CN114262132A - Method for improving sludge dewatering by heat treatment and flocculant - Google Patents
Method for improving sludge dewatering by heat treatment and flocculant Download PDFInfo
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- CN114262132A CN114262132A CN202111530600.5A CN202111530600A CN114262132A CN 114262132 A CN114262132 A CN 114262132A CN 202111530600 A CN202111530600 A CN 202111530600A CN 114262132 A CN114262132 A CN 114262132A
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Abstract
The invention discloses a method for improving sludge dewatering by heat treatment and a flocculating agent, which comprises the following steps: 1) heating a sludge sample to be treated to 80-90 ℃; 2) adding a certain amount of flocculating agent into the heated sludge, and performing magnetic stirring; 3) adding sulfuric acid into the sludge to adjust the pH value of the sludge; continuing magnetic stirring; 4) and (3) carrying out vacuum filtration on the treated sludge for 30min in a Buchner funnel under the pressure condition of 0.06MPa for dehydration. The method overcomes the defects that the traditional flocculating agent only can accelerate the filtration speed and can not reduce the water content very high and the filtration speed is deteriorated by single heat treatment, and the pH value after reaction is in a neutral range, so that the method can not corrode a dehydration instrument and is convenient for subsequent treatment.
Description
Technical Field
The invention belongs to the technical field of sludge treatment, and particularly relates to a method for improving sludge dewatering through cooperation of heat treatment and a flocculating agent.
Background
With the increasing of sewage amount in China, the treatment and disposal problems of sludge become more serious, and the water content of the sludge treated by the sewage treatment plant can reach up to 99%. The excessive water content causes the volume increase of the sludge, the transportation is influenced, and the sludge disposal modes such as landfill and the like also have requirements on the water content of the sludge, so how to improve the sludge dewatering efficiency is important.
The flocculant is proved to eliminate the electrostatic repulsion among the sludge, destroy the stability of a sludge suspension system, release water trapped in a sludge floc structure and enhance the dewatering effect; and simultaneously, the sludge flocculating agent plays a role in bridging in sludge flocculating bodies, so that fine sludge flocculating bodies are connected into large sludge flocculating bodies, thereby improving the filtering speed of sludge and improving the sludge dewatering capacity.
The acid also has a promoting effect on sludge dehydration, the acid can destroy floc structures and sludge cells of the sludge, so that water existing in the floc structures or in the cells is discharged, when the sludge is treated by excessive acid, the sludge cells are seriously cracked, fine sludge cell fragments block a hydrophobic channel, the filtering speed is reduced, the dehydration is adversely affected, and meanwhile, too low pH value can corrode dehydration equipment to influence the service life of the dehydration equipment.
Temperature is also an important factor affecting sludge dewatering. The higher the temperature is, the lower the viscosity of the sludge is, which is beneficial to the acceleration of the sludge filtration speed, and the heating pretreatment and the acid pretreatment can also destroy the net structure of the sludge, and the water in the bound net structure can be released, even the rupture of the sludge cell wall can be caused, the internal water is released, thereby reducing the water content of the sludge.
At present, for sewage treatment, a flocculating agent is mostly added with acid or added with a flocculating agent under a microwave condition for treatment, but no report is found for a method for cooperatively treating activated sludge by using a heat-acid-flocculating agent.
Disclosure of Invention
The invention aims to provide a method for dewatering sludge, which is completed by a method of heat treatment in cooperation with a flocculating agent and an acid, and achieves the effects of reducing the water content of the sludge and increasing the filtering speed of the sludge.
In order to achieve the purpose, the invention adopts the following technical measures:
a method for improving sludge dewatering by heat treatment and a flocculating agent comprises the following steps:
1) heating a sludge sample to be treated to 80-90 ℃;
2) adding a certain amount of flocculating agent into the heated sludge, and performing magnetic stirring;
3) adding sulfuric acid into the sludge to adjust the pH value of the sludge; continuing magnetic stirring;
4) and (3) carrying out vacuum filtration on the treated sludge for 30min in a Buchner funnel under the pressure condition of 0.06MPa for dehydration.
Further, the solid content of the sludge sample in the step 1) is 13mg/L, and the optimal heating temperature is 85 ℃.
Further, the flocculating agent in the step 2) is cationic polyacrylamide, and the addition amount of the flocculating agent is 10.0mg/gDS per 100ml of sludge sample.
Further, the pH value in step 3) is 4 to 6, preferably 6.
Further, the time of magnetic stirring in the step 2) is 2min, and the time of magnetic stirring in the step 3) is 28 min.
Further, the magnetic stirring speed was 150 rpm.
The method of the invention makes full use of the functions of reducing the water content of the sludge by heat and improving the filtering speed of the sludge by the flocculating agent, and provides a method for cooperatively treating the activated sludge by the heat, the acid and the flocculating agent. Provides a brand new idea for improving the dehydration capacity of the activated sludge.
