CN115947509A - Sewage and sludge co-treatment process and system based on sludge component separation - Google Patents
Sewage and sludge co-treatment process and system based on sludge component separation Download PDFInfo
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Abstract
The invention relates to the field of sewage recovery, in particular to a sewage and sludge co-treatment process and system based on sludge component separation. The method adopts an acidification and multistage water washing combined mode, can realize component separation of organic components and inorganic components of the sludge through solid-liquid separation, and respectively carries out subsequent recovery treatment, and can realize improvement of the dehydration performance of the organic sludge, substantial improvement of organic content and substantial reduction of heavy metal content for the organic phase of the sludge. For inorganic components of the sludge, the recovery of phosphorus and flocculant can be realized from the supernatant, and the recovery rate of effective components in the sludge is further optimized. In addition, the sewage and sludge cooperative treatment system fully utilizes the existing process conditions of a sewage plant under the condition of not changing the existing mainstream sewage treatment route and the construction unit, has simple equipment structure, easy operation and maintenance, low cost and good sludge and sewage treatment effect, and is suitable for upgrading and reconstruction of the existing small sewage treatment plant.
Description
Technical Field
The invention relates to the field of sewage recovery, in particular to a sewage and sludge cooperative treatment process and system based on sludge component separation.
Background
The existing sewage and sludge treatment is not beneficial to the benign development of sewage treatment plants because of the problems of low treatment efficiency, high medicament consumption, high energy consumption and the like in the existing sewage and sludge treatment, and the resources such as organic matters, phosphorus and the like in the sludge are wasted due to the difficulty in the subsequent treatment of the sludge, so that the key point of transformation of the existing small-sized sewage treatment plants is to provide a novel process for sludge-water synergistic treatment of the sewage treatment plants aiming at the key difficulty in the existing sludge and sewage treatment.
The excess sludge generated by the sewage treatment plant has the characteristics of difficult dehydration, low organic matter content (only 30-60%), high heavy metal content, low phosphorus recovery rate and the like, so that a large amount of sludge with lower quality generated by the sewage treatment plant cannot be subjected to subsequent final treatment processes such as incineration, composting and the like, and for example, the sludge incineration process usually needs auxiliary combustion in the modes of pre-drying, coal adding and the like; when sludge is composted, auxiliary materials such as straws and the like are required to be added to adjust the water content and the C/N, and the existence of heavy metals causes difficulty in the way of compost products. Therefore, the novel sludge pretreatment technology is provided to realize quality improvement and reduction of the sludge of the sewage treatment plant, and the sludge which realizes separation of organic and inorganic components of the sludge, improvement of dehydration performance, removal of heavy metals and recovery of phosphorus is very important for solving the problem of difficult sludge treatment at the present stage.
Therefore, in the inventor's prior research (Yu Fan et al, 2022, advanced technology for sludge dewatering development, organic components separation and heavy metals removal), a novel pretreatment method of sludge Acidification combined with Multistage Elutriation (AME) is provided, which can be used for improving sludge dewatering, separating inorganic components thereof and removing heavy metal substances thereof. There is still room for further improvement in the coupling of the flocculant recovery and sludge component separation process with the existing sewage treatment plant process.
Disclosure of Invention
The invention aims to solve the problems of difficulty in dehydration, low organic matter content, low phosphorus recovery level and high heavy metal content in the sludge treatment process at the present stage, and designs a sludge component separation-based sewage and sludge cooperative treatment process and system.
Specifically, the invention firstly provides a sewage sludge synergistic treatment process, which comprises the following steps:
carrying out acidification treatment and multi-stage elutriation treatment on concentrated sludge collected from sewage, and respectively collecting washing supernatant and elutriated sludge;
adding alkaline substances into the elutriated sludge, conditioning until the pH value is 7 +/-1, and dehydrating to obtain a sludge cake;
adding Fe to the water-washed supernatant 3+ (such as ferric chloride and the like), obtaining a phosphorus recovery product and a recovered supernatant after the precipitation is finished, adding an alkaline substance into the recovered supernatant until the pH value is 4 +/-0.5, and recovering a ferric salt flocculant for precipitation.
According to the sewage sludge synergistic treatment process provided by the invention, part of sewage and the recovered supernatant are treated according to the proportion of 8-9.5: 1, forming Free Nitrous Acid (FNA) under the conditions of pH value of 5 +/-0.5 and ammonia nitrogen concentration of 40-60 mg/L, enriching Ammonia Oxidizing Bacteria (AOB), and putting the treated sludge into an anaerobic ammonia oxidation unit.
