Sludge modification dehydration pretreatment method

Abstract

The invention belongs to the technical field of sewage treatment, and particularly relates to a sludge modification dehydration pretreatment method which comprises the following steps: (1) adding a composite iron-based catalytic oxidant accounting for 1.5-6% of the volume of concentrated sludge into the concentrated sludge while stirring, and uniformly mixing; (2) adding chlorate; and uniformly stirring until the pH value of the sludge mixed solution reaches 6-7, and completing the reaction to obtain the modified sludge solution. The method provided by the invention can solve the problems of high sludge dewatering difficulty, incomplete dewatering and low dewatering efficiency caused by iron element loss, can improve the sludge dewatering effect, efficiency and stability, and reduces the activated sludge dewatering treatment cost.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and in particular relates to a sludge modification and dehydration pretreatment method. Background Art

[0002] With the development of my country's economy and the acceleration of urbanization, the continuous popularization of urban sewage treatment facilities, the improvement of treatment rates and the deepening of treatment levels, the amount of sludge generated will increase significantly. In the past decade, a large number of newly built and under-designed sewage treatment plants have only simply concentrated, dehydrated and transported sludge due to investment, operator quality, technical level and other reasons. More than 90% of the sludge in domestic sewage treatment plants currently in operation has not been truly stabilized or harmlessly treated, and there is no way to finally dispose of it. It is estimated that by 2025, the annual output of wet sludge in my country's urban sewage treatment plants will reach more than 100,000 tons, and the reduction, stabilization, harmlessness and resource treatment and disposal of sludge has become an urgent problem.

[0003] The biggest problem in the known sludge treatment and disposal is the sludge dehydration link, because sludge dehydration is the most effective way to reduce sludge, and the sludge dehydration efficiency directly affects the sludge reduction, stabilization, harmlessness and resource treatment. At present, polyacrylamide is widely used as a sludge dehydration filter aid in domestic sludge treatment. There are also ferric salts and calcium salts (CN1986788), ferrous chloride and lime as sludge dehydration pretreatment processes (ZJ200910114459.3), ferrous chloride as sludge dehydration pretreatment process (ZL200910114458.9), and polyaluminium chloride and polyferric sulfate also have application examples in the field of sludge dehydration treatment. However, when polyacrylamide is used as a sludge dehydration pretreatment flocculant, the sludge dehydration efficiency is very limited, and the general sludge moisture content can only reach 75%-85%, which brings great difficulties to the next step of landfill or resource utilization; the biggest defect of using iron salt and calcium salt (CN1986788) as filter aids for sludge dehydration pretreatment process is that a large amount of difficult-to-handle odor and ammonia are generated during sludge dehydration, which is very harmful to the health of operators and easily pollutes the environment, and there is a situation where the sludge dehydration treatment effect is unstable and the treatment cost is relatively high; and the amount of polyaluminium chloride used is relatively large and the price is expensive, resulting in high sludge dehydration treatment cost, and the sludge dehydration efficiency is also difficult to reach the level of using iron salt and calcium salt (CN1986788) as sludge dehydration treatment filter aids.

[0004] Therefore, it is very necessary to research and develop a cost-effective and efficient sludge modification and dewatering pretreatment method. Summary of the invention

[0005] The present invention aims to solve the above-mentioned technical problems and provides a sludge modification dewatering pretreatment method, which can solve the problems of difficulty in sludge dewatering, incomplete dehydration and low dehydration efficiency caused by the loss of iron elements, improve the effect, efficiency and stability of sludge dehydration, and reduce the cost of activated sludge dehydration treatment.

[0006] The technical solution of the present invention is:

[0007] A sludge modification and dehydration pretreatment method comprises the following steps:

[0008] (1) adding 1.5% to 6% of the volume of the concentrated sludge composite iron-based catalytic oxidant solution to the concentrated sludge while stirring and mixing evenly;

[0009] (2) Add chlorate, stir evenly, adjust the pH value to 6-7, and the reaction is completed to obtain modified sludge liquid.

