Municipal sludge and kitchen waste cooperative treatment system and treatment method

Abstract

The invention discloses a municipal sludge and kitchen waste cooperative treatment system and method. The treatment system comprises a sludge bin, a kitchen waste bin, a sludge storage tank, an anaerobic digestion tank, a conditioning reactor, a rear sludge storage tank and a plate-and-frame filter press. The sludge bin and the kitchen waste bin are respectively connected to the sludge storage tank through pipelines, so that municipal sludge and kitchen waste are mixed in the sludge storage tank; the sludge storage tank, the anaerobic digestion tank, the conditioning reactor, the rear sludge storage tank and the plate-and-frame filter press are sequentially connected through pipelines, and the conditioning reactor is further connected with the ozone generator, the UV photocatalytic oxidation equipment and the H2O2 dosing device, so that the purpose of treating municipal sludge and kitchen waste through ozone and hydrogen peroxide coupled photocatalytic oxidation is achieved. The sludge dewatering device has the characteristics of compact structure, high stability, high treatment efficiency and the like, and achieves the effects of high-efficiency sludge dewatering, obvious reduction and low operation cost.

Description

Technical Field

[0001] The present invention relates to the technical field of sludge treatment, and in particular to a system and method for coordinating treatment of municipal sludge and kitchen waste. Background Art

[0002] Due to the imperfect construction of urban rainwater and sewage separation pipe network, the use of oxidation ditch and other processes in sewage treatment plants generally leads to low organic matter in sludge due to endogenous respiration. In the anaerobic fermentation process, the C / N ratio is an important parameter, which affects the growth and metabolic activity of microorganisms. The C / N ratio of anaerobic fermentation substrates is preferably between 20:1 and 30:1, and the C / N ratio of municipal sludge is in the range of 7:1 to 10:1. Food waste comes from the "swill" collected uniformly from catering services, centralized catering and other industries. It has high organic content and contains oil. The C / N ratio of food waste is in the range of 65:1 to 75:1. The anaerobic fermentation of sludge and food waste can neutralize the salt in the food waste and adjust the feed C / N ratio, thereby increasing the degradation rate of organic matter and the biogas yield.