According to the sewage sludge synergistic treatment process provided by the invention, the elutriated sludge is subjected to desanding treatment to obtain organic sludge; adding alkaline substances into the organic sludge, conditioning until the pH value is 7 +/-1, and dehydrating to obtain the mud cake.
According to the sewage sludge cooperative treatment process provided by the invention, when concentrated sludge is collected from sewage, the process specifically comprises the following steps:
concentrating sludge separated from sewage, and respectively collecting concentrated supernatant and concentrated sludge (the water content is generally more than 97 wt%);
adding sulfuric acid into the concentrated sludge for the acidification treatment;
mixing the concentrated supernatant with the water-washed supernatant to obtain a mixed supernatant, and adding Fe to the mixed supernatant 3+ Waiting for the precipitation to finish, obtaining phosphorus recovery product and recovering supernatantAnd adding an alkaline substance into the recovered supernatant until the pH value is 4 +/-0.5, and recovering the ferric salt flocculant precipitate.
According to the sewage sludge synergistic treatment process provided by the invention, the alkaline substances comprise one or more of sodium hydroxide, calcium hydroxide, potassium hydroxide, calcium oxide and quicklime.
According to the sewage and sludge co-treatment process provided by the invention, the effluent of a sewage treatment plant is collected and used for the multi-stage elutriation treatment.
The invention also provides a sewage sludge cooperative treatment system, comprising:
a sludge collection unit; used for collecting sludge from sewage;
a sludge modification unit; the material inlet of the sludge treatment device is connected with the sludge outlet of the sludge collection unit, and the sludge treatment device is provided with a medicine adding control element and is used for carrying out acidification treatment on the sludge;
a multi-stage elutriation unit; the material inlet of the device is connected with the sludge outlet of the sludge modification unit and is used for carrying out multi-stage elutriation on the acidified sludge;
a sludge conditioning unit; the feeding port of the device is connected with the sludge outlet of the multi-stage elutriation unit, and the device is provided with a pH value detection element and a dosing control element and is used for conditioning the elutriated sludge to be neutral;
a sludge dewatering unit; the feeding port of the sludge conditioning unit is connected with the sludge outlet of the sludge conditioning unit and is used for dehydrating the conditioned sludge;
a supernatant recovery unit; the feed inlet of the device is connected with the supernatant outlet of the multi-stage elutriation unit, and is provided with a pH value detection element and a dosing control element for recovering phosphorus and flocculating agent from the washing supernatant.
According to the sewage sludge cooperative treatment system provided by the invention, the system further comprises:
an AOB enrichment unit; a feeding port of the device is connected with a supernatant outlet of the supernatant recovery unit, is connected with part of influent branch of sewage, and is provided with a pH value detection element and a dosing control element for enriching Ammonia Oxidizing Bacteria (AOB) in sludge;
an anammox unit; the feed inlet of the AOB enrichment unit is connected with the discharge outlet of the AOB enrichment unit.
According to the sewage sludge coprocessing system that the invention provides, also include:
a desanding unit; the feeding port of the multi-stage elutriation unit is connected with the sludge outlet of the multi-stage elutriation unit, and the sludge outlet of the multi-stage elutriation unit is connected with the feeding port of the sludge conditioning unit.
According to the sewage and sludge co-processing system provided by the invention, in the sludge collection unit, a branch flow pipe is arranged at a water outlet of a sewage treatment plant, and the branch flow pipe is connected with a water inlet of the multi-stage elutriation unit.
The sewage sludge synergistic treatment process adopts a mode of combining acidification and multistage washing, can separate sludge and supernatant, and respectively carries out subsequent recovery treatment, and can realize improvement of the dehydration performance of organic sludge, substantial increase of organic matter content and substantial reduction of heavy metal content for organic sludge phase. For the inorganic supernatant separated from the sludge, the recovery of phosphorus and flocculant can be realized, and the recovery rate of effective components in the sludge is further optimized.
Further, through the optimization of the process, the process can also realize the removal and the reutilization of the gravel.
Furthermore, after the washing supernatant produced in the sludge treatment process is mixed with the inlet water of a sewage plant, the enrichment of AOB bacteria in the sludge can be realized by enriching FNA in an acidic environment, so that the normal operation of an anaerobic ammonia oxidation unit is facilitated, and the high denitrification efficiency is realized under the condition of low sewage energy consumption.
In addition, the sewage and sludge cooperative treatment system fully utilizes the existing process conditions of a sewage plant under the condition of not changing the existing main stream sewage treatment route and the construction unit, has simple equipment structure, easy operation and maintenance, low cost and good sludge and sewage treatment effect, and is suitable for upgrading and reconstruction of the existing small sewage treatment plant.
