Modified sludge, preparation method thereof and slurry fuel

Abstract

The invention provides modified sludge, a preparation method thereof and slurry fuel, and belongs to the technical field of sludge treatment. The preparation method of the modified sludge provided by the invention comprises the following steps: mixing sludge with biomass to obtain a mixture; the carbon nitrogen ratio of the mixture is 12.5 to 15.5; mixing the mixture with a microbial agent, and fermenting to obtain modified sludge; the fermentation temperature is 34 to 42 DEG C. The sludge floc structure is broken by using a fermentation mechanism, the internal space of the sludge floc is fully opened by controlling the carbon nitrogen ratio and the fermentation temperature, a large amount of bound water is changed into free water to meet the pulping requirement, and when the modified sludge is used for preparing the slurry fuel, the sludge mixing ratio is obviously improved.

Description

Technical Field

[0001] The invention belongs to the technical field of sludge treatment, and in particular relates to modified sludge and a preparation method thereof, and a slurry fuel. Background Art

[0002] With the rapid economic growth, urban development and expansion are also becoming more and more rapid. Coupled with the continuous improvement of people's living standards, municipal sludge has also begun to increase in large quantities, which has had a serious impact on people's daily lives. At present, sludge is mainly mixed with slurry fuel to make sludge-containing slurry fuel, which can be used for boiler and kiln combustion, and can also be used as gasification raw material. During combustion and gasification, through optimized configuration and reasonable operation, pollutant emissions can be effectively controlled, thereby realizing the clean utilization of sludge as energy.

[0003] When pulping is directly made from raw sludge, the viscosity of the slurry will increase sensitively due to the addition of sludge, and the pulp concentration will be significantly reduced, resulting in a low sludge blending amount, making it difficult to achieve large-scale resource utilization of sludge, and modification treatment is required. At present, the modification treatment of sludge mainly includes alkali treatment, heat treatment and ultrasonic treatment. After sludge modification, its pulping blending ratio is improved, but in order to ensure a pulping concentration of not less than 60%, the blending amount of modified sludge is generally not higher than 15% of the coal / coke mass. The sludge blending ratio is still at a low level, which is not conducive to large-scale sludge treatment.

[0004] Therefore, how to modify the sludge to increase the sludge blending ratio and realize large-scale resource-based clean utilization of sludge has become a technical problem that needs to be solved urgently in this field. Summary of the invention

[0005] The purpose of the present invention is to provide a modified sludge and a preparation method thereof, and a slurry fuel. The modified sludge prepared by the preparation method provided by the present invention has a higher blending ratio when used for pulping.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing modified sludge, comprising the following steps:

[0008] (1) mixing sludge with biomass to obtain a mixture; the carbon-nitrogen ratio of the mixture is 12.5 to 15.5;

[0009] (2) The mixture obtained in step (1) is mixed with a bacterial agent and fermented to obtain modified sludge; the fermentation temperature is 34-42°C.

[0010] Preferably, the moisture content of the sludge in step (1) is 60-90%.

[0011] Preferably, the biomass in step (1) is organic waste.

[0012] Preferably, the carbon-nitrogen ratio of the mixture in step (1) is 13-15.

[0013] Preferably, the mass of the bacterial agent in step (2) is 1 to 3% of the mass of the sludge in step (1).

[0014] Preferably, the fermentation temperature in step (2) is 35-41° C., and the fermentation time is 3-14 days.

[0015] The present invention also provides modified sludge prepared by the preparation method described in the above technical solution.

[0016] The present invention also provides a slurry fuel prepared from the modified sludge described in the above technical solution.

[0017] Preferably, the raw materials of the slurry fuel include modified sludge, petroleum coke powder, dispersant and water.

[0018] Preferably, the modified sludge accounts for 15-55% of the mass of the petroleum coke powder.

