Sludge modification separation method

Abstract

The invention relates to the technical field of sludge environment-friendly recovery, in particular to a sludge modification separation method. The method comprises the following steps: adding ferrous sulfate and glutaraldehyde into sludge to be treated, stirring for reaction, adding a chelating agent and a flocculating agent, adjusting the pH value, and stirring for reaction to obtain a solid-liquid mixture; carrying out solid-liquid separation on the solid-liquid mixture to obtain inorganic grit, organic sludge and supernate; carrying out leaching treatment on the organic sludge by adopting a leaching agent to obtain leacheate and excess sludge; the excess sludge is repeatedly subjected to solid-liquid separation and leaching, and supernate and high-purity organic sludge are obtained; and drying the high-purity organic sludge to obtain the biomass fuel. Sludge can be effectively separated, and the obtained inorganic grit is low in organic matter content and can be conveniently applied to the fields of building materials and the like subsequently; the high-purity organic sludge is dried to prepare the biomass fuel, and the biomass fuel has a relatively high higher calorific value; and subsequent resource utilization is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of sludge environmental protection recovery, and in particular to a sludge modification and separation method. Background Art

[0002] Sludge is a type of flocculent material with high water content and a mixture of solid and liquid. It is produced in large quantities in the process of sewage treatment, sediment dredging, oil field production, etc. Taking municipal sludge as an example, every 10,000 tons of sewage treated will produce 10-20 tons (calculated at a water content of 90%) of sludge. Sludge not only has a large output but also contains toxic and harmful substances such as parasite eggs, heavy metals, pathogenic microorganisms and persistent organic matter. It must be effectively treated and disposed of, otherwise it is very easy to cause secondary pollution to groundwater and soil, threatening environmental safety and public health.

[0003] Sludge itself has low calorific value and high water content. Independent incineration cannot meet the heat balance of drying incineration and requires the addition of a large amount of fuel. Co-incineration also faces the same dilemma. Anaerobic fermentation of sludge requires a large investment. If it is not combined with thermal hydrolysis, the actual biogas production rate is low, and the final biogas slurry and biogas residue treatment is difficult to handle. When sludge is aerobic composted, it is affected by the high water content of the incoming sludge, the amount of auxiliary materials added is large, the treatment efficiency is low, the amount of odor generated is large, and the final fertilizer product has limited outlets. Economical and efficient mud-water separation technology is the prerequisite for effective sludge treatment and disposal, and is also the key to achieving sludge reduction and resource utilization.

[0004] Therefore, the present invention provides a sludge modification and separation method that can effectively separate sludge and facilitate subsequent resource utilization. Summary of the invention

[0005] The object of the present invention is to provide a sludge modification and separation method, which can solve the above-mentioned technical problems.

[0006] The present invention provides a sludge modification and separation method, comprising the following steps:

[0007] S1. Add ferrous sulfite and glutaraldehyde to the sludge to be treated, stir and react for 30-50 minutes, add a chelating agent and a flocculant, adjust the pH to 6-8, stir and react for 40-80 minutes to obtain a solid-liquid mixture;

[0008] S2. The solid-liquid mixture is subjected to solid-liquid separation to obtain inorganic gravel, organic sludge and a supernatant;

[0009] S3. The organic sludge is eluted with an eluent to obtain an eluent and residual sludge;

[0010] S4. Repeating solid-liquid separation and elution of the residual sludge to obtain a supernatant and high-purity organic sludge; and drying the high-purity organic sludge to obtain biomass fuel.

[0011] Preferably, the mass percentage of each component in step S1 is: 90-99wt% of the sludge to be treated, 0.4-3.0wt% of ferrous sulfite, 0.2-2.0% of glutaraldehyde, 0.3-5.0% of the chelating agent, and 0.1-4.0% of the flocculant.

[0012] Preferably, the chelating agent is any one or more of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, hydroxyethylethylenediaminetriacetic acid, and aminotrimethylenephosphonic acid.

[0013] Preferably, the flocculant is any one or more of polyaluminium chloride, polyferric sulfate, polyacrylamide and polydimethyldiallylammonium chloride.

[0014] Preferably, the specific steps of step S2 are: sending the solid-liquid mixture into a cyclone solid-liquid separation device at a flow rate of 2-4m / s, centrifuging at a rotation speed of 1000-1500r / min, and the inorganic sand and gravel are thrown toward the wall of the device to form an underflow and discharged downward; the organic sludge and liquid phase form an overflow and are discharged from the overflow port above to obtain a mixture of organic sludge and supernatant.

