Preparation of bacterial cellulose-based grafting modified sludge conditioning dewatering agent and method of use

Abstract

The present application provides a method for preparing and using a bacterial cellulose-based graft-modified sludge conditioning dewatering agent. The method for preparing the sludge conditioning dewatering agent comprises the following steps: Step 1: mixing urea, guanidine and tannic acid and heating to 30-50℃; Step 2: adding bacterial cellulose and heating to 70-90℃ for reaction until the reaction is completed; Step 3: cooling to obtain a crude sludge conditioning dewatering agent; Step 4: drying the obtained crude sludge conditioning dewatering agent to obtain the final sludge conditioning dewatering agent. The method for using the sludge conditioning agent to condition sludge comprises: Step a: providing municipal sewage treatment plant sludge, urea peroxide and the sludge conditioning agent; Step b: adding urea peroxide to the sludge, then adding the sludge conditioning agent and stirring uniformly, and then standing; Step c: filtering the product obtained by Step b.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of environmental engineering, and relates to a preparation method of a bacterial cellulose-based grafted modified sludge conditioning dewatering agent, and a method for conditioning and dewatering sludge by using the dewatering agent, thereby improving the dewatering performance of the sludge, promoting the release of water in the sludge filter pressing process, and finally realizing deep dewatering of the sludge (moisture content of sludge cake < 60%). BACKGROUND

[0002] The residual sludge generated by a municipal sewage treatment plant has complex components, contains a large amount of harmful components such as parasitic eggs, pathogenic bacteria, organic residues, heavy metals, and is prone to putrefaction and odor, which leads to a decrease in environmental quality and potential harm to people's life and health. Sludge reduction and harmless treatment is an important problem and major challenge currently faced by sewage treatment plants.

[0003] The organic matter content in sludge is as high as 50-80%, mainly including biological polymers such as polysaccharides, proteins, humic acid and nucleic acid. These organic matters carry negative charges and maintain the stability of biological colloids through electrostatic repulsion. Due to the presence of highly hydrophilic chemical groups, a large amount of water is bound in the network structure of sludge colloids. The particle size of sludge particles is very small, generally with a median particle size (D50) of 30-60 μm, which leads to a very large specific surface area of the sludge and a high water adsorption capacity. These factors promote the high compressibility of the sludge and the high specific resistance of the sludge, and the dewatering performance of the sludge is poor. At present, the methods of coagulation / flocculation + mechanical dewatering are commonly used to remove part of the water in the sludge, but the moisture content of the final dewatered sludge cake is still as high as 75-85%, which is difficult to meet the requirements of the relevant national standards for moisture content in subsequent sludge landfill, composting, land use, etc. Therefore, in order to improve the removal effect of bound water in the sludge, various dewatering agents are studied in the field. For example, urea-modified dicyandiamide-aldehyde is a relatively novel sludge dewatering agent, but its effect on extracellular proteins is too weak, and extracellular proteins are one of the main organic matters that cause the deterioration of sludge dewatering performance, so the dewatering rate of the conditioned sludge is still not satisfactory.

[0004] Therefore, it is urgent to develop a new type of sludge conditioning dewatering agent to enhance the reduction of extracellular proteins in the sludge and further improve the dewatering rate of the sludge. At the same time, the rationality of the selection of the agent should also be considered to promote the resource recycling of the sludge dewatering cake. SUMMARY

[0005] In order to improve the dewatering performance of sludge and promote the resource recycling of sludge, the inventors have conducted in-depth and extensive research. The inventors have unexpectedly found that when bacterial cellulose is grafted and modified with urea, guanidine and tannic acid, the resulting product can significantly reduce the content of extracellular protein in sludge, greatly improve the dewatering performance of sludge, and at the same time, without adding any inorganic medicament, has less impact on the calorific value of sludge, and reduces the environmental risk of dewatered sludge cake.

