Method for deodorizing sludge with metal salt and tannin extract together, deodorized sludge, and use thereof

Abstract

A method for deodorizing sludge with a metal salt and a tannin extract together, deodorized sludge, and use thereof are provided. The present invention provides a sludge deodorization technology that has high treatment efficiency, environmental friendliness, and low investment costs, and satisfies harmless requirements of subsequent resource utilization such as incineration, pyrolysis, or carbonization. Characterized by containing abundant phenolic hydroxyl groups, the tannin extract is used as a multidentate ligand to undergo a complexation reaction with metal ions, which reduces bioavailability of proteins and other macromolecules, and effectively inhibits production of low-volatile sulfides, thereby significantly deodorizing the sludge during standing and combustion. The whole deodorization process of the present invention is simple and feasible, is flexible in operation, requires no complex and harsh reaction conditions or expensive equipment, has low operating costs, and can be used as a supporting pretreatment technology for resource utilization of sludge.

Claims

1. A method for deodorizing sludge with a metal salt and a tannin extract together, comprising the following steps: in parts by weight, uniformly mixing 9320-9910 parts of to-be-deodorized sludge and 20-100 parts of a metal salt treatment solution, and adding a mixture of 50-500 parts of a tannin extract treatment solution and 20-80 parts of a pH adjuster, to obtain a sludge deodorization reaction system, wherein the metal salt treatment solution is an aqueous solution containing 0.5%-2.5% of one or more of ferrous sulfate, ferric sulfate, ferric nitrate, and ferrous ammonium sulfate, the tannin extract treatment solution is an aqueous solution containing 5%-50% of one or more of a Myrica rubra tannin extract, a larch tannin extract, a valonea tannin extract, a quebracho tannin extract, and a wattle tannin extract, and controlling a pH value of the sludge deodorization reaction system to be 6.2-7.5, and stirring the sludge deodorization reaction system at a speed of 15-120 r/min for 1-3 h, prior to standing for 12-48 h.

2. The method according to claim 1, wherein in percentage by mass, the pH adjuster is an aqueous solution containing 2%-8% of one or more of acetic acid, sulfamic acid, sulfuric acid, formic acid, and oxalic acid.

3. The method according to claim 1, wherein a reaction temperature for the sludge deodorization reaction system is controlled to be 25? C.-80? C.

4. The method according to claim 1, wherein the 9320-9910 parts of the to-be-deodorized sludge and the 20-100 parts of the metal salt treatment solution are uniformly mixed by stirring at a speed of 15-120 r/min for 1-3 h.

5. The method according to claim 1, wherein the to-be-deodorized sludge comprises domestic sewage sludge, industrial wastewater sludge, drain-pipe sludge, and/or water-sediment sludge.

6. The method according to claim 1, wherein the to-be-deodorized sludge comprises one or more of untreated primarily precipitated sludge, secondarily precipitated residual sludge, raw sludge obtained by mixing the untreated primarily precipitated sludge and the secondarily precipitated residual sludge, aerobically or anaerobically digested sludge, and dehydrated and dried sludge.

7. Deodorized sludge, wherein the deodorized sludge is obtained through treatment by using the method according to claim 1.

8. Use A method of using the deodorized sludge according to claim 7 in a resource utilization process selected from the group consisting of incineration, pyrolysis, and carbonization.

9. The deodorized sludge according to claim 7, wherein in the method, in percentage by mass, the pH adjuster is an aqueous solution containing 2%-8% of one or more of acetic acid, sulfamic acid, sulfuric acid, formic acid, and oxalic acid.

10. The deodorized sludge according to claim 7, wherein in the method, a reaction temperature for the sludge deodorization reaction system is controlled to be 25? C.-80? C.

11. The deodorized sludge according to claim 7, wherein in the method, the 9320-9910 parts of the to-be-deodorized sludge and the 20-100 parts of the metal salt treatment solution are uniformly mixed by stirring at a speed of 15-120 r/min for 1-3 h.

12. The deodorized sludge according to claim 7, wherein in the method, the to-be-deodorized sludge comprises domestic sewage sludge, industrial wastewater sludge, drain-pipe sludge, and/or water-sediment sludge.