[0015] Preferably, the specific steps of step S3 are: slowly adding the eluent to the organic sludge, stirring at 50-300 r / min for 1-4 hours, the organic sludge and the eluent fully react, and then solid-liquid separation to obtain the eluent and the residual sludge.

[0016] Preferably, the eluent comprises calcium chloride and citric acid, the concentration of the calcium chloride is 0.1-0.5 mol / L, and the concentration of the citric acid is 0.05-0.5 mol / L.

[0017] Preferably, the mass ratio of the sum of the masses of the calcium chloride and the citric acid to the organic sludge is (0.05-0.5):1.

[0018] Preferably, the specific steps of drying the high-purity organic sludge in step S4 are: using a plate and frame filter press to preliminarily dehydrate the high-purity organic sludge to obtain a mud cake with a water content of 30-50%, and drying the mud cake to a water content of 10-15% to obtain biomass fuel.

[0019] Preferably, the method further comprises step S5. Adding a reducing agent to the supernatant obtained in step S2 and step S4 and the eluent obtained in step S3, stirring the reaction for 20-30 minutes, and then performing solid-liquid separation to obtain a precipitate.

[0020] Beneficial effects:

[0021] The sludge modification and separation method provided by the present invention can effectively separate sludge, and the obtained inorganic gravel has a low organic content, which is convenient for subsequent application in the fields of building materials and the like; after drying the high-purity organic sludge, biomass fuel is obtained, and the biomass fuel has a high high calorific value; it is conducive to subsequent resource utilization.

[0022] In the method provided by the present invention, ferrous sulfite, a chelating agent and a flocculant are used to pre-treat the sludge to be treated, thereby destroying the viscosity of the EPS of the sludge and enabling better separation of the inorganic components and organic components in the sludge. The glutaraldehyde treatment can fully penetrate into the sludge during the pre-treatment process, kill the microorganisms, bacteria and viruses in the sludge to be treated, and avoid the spread of the microorganisms, bacteria and viruses in the subsequent separation process, thereby improving the biological safety during the treatment process.

[0023] The present invention adds a reducing agent to the supernatant and the eluting liquid to react, thereby analyzing inorganic groups such as iron, aluminum and phosphorus therein, which is convenient for subsequent recycling. DETAILED DESCRIPTION

[0024] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0025] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form also includes the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this description, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0026] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than 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.

[0027] The sludge to be treated is the sludge collected from the urban sewage treatment plant.

[0028] Example 1

[0029] A sludge modification and separation method comprises the following steps:

[0030] S1. Add ferrous sulfite and glutaraldehyde to the sludge to be treated, stir and react for 40 minutes, then add chelating agent ethylenediaminetetraacetic acid and flocculant polyacrylamide, adjust the pH to 6-8, stir and react for 60 minutes to obtain a solid-liquid mixture; the inorganic components such as iron, aluminum and phosphorus in the sludge can be reduced to ionic state and dissolved in the liquid phase, which is convenient for subsequent separation and recovery;

[0031] The mass percentage of each component is: 98wt% of the sludge to be treated, 0.5wt% of ferrous sulfite, 0.5wt% of glutaraldehyde, 0.7wt% of the chelating agent, and 0.3wt% of the flocculant.

[0032] S2. The solid-liquid mixture is fed into a cyclone solid-liquid separation device at a flow rate of 3 m / s and centrifuged at a speed of 1000 r / min. The inorganic sand and gravel are thrown toward the wall of the device to form an underflow and discharged downward; the organic sludge and the liquid phase form an overflow and are discharged from the overflow port above to obtain a mixture of organic sludge and supernatant;

[0033] S3. slowly add the eluent to the organic sludge, stir at 100r / min for 2h, the organic sludge and the eluent are fully reacted, and then the solid-liquid separation is performed to obtain the eluent and the residual sludge; the eluent comprises calcium chloride and citric acid, the concentration of the calcium chloride is 0.1mol / L, the concentration of the citric acid is 0.2mol / L, the mass ratio of calcium chloride to citric acid is 1:1, and the mass ratio between the sum of the mass of the calcium chloride and the citric acid and the organic sludge is 0.2:1;

