CN115432897A - Method for promoting excess sludge to produce methane based on citric acid reinforced zero-valent iron - Google Patents
Method for promoting excess sludge to produce methane based on citric acid reinforced zero-valent iron Download PDFInfo
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- 239000010802 sludge Substances 0.000 title claims abstract description 171
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 92
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 title claims abstract description 90
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 66
- 238000000034 method Methods 0.000 title claims abstract description 45
- 230000001737 promoting effect Effects 0.000 title claims abstract description 23
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 42
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 18
- 238000002156 mixing Methods 0.000 claims abstract description 18
- 239000002245 particle Substances 0.000 claims abstract description 18
- 238000001914 filtration Methods 0.000 claims abstract description 13
- 239000008367 deionised water Substances 0.000 claims abstract description 10
- 229910021641 deionized water Inorganic materials 0.000 claims abstract description 10
- 238000007865 diluting Methods 0.000 claims abstract description 10
- 238000010438 heat treatment Methods 0.000 claims abstract description 10
- 238000004519 manufacturing process Methods 0.000 claims abstract description 10
- 239000007787 solid Substances 0.000 claims abstract description 10
- 239000006228 supernatant Substances 0.000 claims abstract description 10
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 9
- 238000007789 sealing Methods 0.000 claims abstract description 9
- 238000003756 stirring Methods 0.000 claims abstract description 7
- 238000005273 aeration Methods 0.000 claims abstract description 6
- 238000001816 cooling Methods 0.000 claims description 3
- 238000005057 refrigeration Methods 0.000 claims description 2
- 230000029087 digestion Effects 0.000 abstract description 22
- 239000001257 hydrogen Substances 0.000 abstract description 17
- 229910052739 hydrogen Inorganic materials 0.000 abstract description 17
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 abstract description 15
- 238000005260 corrosion Methods 0.000 abstract description 11
- 230000007797 corrosion Effects 0.000 abstract description 11
- 230000004048 modification Effects 0.000 abstract description 8
- 238000012986 modification Methods 0.000 abstract description 8
- 230000002708 enhancing effect Effects 0.000 abstract description 4
- 230000008901 benefit Effects 0.000 abstract description 3
- 239000012530 fluid Substances 0.000 abstract 1
- 238000011081 inoculation Methods 0.000 description 10
- 150000002500 ions Chemical class 0.000 description 7
- 230000002452 interceptive effect Effects 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 4
- 230000001186 cumulative effect Effects 0.000 description 4
- 238000011084 recovery Methods 0.000 description 4
- 239000000758 substrate Substances 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 150000004666 short chain fatty acids Chemical class 0.000 description 3
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 2
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 230000000696 methanogenic effect Effects 0.000 description 2
- 150000007524 organic acids Chemical class 0.000 description 2
- 102000004169 proteins and genes Human genes 0.000 description 2
- 108090000623 proteins and genes Proteins 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 239000010865 sewage Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 125000002091 cationic group Chemical group 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 229910001448 ferrous ion Inorganic materials 0.000 description 1
- 150000004676 glycans Chemical class 0.000 description 1
- 239000001963 growth medium Substances 0.000 description 1
- 230000003834 intracellular effect Effects 0.000 description 1
- 150000002632 lipids Chemical class 0.000 description 1
- 230000002503 metabolic effect Effects 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000033116 oxidation-reduction process Effects 0.000 description 1
- 239000002957 persistent organic pollutant Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 229920001282 polysaccharide Polymers 0.000 description 1
- 239000005017 polysaccharide Substances 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 235000000346 sugar Nutrition 0.000 description 1
- 150000008163 sugars Chemical class 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/02—Biological treatment
- C02F11/04—Anaerobic treatment; Production of methane by such processes
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2305/00—Use of specific compounds during water treatment
- C02F2305/06—Nutrients for stimulating the growth of microorganisms
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- Chemical Kinetics & Catalysis (AREA)
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- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
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Abstract
The invention provides a method for promoting excess sludge to produce methane based on citric acid reinforced zero-valent iron, which comprises the steps of standing the excess sludge until sludge and water are separated, filtering after supernatant fluid is removed, and diluting the filtered excess sludge by deionized water until the volatile solid concentration of the excess sludge is not less than 8g/L; refrigerating a part of the excess sludge obtained in the step S1 to be used as inoculated sludge, carrying out heat treatment on the other part of the excess sludge to be used as anaerobic excess sludge, and mixing the inoculated sludge and the anaerobic excess sludge in proportion; adding citric acid powder into the mixed inoculated sludge and anaerobic excess sludge, stirring, adding zero-valent iron particles, sealing, and placing in a water bath shaking table after nitrogen aeration to obtain methane; compared with the zero-valent iron modification process, the method for enhancing the zero-valent iron hydrogen evolution corrosion by citric acid to improve the anaerobic digestion methane production performance has the advantages of simpler operation steps, convenient realization and solution of the complicated process and high cost caused by the zero-valent iron.