Drawings
FIG. 1 shows the water content and CST of sludge co-processed at different polyacrylamide concentrations;
FIG. 2 shows the water content and CST of sludge co-processed at different pH values;
FIG. 3 shows the water content and CST of sludge co-processed at different temperatures;
FIG. 4 shows the water content and CST of sludge in different conditioning systems.
Detailed Description
The present invention is further described below with reference to specific examples in order to better understand the technical solutions.
Example 1: source and characteristic parameters of activated sludge
The sludge sample in the experiment was taken from the sludge digestion tank of the good sewage treatment plant in Hangzhou city, Zhejiang province, and after the sludge was taken to the laboratory, it was filtered with a 0.9mm mesh screen and stored in a refrigerator at 4 ℃. The basic parameters of the sludge are as follows: the pH value is 6.81 plus or minus 0.1; the total solid mass (g/L) is 13.15 +/-0.007; specific resistance of sludge (x 10)13m/kg) is 1.49 +/-0.12; the capillary water absorption time is 23.78 +/-0.80 s; the water content was 77.64% + -0.31.
Example 2: effect of Polyacrylamide of different concentrations on sludge dewatering Performance
6 parts of 100mL sludge sample with a solid content of 13g/L are taken into a 250mL beaker, the sludge is heated to 80-90 ℃, then polyacrylamide with a DS of 0.0, 2.5, 5.0, 7.5, 10.0, 12.5 mg/g is added, stirring is carried out for 2min at a stirring speed of 150rpm, then sulfuric acid is added to adjust the pH of the sludge sample to 6.0, and stirring is carried out for 28min at a stirring speed of 150 rpm. After the reaction is finished, the sludge sample is subjected to vacuum filtration for 30min by using a Buchner funnel under the pressure of 0.06MPa, the water content of the sludge is measured, and the sludge sample CST is measured by using a CST instrument to comprehensively evaluate the sludge dewatering efficiency. FIG. 1 shows the effect of different concentrations of polyacrylamide on the water content of sludge and CST, and it can be seen from FIG. 1 that when the concentration of polyacrylamide is 10.0mg/g DS, the water content of sludge and CST are both the lowest, and the dewatering effect is the best.
Example 3: effect of different pH on sludge dewatering
Putting 6 parts of 100mL sludge sample with the solid content of 13g/L into a 250mL beaker, heating the sludge to 80-90 ℃, then adding 10.0mg/g DS polyacrylamide, stirring for 2min at the stirring speed of 150rpm, then adding sulfuric acid to adjust the pH of the sludge sample to 2.0, 3.0, 4.0, 5.0, 6.0 and 6.8 respectively, stirring for 28min at the stirring speed of 150rpm, after the reaction is finished, carrying out vacuum filtration on the sludge sample for 30min at the pressure of 0.06MPa by using a Buchner funnel, measuring the water content of the sludge, measuring the sludge sample CST by using a CST instrument, and comprehensively evaluating the sludge dewatering efficiency. Fig. 2 shows the water content and the CST of the sludge at different pH values, and it can be seen from the figure that the water content decreases at pH =2.0 and 3.0, but the specific resistance of the sludge increases, and the water content and the CST do not change much at pH =4.0, 5.0, and 6.0, and both decrease significantly compared to the original sludge, and pH =6.0 is the optimum condition for saving resources and influencing the equipment.
Example 4: effect of different temperatures on sludge dewatering
Putting 4 parts of 100mL sludge sample with the solid content of 13g/L into a 250mL beaker, respectively heating the sludge to 25 ℃, 45 ℃, 65 ℃ and 85 ℃, then adding 10.0mg/g DS polyacrylamide, stirring for 2min at the stirring speed of 150rpm, then adding sulfuric acid to respectively adjust the pH value of the sludge sample to 6.0, stirring for 28min at the stirring speed of 150rpm, after the reaction is finished, carrying out vacuum filtration on the sludge sample for 30min at the pressure of 0.06MPa by using a Buchner funnel, measuring the water content of the sludge, measuring the CST of the sludge sample by using a CST instrument, and comprehensively evaluating the sludge dewatering efficiency. FIG. 3 shows the water contents and CST at different temperatures, and it can be seen that the water content is the lowest at a temperature of 85 ℃ and the CST is almost the same as those at 45 ℃, 65 ℃ and 85 ℃, and the effect is the best at 85 ℃.