[0006] Based on this, the present application provides a preparation method and use method of bacterial cellulose-based grafted and modified sludge conditioning dewatering agent.

[0007] In a first aspect, a method for preparing a sludge conditioning dewatering agent is provided, the method comprising the following steps:

[0008] Step 1: mixing urea, guanidine and tannic acid and heating to 30-50°C;

[0009] Step 2: adding bacterial cellulose and dialdehyde and heating to 70-90°C for reaction until completion;

[0010] Step 3: cooling to obtain a crude sludge conditioning dewatering agent;

[0011] Step 4: drying the obtained crude sludge conditioning dewatering agent to obtain the final sludge conditioning dewatering agent.

[0012] In one embodiment of the first aspect, the mass percentages of urea, guanidine, tannic acid, bacterial cellulose and dialdehyde are 3-10%, 15-25%, 10-15%, 20-30% and 25-40%, respectively.

[0013] In one embodiment of the first aspect, the guanidine can be selected from any one of the following: polyhexamethylene guanidine, dicyandiamide (i.e., cyanoguanidine), metformin, chlorphenesin, and dodecaquinoic acid.

[0014] In one embodiment of the first aspect, the guanidine can be polyhexamethylene guanidine, and the mass percentages of urea, polyhexamethylene guanidine, tannic acid, bacterial cellulose and dialdehyde are 3-10%, 15-25%, 10-15%, 20-30% and 25-40%, respectively; preferably 3-7%, 20-25%, 10-13%, 25-30% and 35-40%, respectively; more preferably 4%, 21%, 12%, 27%, and 36%, respectively.

[0015] In one embodiment of the first aspect, the guanidine can be dicyandiamide, and the mass percentage of urea, dicyandiamide, tannin, bacterial cellulose, dialdehyde is 3-10%, 15-25%, 10-15%, 20-30%, 25-40%; preferably 4-8%, 17-22%, 12-15%, 22-28%, 30-38%; more preferably 6%, 19%, 14%, 26%, 35%.

[0016] In one embodiment of the first aspect, the dialdehyde can be selected from any one of the following: glutaraldehyde, glyoxal and p-xylylene dialdehyde.

[0017] In one embodiment of the first aspect, the dialdehyde can be glutaraldehyde, and the mass percentage of urea, guanidine, tannin, bacterial cellulose, glutaraldehyde is 3-10%, 15-25%, 10-15%, 20-30%, 25-40% respectively; preferably 3-8%, 17-25%, 10-15%, 22-28%, 28-40%; more preferably 4-6%, 19-21%, 12-14%, 26-27%, 35-36%.

[0018] In one embodiment of the first aspect, the dialdehyde can be glyoxal, and the mass percentage of urea, guanidine, tannin, bacterial cellulose, glyoxal is 3-10%, 15-25%, 10-15%, 20-30%, 25-40% respectively; preferably 3-8%, 17-25%, 10-15%, 22-28%, 28-40%; more preferably 4-6%, 19-21%, 12-14%, 26-27%, 32-34%.

[0019] In one embodiment of the first aspect, the reaction temperature in step 1 can be 35-45°C.

[0020] In one embodiment of the first aspect, the reaction temperature in step 2 can be 75-85°C.

[0021] In one embodiment of the first aspect, the drying of step 4 comprises freeze-drying, room temperature drying, high temperature drying or a combination thereof, preferably freeze-drying.

[0022] In the second aspect, the present application provides a method for conditioning sludge using the sludge conditioner prepared by the method of the first aspect, the method comprising:

[0023] Step a: providing municipal sewage treatment plant sludge, urea peroxide and the sludge conditioner;

[0024] Step b: adding urea peroxide to the sludge, then adding the sludge conditioner and stirring uniformly, and then standing;

[0025] Step c: filtration of the product obtained by step b.

[0026] In one embodiment of the second aspect, the amount of sludge conditioner is 10-300 mg / g TS, preferably 75-250 mg / g TS, more preferably 100-200 mg / g TS, based on the weight of the sludge, wherein TS denotes the dry basis mass of the sludge.