[0010] Preferably, in step (1) of the present invention, the molar ratio of each element in the composite iron-based catalytic oxidant solution is: Fe:Al:Mn is (3-4):(1-2):(0.3-1), and the mass concentration of the three elements of Fe, Al, and Mn in the composite iron-based catalytic oxidant solution is 10-20%. The iron-based catalytic oxidant uses manganese as a catalyst, mainly because manganese is a non-heavy metal element. There are many types of catalyst elements, such as titanium, nickel, etc., which also have good catalytic oxidation effects, but most of them are heavy metal elements, causing new pollution to the generated sludge. The optimal preparation ratio of the iron element, aluminum element, and manganese element described in the present invention varies with factors such as the nature of the sludge (mainly referring to aerobic sludge or anaerobic sludge), the organic matter content, etc. The preparation ratio range of the present invention is aimed at the biochemical sludge generated by the common biochemical treatment of sewage, and has the best effect, the lowest treatment cost, and the highest treatment efficiency.

[0011] Preferably, the preparation method of the composite iron-based catalytic oxidant solution of the present invention is: adding raw materials containing three elements of Fe, Al and Mn into water, adding acid to adjust the pH value to 1.8-2.2, and mixing evenly.

[0012] Preferably, the iron in the present invention is derived from one or more of ferric chloride, ferrous chloride, polyferric sulfate, ferrous sulfate, and ferric hydroxide, preferably ferrous sulfate or ferric oxide; preferably, the aluminum in the present invention is derived from aluminum sulfate or polyaluminum chloride, preferably aluminum sulfate; and the manganese in the present invention is derived from one of manganese sulfate, potassium permanganate, and potassium manganate, preferably manganese sulfate.

[0013] Preferably, in step (1) of the present invention, the moisture content of the concentrated sludge is 90-99%.

[0014] Preferably, in step (2) of the present invention, the chlorate is sodium chlorate or calcium chlorate, and the manganese element added to the sludge is used as a catalyst for the sludge modification reaction, so that the color of the sludge changes from the original black to khaki or grayish yellow, and the sludge modification is basically completed. At this time, the reducing substances such as iron added to the activated sludge are rapidly oxidized under the catalytic action of manganese, and the ferrous ions are converted into trivalent ferrous ions to form ferric hydroxide colloids, thereby changing the electrical balance of the activated sludge mixed liquid system, causing the activated sludge to quickly coagulate and agglomerate, thereby destroying the sludge stability and releasing the cell water therein. When the pH value is adjusted to neutral, the aluminum salt also quickly turns into aluminum hydroxide colloids, accelerating the formation and stabilization of sludge flocs, so that the modified activated sludge is completely completed.