Description
Technical Field
The invention belongs to the technical field of sludge treatment and recycling, and particularly relates to a method for promoting excess sludge to produce methane based on citric acid reinforced zero-valent iron.
Background
Urban sewage treatment plants cause the production of large-scale excess sludge, and as a byproduct of urban sewage treatment, the major components of the excess sludge comprise organic substances such as proteins, sugars and lipids, and can be used as reaction substrates for energy recovery, while anaerobic digestion treatment technology is regarded as an extremely potential excess sludge treatment process, and can simultaneously realize the removal of pollutants and the recycling of energy. Through the process, the complex organic pollutants in the excess sludge can be degraded and converted into forms such as hydrogen, methane, short-chain fatty acid and the like which are convenient for energy recovery. However, the residual sludge has problems of low methane yield and long digestion time due to refractory organic components in the residual sludge and a complicated sludge flocculent structure. In addition, in the existing anaerobic digestion system, methanogens of acetophilic type are mainly used, and methanogens of hydrogenophilic type which are more resistant to high ammonia nitrogen load impact and other extreme conditions occupy a lower ratio in the whole methanogenic stage, so that the stability of the system is influenced.
In order to solve the above problems, zero-valent iron (ZVI) is widely used in the process of enhancing the anaerobic digestion of excess sludge to produce methane by virtue of its low price and environmentally friendly characteristics. Under anaerobic conditions, zero-valent iron can corrode to form Fe 2+ Ions and hydrogen, and then the additional hydrogen is used as a reaction substrate for methanogens to utilize, and finally methane is generated. The method strengthens the way of producing methane by using the hydrogenophilic type through the hydrogen evolution corrosion process of the zero-valent iron, thereby improving the efficiency of producing methane by using the anaerobic digestion of the excess sludge and the stability of the system. In addition, as a strong reducing agent, the zero-valent iron can also regulate the oxidation-reduction potential (ORP) level in the system,so that the culture medium is more suitable for normal growth and metabolic activity of methanogens. However, according to the current research, the hydrogen evolution corrosion process of zero-valent iron generates additional hydrogen to promote the hydrogenophilic methane generation, and the contribution to the methane generation of the whole anaerobic digestion is still low.
On this basis, in order to further enhance the methanogenic efficacy of zero-valent iron in promoting anaerobic digestion of excess sludge, many researchers have attempted to modify zero-valent iron by, for example: and vulcanizing zero-valent iron to further improve the anaerobic methanogenesis performance of the zero-valent iron reinforced excess sludge. However, the modification process of zero-valent iron has the problems of complex operation and high cost, and the large-scale engineering application of the zero-valent iron is limited. Therefore, on the theoretical basis of promoting zero-valent iron hydrogen evolution corrosion, a low-cost and environment-friendly strengthening technology is found, and further the stability and the energy recovery efficiency of the anaerobic digestion system are enhanced and improved, which becomes one of the difficulties in need of solution at present.