[0003] At present, there are two main methods for sludge dewatering. One is conditioning + mechanical dehydration. Conditioning mainly destroys the cell wall structure through flocculation, oxidation, acid-base, hydrolysis and other effects, and then reduces the sludge moisture content through mechanical dehydration methods such as plate and frame machines. Conventional conditioning methods make it difficult to completely break the sludge cells, resulting in a moisture content of about 60% in the mud cake after dehydration. If the moisture content is high, the quality of the sludge will affect the reduction effect. In addition, traditional Fenton oxidation wall breaking technology has problems such as too fast decomposition speed of the agent and low utilization rate. One is thermal drying, which uses heat energy to evaporate the water in the sludge, but thermal drying has high energy consumption and high operating costs. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a municipal sludge and food waste coordinated treatment system and treatment method with a compact structure, high stability and high treatment efficiency, in view of the problems of instability, low efficiency and unbalanced process energy consumption of sludge digestion alone in the prior art.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: A system for coordinated treatment of municipal sludge and kitchen waste, comprising: a sludge silo, a kitchen waste silo, a sludge storage tank, an anaerobic digestion tank, a conditioning reactor, a post-sludge storage tank and a plate-frame filter press; the sludge silo and the kitchen waste silo are respectively connected to the sludge storage tank through pipelines to achieve mixing of municipal sludge and kitchen waste in the sludge storage tank; the sludge storage tank, the anaerobic digestion tank, the conditioning reactor, the post-sludge storage tank and the plate-frame filter press are connected in sequence through pipelines, and the conditioning reactor is also respectively connected to an ozone generator, a UV photocatalytic oxidation device and an H2O2 dosing device to achieve ozone coordinated hydrogen peroxide coupled photocatalytic oxidation treatment of municipal sludge and kitchen waste. As a further improvement of the present invention, it also includes a biogas storage cabinet and a biogas generator. The biogas storage cabinet is connected to the anaerobic digestion tank to collect biogas produced by anaerobic fermentation of municipal sludge and kitchen waste. The biogas generator is connected to the biogas storage cabinet to realize biogas power generation. The ozone generator and UV photocatalytic oxidation equipment are both connected to the biogas generator. As a further improvement of the present invention, a slurrying machine is provided between the sludge silo and the sludge storage tank to achieve sludge conditioning and slurrying. As a further improvement of the present invention, a stirrer is provided in the conditioning reactor. As a general technical concept, the present invention also provides a treatment method based on the above-mentioned municipal sludge and kitchen waste coordinated treatment system, comprising the following steps: Step S1, putting municipal sludge into a sludge silo, and putting food waste into a food waste silo; Step S2, the sludge is slurried by the slurrying machine and then enters the sludge storage tank, and the kitchen waste also enters the sludge storage tank, and the slurried sludge and the kitchen waste are mixed in the sludge storage tank and the temperature and solid content are adjusted; Step S3, the material in the mud storage tank enters the anaerobic digestion tank, the organic matter is fermented in the anaerobic digestion tank, and the generated biogas is stored in the biogas storage cabinet; Step S4, the biogas residue produced in the anaerobic digestion tank enters the conditioning reactor, H2O2 is added to the conditioning reactor and O3 is injected, and at the same time, the UV photocatalytic oxidation device emits ultraviolet light, and after the oxidation reaction of the biogas residue is completed, it is discharged into the rear sludge storage tank; Step S5: The sludge in the rear sludge storage tank is pumped to the plate and frame filter press to complete dehydration. As a further improvement of the present invention, in step S1, the kitchen waste is solid residue after multi-stage sorting, crushing, impurity removal, high-temperature cooking, and three-phase separation, and the solid content is 10% to 15%. As a further improvement of the present invention, in step S2, the sludge is slurried by steam heating, and the sludge is heated to 80°C to 90°C; the feeding ratio of sludge to kitchen waste is 2 to 3:1; the sludge and kitchen waste are adjusted to a solid content of 10% to 12% and a temperature of 50°C to 55°C in the sludge storage tank. As a further improvement of the present invention, in step S3, the anaerobic digestion adopts high-temperature anaerobic fermentation, the operating temperature is 50° C. to 55° C., and the residence time is 15 d to 25 d. As a further improvement of the present invention, in step S4, the tempering reactor adopts mechanical stirring and continuous feeding and discharging operation mode, and the reaction time is 40 min to 60 min; the dosage of O3 is 1.5 g / L to 2.0 g / L, the dosage of H2O2 is 0.5 g / L to 0.8 g / L, and the wavelength of ultraviolet light is 185 nm to 255 nm. As a further improvement of the present invention, in step S5, the mud inlet pressure of the plate and frame filter press reaches 8 bar to 10 bar, and the closing pressure is 15 bar to 20 bar. Compared with the prior art, the advantages of the present invention are: The municipal sludge and kitchen waste coordinated treatment system and treatment method of the present invention connects an ozone generator, UV photocatalytic oxidation equipment and H2O2 dosing device to a conditioning reactor, and applies ozone coordinated hydrogen peroxide coupled photocatalytic oxidation technology to anaerobic digestion sludge dehydration, and utilizes strong oxidizing properties to improve sludge cell wall breaking efficiency and sludge dehydration efficiency, while improving reagent utilization and process stability, reducing operating costs, and achieving significant reduction effects. Moreover, the sludge and kitchen waste coordinated fermentation is combined with ozone coordinated hydrogen peroxide coupled photocatalytic oxidation technology to achieve energy consumption balance, without the need for external energy supplementation, and improve the operating economy of the combined process. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 It is a schematic diagram of the structural principle of a sludge treatment system in a specific embodiment of the present invention; Figure 2 It is a schematic diagram of the process of sludge treatment in a specific embodiment of the present invention; Legend: 1. Sludge silo; 2. Kitchen waste silo; 3. Pulping machine; 4. Mud storage tank; 5. Anaerobic digestion tank; 6. Biogas storage cabinet; 7. Biogas generator; 8. Conditioning reactor; 9. Agitator; 10. Ozone generator; 11. UV photocatalytic oxidation equipment; 12. H2O2 dosing device; 13. Post-sludge storage tank; 14. Plate and frame filter press. DETAILED DESCRIPTION

[0007] The present invention is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby.