[0034] S4. Repeat the solid-liquid separation and elution of the residual sludge three times to obtain a supernatant and high-purity organic sludge; use a plate and frame filter press to preliminarily dehydrate the high-purity organic sludge to obtain a mud cake with a water content of 30%, dry the mud cake to a water content of 10%, and complete the drying to obtain biomass fuel;

[0035] Step S5. Add a reducing agent to the supernatant obtained in step S2 and step S4 and the eluent obtained in step S3, stir and react for 30 minutes, and then perform solid-liquid separation to obtain a precipitate. The main components of the precipitate are iron and aluminum salts and phosphate salts. The iron and aluminum salts can be returned to the sewage treatment plant for recycling as a phosphorus removal agent, and the phosphate salts can be made into phosphate fertilizer for recycling.

[0036] The content of organic components in the inorganic gravel separated in Example 1 is no more than 3%, and the higher calorific value of the biomass fuel is 3500 kcal / kg.

[0037] Example 2

[0038] A sludge modification and separation method comprises the following steps:

[0039] S1. Add ferrous sulfite and glutaraldehyde to the sludge to be treated, stir and react for 30 minutes, then add chelating agent diethylenetriaminepentaacetic acid, aminotrimethylenephosphonic acid and flocculant polyaluminium chloride, polyferric sulfate, adjust the pH to 6-8, stir and react for 40 minutes to obtain a solid-liquid mixture;

[0040] The mass percentage of each component is: 96wt% of the sludge to be treated, 1.5wt% of ferrous sulfite, 0.6wt% of glutaraldehyde, 1.0wt% of the chelating agent, and 0.9wt% of the flocculant.

[0041] S2. The solid-liquid mixture is fed into a cyclone solid-liquid separation device at a flow rate of 2 m / s, and centrifuged at a speed of 1200 r / min. The inorganic gravel is thrown toward the wall of the device to form an underflow and discharged downward; the organic sludge and the liquid phase form an overflow and are discharged from the overflow port above to obtain a mixture of organic sludge and supernatant;

[0042] S3. slowly add the eluent to the organic sludge, stir at 50r / min for 4h, the organic sludge and the eluent fully react, and then separate the solid and liquid to obtain the eluent and the residual sludge; the eluent includes calcium chloride and citric acid, the concentration of the calcium chloride is 0.5mol / L, the concentration of the citric acid is 0.05mol / L, the mass ratio of calcium chloride to citric acid is 1:1, and the mass ratio between the sum of the mass of the calcium chloride and the citric acid and the organic sludge is 0.05:1;

[0043] S4. Repeating the solid-liquid separation and elution of the residual sludge to obtain a supernatant and high-purity organic sludge; using a plate and frame filter press to preliminarily dehydrate the high-purity organic sludge to obtain a mud cake with a water content of 40%, and drying the mud cake to a water content of 12%, completing the drying to obtain biomass fuel;

[0044] Step S5. Add a reducing agent to the supernatant obtained in step S2 and step S4 and the eluent obtained in step S3, stir the reaction for 20 minutes, and then perform solid-liquid separation to obtain a precipitate.

[0045] The content of organic components in the inorganic gravel separated in Example 2 is no more than 10%, and the higher calorific value of the biomass fuel is 2700 kcal / kg.

[0046] Example 3

[0047] A sludge modification and separation method comprises the following steps:

[0048] S1. Adding ferrous sulfite and glutaraldehyde to the sludge to be treated, stirring and reacting for 50 minutes, adding a chelating agent hydroxyethylethylenediaminetriacetic acid and a flocculant polydimethyldiallylammonium chloride, and adjusting the pH to 6-8, stirring and reacting for 80 minutes to obtain a solid-liquid mixture;

[0049] The mass percentage of each component is: 99wt% of the sludge to be treated, 0.4wt% of ferrous sulfite, 0.2wt% of glutaraldehyde, 0.3-5.0wt% of the chelating agent, and 0.1wt% of the flocculant.