Based on the technical scheme, the invention has the beneficial effects that:
(1) Sludge reduction: after the original concentrated sludge is subjected to acidification combined with multi-stage water washing treatment, the sludge dewatering performance is obviously improved, the water content of a mud cake after sludge dewatering is reduced to about 60% from the original 80%, the sludge reduction effect is doubled, and the dewatering rate is increased.
(2) Content of organic matters in the mud cakes: the original sludge (30-60%) with lower organic content is improved to more than 70% after component separation, and can be self-sustained incinerated during subsequent incineration treatment, and the addition of auxiliary materials can be reduced during composting treatment.
(3) Recovering inorganic components such as sand: inorganic components with low organic matter content and low water content can be obtained from the sludge through component separation and are used for building material utilization.
(4) And (3) recovering phosphorus: the phosphorus in the raw sludge is separated from the sludge after acidification and multi-stage water washing treatment, and the phosphorus in the supernatant of the concentration tank is recovered in the form of iron phosphate through subsequent chemical precipitation, the phosphorus recovery efficiency is higher than 40 percent, and the recovery of phosphorus resources in the sludge is effectively realized.
(5) And (3) recovering the flocculant: ferric salt in the sludge and ferric salt excessively added in the phosphorus recovery process can realize the recovery of the flocculant in a mode of accurately adjusting the pH value by using one or more of sodium hydroxide, calcium hydroxide, potassium hydroxide, calcium oxide, quick lime and other alkaline substances, and further reduce the addition amount of the flocculant in a sewage treatment plant.
(6) Heavy metal removal effect: heavy metals in the sludge are separated from the sludge after acidification combined with multi-stage water washing treatment, the content of the heavy metals in the dewatered mud cake is obviously reduced, and the ecological risk of land utilization after composting treatment of the mud cake is greatly reduced.
(7) Denitrification of sewage: after FNA enrichment and AOB domestication, a stable short-cut nitrification process can be realized, and the coupling with an anaerobic ammonia oxidation unit can realize efficient denitrification under the conditions of low energy consumption, low medicine consumption and low sludge yield of a sewage plant.
Drawings
FIG. 1 is a schematic diagram of a sludge-water co-treatment process route of a sewage treatment plant based on separation of sludge components in example 1 of the present invention.
In the figure: 1. feeding water into a sewage plant; 2. a biochemical treatment device; 3. a secondary sedimentation tank; 4. water is discharged from a sewage plant; 5. a first diversion water pipe; 6. a sludge concentration tank; 7. a first mud guide pipe; 8. a pH probe I; 9. a first stirrer; 10. a sludge modification unit; 11. controlling first dosing; 12. a second mud guide pipe; 13. a sludge elutriation unit; 14. a third mud guide pipe; 15. a cyclone desanding device; 16. gravel; 17. a mud guide pipe IV; 18. a sludge conditioning unit; 19. adding chemicals to control II; 20. a fifth mud guide pipe; 21. a plate-and-frame filter press; 22. dehydrating the mud cake; 23. a second diversion water pipe; 24. a diversion water pipe III; 25. a diversion water pipe IV; 26. a pH probe II; 27. thirdly, controlling the dosing; 28. a second stirrer; 29. a supernatant recovery unit; 30. a phosphorus product; 31. a flocculant product; 32. a mud guide pipe six; 33. supernatant liquid is obtained after the supernatant liquid recovery unit precipitates step by step; 34. a pH probe III; 35. an AOB enrichment unit; 36. a membrane module; 37. a diversion water pipe five; 38. a diversion water pipe six; 39. an anammox unit; 40. and a water guide pipe seven.
Detailed Description
The following examples are intended to illustrate the invention, but are not intended to limit the scope of the invention.
The examples do not show the specific techniques or conditions, according to the technical or conditions described in the literature in the field, or according to the product specifications. The reagents or instruments used are conventional products available from regular distributors, not indicated by the manufacturer.
The sewage sludge synergistic treatment process of the invention is described below, comprising the following steps:
carrying out acidification treatment and multi-stage elutriation treatment on concentrated sludge collected from sewage, and respectively collecting washing supernatant and elutriated sludge;
adding alkaline substances into the elutriated sludge, conditioning until the pH value is 7 +/-1, and dehydrating to obtain a sludge cake;
adding Fe to the water-washed supernatant 3+ Waiting for the end of precipitation to obtain phosphorus recovery product and recovering supernatant, and adding the recovered supernatantAdding alkaline substances to the solution until the pH value is 4 +/-0.5, and recovering ferric salt flocculant precipitate.
According to the invention, an acidification and multistage washing combined mode is adopted to separate the sludge organic component from the inorganic component (washing supernatant) through solid-liquid separation, and subsequent recovery treatment is respectively carried out, so that for an organic sludge phase, the dehydration performance of the organic sludge can be improved, the organic content is greatly increased, and the heavy metal content is remarkably reduced. And for the mixed supernatant, the recovery of phosphorus and a flocculating agent can be realized, and the recovery rate of the effective components in the sludge is further optimized.