[0019] The present invention provides a method for preparing modified sludge, comprising the following steps: mixing sludge with biomass to obtain a mixture; the carbon-nitrogen ratio of the mixture is 12.5-15.5; mixing the mixture with a bacterial agent, fermenting, and obtaining modified sludge; the fermentation temperature is 34-42°C. The present invention utilizes a fermentation mechanism to break the sludge floc structure, and by controlling the carbon-nitrogen ratio and the fermentation temperature, the internal space of the sludge floc is fully opened, and a large amount of bound water is converted into free water to meet pulping. When the modified sludge is used to prepare slurry fuel, the sludge blending ratio is significantly improved. Experimental results show that when the modified sludge prepared by the preparation method provided by the present invention has a blending amount of 55% of the mass of petroleum coke powder, its slurry concentration can still be maintained at a level of 60wt%. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is the slurry concentration of the slurry fuel of Application Examples 1 to 4 and Comparative Application Examples 1 to 3;

[0021] Figure 2 is the slurry concentration of the slurry fuel of Application Examples 5 to 7 and Comparative Application Examples 4 to 6;

[0022] Figure 3 is the mass percentage of the modified sludge as petroleum coke powder in the slurry fuel of Application Examples 8 to 10 and Comparative Application Examples 7 to 9;

[0023] Figure 4 It is the moisture content of the modified sludge prepared in Examples 5 to 7 and Comparative Examples 5 to 6 and the original sludge in Comparative Example 4. DETAILED DESCRIPTION

[0024] The present invention provides a method for preparing modified sludge, comprising the following steps:

[0025] (1) mixing sludge with biomass to obtain a mixture; the carbon-nitrogen ratio of the mixture is 12.5 to 15.5;

[0026] (2) The mixture obtained in step (1) is mixed with a bacterial agent and fermented to obtain modified sludge; the fermentation temperature is 34-42°C.

[0027] The present invention has no particular limitation on the sources of the raw materials, and commercially available products known to those skilled in the art may be used.

[0028] The present invention mixes sludge with biomass to obtain a mixture.

[0029] In the present invention, the water content of the sludge is preferably 60-90%. As an embodiment, the water content of the sludge can be 70-87.52%, or 80-85%.

[0030] In the present invention, the sludge is preferably excess activated sludge or mechanically dewatered sludge produced in the process of treating urban sewage or industrial sewage. The present invention has no particular limitation on the source of the sludge, and any sludge well known to those skilled in the art can be used.

[0031] In the present invention, the biomass is preferably organic waste; the organic waste is preferably food residues and / or potato residues. The present invention has no particular limitation on the particle size of the biomass, and any biomass known to those skilled in the art can be used and can be evenly mixed with the sludge.

[0032] The present invention has no special limitation on the amount of the biomass, as long as the carbon-nitrogen ratio in the mixture meets the required requirements.

[0033] The present invention has no special limitation on the operation of mixing the sludge and the biomass, and the technical scheme for preparing the mixed material well known to those skilled in the art can be adopted.

[0034] In the present invention, the carbon-nitrogen ratio of the mixture is 12.5 to 15.5, preferably 13 to 15, and more preferably 14. The present invention can further improve the modification effect by limiting the carbon-nitrogen ratio of the mixture to the above range, thereby further improving the sludge blending ratio.

[0035] After obtaining the mixture, the present invention mixes the mixture with a bacterial agent and ferments it to obtain modified sludge.

[0036] In the present invention, the bacterial agent is preferably methanogens; the mass of the bacterial agent is preferably 1-3% of the mass of the sludge. As an embodiment, the mass of the bacterial agent can be 1.5-2% of the mass of the sludge. In the present invention, the methanogens are cheap and easy to obtain; by limiting the mass of the bacterial agent to the above range, the decomposition effect of the sludge flocs can be further optimized, which can not only greatly improve the sludge slurryability, but also obtain the gasification product biogas.

[0037] The present invention has no particular limitation on the operation of mixing the mixture with the bacterial agent, and the technical scheme for preparing the mixed material well known to those skilled in the art can be adopted.

[0038] In the present invention, the fermentation temperature is 34-42° C. As an embodiment, the fermentation temperature can be 35-41° C., and can also be 36° C., 37° C., 38° C., 39° C. or 40° C. The present invention limits the fermentation temperature within the above range, which can further open the internal space of the sludge flocs, thereby further improving the fermentation effect, thereby further improving the sludge blending ratio.

[0039] In the present invention, the fermentation time is preferably 3 to 14 days. As an embodiment, the fermentation time can be 4 days, 5 days, 6 days, 7 days, 8 days, 9 days, 10 days, 11 days, 12 days or 13 days. The present invention limits the fermentation time within the above range, which can further open the internal space of the sludge flocs, thereby further improving the fermentation effect, thereby further improving the sludge blending ratio.

[0040] In the present invention, the fermentation is preferably carried out under closed conditions. The present invention has no particular limitation on the operation of the closed conditions, and the operation well known to those skilled in the art can be adopted.

