CN109368985B - Sludge dewatering method - Google Patents
Sludge dewatering method Download PDFInfo
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- CN109368985B CN109368985B CN201811603554.5A CN201811603554A CN109368985B CN 109368985 B CN109368985 B CN 109368985B CN 201811603554 A CN201811603554 A CN 201811603554A CN 109368985 B CN109368985 B CN 109368985B
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- sludge
- conditioner
- dewatering method
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
- C02F11/121—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering
- C02F11/122—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering using filter presses
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
- C02F11/14—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents
Abstract
The invention belongs to the technical field of sludge treatment, and particularly discloses a sludge dewatering method, which comprises the steps of pre-reacting sludge with a conditioner M; adding a flocculating agent into the pre-reaction system, carrying out hydrothermal reaction under a closed condition, and finally carrying out solid-liquid separation to recover water in the pre-reaction system to obtain dry sludge; the conditioner M comprises industrial waste residue and an activating agent. The method has the advantages that the content of heavy metal in the sludge removed is low, and the harmlessness and the reduction of the sludge are realized.
Description
Technical Field
The invention relates to a sludge dewatering method, and belongs to the field of sludge reduction treatment.
Background
Since the last decade, China has become a big country for municipal sludge production, and annual sludge production has increased rapidly. In addition, with the push of the 'thirteen-five' plan, more sewage treatment plants can be built all over the country, and the annual production of the excess sludge is estimated to reach 6000 million tons. The sludge is unstable, easy to decay and has foul smell, and besides organic matters which are difficult to degrade and nutrient substances such as nitrogen and phosphorus, biological pollution sources such as heavy metal, pathogenic bacteria and parasites also exist, so the sludge is a semisolid pollutant which is difficult to treat. Therefore, the sludge must be properly treated and disposed, otherwise, the public environment is damaged, the human health is endangered, the social development is influenced, and the serious secondary pollution problem is caused.
The basic principle of sludge treatment and disposal is to reduce, stabilize and make harmless the sludge and realize the recycling of the sludge as much as possible, and the municipal sludge treatment has become an important problem which currently limits the healthy development of the biological method for treating sewage. At present, the main methods for sludge dehydration and reduction are a heat drying method and cold dehydration. The heat drying is a treatment process for evaporating the moisture of the sludge by utilizing external heat energy, the method has certain advantages in the aspects of sludge reduction and stabilization, is a more international common sludge drying technology at present, but has larger investment, high energy consumption, complex equipment and more difficult continuous and stable operation of a heat drying project; the cold dehydration mainly comprises alkaline dehydration and deep dehydration, wherein the alkaline dehydration is to add substances such as lime and the like into ferric chloride for conditioning and then squeeze dehydration, but because more solid substances are added, the water content of the dried sludge is reduced, but the effect is not very obvious. The deep dehydration technology is a novel sludge dehydration reduction technology which changes the existing form of the moisture in the sludge and separates the moisture in the sludge in a liquid form by adding a sludge conditioning agent.
The dehydration effect and the heavy metal passivation effect of the existing sludge dehydration method still need to be improved.
Disclosure of Invention
In order to solve the problems of low sludge dehydration degree and high heavy metal content in water after sludge dehydration, the invention aims to provide a deep dehydration method for municipal sludge, which aims to effectively remove water in the sludge, fix heavy metals in the sludge and avoid secondary pollution of the recovered effluent and the heavy metals in the sludge.
A sludge dewatering method, sludge and conditioner M carry on the pre-reaction; adding a flocculating agent into the pre-reaction system, carrying out hydrothermal reaction under a closed condition, and finally carrying out solid-liquid separation to recover water in the pre-reaction system to obtain dry sludge;
the conditioner M comprises industrial waste residue and an activating agent.
According to the invention, the sludge and the conditioner M are pre-reacted in advance, and then the hydrothermal reaction is carried out innovatively under the condition of adding the flocculating agent, so that the dehydration degree of the sludge is promoted, and not only can the heavy metals in the sludge be effectively fixed, but also the heavy metal pollution of the removed water and the residual dry sludge is avoided. The method effectively improves the dehydration performance of the sludge and passivates heavy metals in the sludge, not only solves the problem of treatment of the dehydrated sludge, but also can effectively reduce the problem of standard exceeding of the heavy metals removed from the sludge.
According to the invention, the sludge is subjected to hydrothermal modification under mild conditions after the pre-reaction, so that the dehydration performance of the sludge is effectively improved, further separation of moisture in the sludge and passivation of heavy metals are realized, and researches show that the moisture content of the sludge (dehydrated sludge) treated by the method disclosed by the invention can be reduced to 35%, and the sludge has the advantages of small investment, low operation cost, effective avoidance of secondary pollution and the like.
