Method for enriching anaerobic granular sludge by adopting charcoal-based three-dimensional composite material

Abstract

The invention provides a method for enriching anaerobic granular sludge by adopting a biochar-based three-dimensional composite material, which comprises the following steps: (1) adding the biochar-based three-dimensional composite material into an anaerobic reactor, and adding the anaerobic granular sludge; (2) pumping synthetic wastewater into the anaerobic reactor, and starting the anaerobic reactor for reaction; and (3) when gas produced by the reaction and effluent are stable, and the volatile suspended matters of the granular sludge account for 70%-90% of the total suspended matters of the sludge, the granular sludge is mature, the operation of the reactor is stopped, and the mature granular sludge is recovered. The method has the characteristics of high stability, high granulation speed of the anaerobic granular sludge, economy, practicability and environmental friendliness, and solves the problems of low enrichment efficiency of the anaerobic granular sludge and non-environment-friendly material use in the prior art.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and in particular to a method for enriching anaerobic granular sludge by using a biochar-based three-dimensional composite material. Background Art

[0002] With the intensification of global environmental problems, water pollution has become a serious global challenge. The large amount of industrial wastewater and domestic sewage discharged by the industrialization process and urbanization development poses a huge threat to the ecological environment. Water pollution and shortage of freshwater resources are key issues facing us today. Therefore, it is very necessary to develop effective, economical and environmentally friendly water treatment methods to provide clean water. Anaerobic granular sludge is a spherical biofilm formed by the aggregation of anaerobic / facultative anaerobic microorganisms. It has the advantages of high density, high stress, and outstanding sedimentation performance. It is usually used in high-concentration organic wastewater treatment technology. However, in actual application, the formation process of granular sludge is relatively slow, and it is difficult to evenly enrich the microbial population, which may eventually lead to unstable treatment effects and fail to give full play to the advantages of granular sludge.

[0003] Biochar has become a potential improved material due to its wide source, green environmental protection, and low cost. First, the high specific surface area and porous structure of biochar can provide abundant attachment sites for microorganisms, help the microbial population to be more evenly enriched, and thus accelerate the formation of granular sludge. Secondly, biochar can regulate the physical and chemical parameters in the environment through adsorption, enhance the structural stability of granular sludge, and prevent the disintegration of particles during the treatment process. However, since biochar is usually in powder form in practical applications, it often settles quickly to the bottom of the water body, resulting in insufficient contact time with pollutants, thus affecting the treatment effect. In addition, biochar is easily impacted by water in water and discharged with the effluent, which increases the difficulty of recovery and causes a large amount of loss and loss of biochar.

[0004] Therefore, it is urgent to study a new high-performance additive to solve the above problems. Summary of the invention

[0005] The present invention proposes a method for enriching anaerobic granular sludge using biochar-based three-dimensional composite materials, which has the characteristics of high stability, fast anaerobic granular sludge granulation speed, economy, practicality and environmental friendliness, and solves the problems of low anaerobic granular sludge enrichment efficiency and environmentally unfriendly material use in the prior art.

[0006] The technical solution of the present invention is achieved in this way:

[0007] A method for enriching anaerobic granular sludge using a biochar-based three-dimensional composite material comprises the following steps:

[0008] (1) adding a biochar-based three-dimensional composite material into an anaerobic reactor and feeding anaerobic granular sludge;

[0009] (2) pumping synthetic wastewater into the anaerobic reactor to start the anaerobic reactor to react;

[0010] (3) When the reaction gas production and effluent are stable, and the proportion of volatile suspended matter in the granular sludge to the total suspended matter in the sludge is 70% to 90% by mass, the granular sludge is mature, the reactor is stopped, and the mature granular sludge is recovered;

[0011] The biochar-based three-dimensional composite material includes biochar, iron-based materials, organic materials and adhesives, and the biochar and iron-based materials are wrapped and loaded on the organic materials through the adhesive.

[0012] Preferably, the biochar-based three-dimensional composite material comprises the following components in weight percentage: 50-70% biochar, 2%-5% iron-based material, 15-40% organic material and 10-20% adhesive.

