/L of TN.
It should be understood that the above examples are only for clearly illustrating the present invention and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the scope of the invention.
Claims (10)
1. A full-scale treatment system for leachate in the middle and later stages of a refuse landfill is characterized by comprising a disc tube type reverse osmosis DTRO device, a primary electric flocculation device, a primary biological filter, a secondary electrolysis device, a secondary biological filter, a tertiary electrolysis device and a gas supply device;
the disc tube type reverse osmosis DTRO device is respectively connected with the primary electric flocculation device and the tertiary electrolysis device, the primary biofilter is respectively connected with the primary electric flocculation device, the secondary electrolysis device and the gas supply device, the secondary electrolysis device is also connected with the primary electric flocculation device, and the secondary biofilter is respectively connected with the secondary electrolysis device and the tertiary electrolysis device;
the disc tube type reverse osmosis DTRO device comprises a disc tube type DTRO membrane module and a two-stage SWRO membrane module.
2. The full scale treatment system of claim 1 wherein the disc tube reverse osmosis DTRO device further comprises a pre-treatment assembly comprising a raw water tank, a sand filter and a filter.
3. The full-scale treatment system according to claim 1, wherein the primary electroflocculation device comprises an electroflocculation tank, a plurality of plate-shaped first anodes and first cathodes are alternately arranged in the electroflocculation tank, the first anodes are metallic iron or metallic titanium electrodes, and the first cathodes are metallic iron, metallic titanium or graphite electrodes.
4. The total treatment system according to claim 1, wherein the primary biofilter is a low-air-volume biological aerated filter, and the filter material of the primary biofilter is one or more of ceramsite, activated carbon and volcanic rock.
5. The full-scale treatment system according to claim 1, wherein the secondary electrolysis device comprises a first electrolysis bath, a plurality of second anodes and second cathodes are alternately arranged in the first electrolysis bath, the second anodes are titanium-based ruthenium iridium electrodes, and the second cathodes are metallic titanium or stainless steel electrodes.
6. The full-scale treatment system according to claim 1, wherein the secondary biofilter is a biological activated carbon filter or an anoxic biological aerated filter, and the filter material of the secondary biofilter is one or more of ceramsite, activated carbon and volcanic rock.
7. The full scale treatment system according to claim 1, wherein the three-stage electrolyzer comprises a second electrolytic tank, a plurality of plate-shaped or net-shaped third anodes and third cathodes are alternately arranged in the second electrolytic tank, the third anodes are titanium-based ruthenium iridium electrodes, and the third cathodes are metallic titanium or stainless steel electrodes.
8. A method of treating middle and late stage leachate from a landfill using the full scale treatment system of any one of claims 1 to 7, comprising:
removing suspended matters from the leachate in the middle and later stages of the refuse landfill, and sending the leachate into the disc tube type DTRO membrane module and the two-stage SWRO membrane module to obtain first produced water and first concentrated water;
feeding the first concentrated water into the primary electric flocculation device, controlling the voltage of the primary electric flocculation device to be 3-5V, and controlling the reaction time to be 30-60 min to obtain second produced water;
feeding the second produced water into the primary biofilter, and controlling the dissolved oxygen concentration of the primary biofilter to be 0.5-1.5 mg/L, pH value to be 6.5-7.5 and the temperature to be 18-30 ℃ to obtain third produced water;
feeding the third produced water into the secondary electrolysis device, controlling the voltage of the secondary electrolysis device to be 3-7V, and controlling the reaction time to be 30-120 min to obtain fourth produced water;
returning part of the fourth produced water to the primary electric flocculation device, and feeding the rest of the fourth produced water to a secondary biological filter, and controlling the pH value of the secondary biological filter to be 6.5-7.5 and the temperature to be 18-30 ℃ to obtain fifth produced water;
feeding the fifth produced water into the third-stage electrolysis device, and controlling the voltage of the third-stage electrolysis device to be 3-7V and the reaction time to be 30-120 min to obtain sixth produced water;
combining and discharging the first produced water and the sixth produced water.
9. The method of claim 8, wherein acid, a sand filter and a filter are used in sequence to remove the leachate from the middle and later stages of the landfill.
10. The method according to claim 8, wherein the grain size of the filter material in the primary biofilter and the secondary biofilter is 5-20 mm.
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