[0027] In one embodiment of the second aspect, 20-100 mg / g TS of urea peroxide is added to the sludge. DETAILED DESCRIPTION

[0028] "RANGES" disclosed herein are expressed in the form of a lower limit and an upper limit. There can be one or more lower limits, and one or more upper limits, respectively. A given range is defined by selecting a lower limit and an upper limit. The selected lower limit and upper limit define the boundaries of a particular range. All ranges that can be defined in this manner are inclusive of the end values and are combinable with one another, i.e., any lower limit can be combined with any upper limit to form a range. For example, where ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if a minimum range value of 1 and 2 are listed, and a maximum range value of 3, 4, and 5 are listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5.

[0029] In the present application, unless otherwise stated, a numerical range "a-b" indicates a shorthand way of describing each and every intervening real number between the upper and lower bounds of that range, wherein a and b are both real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed herein, and "0-5" is merely a shorthand way of describing those numerical combinations.

[0030] In the present application, "above" or "below" a number includes the number. For example, "below 5" means less than or equal to 5, and "above 7" means greater than or equal to 7.

[0031] In the present application, all embodiments and preferred embodiments mentioned herein can be combined with each other to form new technical solutions, if not specifically stated otherwise.

[0032] In the present application, all technical features and preferred features mentioned herein can be combined with each other to form new technical solutions, if not specifically stated otherwise.

[0033] In the present application, if there is no special description, all the steps mentioned in the present application can be carried out in sequence or randomly, but preferably in sequence. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method mentioned herein can also comprise step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0034] In the present application, if there is no special description, "including" mentioned in the present application means open, but also closed. For example, "including" can mean that it can also contain other components not listed, or only include the listed components.

[0035] The above expression is also a common expression in the art. It is emphasized here that the following description is only some specific embodiments of the present application, and the protection scope of the present application is not limited to these specific embodiments. The protection scope of the present application is defined by the claims of the present application, which can include any technical means within the scope of the claims, including but not limited to further improvements and alternatives to these specific embodiments.

[0036] Now the method of the present application will be described in detail.

[0037] Bacterial cellulose is a known cellulose, which is increasingly used in various fields, such as medicine, food, papermaking, weaving and dyeing, etc., due to its unique textile structure. In the field of sludge engineering, although the prior art has tried to replace other cellulose with bacterial cellulose as a sludge conditioning dewatering agent, the dewatering effect is still not satisfactory. The inventors of the present application found that when the bacterial cellulose is grafted and modified, and reacted with urea, guanidine and tannic acid, the modified polymer obtained can significantly improve the dewatering efficiency of sludge.

[0038] Therefore, in a first aspect, a method for preparing a sludge conditioning dewatering agent is provided, which comprises the following steps 1-3.

[0039] Step 1 : Urea, guanidines, tannic acid are mixed and heated to 30-50°C.

[0040] In this step, urea, guanidine and tannic acid are provided, mixed and heated to 30-50°C.

[0041] In some embodiments, the mass percentage of urea, guanidine and tannic acid can be 3-10%, 15-25% and 10-15%, respectively, for example, 4%, 21% and 12%.

[0042] In some embodiments, the guanidine can be selected from any one of the following: polyhexamethylene guanidine, dicyandiamide, metformin, chlorhexidine, dodecaquinium acetate.

[0043] In some embodiments, the reaction temperature of step 1 can be, for example, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C, or within a range having any two of these values as endpoints.

[0044] In some embodiments, the guanidine can be polyhexamethylene guanidine, and the weight ratio of urea, polyhexamethylene guanidine, tannic acid is 3-10%, 15-25%, 10-15%; preferably 3-7%, 20-25%, 10-13%; more preferably 4%, 21%, 12%.