[0050] S2. The solid-liquid mixture is fed into a cyclone solid-liquid separation device at a flow rate of 4 m / s, and centrifuged at a speed of 1500 r / min. The inorganic sand and gravel are thrown toward the wall of the device to form an underflow and discharged downward; the organic sludge and the liquid phase form an overflow and are discharged from the overflow port above to obtain a mixture of organic sludge and supernatant;

[0051] S3. slowly adding an eluent to the organic sludge, stirring at 300 r / min for 1 hour, the organic sludge and the eluent are fully reacted, and then the solid-liquid separation is performed to obtain an eluent and residual sludge; the eluent comprises calcium chloride and citric acid, the concentration of the calcium chloride is 0.3 mol / L, the concentration of the citric acid is 0.5 mol / L, the mass ratio of calcium chloride to citric acid is 1:1, and the mass ratio of the sum of the mass of the calcium chloride and the citric acid to the organic sludge is 0.5:1;

[0052] S4. Repeat the solid-liquid separation and elution of the residual sludge five times to obtain a supernatant and high-purity organic sludge; use a plate and frame filter press to preliminarily dehydrate the high-purity organic sludge to obtain a mud cake with a water content of 50%, dry the mud cake to a water content of 15%, and complete the drying to obtain biomass fuel;

[0053] Step S5. Add a reducing agent to the supernatant obtained in step S2 and step S4 and the eluent obtained in step S3, stir the reaction for 25 minutes, and then perform solid-liquid separation to obtain a precipitate.

[0054] The content of organic components in the inorganic gravel separated in Example 3 is no more than 2%, and the higher calorific value of the biomass fuel is 3700 kcal / kg.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A sludge modification and separation method, characterized in that: The following steps are involved: S1. Add ferrous sulfite and glutaraldehyde to the sludge to be treated, stir and react for 30-50 minutes, add a chelating agent and a flocculant, adjust the pH to 6-8, stir and react for 40-80 minutes to obtain a solid-liquid mixture; S2. The solid-liquid mixture is subjected to solid-liquid separation to obtain inorganic gravel, organic sludge and a supernatant; S3. The organic sludge is eluted with an eluent to obtain an eluent and residual sludge; S4. Repeating solid-liquid separation and elution of the residual sludge to obtain a supernatant and high-purity organic sludge; and drying the high-purity organic sludge to obtain biomass fuel.

2. The sludge modification and separation method according to claim 1, characterized in that: The mass percentages of the components in step S1 are: 90-99wt% of the sludge to be treated, 0.4-3.0wt% of ferrous sulfite, 0.2-2.0wt% of glutaraldehyde, 0.3-5.0wt% of the chelating agent, and 0.1-4.0wt% of the flocculant.

3. The sludge modification and separation method according to claim 2, characterized in that: The chelating agent is any one or more of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, hydroxyethylethylenediaminetriacetic acid, and aminotrimethylenephosphonic acid.

4. The sludge modification and separation method according to claim 2, characterized in that: The flocculant is any one or more of polyaluminium chloride, polyferric sulfate, polyacrylamide and polydimethyldiallylammonium chloride.

5. The sludge modification and separation method according to claim 1, characterized in that: The specific steps of step S2 are: sending the solid-liquid mixture into a cyclonic solid-liquid separation device at a flow rate of 2-4 m / s, centrifuging at a speed of 1000-1500 r / min, and throwing inorganic sand and gravel toward the wall of the device to form an underflow and discharge downward; The organic sludge and liquid phase form an overflow and are discharged from the upper overflow port to obtain a mixture of organic sludge and supernatant.

6. The sludge modification and separation method according to claim 1, characterized in that: The specific steps of step S3 are: slowly adding the eluent to the organic sludge, stirring at 50-300 r / min for 1-4 hours, the organic sludge and the eluent fully react, and then solid-liquid separation to obtain the eluent and the residual sludge.

7. The sludge modification and separation method according to claim 1, characterized in that: The eluent includes calcium chloride and citric acid, the concentration of the calcium chloride is 0.1-0.5 mol / L, and the concentration of the citric acid is 0.05-0.5 mol / L.

8. The sludge modification and separation method according to claim 7, characterized in that: The mass ratio of the sum of the mass of the calcium chloride and the citric acid to the mass of the organic sludge is (0.05-0.5):

1.

9. The sludge modification and separation method according to claim 1, characterized in that: The specific steps of drying the high-purity organic sludge in step S4 are: using a plate and frame filter press to preliminarily dehydrate the high-purity organic sludge to obtain a mud cake with a water content of 30-50%, and drying the mud cake to a water content of 10-15% to obtain biomass fuel.

10. The sludge modification and separation method according to claim 1, characterized in that: The method further comprises step S5. Adding a reducing agent to the supernatant obtained in step S2 and step S4 and the eluent obtained in step S3, stirring the reaction for 20-30 minutes, and then performing solid-liquid separation to obtain a precipitate.