[0041] The present invention utilizes the fermentation mechanism to break down the sludge floc structure. By controlling the carbon-nitrogen ratio and the fermentation temperature, the internal space of the sludge floc is fully opened, and a large amount of bound water is converted into free water to meet the pulping requirements. When the modified sludge is used to prepare slurry fuel, the sludge blending ratio is significantly improved.

[0042] The closed fermentation mechanism in the preparation method provided by the present invention can not only break the floc structure of the sludge and turn the bound water in the sludge into free water, but also decompose a large number of oxygen-containing functional groups in the sludge, completely weakening the hydrophilicity of the sludge; the modified sludge is then mixed with petroleum coke powder, water and dispersant in a certain proportion to prepare sludge coke slurry, and the sludge mixing amount can be greatly increased compared with conventional sludge coke slurry. The present invention prepares sludge coke slurry by pre-treating the sludge through closed fermentation. The method is easy to implement and easy to operate, and can greatly increase the sludge mixing amount. It is an effective way to reduce, harmlessly treat and recycle sludge, and achieves the purpose of waste utilization and environmental protection, so that the slurry concentration of the final slurry fuel is 55-70wt%.

[0043] Sludge contains organic substances such as polysaccharides and proteins, but the carbon-nitrogen ratio (C / N) of sludge is small, generally not more than 10, which is not conducive to the fermentation and degradation of sludge flocs under the action of bacteria. The present invention mixes sludge and biomass according to a certain C / N ratio, and removes the limitation of sludge fermentation and degradation from the perspective of chemical reaction material supply. Sludge and biomass are mixed according to a certain C / N ratio, and then a certain amount of methanogens are added. At a certain fermentation concentration and fermentation temperature, the fermentation is closed for a certain time to obtain modified sludge. Sludge flocs are broken under the action of the fermentation mechanism, and the internal space of the flocs is fully opened. A large amount of bound water becomes free water to meet the needs of pulping, which can greatly save pulping water. During the fermentation process, the macromolecular substances (polysaccharides, proteins, fats, etc.) in the sludge flocs are gradually degraded into organic fragments and soluble small molecular substances, and the soluble small molecular organic matter is conducive to the dispersion and viscosity reduction of the multi-system. In addition, a large number of oxygen-containing functional groups (hydrophilic groups) in the sludge are decomposed under the action of the fermentation mechanism, which completely weakens the hydrophilicity of the sludge. Therefore, the modified sludge is mixed with petroleum coke, water and dispersant for pulping, the pulping performance is significantly improved, and the sludge blending ratio is greatly improved. Although the calorific value of the modified sludge is lower than that of the sludge, the biogas generated during the fermentation process is easy to collect and utilize, and will not cause energy loss. Therefore, the present invention can not only broaden the scope of pulping raw materials and accelerate the promotion and application of slurry fuel, but also greatly improve the blending ratio of sludge, and realize the large-scale treatment and resource utilization of municipal sludge; and the increase in the blending ratio of pulping sludge, on the one hand, can open up new ways for the large-scale clean utilization of sludge; on the other hand, the presence of alkali metals in the sludge is also beneficial to stimulate the gasification reaction activity of petroleum coke. As a gasification raw material, sludge coke slurry is conducive to providing a raw material basis for large-scale, efficient and clean coal gasification technology.

[0044] The present invention utilizes the fermentation mechanism to break the sludge floc structure, and optimizes the breaking effect of the sludge floc by controlling the C / N and fermentation temperature, which can not only greatly improve the sludge slurryability, but also obtain biogas, while greatly saving pulping water. The fermentation process is simple to operate and easy to implement. The biomass (food residues, potato residues) used is organic waste, and the methanogens used are cheap and easy to obtain. When using modified sludge to prepare slurry fuel, the pulping difficulty is low and the cost is low, which is conducive to industrial promotion and application.