[0013] Preferably, the biochar is obtained by hydrothermal carbonization or direct pyrolysis carbonization after drying of biomass raw materials, the hydrothermal carbonization temperature is 180-220°C, the pyrolysis carbonization temperature is 450-550°C, and the mesh number of the biochar is 70-100 meshes. Specifically, the biomass raw materials include one or a combination of at least two of rice straw, corn straw, cotton straw, peanut shells, peach branches, and bamboo.

[0014] Preferably, the iron-based material is an iron-containing metal mineral. Specifically, the iron-containing metal mineral includes one or more of magnetite, hematite, ferrihydrite, limonite, siderite, ilmenite, and pyrite.

[0015] Preferably, the organic material is one or more of polyamide, polyvinyl chloride, polyethylene, polypropylene, polystyrene, polymethyl methacrylate, polyimide, and polycarbonate.

[0016] Preferably, the adhesive is one or more of polyethylene, polyvinyl alcohol, polydopamine, and recycled polyethylene terephthalate.

[0017] Preferably, in step (2), the reaction temperature is 20-37° C., the pH is maintained at 7.0-7.5, and the anaerobic reactor is an upflow anaerobic sludge blanket, an expanded granular sludge blanket or an internal circulation reactor.

[0018] Preferably, the carbon:nitrogen ratio in the synthetic wastewater is 25:1, and the concentration of soluble organic matter is 3-15 g / L.

[0019] Preferably, the synthetic wastewater is municipal wastewater, pig farm wastewater, chicken farm wastewater, cattle farm wastewater, fish farming wastewater or aquatic product processing wastewater.

[0020] Preferably, the volume ratio of anaerobic granular sludge to anaerobic reactor is 1:4-10, and the volume ratio of added biochar-based three-dimensional composite material to anaerobic granular sludge is 1:10-25, so as to ensure that the carbon-based material achieves the treatment effect in the system while saving costs.

[0021] Preferably, the mature granular sludge is separated and recovered by a filter.

[0022] Beneficial effects of the present invention:

[0023] 1. The present invention proposes the use of biochar-based three-dimensional composite materials, in which biochar and iron-based materials are loaded on organic materials through adhesives. The iron-based materials can precipitate a large amount of iron ions, thereby improving the redox capacity of the anaerobic sludge system. In addition, biochar and iron-based materials have a certain electron transfer capacity, which can construct a direct interspecies electron transfer channel for symbiotic bacteria, improve the metabolic efficiency of microorganisms and the stability of the fermentation system, and at the same time effectively improve the granulation rate of anaerobic sludge.

[0024] 2. With three-dimensional organic materials as carriers, the resulting composite material is light in weight and low in density, which can prevent the biochar / iron-based materials from settling to the bottom of the water body and avoid the loss and loss of biochar and iron-based materials; in addition, by loading biochar and iron-based materials on organic materials, it is also beneficial to achieve the recycling and reuse of biochar-based three-dimensional composite materials, achieving economic and environmental protection purposes. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0026] Example 1

[0027] A method for enriching anaerobic granular sludge using a biochar-based three-dimensional composite material comprises the following steps:

[0028] (1) adding a biochar-based three-dimensional composite material into an anaerobic reactor and feeding anaerobic granular sludge;

[0029] (2) pumping synthetic wastewater into the anaerobic reactor to start the anaerobic reactor to react;

[0030] (3) When the reaction gas production and effluent are stable, and the proportion of volatile suspended matter in the granular sludge to the total suspended matter in the sludge is 70% to 90% by mass, the granular sludge is mature, the reactor is stopped, and the mature granular sludge is recovered;

[0031] The biochar-based three-dimensional composite material includes biochar, iron-based materials, organic materials and adhesives, and the biochar and iron-based materials are wrapped and loaded on the organic materials through the adhesive.

[0032] In some embodiments, the biochar-based three-dimensional composite material includes the following components in weight percentage: 50-70% biochar, 2%-5% iron-based material, 15-40% organic material and 10-20% binder.