13. The deodorized sludge according to claim 7, wherein in the method, the to-be-deodorized sludge comprises one or more of untreated primarily precipitated sludge, secondarily precipitated residual sludge, raw sludge obtained by mixing the untreated primarily precipitated sludge and the secondarily precipitated residual sludge, aerobically or anaerobically digested sludge, and dehydrated and dried sludge.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

(1) The following describes in detail the method for deodorizing sludge with a metal salt and a tannin extract together according to the first aspect, the deodorized sludge according to the second aspect, and the use of deodorized sludge according to the third aspect of the present invention.

(2) First, the method for deodorizing sludge with a metal salt and a tannin extract together according to the first aspect of the present invention is described.

(3) According to the first aspect of the present invention, a method for deodorizing sludge with a metal salt and a tannin extract together is provided, including the following steps: in parts by weight, uniformly mixing 9320-9910 parts of to-be-deodorized sludge and 20-100 parts of metal salt treatment solution, and adding a mixture of 50-500 parts of tannin extract treatment solution and 20-80 parts of pH adjuster, to obtain a sludge deodorization reaction system; and controlling a pH value of the sludge deodorization reaction system to be 6.2-7.5, and stirring the sludge deodorization reaction system at a speed of 15-120 r/min for 1-3 h, prior to standing for 12-48 h.

(4) The tannin extract in the present invention is a natural plant extract that is environmentally friendly, and has wide sources and low costs. In the present invention, by innovatively using the characteristic of containing abundant phenolic hydroxyl groups, the tannin extract can be used as a multidentate ligand to undergo a complexation reaction with metal ions, to form a stable five-membered ring chelate. Moreover, the tannin extract also undergoes complexation with extracellular polymers (mainly composed of proteins and polysaccharides) of the sludge, to form crosslinks between protein peptide chains with hydrophobic bonds and hydrogen bonds, which reduces bioavailability of proteins and other macromolecules in the sludge, and effectively inhibits production of low-volatile sulfides with low olfactory thresholds, such as hydrogen sulfide, methyl mercaptan, methyl sulfide, carbon disulfide, and dimethyl disulfide, thereby significantly deodorizing the sludge during standing and combustion.

(5) According to a preferred embodiment of the present invention, in percentage by mass, the metal salt treatment solution is an aqueous solution containing 0.5%-2.5% of one or more of ferrous sulfate, ferric sulfate, aluminum sulfate, ferric nitrate, and ferrous ammonium sulfate. In the present invention, plant tannin contained in the tannin extract reacts with ferrous ions to form ferrous tannate or a ferric tannate complex. Ferrous tannate is unstable and easily oxidized in the air to form a ferric tannate complex that is blue-black. Therefore, the metal salt treatment solution of the present invention is a sulfate or nitrate solution of ferrous ions, aluminum ions, or ferric ions, preferably, a sulfate or nitrate solution of ferrous ions or ferric ions.

(6) According to a preferred embodiment of the present invention, in percentage by mass, the tannin extract treatment solution is an aqueous solution containing 5%-50% of one or more of a Myrica rubra tannin extract, a larch tannin extract, a valonea tannin extract, a quebracho tannin extract, and a wattle tannin extract. The Myrica rubra tannin extract, the larch tannin extract, the valonea tannin extract, the quebracho tannin extract, and the wattle tannin extract are all products obtained through extraction of raw plant materials containing tannin in a high content, such as bark, wood, and shells, prior to concentration, which are brownish yellow to tan and divided into powders and blocks.

(7) According to a preferred embodiment of the present invention, in percentage by mass, the pH adjuster is an aqueous solution containing 2%-8% of one or more of acetic acid, sulfamic acid, sulfuric acid, formic acid, and oxalic acid.

(8) According to a preferred embodiment of the present invention, a reaction temperature for the sludge deodorization reaction system is controlled to be 25? C.-80? C. Increase of the temperature helps dispersion and penetration of tannin in the tannin extract, and also promotes binding of the tannin and the extracellular polymers of the sludge. However, when the temperature is excessively high, oxidation of tannin accelerates, and proteins in the sludge are easily denatured and lose bioactivity. Therefore, in the present invention, the reaction temperature for the sludge deodorization reaction system is controlled to be 25? C.-80? C.