[0008] In the description of the present invention, it should be understood that the terms "side", "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0009] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or suggesting relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0010] Example 1 like Figure 1 As shown, the municipal sludge and kitchen waste coordinated treatment system of the present invention comprises: a sludge silo 1, a kitchen waste silo 2, a sludge storage tank 4, an anaerobic digestion tank 5, a conditioning reactor 8, a post-sludge storage tank 13 and a plate-frame filter press 14. The sludge silo 1 and the kitchen waste silo 2 are respectively connected to the sludge storage tank 4 through pipelines to achieve mixing of municipal sludge and kitchen waste in the sludge storage tank 4. The sludge storage tank 4, the anaerobic digestion tank 5, the conditioning reactor 8, the post-sludge storage tank 13 and the plate-frame filter press 14 are sequentially connected through pipelines, and the conditioning reactor 8 is also respectively connected to the ozone generator 10, the UV photocatalytic oxidation equipment 11 and the H2O2 dosing device 12 to achieve the purpose of ozone synergistic hydrogen peroxide coupled photocatalytic oxidation treatment of municipal sludge and kitchen waste.

[0011] In this embodiment, municipal sludge and food waste are processed in a coordinated manner, and the O3+H2O2+UV advanced oxidation technology is used to destroy the cell membrane and increase the permeability of the cell membrane, which is more conducive to sludge dehydration. At the same time, it can also effectively treat difficult-to-degrade organic matter and reduce the sludge quality.

[0012] like Figure 1 As shown, it also includes a biogas storage cabinet 6 and a biogas generator 7. The biogas storage cabinet 6 is connected to the anaerobic digestion tank 5 to collect biogas generated by anaerobic fermentation of municipal sludge and food waste. The biogas generator 7 is connected to the biogas storage cabinet 6 to realize biogas power generation. The ozone generator 10 and the UV photocatalytic oxidation device 11 are both connected to the biogas generator 7.

[0013] In this embodiment, a slurrying machine 3 is provided between the sludge silo 1 and the sludge storage tank 4 to achieve slurrying of sludge conditioning. A stirrer 9 is provided in the conditioning reactor 8 to achieve uniform stirring of the mixture of sludge and kitchen waste in the conditioning reactor 8.

[0014] The O3 / H2O2 system is an ozone advanced oxidation technology that also uses ·OH produced by ozone in water to degrade organic matter. Adding H2O2 to the reaction system will accelerate the decomposition of ozone to produce ·OH. - The reaction generates hydroperoxide free radicals (HO2 - ), H2O2 will partially dissociate into HO2 - , while HO2 -It is an initiator of ·OH, which can accelerate the decomposition of O3 in water to produce ·OH. The specific reaction is as follows: O3+ OH - →HO 2- + ·O2 When H2O2 exists in the solution system, H2O2 will partially dissociate to produce HO 2- : H2O2+ H2O→OH2 - + H3O + HO2 - It can then react with ozone molecules to produce hydroxyl radicals.

[0015] The O3 / UV system is an ozone advanced oxidation technology. Ozone produces ·OH under ultraviolet radiation, which has been proven to be used to remove organic pollutants in water. At present, there are two main views on the synergistic mechanism of the O3 / UV combined process. One is that ozone molecules react with water under ultraviolet irradiation to generate hydrogen peroxide, which further reacts and decomposes to produce ·OH; the other is that ozone under ultraviolet light decomposes oxygen atoms, which then react with water to generate ·OH.