The sludge acid treatment can ensure that the sludge extracellular polymer is hydrated, so that the viscosity of the sludge is greatly reduced, and meanwhile, insoluble substances such as inorganic phosphate, heavy metal and the like wrapped in the sludge extracellular polymer are dissolved and released into an ionic state, so that conditions are created for the subsequent component separation process. The mud cake produced by dehydration has better quality and reduced volume, the water content can be reduced to about 60 percent, the organic matter can be improved to more than 70 percent, and the mud cake can be used in the field in a sewage plant or transported outside for final disposal such as incineration, composting and the like.
In one embodiment, the Fe 3+ Is FeCl 3 。
In a preferred embodiment of the present invention, a part of the wastewater and the recovered supernatant are mixed in a ratio of 8 to 9.5:1, forming Free Nitrous Acid (FNA) under the conditions of pH value of 5 +/-0.5 and ammonia nitrogen concentration of 40-60 mg/L, enriching Ammonia Oxidizing Bacteria (AOB), and putting the treated sludge into an anaerobic ammonia oxidation unit.
In the sewage treatment process, in order to improve the denitrification effect of sewage in most sewage plants, a large amount of aeration energy consumption and an external carbon source are consumed in the conventional consumption denitrification process, so that the sewage treatment cost is greatly increased. The shortcut nitrification-anaerobic ammonia oxidation process has the advantages of high volume nitrogen removal rate, aeration quantity saving, no need of adding an additional organic carbon source, sludge yield reduction and the like, and is one of the core technologies of low-energy consumption treatment of the current-stage sewage treatment. The key difficulty of the current-stage operation of the shortcut nitrification-anaerobic ammonia oxidation process is to control shortcut nitrification so that an anaerobic ammonia oxidation unit can be smoothly operated.
In view of the above, the present invention further finds that, by generating a large amount of FNAs under low alkalinity conditions and further enriching AOBs, and inhibiting Nitrite Oxidizing Bacteria (NOB), a stable shortcut nitrification process can be achieved, and that coupling the anaerobic ammonium oxidation unit with the device can achieve efficient denitrification under the conditions of low energy consumption, low drug consumption and low sludge production in sewage plants.
In a preferred embodiment of the present invention, the elutriated sludge is subjected to a sand removal treatment to obtain an organic sludge; adding calcium oxide into the organic sludge, conditioning until the pH value is 7 +/-1, and dehydrating to obtain the mud cake.
The method is more beneficial to the recovery effect of the organic sludge, and can separate and obtain inorganic components with low organic content and low water content from the sludge and use the inorganic components for building material utilization, which is also another obvious improvement on the basis of the previous research results of the inventor.
As a preferred embodiment of the invention, when collecting the concentrated sludge from the sewage, the method specifically comprises the following steps:
concentrating sludge separated from sewage, and respectively collecting concentrated supernatant and concentrated sludge;
adding sulfuric acid into the concentrated sludge for the acidification treatment;
mixing the concentrated supernatant with the water-washed supernatant to obtain a mixed supernatant, and adding Fe to the mixed supernatant 3+ And after the precipitation is finished, obtaining a phosphorus recovery product and a recovered supernatant, adding an alkaline substance into the recovered supernatant until the pH value is 4 +/-0.5, and recovering the ferric salt flocculant for precipitation.
Through the treatment, the resource utilization of the treated tail water is further optimized on the basis of the previous research results of the inventor.
As a preferred embodiment of the present invention, the alkaline substance includes one or more of sodium hydroxide, calcium hydroxide, potassium hydroxide, calcium oxide, and quicklime.
In one embodiment of the present invention, the water content in the concentrated sludge is 97wt% or more, for example 97 to 98wt%, which is a conventional parameter in the art for concentrating sludge.
The invention has no special requirements on the treatment process of separating sludge from sewage, and the existing treatment process of separating sludge from sewage can be better applied in the invention.
As an optional specific implementation mode of the invention, when sludge is separated from sewage, the method specifically comprises the following steps:
and (3) treating the sewage in an anaerobic tank, an anoxic tank, an aerobic tank and a secondary sedimentation tank, and separating to obtain sludge.
In a preferred embodiment of the present invention, effluent from a sewage treatment plant is collected and used in the multistage elutriation treatment. It will be understood by those skilled in the art that the term "effluent from a sewage treatment plant" as used herein refers to the clean water that is conventionally discharged from the sewage treatment plant itself.