[0045] In some embodiments, the guanidine can be dicyandiamide, and the mass percentage of urea, dicyandiamide, tannic acid is 3-10%, 15-25%, 10-15%, preferably 4-8%, 17-22%, 12-15%, more preferably 6%, 19%, 14%.

[0046] In some embodiments, the time of step 1 can be about 1-2 hours, for example, 1.5 hours, depending on the amount of urea, guanidine, and tannic acid.

[0047] Step 2: Bacterial cellulose, dialdehyde are added and the temperature is raised to 70-90°C for the reaction to be carried out until completion of the reaction.

[0048] After step 1, bacterial cellulose, a dialdehyde is added to the resulting product, and the temperature is raised to 70-90°C to continue the reaction.

[0049] In some embodiments, the reaction temperature of step 2 can be 75-85°C, for example, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C, or within a range having any two of these values as endpoints.

[0050] In some embodiments, the mass percentage of urea, guanidine, tannic acid, bacterial cellulose, dialdehyde is 3-10%, 15-25%, 10-15%, 20-30%, 25-40%.

[0051] For example, when the guanidine is polyhexamethylene guanidine, the mass percentages of urea, polyhexamethylene guanidine, tannin, bacterial cellulose, dialdehyde are 3-10%, 15-25%, 10-15%, 20-30%, 25-40%, preferably 3-7%, 20-25%, 10-13%, 25-30%, 35-40%, more preferably 4%, 21%, 12%, 27%, 36%. For another example, when the guanidine is dicyandiamide, the mass percentages of urea, dicyandiamide, tannin, bacterial cellulose, dialdehyde are 3-10%, 15-25%, 10-15%, 20-30%, 25-40%, preferably 4-8%, 17-22%, 12-15%, 22-28%, 30-38%, more preferably 6%, 19%, 14%, 26%, 35%.

[0052] In some embodiments, the dialdehyde is selected from any one of the following: glutaraldehyde, glyoxal, and p-xylylene dialdehyde.

[0053] For example, in some embodiments, the dialdehyde is glutaraldehyde, and the mass percentages of urea, guanidine, tannin, bacterial cellulose, glutaraldehyde are 3-10%, 15-25%, 10-15%, 20-30%, 25-40%, respectively; preferably 3-8%, 17-25%, 10-15%, 22-28%, 28-40%; more preferably 4-6%, 19-21%, 12-14%, 26-27%, 35-36%. For another example, in some embodiments, the dialdehyde is glyoxal, and the mass percentages of urea, guanidine, tannin, bacterial cellulose, glyoxal are 3-10%, 15-25%, 10-15%, 20-30%, 25-40%, respectively; preferably 3-8%, 17-25%, 10-15%, 22-28%, 28-40%; more preferably 4-6%, 19-21%, 12-14%, 26-27%, 32-34%.

[0054] In some embodiments, the time of step 2 can be about 1-4 hours, for example, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, or within a range with any two of these values as endpoints, depending on the amounts of urea, guanidine, tannin, bacterial cellulose.

[0055] Step 3: Cooling to obtain crude sludge conditioning dewatering agent

[0056] After step 2, the reacted mixture is cooled to below 38°C to obtain the crude dehydrating agent. Depending on the starting materials used, the obtained dehydrating agent can be a viscous liquid or a solid.

[0057] Step 4: Drying of the crude sludge conditioning dewatering agent obtained to obtain the final sludge conditioning dewatering agent.

[0058] The drying is, for example, freeze-drying, ambient temperature drying, high temperature drying, or a combination thereof. Preferably, the drying is freeze-drying.

[0059] In a second aspect, the present application provides a method of conditioning sludge using the sludge conditioner prepared by the method of the first aspect, the method comprising the following steps a-c.

[0060] Step a: Providing municipal sewage treatment plant sludge and the sludge conditioning agent

[0061] The present application does not limit the source of the sludge, for example, the sludge can be derived from industrial wastewater or domestic sewage treatment.