(9) According to a preferred embodiment of the present invention, the 9320-9910 parts of to-be-deodorized sludge and the 20-100 parts of metal salt treatment solution are uniformly mixed by stirring at a speed of 15-120 r/min for 1-3 h.

(10) According to a preferred embodiment of the present invention, the to-be-deodorized sludge includes domestic sewage sludge, industrial wastewater sludge, drain-pipe sludge, and/or water-sediment sludge.

(11) According to a preferred embodiment of the present invention, the to-be-deodorized sludge includes one or more of untreated primarily precipitated sludge, secondarily precipitated residual sludge, raw sludge obtained by mixing the untreated primarily precipitated sludge and the secondarily precipitated residual sludge, aerobically or anaerobically digested sludge, and dehydrated and dried sludge.

(12) Then, the deodorized sludge according to the second aspect of the present invention is described.

(13) Provided is deodorized sludge. The deodorized sludge is obtained through treatment by using the method according to the first aspect of the present invention.

(14) The deodorized sludge obtained through treatment by using the method according to the first aspect of the present invention produces greatly reduced contents of low-volatile sulfides with low olfactory thresholds, such as hydrogen sulfide, methyl mercaptan, methyl sulfide, carbon disulfide, and dimethyl disulfide. As bound water of the sludge is released, dehydration and drying performance of the deodorized sludge is improved.

(15) Finally, the use of deodorized sludge according to the third aspect of the present invention is described.

(16) Provided is use of deodorized sludge. The deodorized sludge is the deodorized sludge according to the second aspect of the present invention.

(17) The deodorized sludge according to the second aspect of the present invention also contains a large amount of organic matter. After being fully deodorized by using the method according to the first aspect of the present invention, the deodorized sludge may be used in resource utilization including but not limited to incineration, pyrolysis, or carbonization.

(18) To describe in detail the technical content, structural characteristics, and achieved objectives and effects of the technical solutions, the following is described in detail with specific examples. It should be understood that these examples are intended only to illustrate this application but are not intended to limit the scope of this application.

Example 1

(19) This example provides a method for deodorizing sludge with a metal salt and a tannin extract together, including the following specific steps:

(20) First, 9320 parts of to-be-deodorized sludge from domestic sewage were put in a stirring machine at a reaction temperature controlled to be 25? C. Next, 100 parts of metal salt treatment solution were added. A stirrer was turned on to carry out stirring at 120 r/min for 1 h for mixing uniformly. Then, 500 parts of tannin extract treatment solution and 80 parts of pH adjuster were mixed and added into the stirring machine at a pH value controlled to be 6.2, then stirred at 120 r/min for 3 h, and left to stand for 12 h, to effectively deodorize the sludge. In this example, the metal salt treatment solution is an aqueous solution containing 2.5% of ferrous sulfate in percentage by mass, the tannin extract treatment solution is an aqueous solution containing 50% of a Myrica rubra tannin extract in percentage by mass, and the pH adjuster is an aqueous solution containing 8% of acetic acid in percentage by mass.

Example 2

(21) This example provides a method for deodorizing sludge with a metal salt and a tannin extract together, including the following specific steps:

(22) First, 9910 parts of to-be-deodorized sludge from industrial wastewater were put in a stirring machine at a reaction temperature controlled to be 60? C. Next, 20 parts of metal salt treatment solution were added. A stirrer was turned on to carry out stirring at 15 r/min for 1 h for mixing uniformly. Then, 50 parts of tannin extract treatment solution and 20 parts of pH adjuster were mixed and added into the stirring machine at a pH value controlled to be 7.5, then stirred at 15 r/min for 2 h, and left to stand for 12 h, to effectively deodorize the sludge. In this example, the metal salt treatment solution is an aqueous solution containing 0.5% of aluminum sulfate in percentage by mass, the tannin extract treatment solution is an aqueous solution containing 5% of a Myrica rubra tannin extract in percentage by mass, and the pH adjuster is an aqueous solution containing 2% of oxalic acid in percentage by mass.