As an embodiment of the present invention, the water produced in the secondary sedimentation tank may be collected for the multistage elutriation treatment.
The above schemes can be combined by the person skilled in the art according to common knowledge to obtain a better embodiment of the sewage sludge co-treatment process of the invention.
In another aspect, the present invention further provides a sewage sludge co-processing system, comprising:
a sludge collection unit; used for collecting sludge from sewage; a sludge modification unit; a feeding port of the sludge collection unit is connected with a sludge outlet of the sludge collection unit, and a dosing control element is arranged for carrying out acidification treatment on the sludge;
a multi-stage elutriation unit; the material inlet of the device is connected with the sludge outlet of the sludge modification unit and is used for carrying out multi-stage elutriation on the acidified sludge;
a sludge conditioning unit; the feeding port of the device is connected with the sludge outlet of the multi-stage elutriation unit, and the device is provided with a pH value detection element and a dosing control element and is used for conditioning the elutriated sludge to be neutral;
a sludge dewatering unit; the material inlet of the sludge conditioning unit is connected with the sludge outlet of the sludge conditioning unit and is used for dehydrating the conditioned sludge;
a supernatant recovery unit; its pan feeding mouth with the supernatant exit linkage setting of multistage elutriation unit, and be equipped with pH value detecting element and add medicine control element for carry out phosphorus recovery and flocculating agent to washing supernatant and retrieve.
As a specific embodiment of the present invention, the sludge dewatering unit is a plate and frame filter press.
In a preferred embodiment of the present invention, the supernatant from the multistage elutriation is mixed with the supernatant from the sludge concentration tank and pumped to the supernatant recovery unit. Adding Fe into the mixed phosphorus-rich liquid 3+ (e.g., ferric chloride) solution, first rapidly stirred for 5 minutes, then slowly stirred for 30 minutes until the precipitation is complete. The precipitate discharged from the bottom of the supernatant recovery unit is naturally dried or mechanically dehydrated to obtain a phosphorus recovery product (phosphorus content is about 28.6% in terms of P) containing iron phosphate as a main component 2 O 5 Meter). Adding calcium oxide into the supernatant generated by the supernatant recovery unit until the pH value is 4, recovering ferric salt flocculant precipitate, scraping out bottom precipitate, dissolving with a small amount of acid, and recycling as flocculant to the sewage treatment unit. The remaining supernatant may be sent to an AOB enrichment unit.
As a preferred embodiment of the present invention, the sewage and sludge cooperative processing system further comprises:
an AOB enrichment unit; a feeding port of the device is connected with a supernatant outlet of the supernatant recovery unit, is connected with part of influent branch of sewage, and is provided with a pH value detection element and a dosing control element for enriching Ammonia Oxidizing Bacteria (AOB) in sludge;
an anammox unit; the feed inlet of the AOB enrichment unit is connected with the discharge outlet of the AOB enrichment unit.
As a preferred embodiment of the present invention, the sewage sludge co-processing system further comprises:
a desanding unit; the feeding port of the multi-stage elutriation unit is connected with the sludge outlet of the multi-stage elutriation unit, and the sludge outlet of the multi-stage elutriation unit is connected with the feeding port of the sludge conditioning unit.
In the invention, no special requirement is made on the device of the sludge collection unit, and the existing sludge collection unit can obtain better application effect in the invention.
As an optional embodiment of the present invention, the sludge collection unit specifically includes:
a biochemical treatment device (which can be an anaerobic tank, an anoxic tank and an aerobic tank which are connected in sequence, a secondary sedimentation tank and a sludge concentration tank) which are connected in sequence along the sewage flow direction; the biochemical treatment device comprises an anaerobic tank, an anoxic tank and an aerobic tank which are sequentially connected along the sewage flow direction; a sludge outlet of the sludge concentration tank is connected with a feed inlet of the sludge modification unit; and a supernatant outlet of the sludge concentration tank is connected with a feeding port of the supernatant recovery unit.
As a specific embodiment of the present invention, the desanding unit is a cyclone desanding device.
In a preferred embodiment of the present invention, in the sludge collection unit, a bypass pipe is provided at a water outlet of a sewage treatment plant, and the bypass pipe is connected to a water inlet of the multistage elutriation unit. It will be understood by those skilled in the art that the term "outlet of a sewage treatment plant" as used herein refers to an outlet from a sewage treatment plant that conventionally discharges purified water. In a specific embodiment, the water outlet of the secondary sedimentation tank can be connected with the water inlet of the multi-stage elutriation unit.