On one hand, the high cost caused by modification of zero-valent iron can be reduced, and the complexity of the operation process is reduced, so that the method is more suitable for large-scale engineering application; on the other hand, the methanogenesis performance in an anaerobic digestion system is enhanced through the enhancement of zero-valent iron hydrogen evolution corrosion. The invention provides a method for enhancing a zero-valent iron hydrogen evolution corrosion process by introducing citric acid, so that the proportion of a hydrogen-philic methane production approach in an excess sludge anaerobic digestion system is improved, the contents of hydrogen and methane in biogas are further improved, and the stability of the anaerobic digestion system and the energy recovery efficiency are enhanced.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a method for promoting excess sludge to produce methane based on citric acid reinforced zero-valent iron, which solves the problems of complex modification process, complex operation, high modification cost, low occupation ratio of a hydrogenophilic methane production way, poor system tolerance and unstable reinforcing efficiency for promoting anaerobic digestion to produce methane in the prior art.
The invention is realized by the following technical scheme:
a method for promoting excess sludge to produce methane based on citric acid reinforced zero-valent iron comprises the following steps:
s1: standing the residual sludge until mud and water are separated, removing supernatant, filtering, and diluting the filtered residual sludge with deionized water until the volatile solid concentration of the residual sludge is not less than 8g/L;
s2: refrigerating a part of the excess sludge obtained in the step S1 to be used as inoculated sludge, carrying out heat treatment on the other part of the excess sludge to be used as anaerobic excess sludge, and mixing the inoculated sludge and the anaerobic excess sludge in proportion;
s3: and adding citric acid powder into the mixed inoculated sludge and anaerobic excess sludge, stirring, adding zero-valent iron particles, sealing, carrying out nitrogen aeration, and placing in a water bath shaking table to obtain methane.
Preferably, a 0.45 μm sieve is used for the filtration in step S1.
Preferably, the sludge inoculated in the step S2 is obtained by refrigeration at the temperature of below 4 ℃.
Preferably, the anaerobic excess sludge in the step S2 is obtained by treating the anaerobic excess sludge in a water bath kettle at a constant temperature of 80 ℃ for not less than 30min and then cooling the treated anaerobic excess sludge to room temperature.
Preferably, the mixing ratio of the inoculated sludge and the anaerobic excess sludge in the step S2 is 1:4.
preferably, the addition amount of the citric acid powder in the step S3 is 3-12mmol/L, and the purity of the citric acid powder is not lower than 99.5%.
Preferably, the addition amount of the zero-valent iron particles in the step S3 is not less than 30mmol/L.
Preferably, the particle size of the zero-valent iron particles is not more than 100nm, and the purity is not less than 99.9%.
Preferably, the temperature of the water bath shaking table in the step S3 is not more than 35 ℃, and the rotating speed is not less than 140rpm.
Compared with the prior art, the invention has the following beneficial technical effects:
the invention provides a method for promoting excess sludge to produce methane based on citric acid reinforced zero-valent iron, which comprises the steps of standing the excess sludge until sludge and water are separated, filtering after supernatant is removed, and diluting the filtered excess sludge by deionized water until the volatile solid concentration of the excess sludge is not less than 8g/L; refrigerating a part of the obtained excess sludge to be used as inoculated sludge, carrying out heat treatment on the other part of the obtained excess sludge to be used as anaerobic excess sludge, and mixing the inoculated sludge and the anaerobic excess sludge in proportion; adding citric acid powder into the mixed inoculated sludge and anaerobic excess sludge, stirring, adding zero-valent iron particles, sealing, and placing in a water bath shaking table after nitrogen aeration to obtain methane; compared with the zero-valent iron modification process, the method for enhancing the zero-valent iron hydrogen evolution corrosion by citric acid to improve the anaerobic digestion methane production performance has the advantages of simpler operation steps, convenient realization and solution of the complicated process and high cost caused by the zero-valent iron. In addition, the method further strengthens the zero-valent iron hydrogen evolution corrosion, on one hand, the proportion of the hydrogenophilic methanogens in the anaerobic digestion process of the excess sludge can be greatly improved, and the tolerance of the system to high ammonia nitrogen load impact and other extreme conditions is enhanced, so that the application range of zero-valent iron for promoting the anaerobic methanogenesis of the excess sludge is enlarged. On the other hand, citric acid is used as an exogenous addition substance with better biodegradability, plays a role in promoting the dissolution of zero-valent iron under anaerobic conditions, can improve the yield of short-chain fatty acid in the anaerobic digestion process of excess sludge, and provides sufficient reaction substrates for the methanogenesis stage. Compared with the modification of zero-valent iron, the citric acid adding cost is lower. Meanwhile, after citric acid is introduced, the amount of methane produced by anaerobic digestion of excess sludge added based on zero-valent iron is remarkably increased, a benefit basis is provided for application and popularization of the invention, and the method has large-scale application rate possibility.