[0016] In this embodiment, ozone is combined with UV (ultraviolet catalytic oxidation) and H2O2 (hydrogen peroxide) to produce ·OH with stronger oxidizing properties. Moreover, the oxidation potential of the generated ·OH reaches 2.8 V, which is more oxidizing than ozone. Therefore, the ozone advanced oxidation process, such as ozone / ultraviolet (O3 / UV) and ozone / hydrogen peroxide (O3 / H2O2), can oxidize most of the difficult-to-degrade organic matter and destroy the cell wall membrane, thereby being able to efficiently treat high-content organic solid waste.

[0017] like Figure 2 As shown, in this embodiment, a treatment method based on the above-mentioned municipal sludge and kitchen waste coordinated treatment system is also provided, comprising the following steps: Step S1, putting municipal sludge into sludge silo 1, and putting food waste into food waste silo 2.

[0018] Step S2, the sludge is conditioned and slurried by the slurrying machine 3 and then enters the sludge storage tank, and the food waste also enters the sludge storage tank 4, and the slurried sludge and the food waste are mixed in the sludge storage tank 4 and the temperature and solid content are adjusted.

[0019] Step S3: the material in the sludge tank 4 enters the anaerobic digestion tank 5, where the organic matter is fermented cooperatively, and the generated biogas is stored in the biogas storage cabinet 6. The biogas in the biogas storage cabinet 6 is used for biogas power generation to provide power for the pulping machine 3, the ozone generator 10 and the UV photocatalytic oxidation device 11.

[0020] Step S4, the biogas residue produced in the anaerobic digestion tank 5 enters the conditioning reactor 8, H2O2 is added into the conditioning reactor 8 and O3 is injected, and at the same time, the UV photocatalytic oxidation device 11 emits ultraviolet light, and after the oxidation reaction of the biogas residue is completed, it is discharged into the rear sludge storage tank 13.

[0021] Step S5, the sludge in the rear sludge storage tank 13 is pumped to the plate and frame filter press 14 to complete dehydration.

[0022] The treatment process of this embodiment does not add solid reagents, does not increase the dry solid content of the sludge, and has a significant sludge reduction effect. At the same time, it is economical to operate, has high treatment efficiency, and has good effects. The sludge and kitchen synergistic fermentation is combined with ozone synergistic hydrogen peroxide coupled photocatalytic oxidation technology to achieve energy consumption balance without external energy supplementation, thereby improving the economic operation of the combined process.

[0023] In step S1 of this embodiment, the kitchen waste is solid residue after multi-stage sorting, crushing, impurity removal, high-temperature cooking, and three-phase separation, and the solid content is 10% to 15%.

[0024] In step S2 of this embodiment, sludge slurry is steam heated, and the sludge is heated to 80°C-90°C; the feeding ratio of sludge to kitchen waste is 2-3:1; the sludge and kitchen waste are adjusted in the sludge storage tank 4 to a solid content of 10%-12% and a temperature of 50°C-55°C.

[0025] In step S3 of this embodiment, anaerobic digestion adopts high-temperature anaerobic fermentation, the operating temperature is 50° C. to 55° C., and the residence time is 15 d to 25 d.

[0026] In step S4 of this embodiment, the conditioning reactor 8 adopts mechanical stirring and continuous feeding and discharging operation mode, and the reaction time is 40 min to 60 min; the addition amount of O3 is 1.5 g / L to 2.0 g / L, the addition amount of H2O2 is 0.5 g / L to 0.8 g / L, and the wavelength of ultraviolet light is 185 nm to 255 nm.

[0027] In step S5 of this embodiment, the mud inlet pressure of the plate and frame filter press 14 reaches 8 bar to 10 bar, and the closing pressure is 15 bar to 20 bar.