As a preferred embodiment of the invention, the sludge after acidification modification in the sludge modification unit is pumped into a multi-stage elutriation unit, and clean effluent generated by a secondary sedimentation tank of a sewage plant is added into the multi-stage elutriation unit for multiple times of water washing to realize separation of organic and inorganic components of the sludge. Discharging clear liquid from the upper end after the previous elutriation treatments in the multi-stage elutriation unit, retaining sludge at the bottom, and then adding clean water from the secondary sedimentation tank again to perform next mixing and stirring, standing and settling and mud-water separation; and after the last washing, reserving the supernatant in the elutriation unit, and discharging the sludge phase from the bottom of the multistage elutriation unit to the sludge conditioning unit.
As a specific embodiment of the invention, in the sewage and sludge co-processing system, different devices are connected through a diversion water pipe and/or a sludge guide pipe.
The above-described preferred embodiments can be combined by the person skilled in the art in accordance with common general knowledge to obtain a preferred embodiment of the sewage sludge co-treatment system according to the present invention.
Example 1
The following describes the combination and embodiment of the present invention in detail with reference to fig. 1:
a sludge-water cooperative treatment process of a sewage treatment plant based on sludge component separation is additionally provided with a sludge component separation and supernatant inorganic component recovery branch system on the basis of the original sewage-sludge cooperative treatment process (1, sewage plant inlet water, 2, biochemical treatment unit, 3, secondary sedimentation tank, 4, sewage plant outlet water, 6, sludge concentration tank, 18, sludge conditioning unit and 21, plate-and-frame filter press).
The sludge component separation branch system comprises a sludge modification unit 10 connected with a sludge concentration tank 6 through a first sludge guide pipe 7, a sludge elutriation unit 13 connected with the sludge modification unit 10 through a second sludge guide pipe 12, elutriation supernatant in the sludge elutriation unit 13 is introduced into clean effluent of a secondary sedimentation tank through a first flow guide pipe 5, a cyclone sand removal device 15 is connected with a sludge discharge port at the bottom of the sludge elutriation unit 13, gravel 16 is discharged after cyclone, a sludge conditioning unit 18 is connected with an organic sludge discharge port of the cyclone sand removal device 15 through a fourth sludge guide pipe 17, a plate and frame filter press 21 is connected with a sludge discharge port of the sludge conditioning unit 18 through a fifth sludge guide pipe 20, dehydrated sludge cakes 22 generated by filter pressing of the plate and frame filter press 21 are transported outwards, and generated filtrate is discharged into an AOB enrichment unit 35 through a second flow guide pipe 23. The sludge modification unit 10 is internally provided with a pH probe I8 and a stirrer I9, the acidification tank is connected with a dosing control I11, a sulfuric acid solution is arranged in the dosing control I11, the sludge conditioning unit 18 is connected with a dosing control II 19, and a calcium oxide suspension is arranged in the dosing control II 19.
The supernatant inorganic component recycling branch system comprises a supernatant recycling unit 29 which is discharged from a supernatant generated by a sludge elutriation unit 13 through a flow guide water pipe four 25, a supernatant generated by a sludge concentration tank 6 is discharged into the supernatant recycling unit 29 through a flow guide water pipe three 24, a pH probe two 26 and a stirrer two 28 are connected in the supernatant recycling unit 29, a dosing control three 27 is connected on the supernatant recycling unit 29, ferric chloride solution and calcium oxide suspension are arranged in the dosing control three 27, and a phosphorus product 30 and a flocculant product 31 generated by the supernatant recycling unit 29 are discharged from the bottom of the supernatant recycling unit 29. The influent branch 38 of the sewage plant, the sludge dewatering filtrate 23 and the supernatant 33 obtained after fractional precipitation of the supernatant recovery unit are mixed in the AOB enrichment unit 35, part of the returned sludge is inoculated in the AOB enrichment unit 35 through a sludge guide pipe six 32, a pH probe three 34 is connected in the AOB enrichment unit 35, and a discharge port of the AOB enrichment unit 35 is connected with an anaerobic ammonia oxidation unit 39.