[0062] Step b: Adding the sludge conditioning agent to the sludge and stirring uniformly, followed by resting

[0063] In some embodiments, the amount of the sludge conditioner is 10-300 mg / g TS, preferably 75-250 mg / g TS, more preferably 100-200 mg / g TS, based on the weight of the sludge.

[0064] In some embodiments, the sludge conditioner can be added directly to the sludge.

[0065] In other embodiments, the sludge can be pretreated before the addition of the sludge conditioner. For example, a peroxide can be added to the sludge and allowed to react for an appropriate time to serve a sterilization or the like. The sludge conditioner is then added and stirred to react. In some embodiments, the peroxide is selected from any one or more of urea peroxide, hydrogen peroxide, or peracetic acid. Preferably, the peroxide is urea peroxide. In some embodiments, the amount of the peroxide added is about 20-100 mg / g TS, for example, 40-100 mg / g TS, 50-80 mg / g TS, or 60-80 mg / g TS, based on the weight of the sludge. For example, the amount of urea peroxide added is 20-100 mg / g, for example, 40-100 mg / g TS, 50-80 mg / g TS, or 60-80 mg / g TS, based on the weight of the sludge.

[0066] Step c: Filtering the product obtained by step b.

[0067] The filtration can be performed by normal pressure filtration, pressure filtration, or reduced pressure filtration. In one embodiment, the filtration is normal pressure filtration. In another embodiment, the filtration is pressure filtration. In another embodiment, the filtration is reduced pressure filtration.

[0068] In embodiments, the filtration is performed by passing the product from step c through a sieve having a mesh size of 100-800, for example, a sieve having a mesh size of 200, 400.

[0069] By the sludge conditioning method of the present application, the moisture content of the filtered sludge can be significantly reduced, for example, its moisture content can be as low as 50-65%, which is significantly lower than the moisture content of 75-80% that can be achieved in the art.

[0070] Optionally, after step c is completed, the filter residue can also be dried. Those skilled in the art know that this drying can be carried out at low temperature, room temperature or high temperature.

[0071] Compared with the prior art, the present application has the following beneficial effects:

[0072] (1) Using bacteria cellulose grafted with urea, guanidine and tannin as a sludge conditioning glue agent, the moisture content of the dewatered sludge is significantly reduced. Without being bound by theory, it is believed that this is because the amino groups and guanidine groups contained in urea and guanidine (such as polyhexamethylene guanidine) help to electrically neutralize the negatively charged colloidal particles, while urea can promote the denaturation of proteins in the sludge, and its amino groups are conducive to the formation of hydrogen bonds between the conditioning agent and the biological organic matter in the sludge, and the guanidine groups are easy to combine with the carboxyl groups on the amino acids of proteins, thereby improving the adsorption effect; tannin can form a stable complex with protein substances in the sludge through hydrogen bonding and hydrophobic bonding; after crosslinking and grafting, a high-molecular long-chain organic polymer is formed, which is conducive to the bridging, trapping and sweeping effect, while bacteria cellulose can be used as a sludge skeleton building block to improve the rigid structure of the sludge, reduce the compression performance, and promote the continuous release of water during the sludge pressure filtration process.

[0073] (2) When using urea peroxide, it has strong sterilization power, broad spectrum, low use concentration, no secondary pollution, etc., can efficiently oxidize and break down the sludge cells, release and degrade biological polymers such as proteins and polysaccharides, and the urea component of urea peroxide will promote the denaturation and precipitation of proteins, reducing the content of hydrophilic organic matter in the sludge.

[0074] (3) Using bacteria cellulose as a raw material to build a rigid structure for the sludge, the prepared dewatering agent has multiple effects such as electrostatic effect, electric neutralization, hydrophobic combination, bridging, trapping and sweeping to reduce the content of extracellular organic matter in the sludge.

[0075] (4) Avoiding the use of formaldehyde crosslinking agent commonly used in the art reduces the harm to the environment.