[0015] If a certain amount of soluble iron salt or ferrous salt (including soluble iron compounds such as ferric sulfate, ferric chloride, ferric nitrate, ferrous sulfate, ferrous chloride, ferrous nitrate, etc.) or a single aluminum salt (including polyaluminum chloride, aluminum sulfate, etc.) is added to the activated sludge, the modification of the sludge is incomplete, the mud-water separation effect is not thorough, and there are problems such as difficulty in sludge dehydration, long dehydration time and high moisture content of the final sludge. The main reasons are: the single addition of iron salt and stirring makes the iron element in the soluble iron compound evenly distributed in the activated sludge mixed suspension, the soluble iron ions adsorb with the activated sludge particles through the bridging effect to form a large alum flower, and a large part of the iron element becomes divalent iron ions and forms complexes or chelates with ammonium, carbonyl, hydroxyl and other ions or groups in the activated sludge and dissolves in the mixed solution, such as pentacarbonyl iron Fe(CO)5, Fe(CO) nEtc., resulting in a large amount of iron loss leading to poor sludge flocculation and sedimentation effect, sludge and water cannot be effectively separated, resulting in poor subsequent sludge dehydration effect and efficiency, sludge dehydration difficulty and incomplete dehydration, and high sludge moisture content after dehydration; single addition of aluminum salt is mainly due to the small density of aluminum hydroxide, and the small density of the formed sludge flocculent alum flowers causes incomplete mud and water separation. In order to overcome the above problems, the present invention adds iron ions as strong oxidizing substances, under the catalytic action of manganese elements, even a trace amount of oxidant chlorate molecules and oxygen molecules in contact with air during stirring can quickly oxidize a large amount of ferrous complexes into trivalent iron, thereby destroying the stable structure of the ferrous complex, forming a difficult-tolerance iron hydroxide colloid, and turning the soluble ferrous complex into a trivalent iron precipitation, and utilizing the powerful adsorption bridging effect of the flocculent iron hydroxide colloid to flocculate and settle the fine granular sludge in the sludge mixed liquor, realize efficient separation of mud and water, and greatly improve the utilization rate and use effect of the iron element. Manganese plays a very important role as a catalyst in the whole reaction process, prompting the divalent iron to react rapidly with oxygen molecules and added chlorate to generate ferric hydroxide colloid. Aluminum ions are hydrolyzed in the mixed solution to form aluminum hydroxide colloid, which adsorbs the negatively charged fine particles in the mixed solution to form large alum flowers, and achieves complete separation of mud and water. The present invention is based on the theory that manganese metal has efficient catalytic oxidation performance, and uses this technology to solve the various shortcomings and deficiencies of the aforementioned iron salts in sludge conditioning in principle, fundamentally changing the shortcomings of the aforementioned technology such as large iron element loss, low utilization rate, large dosage of reagents, and relatively high treatment cost. It can also be said that the aforementioned iron salt or ferrous iron used in sludge conditioning technology is only an imperfect technology under the content of this technology.

[0016] The present invention first adds a composite iron-based catalytic oxidant solution, mainly to allow the composite iron-based catalytic oxidant to combine with a large number of organic molecules and sludge particles in the sludge, and then adds and then adds chlorate. Preferably, in the step (2), the amount of chlorate added is 3.07-9.09g per liter of concentrated sludge. Chlorate reacts with divalent iron with strong reducibility under manganese catalysis to form trivalent iron (Fe(OH)3), which has very strong adsorption and can flocculate a large number of sludge particles in the sludge system, destroying the balance of the sludge dispersion system, thereby achieving the mud-water separation effect and completing the purpose of sludge modification; if chlorate is added first, the chlorate will react with the reducible organic matter in the sludge and become ineffective, and will lose its effect when the composite iron-based catalytic oxidant is added, and the purpose of sludge modification cannot be achieved.

[0017] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0018] 1. The method of the present invention is used to treat sludge, which can solve the problems of difficulty in sludge dehydration and low dehydration efficiency caused by the loss of iron elements, improve the subsequent dehydration effect and efficiency, reduce the difficulty of subsequent dehydration, make the dehydration more thorough, and the moisture content of the dehydrated sludge is low.

[0019] 2. The method of the present invention adds a composite iron-based catalytic oxidant solution to activated sludge, and the iron element in the composite iron-based catalytic oxidant solution combines with atomic groups such as carbonyl and hydroxyl groups in organic matter present in large quantities in the activated sludge to form soluble chemical substances of complexes or chelates. The manganese element in the composite iron-based catalytic oxidant solution acts as a catalyst, and under the continuous stirring process, the complex iron in the sludge is quickly oxidized by oxygen in the air and trace amounts of chlorate ions added to form trivalent iron hydroxide colloid, which is then combined with aluminum hydroxide colloid formed by aluminum ions in the composite iron-based catalytic oxidant in water to complete sludge modification, and finally achieve efficient and thorough separation of mud and water.

[0020] 3. The method of the present invention can also solve the environmental problems such as the generation of a large amount of ammonia due to the addition of a large amount of lime in the existing activated sludge dehydration process.

[0021] 4. The raw materials used in the method of the present invention are simple and easy to obtain, which can reduce the cost of activated sludge dehydration treatment. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Example 1

[0024] A sludge modification and dehydration pretreatment method comprises the following steps:

[0025] (1) adding a composite iron-based catalytic oxidant solution to the concentrated sludge while stirring and mixing evenly;

[0026] (2) Sodium chlorate is added, stirred evenly, and the pH value is adjusted to 6. The reaction is completed to obtain modified sludge liquid.