Drawings
FIG. 1 is a flow chart of a method for promoting excess sludge to produce methane based on citric acid-reinforced zero-valent iron according to the invention;
FIG. 2 is a graph comparing the methane production in the examples of the present invention.
Detailed Description
The present invention will now be described in further detail with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, shall fall within the protection scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Moreover, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The invention provides a method for promoting excess sludge to produce methane based on citric acid reinforced zero-valent iron, which is characterized by comprising the following steps:
s1: standing the residual sludge for more than 24 hours until mud and water are separated, removing supernatant, filtering by using a 0.45-micrometer screen, and diluting the filtered residual sludge by using deionized water, namely pure water without interfering ions until the volatile solid concentration of the residual sludge is not less than 8g/L;
s2: refrigerating a part of the excess sludge obtained in the step S1 to be used as inoculated sludge, carrying out heat treatment on the other part of the excess sludge to be used as anaerobic excess sludge, and mixing the inoculated sludge and the anaerobic excess sludge in proportion;
s3: adding citric acid powder into the mixed inoculated sludge and anaerobic excess sludge, stirring, adding zero-valent iron particles, immediately sealing, carrying out nitrogen aeration, and placing in a water bath shaking table to obtain methane, wherein specifically, the zero-valent iron hydrogen evolution corrosion degree can be effectively strengthened by adding citric acid, so that the anaerobic digestion performance of the whole excess sludge is improved; citric acid, as a cationic binder, promotes the dispersion of excess sludge and thus increases the efficiency of substrate utilization during anaerobic digestion. In addition, as an organic acid, the addition of citric acid can promote the pH value of sludge in the system to be reduced, so that intracellular organic matters in the residual sludge are dissolved out, and therefore, the organic acid is better utilized by microorganisms, and the anaerobic digestion performance is improved. Along with the increase of the adding concentration of the citric acid, the content of the dissolved polysaccharide, protein and short-chain fatty acid in the system is obviously increased. And by combining the change condition of the ferrous concentration and with the addition of citric acid, zero-valent iron generates hydrogen evolution corrosion to generate more hydrogen and ferrous ions, so that the methane production performance of the anaerobic digestion of the excess sludge is finally improved.
Specifically, a 0.45 μm sieve is used for the filtration in step S1.
Specifically, the sludge inoculated in the step S2 is obtained by refrigerating at the temperature of below 4 ℃.
Specifically, the anaerobic excess sludge in the step S2 is obtained by treating the anaerobic excess sludge in a water bath kettle at a constant temperature of 80 ℃ for not less than 30min and then cooling the treated anaerobic excess sludge to room temperature.
Specifically, the mixing ratio of the inoculated sludge and the anaerobic excess sludge in the step S2 is 1:4.
specifically, the addition amount of the citric acid powder in the step S3 is 3-12mmol/L, namely 0.0375-1.5mmol/Lol CA/g VSS, and the purity is not lower than 99.5%.
Specifically, the addition amount of the zero-valent iron particles in the step S3 is not less than 30mmol/L.
Specifically, the particle size of the zero-valent iron particles is not more than 100nm, and the purity is not less than 99.9%.
Specifically, the temperature of the water bath shaking table in the step S3 is not more than 35 ℃, and the rotating speed is not less than 140rpm.