The sludge is municipal sludge. The water content is not lower than 80%; preferably 90 to 95%.
Researches find that the pretreatment of the sludge by using the conditioner M with the components is the key for ensuring the subsequent hydrothermal dehydration effect and the heavy metal passivation effect.
Preferably, the industrial waste residue comprises at least one of slag, phosphorous slag, fly ash liquid slag and boiling furnace slag.
The activating agent is sulfite, triethanolamine, sodium acetate, lignosulfonic acid, Na2CO3、NaOH、KOH、KAl(SO4)2·12H2O、KNO2、NaF、CaSO4At least one of (1).
In the conditioner M, the weight ratio of the industrial waste residue to the activating agent is 80-100: 5-20.
The conditioner M is a novel ash cementing material with wide application, and is prepared by mixing and grinding industrial waste residues (more than 80 percent) as main raw materials, wherein the industrial waste residues comprise slag, phosphorous slag, fly ash liquid slag, fluidized bed furnace slag and the like, and an activating agent in a certain proportion. And the material has excellent curing and dewatering performance, and does not need washing and screening.
Preferably, the amount of the conditioner M is 5-15% of the weight of the sludge (the sludge is calculated by wet weight); more preferably 8 to 15%. The sludge dewatering effect and the heavy metal passivation effect can be further improved under the preferable adding amount.
The pre-reaction is carried out with stirring.
Preferably, the pre-reaction time is 0.5 to 2 hours.
The pre-reaction process may be carried out at room temperature, preferably at a temperature of 10-40 ℃.
The inventor researches and unexpectedly finds that the time for adding the flocculating agent has influence on the hydrothermal dehydration and heavy metal passivation effects, and the flocculating agent is added into the pretreated system, so that the subsequent hydrothermal sludge dehydration effect can be synergistically improved, the content of heavy metals in sludge can be effectively fixed, and the content of heavy metals in effluent and the heavy metal secondary pollution of dry sludge can be effectively reduced.
Preferably, the flocculant is FeCl3、FeSO4、Al2(SO4)3、Fe2(SO4)3At least one of (1).
More preferably, the flocculant is FeCl3. It was found that the use of FeCl3The hydrothermal dehydration effect can be further improved unexpectedly, and the pollution of sludge heavy metal is further facilitated.
Preferably, the flocculant is used in an amount of 2-8% by weight of the sludge (wet weight); preferably 4-6%. The sludge dewatering is facilitated under the optimal range, the heavy metal passivation effect can be improved, and the heavy metal secondary pollution of the treated sludge and the heavy metal content of the effluent are further effectively reduced.
In the invention, the key to realize dehydration and heavy metal passivation is the adoption of hydrothermal reaction. Preferably, the hydrothermal reaction temperature is 80-185 ℃; preferably 90-145 ℃; more preferably 105-120 ℃. In the preferable range, the dehydration effect can be further improved, and in addition, the heavy metal passivation effect can be further improved.
Preferably, the hydrothermal reaction time is 0.1 to 0.5 h.
And (3) carrying out solid-liquid separation on the hydrothermal reaction system, and separating water in the hydrothermal reaction system, wherein the solid part is the treated dry sludge. The solid-liquid separation can be carried out by conventional means, such as filtration.
The invention discloses a preferable sludge dewatering method, which comprises the following specific steps:
(1) conveying the raw sludge with the water content of 90-95% to a conditioning kettle, adding a conditioning agent M, and pre-reacting for 0.5-2h under the stirring condition;
(2) conveying the sludge treated by the conditioning kettle to a hydrothermal modification conditioning kettle by a pump, and adding a modified conditioning medicament FeCl3The hydrothermal temperature is 80-185 ℃, and the stirring reaction is carried out for 0.1-0.5 h;
(3) conveying the sludge in the hydrothermal modification conditioning kettle to a diaphragm type filter press by using a screw pump, and performing filter pressing and dehydration to separate water in the sludge;
(4) the sludge enters a diaphragm type filter press for 0.2 to 1.5 hours, and a diaphragm of the filter press is pressurized by compressed air or pressurized water to obtain dehydrated dry sludge with the water content of 35 to 40 percent;
(5) and finally, conveying the dewatered mud cakes to a dry mud storehouse through a conveying device.
According to the invention, the pretreatment of the conditioner M with the component ratio plays a role in supporting a framework and constructing a composite flocculating constituent, the mechanical dehydration capacity of the sludge is effectively improved, a flocculating agent and a hydrothermal treatment means are further cooperated to effectively and synergistically improve the dehydration effect, and not only can the heavy metal in the sludge be fixed, but also the heavy metal content in the effluent and the heavy metal secondary pollution of the dry sludge are reduced.