[0027] In the composite iron-based catalytic oxidant, the molar ratio of each element is: Fe:Al:Mn is 4:2:0.5 (Fe is derived from polyferric sulfate, Al is derived from aluminum sulfate, and Mn is derived from potassium permanganate); the preparation method of the composite iron-based catalytic oxidant is: polyferric sulfate, aluminum sulfate, and potassium permanganate are added into water so that the total mass concentration of the three elements Fe, Al, and Mn in the composite iron-based catalytic oxidant solution is 20%, then acid is added to adjust the pH value to 1.8, and the mixture is evenly mixed to obtain the composite iron-based catalytic oxidant solution.

[0028] The concentrated sludge produced by the treatment of the same batch of high-concentration wastewater of liquor was taken, and the sludge moisture content was 98.77%. The concentrated sludge was modified according to the method of Example 1 to obtain a modified sludge liquid, and the modified sludge liquid was transported to a vacuum filter with a rated pressure of minus 0.10 MPa, and the modified sludge liquid was filtered and dehydrated until the water was drained, the sludge dehydration rate was calculated, and the final sludge moisture content was detected. The specific results are shown in Table 1.

[0029] Table 1 Effect of treatment method in Example 1 on dehydration performance of high concentration liquor wastewater

[0030]

[0031] As can be seen from Table 1, when the dosage of the iron-based composite catalyst solution of the present invention is 1.5%-6% of the concentrated sludge volume, the obtained sludge moisture content is low and the filtration rate is fast. Considering the dosage of the iron-based composite catalyst, the filtration rate and the sludge moisture content (final sludge moisture content), when the dosage of the iron-based composite catalyst is 3% of the concentrated sludge volume, it has the best modified dehydration pretreatment effect and the highest efficiency.

[0032] Comparative Example 1

[0033] In order to verify the effect of different composite iron-based catalytic oxidant solutions on the dehydration performance of high-concentration liquor wastewater, the following comparative test was conducted (Comparative Example 1): The difference from Example 1 is that in the composite iron-based catalytic oxidant solution, the molar ratio of each element is: Fe:Mn is 4:0.5 (Fe comes from polyferric sulfate, Mn comes from potassium manganate), and the rest is the same as Example 1.

[0034] The same batch of high-concentration liquor wastewater as in Table 1 was concentrated to a water content of 98.77% to obtain concentrated sludge. The concentrated sludge was modified according to the method of Comparative Example 1 to obtain modified sludge liquid. The modified sludge liquid was transported to a vacuum filter with a rated pressure of minus 0.10 MPa, and the modified sludge liquid was filtered and dehydrated until the water was drained, the sludge dehydration rate was calculated, and the final sludge water content was detected. The specific results are shown in Table 2.

[0035] Table 2 Effect of the treatment method of comparative example 1 on the dehydration performance of high-concentration liquor wastewater

[0036]

[0037] It can be seen from Table 2 that when the composite iron-based catalytic oxidant solution lacks Al element, when the amount of added catalyst is the same, the filtration rate is much lower than that of Example 1, and the efficiency is not high. Therefore, in order to improve the sludge dehydration efficiency and dehydration effect at the same time, it is necessary to control the composition and dosage of the composite iron-based catalytic oxidant solution within the scope of the present invention.

[0038] Comparative Example 2

[0039] In order to verify the effect of different composite iron-based catalytic oxidant solutions on the dehydration performance of high-concentration liquor wastewater, the following comparative test (Comparative Example 2) was conducted: Different from Example 1, in the composite iron-based catalytic oxidant solution, the molar ratio of each element is: Al:Mn is 2:0.5 (Al comes from aluminum sulfate, Mn comes from potassium manganate), and the rest is the same as Example 1.