[0045] Taking the preparation of sludge coke slurry with an apparent viscosity of 1000mPa·s and a solid mass concentration of 60% as an example, the blending amount of the modified sludge of the present invention (converted according to the sludge water content of 80%) can reach 55% of the mass of petroleum coke, which can save about 50% of industrial water. At this time, the calorific value of the sludge coke slurry is about 4490 kcal / kg (calculated based on the calorific value of petroleum coke of 8000 kcal / kg, the dry calorific value of fermented sludge of 2800 kcal / kg, and the sludge water content of 80%). For traditional sludge water coal / coke slurry with an apparent viscosity of 1000mPa·s and a solid mass concentration of 60%, even if the sludge is modified and improved by alkali treatment, heat treatment and ultrasonic treatment, the blending amount of wet sludge (converted according to the sludge water content of 80%) generally does not exceed 15% of the mass of coal / coke. It shows that the method provided by the present invention can improve the sludge blending ratio.

[0046] The present invention also provides modified sludge prepared by the preparation method described in the above technical solution.

[0047] The present invention also provides a slurry fuel prepared from the modified sludge described in the above technical solution.

[0048] In the present invention, the raw materials of the slurry fuel preferably include modified sludge, petroleum coke powder, dispersant and water.

[0049] The present invention has no particular limitation on the particle size of the petroleum coke powder, and petroleum coke powder well known to those skilled in the art may be used.

[0050] In the present invention, the modified sludge is preferably 15-55% of the mass of the petroleum coke powder. As an embodiment, the modified sludge can be 25%, 30%, 35%, 40%, 45%, 47%, 50% or 52% of the mass of the petroleum coke powder.

[0051] In the present invention, the dispersant is preferably 0.8-1.2% of the mass of the petroleum coke powder, more preferably 0.9%; the dispersant preferably includes at least one of sodium lignin sulfonate, sodium methylene naphthalene sulfonate-sodium styrene sulfonate-sodium maleate and sodium methylene bis naphthalene sulfonate.

[0052] The present invention has no special limitation on the amount of water used, and it can be adjusted according to actual needs (the apparent viscosity of the slurry fuel).

[0053] The present invention has no special limitation on the preparation method of the slurry fuel, as long as the raw materials are mixed evenly.

[0054] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] The bacterial agent in the embodiment is a commercially available methanogen; the selected sludge is mechanically dehydrated sludge (water content 87.52%) from a sewage treatment plant in Ningbo City, and the petroleum coke is from Sinopec Ningbo Zhenhai Refining and Chemical Co., Ltd. The characteristics of the sludge and petroleum coke are shown in Table 1; the samples sent for measuring the data in the following table must be dried samples to be measured: the sludge with a water content of 87.52% is air-dried in an oven at 60°C to constant weight (such as the test results show that its water content M ad It is 3.6%. Normal samples are dried at 100°C. Because the sludge contains a high content of volatile matter, a low-temperature drying temperature of 60°C is used). Petroleum coke is an air-dried sample and is sent directly.

[0056] Table 1 Industrial analysis and elemental analysis data of sludge and petroleum coke

[0057]

[0058] Example 1

[0059] The preparation method of modified sludge is as follows:

[0060] (1) mixing sludge with potato residue to obtain a mixture; the carbon-nitrogen ratio of the mixture is 15;

[0061] (2) The mixture obtained in step (1) is mixed with methanogens, and fermented at 35° C. for 7 days to obtain modified sludge; wherein the mass of the methanogens is 2% of the mass of the sludge.

[0062] Example 2

[0063] On the basis of Example 1, the fermentation temperature was changed to 37° C., and other conditions remained unchanged.

[0064] Example 3

[0065] On the basis of Example 1, the fermentation temperature was changed to 39° C., and other conditions remained unchanged.

[0066] Example 4

[0067] On the basis of Example 1, the fermentation temperature was changed to 41° C., and other conditions remained unchanged.

[0068] Comparative Example 1

[0069] On the basis of Example 1, the fermentation temperature was changed to 31° C., and other conditions remained unchanged.

[0070] Comparative Example 2

[0071] On the basis of Example 1, the fermentation temperature was changed to 33° C., and other conditions remained unchanged.

[0072] Comparative Example 3

[0073] On the basis of Example 1, the fermentation temperature was changed to 43° C., and other conditions remained unchanged.

[0074] Application Examples 1 to 4

[0075] The raw materials of the slurry fuel are modified sludge, petroleum coke powder, sodium lignin sulfonate and water; wherein, the modified sludge prepared in Examples 1 to 4 is 30wt% of the mass of the petroleum coke powder; the sodium lignin sulfonate is 0.9wt% of the mass of the petroleum coke powder; the amount of water is added according to the apparent viscosity of the slurry fuel; the apparent viscosity of the slurry fuel is 1000mPa·s (the apparent viscosity is measured by a rotational viscometer, the same below).