The sludge-water cooperative treatment process flow of the sewage treatment plant based on the system and based on the separation of sludge components is as follows:
the method comprises the following steps: after being treated by a biochemical treatment device 2, inlet water 1 of a sewage plant enters a secondary sedimentation tank 3, excess sludge generated at the moment is discharged into a sludge concentration tank 6, so that the excess sludge is subjected to gravity concentration, the upper layer is a phosphorus-rich supernatant after concentration, and the lower layer is concentrated sludge with the water content of more than 97%;
step two: discharging the concentrated sludge into a sludge modification unit 10, starting a drug adding control unit 11, adding a sulfuric acid solution into the sludge modification unit 10, uniformly stirring by a stirrer I9, detecting the pH value in the sludge modification unit 10 by a pH probe I8, further controlling the drug adding amount of the drug adding control unit 11 to ensure that the pH value of the sludge in the sludge modification unit 10 is about 2, performing acid treatment modification on the sludge to dissolve sludge extracellular polymers, and dissolving insoluble inorganic salt components into Fe 2+ ,Fe 3+ ,PO 4 3- ,Al 3+ Ionic state, released into the liquid phase;
step three: transferring the acid sludge in the sludge modification unit 10 to a sludge elutriation unit 13 through a sludge guide pipe II 12, adding clean secondary sedimentation tank effluent into the acid sludge through a diversion water pipe I5, stirring and mixing the acid sludge for multiple times, standing and settling the acid sludgeAnd (3) precipitating and performing solid-liquid separation, transferring the washing supernatant generated after separation into a mixed supernatant recovery unit 29 through a diversion water pipe IV 25, and discharging the sludge phase generated after separation into a cyclone desanding device 15 through a sludge guide pipe III 14. The acid sludge is washed in multiple stages and dissolved Fe 2+ ,Fe 3+ ,PO 4 3- ,Al 3+ And the extracellular polymeric substances are stripped from the surface of the sludge flocs, the viscosity of the sludge flocs is greatly reduced, and Fe 2+ ,Fe 3+ ,PO 4 3- ,Al 3+ The supernatant is transferred to a mixed supernatant recovery unit 29, so that the preliminary separation of organic and inorganic components of the sludge is realized;
step four: the viscosity of a sludge phase generated by the sludge elutriation unit 13 is remarkably reduced, the content of organic matters is improved, the sludge phase is pumped into a cyclone desanding device 15, the sludge components are further separated by utilizing the specific gravity difference between organic sludge and sand, the separated gravel 16 can be used for building materials, the separated organic sludge is discharged to a sludge conditioning unit 18, a calcium oxide suspension is added into the organic sludge through a dosing control unit 19 to adjust the pH value of the organic sludge to be neutral, mechanical dehydration is performed by using a plate-and-frame filter press 21, the water content of a dehydrated mud cake 22 is about 60%, the content of organic matters can be improved to more than 70%, and a filtrate generated by dehydration is transferred into an AOB enrichment unit 35;
step five: the supernatant generated by the sludge elutriation unit 13 and the sludge concentration tank 6 contains phosphorus with higher concentration, the phosphorus is transferred to a mixed supernatant recovery unit 29 through a diversion water pipe four 25 and a diversion water pipe three 24 respectively, iron chloride solution is added into the mixed supernatant recovery unit by a medicine adding control unit three 27 until the molar ratio of Fe to P is 1.5 4 The precipitation reaction of (2): fe 3+ +PO 4 3- ＝FePO 4 And ↓, standing and precipitating for 30 minutes, and then discharging a phosphorus product 30 from the bottom of the mixed supernatant collecting unit 29, wherein more than 40% of phosphorus in the sludge can be recovered by the process. After the phosphorus product is discharged and deposited, caO is continuously added into the supernatant of the mixed supernatant collecting unit 29 to increase the pH value to 4, and the mixture is kept stand to depositThen Fe (OH) can be obtained 3 And Al (OH) 3 Transferring the flocculant precipitate to an AOB enrichment unit 35;
step six: supernatant produced after the mixed supernatant recovery unit 29 precipitates step by step, filtrate obtained after sludge plate frame dehydration and influent tributaries of a sewage plant are connected into the AOB enrichment unit 35 through a diversion water pipe six 38, part of returned sludge is inoculated into the FNA enrichment pool through a diversion sludge pipe six 32, the FNA enrichment pool adopts an MBR (membrane bioreactor) process internal mold assembly 36, the pH value of the reactor is controlled through a pH probe three 34, so that stable short-range nitrification is realized, effluent after FNA enrichment is connected into the anaerobic ammonia oxidation unit 39 through a diversion water pipe five 37, and accordingly anaerobic ammonia oxidation denitrification is completed. And the residual effluent is discharged to the front end of a sewage treatment plant through a diversion water pipe seven 40 and then discharged after treatment.
Comparative example 1
This comparative example provides a wastewater treatment process which differs from example 1 only in that: and (3) after the sludge is concentrated in the first step, adding a conventional flocculating agent Polyacrylamide (PAM), and directly performing plate-and-frame dehydration.
The result shows that the sludge dehydration rate is slow, the water content of the dehydrated mud cake is more than 80%, and the organic matter content is low (30-60%), so the sludge has low heat value, large volume and high heavy metal content. Therefore, the outward transportation cost of the sludge in the sewage plant is obviously increased, and the subsequent incineration and composting treatment cost is increased due to low heat value, high heavy metal content and high water content of the sludge.
Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.