Example 3

(23) This example provides a method for deodorizing sludge with a metal salt and a tannin extract together, including the following specific steps:

(24) First, 9780 parts of to-be-deodorized sludge from municipal sewage treatment plants were put in a stirring machine at a reaction temperature controlled to be 40? C. Next, 100 parts of metal salt treatment solution were added. A stirrer was turned on to carry out stirring at 90 r/min for 1 h for mixing uniformly. Then, 100 parts of tannin extract treatment solution and 20 parts of pH adjuster were mixed and added into the stirring machine at a pH value controlled to be 7.5, then stirred at 90 r/min for 2 h, and left to stand for 12 h, to effectively deodorize the sludge. In this example, the metal salt treatment solution is an aqueous solution containing 2.5% of ferrous sulfate in percentage by mass, the tannin extract treatment solution is an aqueous solution containing 10% of a Myrica rubra tannin extract in percentage by mass, and the pH adjuster is an aqueous solution containing 2% of sulfamic acid in percentage by mass.

Example 4

(25) This example provides a method for deodorizing sludge with a metal salt and a tannin extract together, including the following specific steps:

(26) First, 9830 parts of to-be-deodorized sludge from domestic sewage were put in a stirring machine at a reaction temperature controlled to be 40? C. Next, 50 parts of metal salt treatment solution were added. A stirrer was turned on to carry out stirring at 90 r/min for 1 h for mixing uniformly. Then, 100 parts of tannin extract treatment solution and 20 parts of pH adjuster were mixed and added into the stirring machine at a pH value controlled to be 7.5, then stirred at 90 r/min for 2 h, and left to stand for 12 h, to effectively deodorize the sludge. In this example, the metal salt treatment solution is an aqueous solution containing 1.25% of ferrous sulfate in percentage by mass, the tannin extract treatment solution is an aqueous solution containing 10% of a Myrica rubra tannin extract in percentage by mass, and the pH adjuster is an aqueous solution containing 2% of sulfamic acid in percentage by mass.

Example 5

(27) This example provides a method for deodorizing sludge with a metal salt and a tannin extract together, including the following specific steps:

(28) First, 9830 parts of to-be-deodorized sludge from domestic sewage were put in a stirring machine at a reaction temperature controlled to be 40? C. Next, 50 parts of metal salt treatment solution were added. A stirrer was turned on to carry out stirring at 90 r/min for 1 h for mixing uniformly. Then, 100 parts of tannin extract treatment solution and 20 parts of pH adjuster were mixed and added into the stirring machine at a pH value controlled to be 7.5, then stirred at 90 r/min for 2 h, and left to stand for 18 h, to effectively deodorize the sludge. In this example, the metal salt treatment solution is an aqueous solution containing 2.5% of ferric nitrate in percentage by mass, the tannin extract treatment solution is an aqueous solution containing 10% of a Myrica rubra tannin extract in percentage by mass, and the pH adjuster is an aqueous solution containing 2% of sulfuric acid in percentage by mass.

Example 6

(29) This example provides a method for deodorizing sludge with a metal salt and a tannin extract together, including the following specific steps:

(30) First, 9830 parts of to-be-deodorized sludge from domestic sewage were put in a stirring machine at a reaction temperature controlled to be 40? C. Next, 50 parts of metal salt treatment solution were added. A stirrer was turned on to carry out stirring at 90 r/min for 1 h for mixing uniformly. Then, 100 parts of tannin extract treatment solution and 20 parts of pH adjuster were mixed and added into the stirring machine at a pH value controlled to be 7.5, then stirred at 90 r/min for 2 h, and left to stand for 18 h, to effectively deodorize the sludge. In this example, the metal salt treatment solution is an aqueous solution containing 1.25% of ferrous ammonium sulfate in percentage by mass, the tannin extract treatment solution is an aqueous solution containing 10% of a Myrica rubra tannin extract in percentage by mass, and the pH adjuster is an aqueous solution containing 2% of formic acid in percentage by mass.