[0076] Embodiments

[0077] The present application will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present application, but do not limit the present application in any form. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present application. These all belong to the protection scope of the present application.

[0078] In the following examples, sludge was taken from Shanghai Qingpu Sewage Treatment Plant, which has a water content of >99%, and after gravity settling for 24-48 hours, the water content of the sludge was reduced to 97%, with a tolerance of 0.5%, and the sludge after gravity settling was used for conditioning. After conditioning, the sludge was subjected to pressure filtration using a plate and frame filter press, with a pressure of 1 MPa and a pressure filtration time of 30 minutes.

[0079] Example 1 : Conditioning of sludge using bacterial cellulose modified with urea, polyhexamethylene guanidine, tannic acid Example 2: Preparation of bacterial cellulose sludge conditioning dewatering agent modified with urea, dicyandiamide, tannic acid.

[0080] The urea, polyhexamethylene guanidine, tannic acid shown in Table 1 below were weighed, mixed and heated to temperature T1 (40°C) in Table 1 for time t1 (1.5 hours), then the amount of bacterial cellulose shown in Table 1 was added, followed by heating to temperature T2 (80°C) for time t2 (1.5 hours), and then cooling to below 38°C to obtain a viscous liquid. The solid powder was obtained by freeze-drying at -75°C. 4.5 g of the solid powder was added to 1 L of sludge (water content of 97%, TS content of 30) for conditioning for 3 minutes. The above product was subjected to pressure filtration using a plate and frame filter press, thereby obtaining a dewatered cake. The water content of the cake was calculated according to the gravimetric method (CJ / T 221).

[0081] Table 1

[0082]

[0083] Comparative Example 1 : Using bacterial cellulose as sludge conditioning dewatering agent

[0084] The urea, dicyandiamide, tannic acid shown in Table 2 below were weighed, mixed and heated to temperature T1 (40°C) in Table 2 for time t1 (1 hour), then the amount of bacterial cellulose shown in Table 2 was added, followed by heating to temperature T2 (82°C) for time t2 (2.5 hours), and then cooling to below 38°C to obtain a viscous liquid. The solid powder was obtained by freeze-drying at -75°C.

[0085] Table 2

[0086]

[0087] dicyandiamide, and the mass percentages of urea, dicyandiamide, tannic acid, bacterial cellulose, dialdehyde are 3-10%, 15-25%, 10-15%, 20-30%, 25-40%; preferably 4-8%, 17-22%, 12-15%, 22-28%, 30-38%; more preferably 6%, 19%, 14%, 26%, 35%.

[0088] Example 3: Pretreatment of sludge using peroxide

[0089] The above Example 1A was repeated except that the peroxide in Table 3 below was added to the sludge and reacted for a time t3 before the sludge conditioning dewatering agent was added to the sludge.

[0090]

[0091]

[0092] As can be seen from the above table, the water content was further reduced when the peroxide was added, especially when urea hydrogen peroxide was used, the water content was reduced to 55.2%.

[0093] Comparative Example 2: Using modified carboxymethyl cellulose as sludge conditioning dewatering agent

[0094] Example 1A was repeated except that 13 g of bacterial cellulose was used instead of the bacterial cellulose modified with urea, polyhexamethylene guanidine, tannic acid to condition the sludge. The conditioned cake had a water content of 75.4%.

[0095] Step 1 : Urea, guanidines, tannic acid are mixed and heated to 30-50°C. Step 2: Bacterial cellulose, dialdehyde are added and the temperature is raised to 70-90°C for the reaction to be carried out until completion of the reaction. Step 3: Cooling to obtain crude sludge conditioning dewatering agent Step 4: Drying of the crude sludge conditioning dewatering agent obtained to obtain the final sludge conditioning dewatering agent. Step a: Providing municipal sewage treatment plant sludge and the sludge conditioning agent Step b: Adding the sludge conditioning agent to the sludge and stirring uniformly, followed by resting Step c: Filtering the product obtained by step b. Example 1 : Conditioning of sludge using bacterial cellulose modified with urea, polyhexamethylene guanidine, tannic acid Example 2: Preparation of bacterial cellulose sludge conditioning dewatering agent modified with urea, dicyandiamide, tannic acid. Comparative Example 1 : Using bacterial cellulose as sludge conditioning dewatering agent Comparative Example 2: Using modified carboxymethyl cellulose as sludge conditioning dewatering agent