[0040] The same batch of high-concentration liquor wastewater as in Table 1 was concentrated to a water content of 98.77% to obtain concentrated sludge. The concentrated sludge was modified according to the method of Comparative Example 2 to obtain modified sludge liquid. The modified sludge liquid was transported to a vacuum filter with a rated pressure of minus 0.10 MPa, and the modified sludge liquid was filtered and dehydrated until the water was drained. The sludge dehydration rate was calculated, and the final sludge water content was detected. The specific results are shown in Table 3.

[0041] Table 3 Effect of the treatment method of comparative example 2 on the dehydration performance of high-concentration liquor wastewater

[0042]

[0043] It can be seen from Table 3 that when the composite iron-based catalytic oxidant solution lacks the Fe element, when the amount of added catalyst is the same, the filtration rate is much lower than that in Example 1, the efficiency is not high, and the moisture content of the sludge is higher than that in Example 1. Therefore, in order to simultaneously improve the sludge dehydration efficiency and dehydration effect, it is necessary to control the composition and dosage of the composite iron-based catalytic oxidant solution within the scope of the present invention.

[0044] Comparative Example 3

[0045] In order to verify the effect of different composite iron-based catalytic oxidant solutions on the dehydration performance of high-concentration liquor wastewater, the following comparative test (Comparative Example 3) was conducted: Different from Example 1, the molar ratio of each element in the composite iron-based catalytic oxidant solution is: Fe:Al is 4:2 (Fe comes from polyferric sulfate, Al comes from aluminum sulfate), and the rest is the same as Example 1.

[0046] The same batch of high-concentration liquor wastewater as in Table 1 was concentrated to a water content of 98.77% to obtain concentrated sludge. The concentrated sludge was modified according to the method of Comparative Example 3 to obtain modified sludge liquid. The modified sludge liquid was transported to a vacuum filter with a rated pressure of minus 0.10 MPa, and the modified sludge liquid was filtered and dehydrated until the water was drained. The sludge dehydration rate was calculated, and the final sludge water content was detected. The specific results are shown in Table 4.

[0047] Table 4 Effect of the treatment method of comparative example 3 on the dehydration performance of high-concentration liquor wastewater

[0048]

[0049]

[0050] It can be seen from Table 4 that when the composite iron-based catalytic oxidant solution lacks the Mn element, when the amount of added catalyst is the same, the filtration rate is much lower than that in Example 1, that is, the filtration efficiency is extremely low, and the moisture content of the sludge is higher than that in Example 1. Therefore, when the composite iron-based catalytic oxidant solution of the present invention lacks the Mn element, the obtained composite iron-based catalytic oxidant solution cannot simultaneously improve the sludge dehydration efficiency and dehydration effect.

[0051] Comparative Example 4

[0052] In order to verify the effect of different composite iron-based catalytic oxidant solutions on the dehydration performance of high-concentration liquor wastewater, the following comparative test (Comparative Example 4) was conducted: Different from Example 1, the molar ratio of each element in the composite iron-based catalytic oxidant solution is: Fe:Al:Mn is 6:3:0.1 (Fe comes from polyferric sulfate, Al comes from aluminum sulfate, and Mn comes from potassium manganate), and the rest is the same as Example 1.

[0053] The same batch of high-concentration liquor wastewater sludge as in Table 1 was concentrated to a water content of 98.77% to obtain concentrated sludge. The concentrated sludge was modified according to the method of Comparative Example 4 to obtain modified sludge liquid. The modified sludge liquid was transported to a vacuum filter with a rated pressure of minus 0.10 MPa, and the modified sludge liquid was filtered and dehydrated until the water was drained. The sludge dehydration rate was calculated, and the final sludge water content was detected. The specific results are shown in Table 5.