[0033] In some embodiments, the biochar is obtained by hydrothermal carbonization or direct pyrolysis carbonization after drying of biomass raw materials, the hydrothermal carbonization temperature is 180-220°C, the pyrolysis carbonization temperature is 450-550°C, and the mesh size of the biochar is 70-100 meshes. Specifically, the biomass raw materials include one or a combination of at least two of rice straw, corn straw, cotton straw, peanut shells, peach branches, and bamboo.

[0034] In some embodiments, the iron-based material is an iron-containing metal mineral. Specifically, the iron-containing metal mineral includes one or more of magnetite, hematite, ferrihydrite, limonite, siderite, ilmenite, and pyrite.

[0035] In some embodiments, the organic material is one or more of polyamide, polyvinyl chloride, polyethylene, polypropylene, polystyrene, polymethyl methacrylate, polyimide, and polycarbonate.

[0036] In some embodiments, the binder is one or more of polyethylene, polyvinyl alcohol, polydopamine, and recycled polyethylene terephthalate.

[0037] In some embodiments, the reaction temperature in step (2) is 20-37° C., the pH is maintained at 7.0-7.5, and the anaerobic reactor is an upflow anaerobic sludge blanket, an expanded granular sludge blanket or an internal circulation reactor.

[0038] In some embodiments, the carbon:nitrogen ratio in the synthetic wastewater is 25:1, and the concentration of soluble organic matter is 3-15 g / L.

[0039] In some embodiments, the synthetic wastewater is municipal wastewater, pig farm wastewater, chicken farm wastewater, cattle farm wastewater, fish farming wastewater or aquaculture processing wastewater.

[0040] Synthetic wastewater refers to wastewater generated in the industrial production process, mainly from petrochemical, pharmaceutical, printing and dyeing, metallurgy and other industries.

[0041] In some embodiments, the volume ratio of anaerobic granular sludge to anaerobic reactor is 1:4-10, and the volume ratio of added biochar-based three-dimensional composite material to anaerobic granular sludge is 1:10-25, so as to ensure that the carbon-based material achieves the treatment effect in the system while saving costs.

[0042] In some embodiments, the mature granular sludge is separated and recovered by a filter.

[0043] Example 2

[0044] In two UASB anaerobic reactors A and B with a diameter of 80 cm and a total volume of 10.0 L, 2.5 L of anaerobic sludge from a municipal sewage treatment plant was inoculated. The specific parameters are shown in Table 1. The synthetic wastewater is synthetic cattle farm wastewater. The synthetic wastewater inflow is 7 L. The specific parameters are shown in Table 2. The reactor temperature of UASB anaerobic reactor A is controlled at 35 ℃ ~ 37 ℃, and the pH is maintained at 7.0-7.5. The preparation of biochar is as follows: peach wood is selected as the raw material, and the temperature is kept at 500 ℃ for 2 hours at a heating rate of 10 ℃ / min in a drawer-type carbonization furnace, and then sieved through a 100 mesh sieve. The iron-based material is magnetite with a purity higher than 90%, which is crushed and sieved through a 300 mesh sieve. 97.5 g of pyrolytic carbon, 4.5 g of magnetite and 30 g of polyamide are bonded together by 18 g of polyethylene to form a biochar-based three-dimensional composite material. 150g of biochar-based three-dimensional composite material (density of 1.15g / cm3) was added to anaerobic reactor A. No material was added to UASB anaerobic reactor B, and other parameters were consistent with UASB anaerobic reactor A. The initial hydraulic retention time of each reactor was 8h, and the reflux ratio was controlled to 0.8 so that the inlet rise velocity was 0.15m / h. After 15 days, the reflux ratio was increased to 1.5, and the rise velocity was increased to 0.3m / h. On the 30th day of the reactor, the operation was stopped, and the anaerobic granular sludge was recovered by a filter and stored in a -4℃ refrigerator. The effluent COD concentration and anaerobic granular sludge particle size of UASB anaerobic reactors A and B on the 15th and 30th days were measured, as shown in Table 3.