Example 1
S1: standing the residual sludge for more than 24 hours until mud and water are separated, removing supernatant, filtering by adopting a 0.45-micron screen, and diluting the filtered residual sludge by adopting deionized water, namely pure water without interfering ions until the volatile solid concentration of the residual sludge is 8g/L;
s2: refrigerating a part of the excess sludge obtained in the step S1 to be used as inoculation sludge, carrying out heat treatment on the other part of the excess sludge to be used as anaerobic excess sludge, and mixing the inoculation sludge and the anaerobic excess sludge according to a ratio of 1:4, mixing in proportion;
s3: and adding 3mmol/L citric acid powder into the mixed inoculated sludge and anaerobic excess sludge, stirring, adding 30mmol/L zero-valent iron particles, immediately sealing, aerating for 5 minutes by nitrogen, and placing in a water bath shaking table with the temperature of 35 ℃ and the rotating speed of 140rpm, wherein the accumulated methane yield is 149.10mL/g VSS.
Example 2
S1: standing the residual sludge for more than 24 hours until mud and water are separated, removing supernatant, filtering by adopting a 0.45-micron screen, and diluting the filtered residual sludge by adopting deionized water, namely pure water without interfering ions until the volatile solid concentration of the residual sludge is 8g/L;
s2: refrigerating a part of the excess sludge obtained in the step S1 to be used as inoculation sludge, performing heat treatment on the other part of the excess sludge to be used as anaerobic excess sludge, and mixing the inoculation sludge and the anaerobic excess sludge according to a ratio of 1:4, mixing in proportion;
s3: 6mmol/L citric acid powder is added into the mixed inoculated sludge and anaerobic excess sludge and stirred, 30mmol/L zero-valent iron particles are added, sealing is carried out immediately, aeration is carried out for 5 minutes by nitrogen, and then the mixture is placed into a water bath shaking table with the temperature of 35 ℃ and the rotating speed of 140rpm, and the cumulative methane yield is 172.94mL/g VSS.
Example 3
S1: standing the residual sludge for more than 24 hours until mud and water are separated, removing supernatant, filtering by adopting a 0.45-micron screen, and diluting the filtered residual sludge by adopting deionized water, namely pure water without interfering ions until the volatile solid concentration of the residual sludge is 8g/L;
s2: refrigerating a part of the excess sludge obtained in the step S1 to be used as inoculation sludge, carrying out heat treatment on the other part of the excess sludge to be used as anaerobic excess sludge, and mixing the inoculation sludge and the anaerobic excess sludge according to a ratio of 1:4, mixing in proportion;
s3: adding 12mmol/L citric acid powder into the mixed inoculated sludge and anaerobic excess sludge, stirring, adding 30mmol/L zero-valent iron particles, immediately sealing, aerating for 5 minutes by nitrogen, and placing in a water bath shaking table with the temperature of 35 ℃ and the rotating speed of 140rpm, wherein the accumulated methane yield is 157.84mL/g VSS.
COMPARATIVE EXAMPLE 1 (blank group)
S1: standing the residual sludge for more than 24 hours until mud and water are separated, removing supernatant, filtering by adopting a 0.45-micron screen, and diluting the filtered residual sludge by adopting deionized water, namely pure water without interfering ions until the volatile solid concentration of the residual sludge is 8g/L;
s2: refrigerating a part of the excess sludge obtained in the step S1 to be used as inoculation sludge, carrying out heat treatment on the other part of the excess sludge to be used as anaerobic excess sludge, and mixing the inoculation sludge and the anaerobic excess sludge according to a ratio of 1:4, mixing in proportion;
s3: the mixed inoculated sludge and anaerobic excess sludge were placed in a water bath shaker at a temperature of 35 ℃ and a rotation speed of 140rpm, and the cumulative methane yield was 141.14mL/g VSS.
COMPARATIVE EXAMPLE 2 (addition of zero valent iron only)
S1: standing the residual sludge for more than 24 hours until mud and water are separated, removing supernatant, filtering by adopting a 0.45-micron screen, and diluting the filtered residual sludge by adopting deionized water, namely pure water without interfering ions until the volatile solid concentration of the residual sludge is 8g/L;
s2: refrigerating a part of the excess sludge obtained in the step S1 to be used as inoculation sludge, carrying out heat treatment on the other part of the excess sludge to be used as anaerobic excess sludge, and mixing the inoculation sludge and the anaerobic excess sludge according to a ratio of 1:4, mixing in proportion;
s3: and adding zero-valent iron particles into the mixed inoculated sludge and anaerobic excess sludge, immediately sealing, aerating for 5 minutes by nitrogen, and placing in a water bath shaking table with the temperature of 35 ℃ and the rotating speed of 140rpm, wherein the accumulated methane yield is 144.22mL/g VSS.