[0054] Table 5 Effect of treatment method in comparative example 4 on dehydration performance of high-concentration liquor wastewater sludge

[0055]

[0056]

[0057] It can be seen from Table 5 that when the ratio of the three elements of Fe, Al, and Mn in the composite iron-based catalytic oxidant solution is not within the scope of the present invention, when the amount of catalyst added is the same, the filtration rate is much lower than that in Example 1, that is, the filtration efficiency is extremely low. Therefore, only by strictly following the ratio of the embodiment of the present invention so that the ratio of the three elements of Fe, Al, and Mn is within the scope of the present invention, the obtained composite iron-based catalytic oxidant solution can simultaneously improve the sludge dehydration efficiency and dehydration effect.

[0058] Comparative Example 5

[0059] In order to verify the influence of different steps on the dehydration performance of high-concentration liquor wastewater, the following comparative test (Comparative Example 5) was conducted: The difference from Example 1 is that step (2) is not included, and the rest is the same as Example 1.

[0060] The same batch of high-concentration liquor wastewater as in Table 1 was concentrated to a water content of 98.77% to obtain concentrated sludge. The concentrated sludge was modified according to the method of Comparative Example 5 to obtain modified sludge liquid. The modified sludge liquid was transported to a vacuum filter with a rated pressure of minus 0.10 MPa, and the modified sludge liquid was filtered and dehydrated until the water was drained. The sludge dehydration rate was calculated, and the final sludge water content was detected. The specific results are shown in Table 6.

[0061] Table 6 Effect of the treatment method of comparative example 5 on the dehydration performance of high-concentration liquor wastewater

[0062]

[0063] As can be seen from Table 6, when sludge is modified, chlorate is not added for further treatment, and when the sludge is subsequently dehydrated, the filtration rate cannot be increased at the same time, and the dehydration rate of the sludge will also be high. Therefore, the method of the present invention can simultaneously improve the sludge dehydration efficiency and dehydration effect.

[0064] Example 2

[0065] A sludge modification and dehydration pretreatment method comprises the following steps:

[0066] (1) adding a composite iron-based catalytic oxidant to the concentrated sludge while stirring and mixing evenly;

[0067] (2) Calcium chlorate is added, stirred evenly, and the pH value is adjusted to 6. The reaction is completed to obtain modified sludge liquid.

[0068] In the composite iron-based catalytic oxidant, the molar ratio of each element is: Fe:Al:Mn is 3:1:1 (Fe is derived from ferrous sulfate and ferrous chloride with a molar ratio of 1:1, Al is derived from polyaluminium chloride, and Mn is derived from manganese sulfate); the preparation method of the composite iron-based catalytic oxidant is: ferrous sulfate, ferrous chloride, polyaluminium chloride and manganese sulfate are added into water so that the total mass concentration of the three elements Fe, Al and Mn in the composite iron-based catalytic oxidant solution is 20%, then acid is added to adjust the pH value to 2.0, and the composite iron-based catalytic oxidant solution is obtained by uniformly mixing.

[0069] The same batch of high-concentration liquor wastewater as in Table 1 was concentrated to a water content of 90% to obtain concentrated sludge. The concentrated sludge was modified according to the method of Example 2 to obtain modified sludge liquid. The modified sludge liquid was transported to a vacuum filter with a rated pressure of minus 0.10 MPa, and the modified sludge liquid was filtered and dehydrated until the water was drained out. The sludge dehydration rate was calculated, and the final sludge water content was detected. The specific results are shown in Table 7.

[0070] Table 7 Effect of treatment method in Example 2 on dehydration performance of high concentration liquor wastewater

[0071]

[0072] Example 3

[0073] A sludge modification and dehydration pretreatment method comprises the following steps:

[0074] (1) adding a composite iron-based catalytic oxidant to the concentrated sludge while stirring and mixing evenly;

[0075] (2) adding calcium chlorate and stirring evenly until the pH value of the sludge mixture reaches 7, the reaction is completed, and a modified sludge liquid is obtained;

[0076] (3) The modified sludge liquid is transported to a vacuum filter with a pressure of minus 0.1 MPa, and the mixed liquid is filtered and dehydrated until the water is drained out, and the sludge dehydration rate is calculated.