Example 5: effect of different conditioning methods on sludge dewatering
8 parts of 100mL sludge sample having a solid content of 13g/L was placed in a 250mL beaker, and a control group (RS), a polyacrylamide group (PAM), an acid group (H), a Heat group (Heat), a polyacrylamide + acid group (PAM + H), a Heat + polyacrylamide group (PAM + Heat), a Heat + acid group (H + Heat), and a Heat + polyacrylamide + acid group (Heat + PAM + H) were set, respectively. Wherein the PAM group only uses 10.0mg/g DS to process an original sludge sample, and reacts for 30min at the stirring speed of 150 rpm; only adding sulfuric acid to the H group, adjusting the pH value of a sludge sample to 6.0, and reacting for 30min at the stirring speed of 150 rpm; the Heat group reacts for 30min only under the condition of 80-90 ℃ and the stirring speed of 150 rpm; adding 10.0mg/gDS polyacrylamide into the PAM + H group, reacting for 2min at the stirring speed of 150rpm, adding sulfuric acid to adjust the pH value of the sample to 6.0, and reacting for 28min at the stirring speed of 150 rpm; in the PAM + Heat group, a sludge sample is heated to 80-90 ℃, then 10.0mg/gDS polyacrylamide is added, and the reaction is carried out for 30min at the stirring speed of 150 rpm; in the H + Heat group, the sample is heated to 80-90 ℃, then sulfuric acid is added to adjust the pH of the sludge sample to 6.0, and the sludge sample is reacted for 30min at the stirring speed of 150 rpm. Heating the sample to 80-90 ℃ in the Heat + PAM + H group, adding 10.0mg/g DS polyacrylamide, reacting for 2min at the stirring speed of 150rpm, adding sulfuric acid to adjust the pH of the sample to 6.0, and reacting for 28min at the stirring speed of 150 rpm. The control group was not treated. And (3) measuring the water content and CST of the sludge after each group of reactions are finished, wherein FIG. 4 shows the water content and CST of the sludge in different conditioning modes, and the optimal effect of the group of comprehensive sludge water content and CST, Heat + PAM + H, namely the optimal dehydration effect under the conditions of 80-90 ℃, pH =6.0 and polyacrylamide concentration of 10.0mg/g DS.
The above examples fully illustrate that the method of the present invention can greatly reduce the water content of the excess sludge and greatly increase the sludge filtration speed, compared with the original sludge, the water content of the sludge treated by the method is reduced from 77.64% to 70.72%, and is reduced by 6.92%, the filtration speed is represented by CST, and is reduced from 24.78 s to 13.4 s of the original sludge, and is reduced by 42%, and the method has positive effects on the subsequent treatment of the sewage plant. Meanwhile, the pH value of the sludge is not obviously changed and the sludge sample treated by the method does not corrode dewatering equipment, and the low-temperature environment of 80-90 ℃ is easy to realize, so that the method is an effective and easy-to-realize dewatering method.
Claims (7)
1. A method for improving sludge dewatering by heat treatment and a flocculant is characterized by comprising the following steps:
1) heating a sludge sample to be treated to 80-90 ℃;
2) adding a certain amount of flocculating agent into the heated sludge, and performing magnetic stirring;
3) adding sulfuric acid into the sludge to adjust the pH value of the sludge; continuing magnetic stirring;
4) and (3) carrying out vacuum filtration on the treated sludge for 30min in a Buchner funnel under the pressure condition of 0.06MPa for dehydration.
2. The method for improving sludge dewatering by using heat treatment in combination with flocculant as claimed in claim 1, wherein the solid content in the sludge sample in step 1) is 13mg/L, and the optimal heating temperature is 85 ℃.
3. The method of claim 1, wherein the flocculant in step 2) is cationic polyacrylamide and is added in an amount of 10.0mg/g DS per 100ml of sludge sample.
4. The method for improving sludge dewatering by using heat treatment in combination with a flocculant according to claim 1, wherein the pH value in step 3) is 4 to 6.
5. The method of claim 4, wherein the pH is 6.
6. The method for improving sludge dewatering by using the heat treatment synergistic flocculant as claimed in claim 1, wherein the time for magnetic stirring in step 2) is 2min, and the time for magnetic stirring in step 3) is 28 min.
7. The method of claim 1, wherein the magnetic stirring speed is 150 rpm.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4221661A (en) * | 1978-06-20 | 1980-09-09 | Kurita Water Industries Ltd. | Method of dehydrating organic sludge |
| JPS5710400A (en) * | 1980-05-21 | 1982-01-19 | Upuraburenie Bodopurobodonooka | Method of treating sewage sludge |
| CN112608003A (en) * | 2021-01-25 | 2021-04-06 | 浙江工业大学 | Method for improving sludge dewatering |
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- 2021-12-15 CN CN202111530600.5A patent/CN114262132A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4221661A (en) * | 1978-06-20 | 1980-09-09 | Kurita Water Industries Ltd. | Method of dehydrating organic sludge |
| JPS5710400A (en) * | 1980-05-21 | 1982-01-19 | Upuraburenie Bodopurobodonooka | Method of treating sewage sludge |
| DE3120280A1 (en) * | 1980-05-21 | 1982-06-16 | Upravlenie vodoprovodno-kanalizacionnogo chozjajstva, Leningrad | Process for treating wastewater sludges |
| CN112608003A (en) * | 2021-01-25 | 2021-04-06 | 浙江工业大学 | Method for improving sludge dewatering |
Non-Patent Citations (1)
| Title |
|---|
| DONGQIN HE等: "Enhanced dewatering of activated sludge by acid assisted Heat–CaO2", 《JOURNAL OF HAZARDOUS MATERIALS 》 * |
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