[0045] Table 1 Inoculation sludge parameters

[0046] pH TCOD(mg / L) SCOD(mg / L) TS% VS% Ammonia nitrogen concentration / (mg / L) 7.48 31680 15940 4.75 2.13 442.1

[0047] Among them, COD (Chemical Oxygen Demand), TCOD (Total Chemical Oxygen Demand), SCOD (Solluted Chemical Oxygen Demand), TS (Total Solid), and VS (Volatile Solid).

[0048] Table 2 Composition and concentration of synthetic wastewater

[0049] Element glucose <![CDATA[NH4Cl]]> <![CDATA[KH2PO4]]> <![CDATA[K2HPO4]]> <![CDATA[CaCl2]]> <![CDATA[MgCl2]]> <![CDATA[NaHCO3]]> Content (mg / L) 5400 846 250 250 25 300 1980

[0050] Table 3 Operation data

[0051]

[0052] From the results in Table 3, it can be seen that at the end of the reaction, more than 85% of the granular sludge in the UASB anaerobic reactor B without the addition of biochar-based three-dimensional composite materials had a particle size of less than 1 mm, while 45.2% of the granular sludge in the UASB anaerobic reactor A with the addition of biochar-based composite materials reached 5 mm on the 15th day, and the proportion of granular sludge with a particle size of 5 mm exceeded 70% at the end of the reaction. In addition, the COD removal rate was improved after the addition of the composite materials. On the 15th day, the COD removal rate exceeded 70%, and when it was in operation for the 30th day, the COD removal rate reached 88.6%, which was 23.3% higher than that of the B reactor.

[0053] Therefore, in the UASB anaerobic reactor A with the addition of biochar-based three-dimensional composite materials, the anaerobic granular sludge has a higher degree of maturity, a faster maturation rate and an improved COD removal rate.

[0054] Example 3

[0055] In two 400cm diameter, total volume 3m 3 The UASB anaerobic reactors A and B were inoculated with 0.5 m anaerobic sludge from a municipal sewage treatment plant. 3 The specific parameters are shown in Table 1. The synthetic wastewater is pig farm wastewater, and the synthetic wastewater inflow is 2m 3 , the specific parameters are shown in Table 4. Both UASB anaerobic reactors A and B are operated in a natural state without temperature adjustment. The reactor temperature is consistent with the ambient temperature and fluctuates between 20°C and 30°C. The preparation of biochar is as follows: rice straw is used as raw material, hydrothermal carbonization is performed at a temperature of 200°C, and sieved through a 100-mesh sieve. The iron-based material is limonite with a purity higher than 95%, which is crushed and sieved through a 200-mesh sieve. 12.5kg of biochar, 0.875kg of limonite and 7.5kg of polyvinyl chloride are bonded together with 4.125kg of polyvinyl alcohol to form a biochar-based three-dimensional composite material. 25kg of carbon-based three-dimensional composite material (density 1.17g / cm 3). No biochar-based three-dimensional composite material was added to the UASB anaerobic reactor B, and the other parameters were consistent with those of the UASB anaerobic reactor A. The initial hydraulic retention time of each reactor was 10 h, and the reflux ratio was controlled to 0.8 so that the inlet rise velocity was 0.15 m / h. After 10 days, the reflux ratio was increased to 2.0, and the rise velocity was increased to 0.3 m / h. On the 20th day of the reactor, the operation was stopped, and the granular sludge was recovered by a filter and stored in a -4°C refrigerator. The effluent COD concentration and anaerobic granular sludge particle size of UASB anaerobic reactors A and B on the 10th and 20th days were measured, as shown in Table 5.