[0077] In the composite iron-based catalytic oxidant, the ratio of each element is 3:1:0.3 according to the molar ratio: Fe:Al:Mn (Fe is derived from ferric hydroxide and ferric chloride with a molar ratio of 1:1, Al is derived from polyaluminium chloride, and Mn is derived from potassium manganate); ferric hydroxide, ferric chloride, polyaluminium chloride and potassium manganate are added into water so that the total mass concentration of the three elements Fe, Al and Mn in the composite iron-based catalytic oxidant solution is 10%, and then acid is added to adjust the pH value to 2.2, and the composite iron-based catalytic oxidant solution is obtained by mixing evenly.

[0078] The same batch of high-concentration liquor wastewater as in Table 1 was concentrated to a water content of 90% to obtain concentrated sludge. The concentrated sludge was modified according to the method of Example 3 to obtain modified sludge liquid. The modified sludge liquid was transported to a vacuum filter with a rated pressure of minus 0.10 MPa, and the modified sludge liquid was filtered and dehydrated until the water was drained. The sludge dehydration rate was calculated, and the final sludge water content was detected. The specific results are shown in Table 8.

[0079] Table 8 Effect of treatment method in Example 3 on dehydration performance of high concentration liquor wastewater

[0080]

[0081] It can be seen from the data in Tables 7 and 8 that after the sludge is modified by the method of the present invention, the subsequent dehydration efficiency of the sludge and the dehydration effect can be improved (the moisture content of the sludge filtered out by negative pressure is low), especially when a 3% composite iron-based catalytic oxidant solution is added to the concentrated sludge volume, the sludge dehydration efficiency and dehydration effect can be significantly improved.

[0082] The above description is a detailed description of the preferred feasible embodiments of the present invention, but the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modified changes completed under the technical spirit suggested by the present invention should fall within the patent scope covered by the present invention.

Claims

1. A sludge modification and dehydration pretreatment method, characterized in that: The following steps are involved: (1) adding 1.5% to 6% of the volume of the concentrated sludge composite iron-based catalytic oxidant solution to the concentrated sludge while stirring and mixing evenly; (2) Add chlorate, stir evenly, adjust the pH value to 6-7, and the reaction is completed to obtain modified sludge liquid.

2. The sludge modification and dehydration pretreatment method according to claim 1, characterized in that: In the step (1), the molar ratio of each element in the composite iron-based catalytic oxidant solution is: Fe:Al:Mn is (2-4):(1-2):(0.3-1), and the mass concentration of the three elements Fe, Al and Mn in the composite iron-based catalytic oxidant solution is 10-20%.

3. The sludge modification and dehydration pretreatment method according to claim 2, characterized in that: The preparation method of the composite iron-based catalytic oxidant solution is as follows: adding raw materials containing three elements of Fe, Al and Mn into water, adding acid to adjust the pH value to 1.8-2.2, and mixing evenly.

4. The sludge modification and dehydration pretreatment method according to claim 2, characterized in that: The Fe element is derived from one or more of ferric chloride, ferrous chloride, polyferric sulfate, ferrous sulfate, and ferric hydroxide.

5. The sludge modification and dehydration pretreatment method according to claim 2, characterized in that: The aluminum is derived from aluminum sulfate or polyaluminum chloride.

6. The sludge modification and dehydration pretreatment method according to claim 2, characterized in that: The manganese is derived from one of manganese sulfate, potassium permanganate and potassium manganate.

7. The sludge modification and dehydration pretreatment method according to claim 1, characterized in that: In the step (1), the moisture content of the concentrated sludge is 90-99%.

8. The sludge modification and dehydration pretreatment method according to claim 1, characterized in that: In the step (2), the amount of the composite iron-based catalytic oxidant solution added is 3%-6% of the volume of the concentrated sludge.

9. The sludge modification and dehydration pretreatment method according to claim 1, characterized in that: In the step (2), the chlorate is sodium chlorate or calcium chlorate.

10. The sludge modification and dehydration pretreatment method according to claim 1, characterized in that: In the step (2), the amount of chlorate added is 3.12-8.79 g per liter of concentrated sludge.

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