[0028] In this embodiment, by connecting the ozone generator 10, UV photocatalytic oxidation equipment 11 and H2O2 dosing device 12 to the conditioning reactor 8, the ozone synergistic hydrogen peroxide coupled photocatalytic oxidation technology is applied to the anaerobic digestion sludge dehydration, and the sludge cell wall breaking efficiency and sludge dehydration efficiency are improved by using strong oxidizing properties, while the reagent utilization rate and process stability are improved, the operating cost is reduced, and the reduction effect is obvious. In addition, the sludge and kitchen synergistic fermentation is combined with the ozone synergistic hydrogen peroxide coupled photocatalytic oxidation technology to achieve energy consumption balance, without the need for external energy supplementation, and improve the operating economy of the combined process.

[0029] Example 2 During the operation of the system, 200t of municipal sludge with a solid content of 20% and a VSS of 30% is put into the sludge silo 1 every day, and the sludge is pumped into the pulper 3 by a plunger pump. The sludge in the pulper 3 is heated to 85°C and then enters the sludge storage tank 4. At the same time, 100t / d of food waste with a solid content of 30% and a VSS of 80% is pumped into the sludge storage tank 4 by a plunger pump. After the municipal sludge and food waste are mixed in the sludge storage tank 4 and the temperature is adjusted to 55°C and the solid content is 12%, the mixed material enters the anaerobic digestion tank 5 at a feed rate of 580t / d. The residence time in the anaerobic digestion tank 5 is 20d, and the generated biogas is stored in the biogas storage cabinet 6. After the anaerobic digestion is completed, the solid content of the discharge is 8.1%, the VSS is 27%, and the pH is 8.0. The discharge enters the conditioning reactor 8, in which the ozone generator 10 uses biogas to generate O3, the amount of O3 added is 900kg / d, the amount of H2O2 (30%) added by the H2O2 dosing device 12 is 420kg / d, and the UV photocatalytic oxidation device 11 emits a single-stage ultraviolet light with a wavelength of 255nm for photocatalytic oxidation, and the reaction time is 40min. After the reaction is completed, the material of the conditioning reactor 8 is discharged into the rear mud storage tank 13 for storage, and then enters the plate and frame filter press 14 for dehydration. The mud inlet pressure of the plate and frame filter press 14 is 10bar and the closing pressure is 18bar.

[0030] During the operation of the system, various data were recorded. The daily biogas production in anaerobic digester 5 was 21000m 3 / d, equivalent to 36m3 of biogas per unit feed of the anaerobic tank 3 / t, while the daily biogas production of sludge digestion alone is 4000m 3 / d, equivalent to 10m3 of biogas per unit feed 3 / t, biogas for sludge heating section 5000m 3 / d, biogas used by ozone generator 10 and UV photocatalytic oxidation equipment 11 5500m 3 / d, indicating that there is an energy gap in the digestion of sludge alone, while the coordinated treatment makes up for the overall energy gap and has a large energy surplus. The dosage of hydrogen peroxide agent is only a small amount, which improves the comprehensive operation economy of the treatment system. At the same time, the average moisture content of the mud discharged from the plate and frame filter press 14 is 35%, while the average moisture content of the mud discharged from the traditional chemical conditioning + mechanical dehydration is about 50% to 60%. At the same time, the treatment method of the present invention does not use solid reagents, does not increase the dry solid content, and the weight of the sludge after dehydration is greatly reduced, reducing the subsequent disposal costs. The dehydrated filtrate produced was tested for obvious oil pollution, and the filter cloth of the plate and frame machine was operated continuously for several months without clogging.

[0031] In this embodiment, ozone synergistic hydrogen peroxide coupled photocatalytic oxidation technology is applied to anaerobic digestion sludge dehydration, and the strong oxidizing property is used to improve the sludge cell wall breaking efficiency and sludge dehydration efficiency. At the same time, the agent utilization rate and process stability are improved, the operating cost is reduced, and the reduction effect is obvious.