[0096] Example 1A was repeated except that 13 g of carboxymethyl cellulose was used instead of the bacterial cellulose to condition the sludge. The conditioned cake had a water content of 65.7%.

[0097] As can be seen from the above examples and comparative examples, the water content of the sludge was significantly reduced when the bacterial cellulose modified with urea, guanidine, tannic acid was used to condition the sludge compared to using bacterial cellulose alone or carboxymethyl cellulose modified in a similar manner, which demonstrates that the bacterial cellulose modified with urea, guanidine, tannic acid has improved dewatering properties.

[0098] The water content can be further reduced by pretreating the sludge with a peroxide, especially urea hydrogen peroxide, prior to using the sludge conditioning dewatering agent of the present application.

[0099] Low water contents were obtained when the mass percentages of urea, guanidine, tannic acid, bacterial cellulose, glutaraldehyde were 3-10%, 15-25%, 10-15%, 20-30%, 25-40%, respectively. Especially when the guanidine was polyhexamethylene guanidine, the mass percentages of urea, polyhexamethylene guanidine, tannic acid, bacterial cellulose, glutaraldehyde were 4%, 21%, 12%, 27%, 36%, respectively, the water content was only 56.7%; when the guanidine was dicyandiamide, the mass percentages of urea, dicyandiamide, tannic acid, bacterial cellulose, glutaraldehyde were 6%, 19%, 14%, 26%, 35%, respectively, the water content was only 56.8%.

[0100] While the claimed subject matter has been described in terms of various embodiments / implementations, those skilled in the art will recognize that the claimed subject matter can be practiced with modifications / modifications, substitutions, omissions, and alterations / changes within the scope of the invention. Accordingly, it is intended that the scope of the claimed subject matter be limited by the scope of the claims and equivalents thereof.

[0101] The specific embodiments of the present application have been described. It is to be understood that the application is not limited to the specific devices, methods, and / or parameters described and as such can be practiced with modifications and changes within the scope of the appended claims including providing equivalents. Embodiments of the present application and features of embodiments of the present application can be any one of the following, in any combination:

Claims

1. A method for preparing a bacterial cellulose-based sludge conditioner and dewatering agent, the method comprising the following steps: Step 1: Mix urea, guanidines, and tannic acid and heat to 30-50℃; Step 2: Add bacterial cellulose and dialdehyde and heat to 70-90℃ to react until the reaction is complete; Step 3: Cool to obtain crude sludge conditioner and dewatering agent; Step 4: Dry the obtained crude sludge conditioner and dewatering agent to obtain the final sludge conditioner and dewatering agent. in, The mass percentages of urea, guanidines, tannic acid, bacterial cellulose, and dialdehyde are 3-10%, 15-25%, 10-15%, 20-30%, and 25-40%, respectively. The guanidines are selected from any one of the following: polyhexamethylene guanidine, dicyandiamide, metformin, chlorophenoxyguanidine hexane, and dodecaguanidine acetate.

2. The method as described in claim 1, wherein, The guanidine is polyhexamethylene guanidine, and the mass percentages of urea, polyhexamethylene guanidine, tannic acid, bacterial cellulose, and dialdehyde are 3-10%, 15-25%, 10-15%, 20-30%, and 25-40%, respectively.

3. The method as described in claim 2, wherein, The mass percentages of urea, polyhexamethylene guanidine, tannic acid, bacterial cellulose, and dialdehyde are 3-7%, 20-25%, 10-13%, 25-30%, and 35-40%, respectively.