[0076] Comparative Application Examples 1 to 3

[0077] On the basis of Application Example 1, the modified sludge of Comparative Examples 1 to 3 was used, and other conditions remained unchanged.

[0078] The slurry concentrations of the slurry fuels of Application Examples 1 to 4 and Comparative Application Examples 1 to 3 are shown in Tables 2 and Figure 1 shown.

[0079] Table 2 Slurry concentration of slurry fuel of application examples 1 to 4 and comparative application examples 1 to 3

[0080] project Fermentation temperature (℃) Slurry concentration (wt%) Comparative application example 1 31 60.42 Comparative Application Example 2 33 62.31 Application Example 1 35 63.86 Application Example 2 37 64.75 Application Example 3 39 64.93 Application Example 4 41 63.94 Comparative Application Example 3 43 61.87

[0081] From Table 2 and Figure 1 It can be seen that at the same C / N ratio and the same amount of modified sludge (30%), the optimal fermentation temperature is 37-39°C.

[0082] Example 5

[0083] On the basis of Example 1, the fermentation temperature was changed to 38° C., and other conditions remained unchanged.

[0084] Example 6

[0085] On the basis of Example 5, the carbon-nitrogen ratio was changed to 13, while other conditions remained unchanged.

[0086] Example 7

[0087] On the basis of Example 5, the carbon-nitrogen ratio was changed to 14, while other conditions remained unchanged.

[0088] Comparative Example 4

[0089] Original sludge (carbon-nitrogen ratio is 8).

[0090] Comparative Example 5

[0091] On the basis of Example 5, the carbon-nitrogen ratio was changed to 12, while other conditions remained unchanged.

[0092] Comparative Example 6

[0093] On the basis of Example 5, the carbon-nitrogen ratio was changed to 16, while other conditions remained unchanged.

[0094] Application Examples 5 to 7

[0095] The raw materials of the slurry fuel are modified sludge, petroleum coke powder, sodium lignin sulfonate and water; wherein, the modified sludge prepared in Examples 5 to 7 is 15wt% of the mass of the petroleum coke powder; the sodium lignin sulfonate is 0.9wt% of the mass of the petroleum coke powder; the amount of water is added according to the apparent viscosity of the slurry fuel; the apparent viscosity of the slurry fuel is 1000mPa·s.

[0096] Comparative Application Examples 4 to 6

[0097] On the basis of Application Example 5, the sludge of Comparative Examples 4 to 6 was used, and other conditions remained unchanged.

[0098] The slurry concentrations of the slurry fuels of Application Examples 5 to 7 and Comparative Application Examples 4 to 6 are shown in Tables 3 and Figure 2 shown.

[0099] Table 3 Slurry concentration of slurry fuel of application examples 5 to 7 and comparative application examples 4 to 6

[0100] project Carbon Nitrogen Ratio Slurry concentration (wt%) Comparative Application Example 4 8 56.25 Comparative Application Example 5 12 65.67 Application Example 6 13 67.23 Application Example 7 14 68.41 Application Example 5 15 68.04 Comparative Application Example 6 16 67.10

[0101] From Table 3 and Figure 2 It can be seen that when the C / N ratio is 14, it can significantly increase the pulp concentration compared to 8, 12 and 16.

[0102] Application Example 8

[0103] The raw materials of the slurry fuel are modified sludge, petroleum coke powder, sodium lignin sulfonate and water; wherein, the modified sludge prepared in Example 6 is 47wt% of the mass of the petroleum coke powder; the sodium lignin sulfonate is 0.9wt% of the mass of the petroleum coke powder; and the water is 25.67wt% of the mass of the petroleum coke powder. The apparent viscosity of the slurry fuel is 1000mPa·s, and the slurry concentration is 60wt%.

[0104] Application Example 9

[0105] The raw materials of the slurry fuel are modified sludge, petroleum coke powder, sodium lignin sulfonate and water; wherein, the modified sludge prepared in Example 7 is 55wt% of the mass of the petroleum coke powder; the sodium lignin sulfonate is 0.9wt% of the mass of the petroleum coke powder; and the water is 29.65wt% of the mass of the petroleum coke powder. The apparent viscosity of the slurry fuel is 1000mPa·s, and the slurry concentration is 60wt%.