Claims (10)
1. The sewage sludge synergistic treatment process is characterized by comprising the following steps:
carrying out acidification treatment and multi-stage elutriation treatment on concentrated sludge collected from sewage, and respectively collecting washing supernatant and elutriated sludge;
adding alkaline substances into the elutriated sludge, conditioning until the pH value is 7 +/-1, and dehydrating to obtain a sludge cake;
adding Fe to the water-washed supernatant 3+ And after the precipitation is finished, obtaining a phosphorus recovery product and a recovered supernatant, adding an alkaline substance into the recovered supernatant until the pH value is 4 +/-0.5, and recovering the ferric salt flocculant for precipitation.
2. The sewage sludge co-processing technology of claim 1, wherein a part of sewage and the recovered supernatant are mixed according to a ratio of 8-9.5: 1, forming free nitrous acid under the conditions of pH value of 5 +/-0.5 and ammonia nitrogen concentration of 40-60 mg/L, enriching ammonia oxidizing bacteria, and putting the treated sludge into an anaerobic ammonia oxidation unit.
3. The sewage sludge co-treatment process according to claim 1 or 2, wherein the elutriated sludge is subjected to sand removal treatment to obtain organic sludge; adding alkaline substances into the organic sludge, conditioning until the pH value is 7 +/-1, and dehydrating to obtain the mud cake.
4. The sewage sludge co-treatment process according to any one of claims 1 to 3, wherein the process specifically comprises the following steps when collecting the concentrated sludge from the sewage:
concentrating sludge separated from sewage, and respectively collecting concentrated supernatant and concentrated sludge;
adding sulfuric acid into the concentrated sludge for the acidification treatment;
mixing the concentrated supernatant with the water-washed supernatant to obtain a mixed supernatant, and adding Fe to the mixed supernatant 3+ And after the precipitation is finished, obtaining a phosphorus recovery product and a recovered supernatant, adding an alkaline substance into the recovered supernatant until the pH value is 4 +/-0.5, and recovering the ferric salt flocculant for precipitation.
5. The sewage sludge co-processing technology as claimed in any one of claims 1 to 4, wherein the alkaline substance comprises one or more of sodium hydroxide, calcium hydroxide, potassium hydroxide, calcium oxide and quicklime.
6. The sewage sludge co-treatment process as claimed in claim 4, wherein the effluent of sewage treatment plant is collected and used for the multi-stage elutriation treatment.
7. A sewage sludge coprocessing system is characterized by comprising:
a sludge collection unit; the device is used for collecting sludge from sewage;
a sludge modification unit; a feeding port of the sludge collection unit is connected with a sludge outlet of the sludge collection unit, and a dosing control element is arranged for carrying out acidification treatment on the sludge;
a multi-stage elutriation unit; the material inlet of the device is connected with the sludge outlet of the sludge modification unit and is used for carrying out multi-stage elutriation on the acidified sludge;
a sludge conditioning unit; the feeding port of the device is connected with the sludge outlet of the multi-stage elutriation unit, and the device is provided with a pH value detection element and a dosing control element and is used for conditioning the elutriated sludge to be neutral;
a sludge dewatering unit; the material inlet of the sludge conditioning unit is connected with the sludge outlet of the sludge conditioning unit and is used for dehydrating the conditioned sludge;
a supernatant recovery unit; the feed inlet of the device is connected with the supernatant outlet of the multi-stage elutriation unit, and is provided with a pH value detection element and a dosing control element for recovering phosphorus and flocculating agent from the washing supernatant.
8. The sewage sludge co-processing system as claimed in claim 7, further comprising:
an AOB enrichment unit; the feeding port of the device is connected with the supernatant outlet of the supernatant recovery unit, is connected with part of influent water branches of sewage, and is provided with a pH value detection element and a dosing control element for enriching ammonia oxidizing bacteria in sludge;
an anammox unit; the feed inlet of the AOB enrichment unit is connected with the discharge outlet of the AOB enrichment unit.
9. The sewage sludge co-processing system as claimed in claim 7 or 8, further comprising:
a desanding unit; the feeding port of the multi-stage elutriation unit is connected with the sludge outlet of the multi-stage elutriation unit, and the sludge outlet of the multi-stage elutriation unit is connected with the feeding port of the sludge conditioning unit.
10. The sewage sludge co-processing system as claimed in any one of claims 7 to 9, wherein in the sludge collection unit, a branch pipe is provided at a water outlet of a sewage treatment plant, and the branch pipe is connected to a water inlet of the multi-stage elutriation unit.
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| CN202211678700.7A CN115947509A (en) | 2022-12-26 | 2022-12-26 | Sewage and sludge co-treatment process and system based on sludge component separation |
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