4. The method of claim 2, wherein, The mass percentages of urea, polyhexamethylene guanidine, tannic acid, bacterial cellulose, and dialdehyde were 4%, 21%, 12%, 27%, and 36%, respectively.

5. The method of claim 1, wherein, The guanidine is dicyandiamide, and the mass percentages of urea, dicyandiamide, tannic acid, bacterial cellulose, and dialdehyde are 3-10%, 15-25%, 10-15%, 20-30%, and 25-40%, respectively.

6. The method of claim 5, wherein, The mass percentages of urea, dicyandiamide, tannic acid, bacterial cellulose, and dialdehyde are 4-8%, 17-22%, 12-15%, 22-28%, and 30-38%, respectively.

7. The method of claim 5, wherein, The mass percentages of urea, dicyandiamide, tannic acid, bacterial cellulose, and dialdehyde were 6%, 19%, 14%, 26%, and 35%, respectively.

8. The method according to any one of claims 1-7, wherein, The dialdehyde is selected from any one of the following: glutaraldehyde, glyoxal, and terephthalaldehyde.

9. The method according to any one of claims 1-7, wherein, The dialdehyde is glutaraldehyde, and the mass percentages of urea, guanidines, tannic acid, bacterial cellulose, and glutaraldehyde are 3-10%, 15-25%, 10-15%, 20-30%, and 25-40%, respectively.

10. The method of claim 9, wherein, The mass percentages of urea, guanidines, tannic acid, bacterial cellulose, and glutaraldehyde are 3-8%, 17-25%, 10-15%, 22-28%, and 28-40%, respectively.

11. The method of claim 9, wherein, The mass percentages of urea, guanidines, tannic acid, bacterial cellulose, and glutaraldehyde are 4-6%, 19-21%, 12-14%, 26-27%, and 35-36%, respectively.

12. The method according to any one of claims 1-7, wherein, The dialdehyde is glyoxal, and the mass percentages of urea, guanidines, tannic acid, bacterial cellulose, and glyoxal are 3-10%, 15-25%, 10-15%, 20-30%, and 25-40%, respectively.

13. The method of claim 12, wherein, The mass percentages of urea, guanidines, tannic acid, bacterial cellulose, and glyoxal are 3-8%, 17-25%, 10-15%, 22-28%, and 28-40%, respectively.

14. The method of claim 12, wherein, The mass percentages of urea, guanidines, tannic acid, bacterial cellulose, and glyoxal are 4-6%, 19-21%, 12-14%, 26-27%, and 32-34%, respectively.

15. The method of claim 1, wherein, The reaction temperature in step 1 is 35-45℃.

16. The method of claim 1, wherein, The reaction temperature in step 2 is 75-85℃.

17. The method of claim 1, wherein, The drying process in step 4 includes freeze drying, room temperature drying, high temperature drying, or a combination thereof.

18. The method of claim 17, wherein, The drying process is freeze-drying.

19. A method for conditioning sludge using a sludge conditioner prepared by any one of the methods of claims 1-18, the method comprising: Step a: Provide sludge from a municipal wastewater treatment plant, urea peroxide, and the sludge conditioner; Step b: Add urea peroxide to the sludge, then add the sludge conditioner and stir evenly, then let it stand; Step c: Filter the product obtained in step b.

20. The method of claim 19, wherein, The amount of the sludge conditioner is 10-300 mg / gTS based on the weight of the sludge, where TS represents the dry weight of the sludge.

21. The method of claim 19, wherein, The amount of the sludge conditioner is 75-250 mg / gTS based on the weight of the sludge, where TS represents the dry weight of the sludge.

22. The method of claim 19, wherein, The amount of the sludge conditioner is 100-200 mg / gTS based on the weight of the sludge, where TS represents the dry weight of the sludge.

23. The method of claim 19, wherein, Based on the weight of the sludge, 20-100 mg / gTS of urea peroxide was added to the sludge.

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