[0106] Application Example 10

[0107] The raw materials of the slurry fuel are modified sludge, petroleum coke powder, sodium lignin sulfonate and water; wherein, the modified sludge prepared in Example 5 is 52wt% of the mass of the petroleum coke powder; the sodium lignin sulfonate is 0.9wt% of the mass of the petroleum coke powder; and the water is 23.27wt% of the mass of the petroleum coke powder. The apparent viscosity of the slurry fuel is 1000mPa·s, and the slurry concentration is 60wt%.

[0108] Comparative Application Example 7

[0109] The raw materials of the slurry fuel are sludge, petroleum coke powder, sodium lignin sulfonate and water; wherein, the sludge in Comparative Example 4 is 10wt% of the mass of the petroleum coke powder; the sodium lignin sulfonate is 0.9wt% of the mass of the petroleum coke powder; and the water is 59.24wt% of the mass of the petroleum coke powder; the apparent viscosity of the slurry fuel is 1000mPa·s, and the slurry concentration is 60wt%.

[0110] Comparative Application Example 8

[0111] The raw materials of the slurry fuel are sludge, petroleum coke powder, sodium lignin sulfonate and water; wherein, the sludge prepared in Comparative Example 5 is 31wt% of the mass of the petroleum coke powder; the sodium lignin sulfonate is 0.9wt% of the mass of the petroleum coke powder; and the water is 42.45wt% of the mass of the petroleum coke powder; the apparent viscosity of the slurry fuel is 1000mPa·s, and the slurry concentration is 60wt%.

[0112] Comparative Application Example 9

[0113] The raw materials of the slurry fuel are modified sludge, petroleum coke powder, sodium lignin sulfonate and water; wherein, the modified sludge prepared in Comparative Example 6 is 45wt% of the mass of the petroleum coke powder; the sodium lignin sulfonate is 0.9wt% of the mass of the petroleum coke powder; and the water is 31.27wt% of the mass of the petroleum coke powder; the apparent viscosity of the slurry fuel is 1000mPa·s, and the slurry concentration is 60wt%.

[0114] The mass percentage content (i.e., blending ratio) of the modified sludge as petroleum coke powder in the slurry fuel of Application Examples 8 to 10 and Comparative Application Examples 7 to 9 is shown in Tables 4 and Figure 3 shown.

[0115] Table 4 Mass percentage of modified sludge in slurry fuel of application examples 8 to 10 and comparative application examples 7 to 9 in petroleum coke powder

[0116] project Carbon Nitrogen Ratio Mass percentage of modified sludge in petroleum coke powder Comparative Application Example 7 8 10 Comparative Application Example 8 12 31 Application Example 8 13 47 Application Example 9 14 55 Application Example 10 15 52 Comparative Application Example 9 16 45

[0117] From Table 4 and Figure 3 It can be seen that when the fermentation temperature is 38°C, the sludge char slurry with an apparent viscosity of 1000 mPa·s is prepared by fermentation sludge under different C / N, and the slurry concentration is controlled to be the same as 60wt%, the modified sludge of the present invention can significantly improve the sludge blending ratio.

[0118] The moisture content (mass percentage of bound water in air-dried sludge) of the modified sludge prepared in Examples 5 to 7 and Comparative Examples 5 to 6 and the original sludge of Comparative Example 4 are shown in Tables 5 and Figure 4 shown.

[0119] Table 5 Water content of modified sludge prepared in Examples 5 to 7 and Comparative Examples 5 to 6 and the original sludge of Comparative Example 4

[0120] project Carbon Nitrogen Ratio Moisture content% Comparative Example 4 8 87.52 Comparative Example 5 12 56.31 Example 6 13 49.42 Example 7 14 44.83 Example 5 15 46.17 Comparative Example 6 16 51.56

[0121] From Table 5 and Figure 4 It can be seen that the modified sludge of the present invention can significantly improve the dewatering performance of the sludge.

[0122] Comparative Application Example 10

[0123] Based on Application Example 7, the modified sludge is omitted, that is, the modified sludge is not added, and other conditions remain unchanged.

[0124] Application Example 11

[0125] The raw materials of the slurry fuel are modified sludge, petroleum coke powder, sodium lignin sulfonate and water; wherein, the modified sludge prepared in Example 7 is 25wt% of the mass of the petroleum coke powder; the sodium lignin sulfonate is 0.9wt% of the mass of the petroleum coke powder; the amount of water is added according to the apparent viscosity of the slurry fuel; the apparent viscosity of the slurry fuel is 1000mPa·s.