Example 7

(31) This example provides a method for deodorizing sludge with a metal salt and a tannin extract together, including the following specific steps:

(32) First, 9830 parts of to-be-deodorized sludge from domestic sewage were put in a stirring machine at a reaction temperature controlled to be 40? C. Next, 50 parts of metal salt treatment solution were added. A stirrer was turned on to carry out stirring at 90 r/min for 1 h for mixing uniformly. Then, 100 parts of tannin extract treatment solution and 20 parts of pH adjuster were mixed and added into the stirring machine at a pH value controlled to be 7.5, then stirred at 90 r/min for 2 h, and left to stand for 12 h, to effectively deodorize the sludge. In this example, the metal salt treatment solution is an aqueous solution containing 1.25% of ferrous sulfate in percentage by mass, the tannin extract treatment solution is an aqueous solution containing 10% of a larch tannin extract in percentage by mass, and the pH adjuster is an aqueous solution containing 2% of sulfamic acid in percentage by mass.

Example 8

(33) This example provides a method for deodorizing sludge with a metal salt and a tannin extract together, including the following specific steps:

(34) First, 9810 parts of to-be-deodorized sludge from drain pipes were put in a stirring machine at a reaction temperature controlled to be 40? C. Next, 50 parts of metal salt treatment solution were added. A stirrer was turned on to carry out stirring at 90 r/min for 1 h for mixing uniformly. Then, 100 parts of tannin extract treatment solution and 40 parts of pH adjuster were mixed and added into the stirring machine at a pH value controlled to be 6.6, then stirred at 90 r/min for 2 h, and left to stand for 12 h, to effectively deodorize the sludge. In this example, the metal salt treatment solution is an aqueous solution containing 1.25% of ferric sulfate in percentage by mass, the tannin extract treatment solution is an aqueous solution containing 10% of a wattle tannin extract in percentage by mass, and the pH adjuster is an aqueous solution containing 4% of acetic acid in percentage by mass.

Example 9

(35) This example provides a method for deodorizing sludge with a metal salt and a tannin extract together, including the following specific steps:

(36) First, 9760 parts of to-be-deodorized sludge from water sediment were put in a stirring machine at a reaction temperature controlled to be 60? C. Next, 20 parts of metal salt treatment solution were added. A stirrer was turned on to carry out stirring at 60 r/min for 1 h for mixing uniformly. Then, 200 parts of tannin extract treatment solution and 20 parts of pH adjuster were mixed and added into the stirring machine at a pH value controlled to be 7.5, then stirred at 60 r/min for 2 h, and left to stand for 12 h, to effectively deodorize the sludge. In this example, the metal salt treatment solution is an aqueous solution containing 0.5% of ferrous sulfate in percentage by mass, the tannin extract treatment solution is an aqueous solution containing 20% of a quebracho tannin extract in percentage by mass, and the pH adjuster is an aqueous solution containing 2% of oxalic acid in percentage by mass.

Example 10

(37) This example provides a method for deodorizing sludge with a metal salt and a tannin extract together, including the following specific steps:

(38) First, 9830 parts of to-be-deodorized sludge from water sediment were put in a stirring machine at a reaction temperature controlled to be 80? C. Next, 50 parts of metal salt treatment solution were added. A stirrer was turned on to carry out stirring at 90 r/min for 1 h for mixing uniformly. Then, 100 parts of tannin extract treatment solution and 20 parts of pH adjuster were mixed and added into the stirring machine at a pH value controlled to be 7.5, then stirred at 90 r/min for 2 h, and left to stand for 12 h, to effectively deodorize the sludge. In this example, the metal salt treatment solution is an aqueous solution containing 1.25% of ferrous sulfate in percentage by mass, the tannin extract treatment solution is an aqueous solution containing 10% of a larch tannin extract in percentage by mass, and the pH adjuster is an aqueous solution containing 2% of acetic acid in percentage by mass.

Comparative Example 1

(39) First, 9930 parts of to-be-deodorized sludge from water sediment were put in a stirring machine at a reaction temperature controlled to be 40? C. Next, 50 parts of metal salt treatment solution were added. A stirrer was turned on to carry out stirring at 90 r/min for 1 h for mixing uniformly. 20 parts of pH adjuster were mixed and added into the stirring machine at a pH value controlled to be 7.5, and stirred at 90 r/min for 2 h. In this comparative example, the metal salt treatment solution is an aqueous solution containing 1.25% of ferrous sulfate in percentage by mass, and the pH adjuster is an aqueous solution containing 2% of acetic acid in percentage by mass.