[0032] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A system for the coordinated treatment of municipal sludge and kitchen waste, characterized in that: include: A sludge silo (1), a food waste silo (2), a sludge storage tank (4), an anaerobic digestion tank (5), a conditioning reactor (8), a post-sludge storage tank (13) and a plate-frame filter press (14); the sludge silo (1) and the food waste silo (2) are respectively connected to the sludge storage tank (4) through pipelines, so that municipal sludge and food waste are mixed in the sludge storage tank (4); the sludge storage tank (4), the anaerobic digestion tank (5), the conditioning reactor (8), the post-sludge storage tank (13) and the plate-frame filter press (14) are connected in sequence through pipelines, and the conditioning reactor (8) is also respectively connected to an ozone generator (10), a UV photocatalytic oxidation device (11) and a H2O2 dosing device (12), so that ozone and hydrogen peroxide are coupled to photocatalytic oxidation to treat municipal sludge and food waste.

2. The municipal sludge and kitchen waste coordinated treatment system according to claim 1, characterized in that: It also includes a biogas storage cabinet (6) and a biogas generator (7). The biogas storage cabinet (6) is connected to the anaerobic digestion tank (5) to collect biogas generated by anaerobic fermentation of municipal sludge and kitchen waste. The biogas generator (7) is connected to the biogas storage cabinet (6) to realize biogas power generation. The ozone generator (10) and the UV photocatalytic oxidation device (11) are both connected to the biogas generator (7).

3. The municipal sludge and kitchen waste coordinated treatment system according to claim 2 is characterized in that: A slurrying machine (3) is provided between the sludge silo (1) and the sludge storage tank (4) to achieve slurrying of sludge by conditioning.

4. The municipal sludge and kitchen waste coordinated treatment system according to claim 2, characterized in that: The conditioning reactor (8) is provided with a stirrer (9).

5. A treatment method based on the municipal sludge and food waste coordinated treatment system according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step S1, putting municipal sludge into a sludge silo (1), and putting food waste into a food waste silo (2); Step S2, the sludge is tempered and slurried by the slurrying machine (3) and then enters the sludge storage tank (4), and the food waste also enters the sludge storage tank (4), and the slurried sludge and the food waste are mixed in the sludge storage tank (4) and the temperature and solid content are adjusted; Step S3, the material in the mud storage tank (4) enters the anaerobic digestion tank (5), the organic matter is co-fermented in the anaerobic digestion tank (5), and the generated biogas is stored in the biogas storage cabinet (6); Step S4, the biogas residue produced in the anaerobic digestion tank (5) enters the conditioning reactor (8), H2O2 is added to the conditioning reactor (8) and O3 is injected, and at the same time, the UV photocatalytic oxidation device (11) emits ultraviolet light, and after the oxidation reaction of the biogas residue is completed, it is discharged into the rear sludge storage tank (13); Step S5: The biogas residue in the rear sludge storage tank (13) is pumped to the plate and frame filter press (14) to complete dehydration.

6. The processing method according to claim 5, characterized in that: In the step S1, the kitchen waste is solid residue after multi-stage sorting, crushing, impurity removal, high-temperature cooking, and three-phase separation, and the solid content is 10% to 15%.

7. The processing method according to claim 5, characterized in that: In step S2, the sludge is slurried by steam heating, and the sludge is heated to 80°C to 90°C; the feeding ratio of sludge to kitchen waste is 2 to 3:1; the sludge and kitchen waste are adjusted in the sludge storage tank (4) to a solid content of 10% to 12% and a temperature of 50°C to 55°C.

8. The processing method according to claim 5, characterized in that In step S3, anaerobic digestion adopts high-temperature anaerobic fermentation, the operating temperature is 50° C. to 55° C., and the residence time is 15 d to 25 d.

9. The processing method according to claim 5, characterized in that In step S4, the conditioning reactor (8) is operated in a mechanical stirring and continuous feeding and discharging mode, and the reaction time is 40 min to 60 min; the dosage of O3 is 1.5 g / L to 2.0 g / L, the dosage of H2O2 is 0.5 g / L to 0.8 g / L, and the wavelength of the ultraviolet light is 185 nm to 255 nm.

10. The processing method according to claim 5, characterized in that In step S5, the mud inlet pressure of the plate and frame filter press (14) reaches 8 bar to 10 bar, and the closing pressure reaches 15 bar to 20 bar.

Images