[0126] Application Example 12

[0127] The raw materials of the slurry fuel are modified sludge, petroleum coke powder, sodium lignin sulfonate and water; wherein, the modified sludge prepared in Example 7 is 35wt% of the mass of the petroleum coke powder; the sodium lignin sulfonate is 0.9wt% of the mass of the petroleum coke powder; the amount of water is added according to the apparent viscosity of the slurry fuel; the apparent viscosity of the slurry fuel is 1000mPa·s.

[0128] Application Example 13

[0129] The raw materials of the slurry fuel are modified sludge, petroleum coke powder, sodium lignin sulfonate and water; wherein, the modified sludge prepared in Example 7 is 45wt% of the mass of the petroleum coke powder; the sodium lignin sulfonate is 0.9wt% of the mass of the petroleum coke powder; the amount of water is added according to the apparent viscosity of the slurry fuel; the apparent viscosity of the slurry fuel is 1000mPa·s.

[0130] Application Example 14

[0131] The raw materials of the slurry fuel are modified sludge, petroleum coke powder, sodium lignin sulfonate and water; wherein, the modified sludge prepared in Example 7 is 55wt% of the mass of the petroleum coke powder; the sodium lignin sulfonate is 0.9wt% of the mass of the petroleum coke powder; the amount of water is added according to the apparent viscosity of the slurry fuel; the apparent viscosity of the slurry fuel is 1000mPa·s.

[0132] The slurry concentration (solid phase mass concentration) of the slurry fuels of Examples 7, 11 to 14 and Comparative Application Examples 4 and 10 was measured, and the results are shown in Table 6.

[0133] Table 6 Slurry concentration of slurry fuel of application examples 7, 11 to 14 and comparative application examples 4 and 10

[0134] project Sludge blending amount wt% Pulp concentration wt% Comparative Application Example 10 0％ 70.63 Comparative Application Example 4 15% (original sludge) 56.25 Application Example 7 15％ 68.41 Application Example 11 25％ 67.39 Application Example 12 35％ 65.85 Application Example 13 45％ 63.74 Application Example 14 55％ 60.13

[0135] As can be seen from Table 6, the slurry concentration of the slurry fuel prepared from pure petroleum coke powder (i.e., comparative application example 10) can reach more than 70%. The addition of sludge will reduce the slurry concentration, especially when the original sludge is directly added. When the original sludge is only 15% of the mass of the petroleum coke powder, the slurry concentration quickly drops to below 60wt%. However, the slurryability of the modified sludge is significantly improved. As the amount of modified sludge increases, the slurry concentration slowly decreases. When the amount of modified sludge is 55% of the mass of the petroleum coke powder, its slurry concentration can still be maintained at 60wt%.

[0136] It can be seen from the above embodiments and comparative examples that the modified sludge prepared by the preparation method provided by the present invention has a higher blending ratio when used for pulping.

[0137] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing modified sludge, comprising the following steps: (1) mixing sludge with biomass to obtain a mixture; the carbon-nitrogen ratio of the mixture is 12.5 to 15.5; (2) The mixture obtained in step (1) is mixed with a bacterial agent and fermented to obtain modified sludge; the fermentation temperature is 34-42°C.

2. The preparation method according to claim 1, characterized in that: The moisture content of the sludge in step (1) is 60-90%.

3. The preparation method according to claim 1, characterized in that: The biomass in step (1) is organic waste.

4. The preparation method according to claim 1, characterized in that: The carbon-nitrogen ratio of the mixture in step (1) is 13-15.

5. The preparation method according to claim 1, characterized in that: The mass of the bacterial agent in step (2) is 1 to 3% of the mass of the sludge in step (1).

6. The preparation method according to claim 1, characterized in that: In step (2), the fermentation temperature is 35-41° C. and the fermentation time is 3-14 days.

7. The modified sludge prepared by the preparation method according to any one of claims 1 to 6.

8. A slurry fuel prepared from the modified sludge according to claim 7.

9. The slurry fuel according to claim 8, characterized in that: The raw materials of the slurry fuel include modified sludge, petroleum coke powder, dispersant and water.

10. The slurry fuel according to claim 9, characterized in that: The modified sludge accounts for 15-55% of the mass of the petroleum coke powder.

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