Comparative Example 2

(40) First, 9880 parts of to-be-deodorized sludge from water sediment were put in a stirring machine at a reaction temperature controlled to be 40? C. A stirrer was turned on to carry out stirring at 90 r/min for 1 h for mixing uniformly. Then, 100 parts of tannin extract treatment solution and 20 parts of pH adjuster were mixed and added into the stirring machine at a pH value controlled to be 7.5, and stirred at 90 r/min for 2 h. In this comparative example, the tannin extract treatment solution is an aqueous solution containing 10% of a larch tannin extract in percentage by mass, and the pH adjuster is an aqueous solution containing 2% of acetic acid in percentage by mass.

(41) Process parameters involved in the methods for deodorizing sludge used in Example 1 to Example 10, and Comparative Example 1 and Comparative Example 2 are detailed in Table 1.

(42) TABLE-US-00001 TABLE 1 Process parameters of Example 1 to Example 10 in the present invention Metal salt Tannin extract Stirring of deodorization PH value for To-be-deodorized treatment treatment reaction system deodorization sludge solution solution PH adjuster Speed Time Temperature reaction Item Type Parts Type Parts Type Parts Type Parts (r/min) (h) (? C.) / Example 1 Domestic 9320 Aqueous 100 Aqueous 500 Aqueous 80 120 3 25 6.2 sewage parts solution solution solution sludge containing containing containing 2.5% of 50% of 8% of ferrous Myrica acetic sulfate rubra acid tannin extract Example 2 Industrial 9910 Aqueous 20 Aqueous 50 Aqueous 20 15 2 60 7.5 wastewater parts solution solution solution sludge containing containing containing 0.5% of 5% of 2% of aluminum valonea oxalic sulfate tannin acid extract Example 3 Domestic 9780 Aqueous 100 Aqueous 100 Aqueous 20 90 2 40 7.5 sewage parts solution solution solution sludge containing containing containing 2.5% of 10% of 2% of ferrous Myrica sulfamic sulfate rubra acid tannin extract Example 4 Domestic 9830 Aqueous 50 Aqueous 100 Aqueous 20 90 2 40 7.5 sewage parts solution solution solution sludge containing containing containing 1.25% of 10% of 2% of ferrous Myrica sulfamic sulfate rubra acid tannin extract Example 5 Domestic 9830 Aqueous 50 Aqueous 100 Aqueous 20 90 2 40 7.5 sewage parts solution solution solution sludge containing containing containing 1.25% of 10% of 2% of ferric Myrica sulfuric nitrate rubra acid tannin extract Example 6 Domestic 9830 Aqueous 50 Aqueous 100 Aqueous 20 90 2 40 7.5 sewage parts solution solution solution sludge containing containing containing 1.25% of 10% of 2% of ferrous Myrica formic ammonium rubra acid sulfate tannin extract Example 7 Domestic 9830 Aqueous 50 Aqueous 100 Aqueous 20 90 2 40 7.5 sewage parts solution solution solution sludge containing containing containing 1.25% of 10% of 2% of ferrous larch sulfamic sulfate tannin acid extract Example 8 Drain-pipe 9810 Aqueous 50 Aqueous 100 Aqueous 40 90 2 40 6.6 sludge parts solution solution solution containing containing containing 1.25% of 10% of 4% of ferrous wattle acetic sulfate tannin acid extract Example 9 Water- 9760 Aqueous 20 Aqueous 200 Aqueous 20 60 1 60 7.5 sediment parts solution solution solution sludge containing containing containing 0.5% of 20% of 2% of ferrous quebracho oxalic sulfate tannin acid extract Example 10 Domestic 9830 Aqueous 50 Aqueous 100 Aqueous 20 90 2 80 7.5 sewage parts solution solution solution sludge containing containing containing 1.25% of 10% of 2% of ferrous larch acetic sulfate tannin acid extract Comparative Domestic 9930 Aqueous 50 Aqueous 20 90 2 40 7.5 Example 1 sewage parts solution solution sludge containing containing 1.25% of 2% of ferrous acetic sulfate acid Comparative Domestic 9880 Aqueous 100 Aqueous 20 90 2 40 7.5 Example 2 sewage parts solution solution sludge containing containing 10% of 2% of larch acetic tannin acid extract

(43) Detection and analysis of deodorization data were carried out on the deodorized sludge obtained by using the methods in Example 1 to Example 10, and Comparative Example 1 and Comparative Example 2. Gas indicators of an ammonia gas (including ammonia gas indicators in a standing state and a combustion state) and hydrogen sulfide obtained by using a gas detector are listed in Table 2 and Table 3.