[0056] Table 4 Composition and concentration of pig farm wastewater

[0057] project COD SCOD Acetic acid Propionic acid Butyric acid NH4+ Value (mg / L) 3500 1800 1025 361 95.2 500

[0058] Table 5 Operation data

[0059]

[0060] From the results in Table 5, it can be seen that the UASB anaerobic reactor A with the addition of biochar-based three-dimensional composite materials can effectively alleviate the interference of temperature changes and the low temperature inhibition effect, and the methane volumetric gas production rate and COD removal rate are increased by 103.23% and 36.5% respectively compared with the control reactor. In addition, the biochar-based three-dimensional composite material helps to improve the maturity and maturation rate of granular sludge at low temperatures. When the temperature is below 25°C, the particle size of anaerobic granular sludge in the control group UASB anaerobic reactor B is almost less than 1mm, while more than 30% of the anaerobic granular sludge in the UASB anaerobic reactor A with the addition of biochar-based three-dimensional composite materials has a particle size of 5mm. When the temperature is 28°C, more than 60% of the anaerobic granular sludge in the UASB anaerobic reactor A with the addition of biochar-based three-dimensional composite materials has a particle size of 5mm, while 92.3% of the anaerobic granular sludge in the control group UASB anaerobic reactor B has a particle size of less than 1mm.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for enriching anaerobic granular sludge using a biochar-based three-dimensional composite material, characterized in that: The following steps are involved: (1) adding a biochar-based three-dimensional composite material into an anaerobic reactor and feeding anaerobic granular sludge; (2) pumping synthetic wastewater into the anaerobic reactor to start the anaerobic reactor to react; (3) When the reaction gas production and effluent are stable, and the proportion of volatile suspended matter in the granular sludge to the total suspended matter in the sludge is 70% to 90% by mass, the granular sludge is mature, the reactor is stopped, and the mature granular sludge is recovered; The biochar-based three-dimensional composite material includes biochar, iron-based materials, organic materials and adhesives, and the biochar and iron-based materials are wrapped and loaded on the organic materials through the adhesive.

2. The method for enriching anaerobic granular sludge using a biochar-based three-dimensional composite material according to claim 1, characterized in that: The biochar-based three-dimensional composite material comprises the following components in weight percentage: 50-70% of biochar, 2%-5% of iron-based material, 15-40% of organic material and 10-20% of adhesive.

3. The method for enriching anaerobic granular sludge using a biochar-based three-dimensional composite material according to claim 1, characterized in that: The biochar is obtained by hydrothermal carbonization or direct pyrolysis carbonization after drying of biomass raw materials. The hydrothermal carbonization temperature is 180-220° C., the pyrolysis carbonization temperature is 450-550° C., and the mesh size of the biochar is 70-100 meshes.

4. The method for enriching anaerobic granular sludge using a biochar-based three-dimensional composite material as claimed in claim 3, characterized in that: The biomass energy raw material includes one or a combination of at least two of rice straw, corn straw, cotton straw, peanut shell, peach wood branch and bamboo.

5. The method for enriching anaerobic granular sludge using a biochar-based three-dimensional composite material according to claim 1, characterized in that: The iron-based material is an iron-containing metal mineral, and the iron-containing metal mineral includes one or more of magnetite, hematite, ferrihydrite, limonite, siderite, ilmenite, and pyrite.

6. The method for enriching anaerobic granular sludge using a biochar-based three-dimensional composite material according to claim 1, characterized in that: The organic material is one or more of polyamide, polyvinyl chloride, polyethylene, polypropylene, polystyrene, polymethyl methacrylate, polyimide and polycarbonate.

7. The method for enriching anaerobic granular sludge using a biochar-based three-dimensional composite material according to claim 1, characterized in that: The adhesive is one or more of polyethylene, polyvinyl alcohol, polydopamine, and recycled polyethylene terephthalate.

8. The method for enriching anaerobic granular sludge using a biochar-based three-dimensional composite material according to claim 1, characterized in that: In step (2), the reaction temperature is 20-37° C. and the pH is maintained at 7.0-7.

5.

9. The method for enriching anaerobic granular sludge using a biochar-based three-dimensional composite material according to claim 1, characterized in that: The ratio of carbon to nitrogen in the synthetic wastewater is 25:1, and the concentration of soluble organic matter is 3-15 g / L.

10. The method for enriching anaerobic granular sludge using a biochar-based three-dimensional composite material according to claim 1, characterized in that: The synthetic wastewater is municipal wastewater, pig farm wastewater, chicken farm wastewater, cattle farm wastewater, fish breeding wastewater or aquatic product processing wastewater.

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