According to the methane yield obtained in the example 1, the example 2, the example 3, the comparative example 1 and the comparative example 2, as shown in fig. 2, the methane yield can be obtained, wherein the hydrogen evolution corrosion degree of zero-valent iron can be promoted by adding citric acid, so that the proportion of the hydrogenophilic methanogen in the system is improved, the methane production performance of anaerobic digestion of residual sludge is finally improved, compared with the method of adding a zero-valent iron group (144.22 mL/g VSS) alone, the accumulated methane yield of the example 1, the example 2 and the example 3 is respectively as follows: 149.10mL/g VSS, 172.94mL/g VSS and 157.84mL/g VSS, which respectively improve the cumulative methane yield by 3.38%, 19.91% and 9.44%; cumulative methane production was increased compared to the blank (141.14 mL/g VSS): 5.64%, 22.53% and 11.83%.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (9)
1. A method for promoting excess sludge to produce methane based on citric acid reinforced zero-valent iron is characterized by comprising the following steps:
s1: standing the residual sludge until mud and water are separated, removing supernatant, filtering, and diluting the filtered residual sludge with deionized water until the volatile solid concentration of the residual sludge is not less than 8g/L;
s2: refrigerating a part of the excess sludge obtained in the step S1 to be used as inoculated sludge, carrying out heat treatment on the other part of the excess sludge to be used as anaerobic excess sludge, and mixing the inoculated sludge and the anaerobic excess sludge in proportion;
s3: and adding citric acid powder into the mixed inoculated sludge and anaerobic excess sludge, stirring, adding zero-valent iron particles, sealing, carrying out nitrogen aeration, and placing in a water bath shaking table to obtain methane.
2. The method for promoting the production of methane from excess sludge based on citric acid-fortified zero-valent iron as claimed in claim 1, wherein a 0.45 μm screen is used for filtering in step S1.
3. The method for promoting excess sludge methanogenesis based on citric acid fortified zero valent iron of claim 1, wherein the inoculated sludge in step S2 is obtained by refrigeration at a temperature below 4 ℃.
4. The method for promoting excess sludge to produce methane based on citric acid-fortified zero-valent iron according to claim 1, wherein the anaerobic excess sludge in step S2 is obtained by treating the excess sludge in a water bath kettle at a constant temperature of 80 ℃ for not less than 30min and then cooling the treated excess sludge to room temperature.
5. The method for promoting excess sludge to produce methane based on citric acid reinforced zero-valent iron according to claim 1, wherein the mixing ratio of the inoculated sludge and the anaerobic excess sludge in the step S2 is 1:4.
6. the method for promoting excess sludge methanogenesis based on citric acid fortified zero valent iron as claimed in claim 1, wherein the citric acid powder is added in an amount of 3-12mmol/L in step S3, and the purity is not less than 99.5%.
7. The method for promoting excess sludge methanogenesis based on citric acid fortified zero valent iron of claim 1, wherein the amount of zero valent iron particles added in step S3 is not less than 30mmol/L.
8. The method for promoting excess sludge methanogenesis based on citric acid fortified zero valent iron of claim 1 wherein the zero valent iron particles have a particle size of no greater than 100nm and a purity of no less than 99.9%.
9. The method for promoting excess sludge methanogenesis based on citric acid-fortified zero-valent iron of claim 1, wherein the temperature of the water bath shaker in step S3 is not more than 35 ℃ and the rotation speed is not less than 140rpm.
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| CN103343145A (en) * | 2013-06-25 | 2013-10-09 | 同济大学 | Method for promoting anaerobic sludge fermentation to produce short-chain fatty acids by utilizing reduced iron powder |
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