(44) TABLE-US-00002 TABLE 2 Ammonia gas indicators before and after sludge deodorization in examples of the present invention Standing ammonia gas indicator Combustion ammonia gas indicator (mg/m.sup.3) (mg/m.sup.3) Before After Removal Before After Removal Group deodorization deodorization rate deodorization deodorization rate Example 1 20.7 8.2 60.39% 48.2 20.2 58.09% Example 2 20.7 7.3 64.73% 48.2 23.6 51.04% Example 3 20.7 4.1 80.19% 48.2 16.5 65.77% Example 4 20.7 3.8 81.64% 48.2 11.1 76.97% Example 5 20.7 3.9 81.16% 48.2 17.5 63.69% Example 6 20.7 4.3 79.23% 48.2 15.3 68.26% Example 7 20.7 3.3 84.06% 48.2 10.6 78.01% Example 8 20.7 5.0 75.85% 48.2 12.4 74.27% Example 9 20.7 4.7 77.29% 48.2 17.1 64.52% Example 10 20.7 4.0 80.68% 48.2 10.8 77.59% Comparative 20.7 18.8 9.18% 48.2 35.6 26.14% Example 1 Comparative 20.7 12.4 40.10% 48.2 28.1 41.70% Example 2

(45) TABLE-US-00003 TABLE 3 Hydrogen sulfide indicators before and after sludge deodorization in examples of the present invention Standing hydrogen sulfide indicator Combustion hydrogen sulfide (mg/m.sup.3) indicator (mg/m.sup.3) Before After Removal Before After Removal Group deodorization deodorization rate deodorization deodorization rate Example 1 0.6 0.2 66.66% 4.6 2.1 54.35% Example 2 0.6 0.2 66.66% 4.6 2.4 47.83% Example 3 0.6 <0.1 >83.33% 4.6 1.5 67.39% Example 4 0.6 <0.1 >83.33% 4.6 1.1 76.09% Example 5 0.6 <0.1 >83.33% 4.6 1.2 73.91% Example 6 0.6 <0.1 >83.33% 4.6 1.8 60.87% Example 7 0.6 <0.1 >83.33% 4.6 1.1 76.09% Example 8 0.6 <0.1 >83.33% 4.6 1.8 60.87% Example 9 0.6 <0.1 >83.33% 4.6 1.4 69.57% Example 10 0.6 <0.1 >83.33% 4.6 1.8 60.87% Comparative 0.6 0.6 0.00% 4.6 3.9 15.22% Example 1 Comparative 0.6 0.5 16.67% 4.6 2.9 36.96% Example 2

(46) Through analysis on the examples and comparative examples, it can be learned that the ammonia gas and hydrogen sulfide can be significantly removed from the sludge by using the method with a metal salt and a tannin extract together, implementing efficient deodorization of the sludge, and deodorization efficiency is much higher than that of the method using a metal salt alone (in Comparative Example 1) or the method using a tannin extract alone (in Comparative Example 2). The treatment in Example 7 has the best effect on sludge deodorization. In the standing state, 84.06% of ammonia gas and greater than 83.33% of hydrogen sulfide can be removed. In the combustion state, 78.01% of ammonia gas and 76.09% of hydrogen sulfide can be removed. It can be found through comprehensive comparative analysis that an effect of sludge deodorization with the larch tannin extract in the present invention is better than that of sludge deodorization with other tannin extracts, and an effect of sludge deodorization with ferrous sulfate is better than that of sludge deodorization with other metal salts.

(47) It is to be noted that the foregoing embodiments have been described in this specification, but cannot therefore limit the protection scope of the present invention. Therefore, changes and modifications of the embodiments in this specification based on the innovative concept of the present invention, or equivalent structure or process transformation made based on the description of the present invention, or direct or indirect application of the foregoing technical solutions to other related technical fields are all included in the protection scope of the present invention.