Compared with the prior art, the application has the following obvious advantages and effects:
(1) the water content of the treated sludge can be reduced from more than 90 percent to 35 percent; the dewatering effect is excellent;
(2) deep dehydration of the sludge is realized under mild conditions, and the dehydrated sludge can be used for incineration, cement production, brick making or landfill disposal;
(3) the heavy metal content in the water removed from the sludge is low, the operation cost is low, and the harmlessness and the reduction of the sludge are realized.
Drawings
FIG. 1 is a graph showing the water content of the mudcake in examples 1 to 3 of the present invention and comparative examples 1 to 4.
FIG. 2 is a graph showing the data of the heavy metal content in the sludge dewatered in examples 1 to 3 of the present invention and comparative examples 1 to 4.
Detailed Description
In order to facilitate understanding of the invention, the invention will be described more fully and in detail with reference to the accompanying drawings and preferred embodiments, but the scope of the invention is not limited to the specific embodiments below.
Example 1
The invention relates to a mild hydrothermal modification dehydration method for sludge, which comprises the following raw materials: municipal sludge, conditioning agent M and modified agent FeCl3. The method comprises the following specific steps:
(1) raw sludge (water content of 92 wt.%) from Wuhan Sanjin Tan sewage treatment plant is conveyed to a conditioning kettle, and a conditioning agent M (wherein the industrial waste residue contains phosphorus slag, slag and boiling slag in a mass ratio of 1: 12: 4, and an activating agent is Na in a mass ratio of 8: 1: 4: 7)2CO3、NaOH、KAl(SO4)2·12H2O and CaSO4(ii) a The mass ratio of the industrial waste residue to the activating agent is 85:10), the addition amount of the conditioner M is 8 wt.% of the sludge amount, and the reaction is carried out for 1h under the stirring condition;
(2) conveying the sludge treated by the conditioning kettle to a hydrothermal modification conditioning kettle by a pump, and adding a modified conditioning medicament FeCl3The adding amount is 4 wt% of the sludge amount, the hydrothermal temperature is 105 ℃, and the stirring reaction is carried out for 0.5 h;
(3) conveying the sludge in the hydrothermal modification conditioning kettle to a diaphragm type filter press by using a screw pump, and performing filter pressing and dehydration to separate water in the sludge;
(4) the sludge enters a diaphragm type filter press for 0.5h, and a diaphragm of the filter press is pressurized by compressed air or pressurized water to obtain dehydrated dry sludge;
(5) and finally, conveying the dewatered mud cakes to a dry mud storehouse through a conveying device.
Example 2
The invention relates to a mild hydrothermal modification dehydration method for sludge, which comprises the following raw materials: municipal sludge, conditioning agent M and modified agent FeCl3. The method comprises the following specific steps:
(1) raw sludge (water content of 92 wt.%) from Wuhan Sanjin Tan sewage treatment plant is conveyed to a conditioning kettle, and a conditioning agent M (wherein the industrial waste residue contains phosphorus slag, slag and boiling slag in a mass ratio of 1: 12: 4, and an activating agent is Na in a mass ratio of 8: 1: 4: 7)2CO3、NaOH、KAl(SO4)2·12H2O and CaSO4(ii) a The mass ratio of the industrial waste residue to the activating agent is 85:10), the addition amount of the conditioner M is 15 wt.% of the sludge amount, and the reaction is carried out for 1.5h under the stirring condition;
(2) conveying the sludge treated by the conditioning kettle to a hydrothermal modification conditioning kettle by a pump, and adding a modified conditioning medicament FeCl3The adding amount is 4 wt% of the sludge amount, the hydrothermal temperature is 120 ℃, and the stirring reaction is carried out for 0.3 h;
(3) conveying the sludge in the hydrothermal modification conditioning kettle to a diaphragm type filter press by using a screw pump, and performing filter pressing and dehydration to separate water in the sludge;
(4) the sludge enters a diaphragm type filter press for 0.8h, and a diaphragm of the filter press is pressurized by compressed air or pressurized water to obtain dehydrated dry sludge;
(5) and finally, conveying the dewatered mud cakes to a dry mud storehouse through a conveying device.
Example 3
The invention relates to a mild hydrothermal modification dehydration method for sludge, which comprises the following raw materials: municipal sludge, conditioning agent M and modified agent FeCl3. The method comprises the following specific steps:
(1) raw sludge (water content of 92 wt.%) from Wuhan Sanjin Tan sewage treatment plant is conveyed to a conditioning kettle, and a conditioning agent M (wherein the industrial waste residue contains phosphorus slag, slag and boiling slag in a mass ratio of 1: 12: 4, and an activating agent is Na in a mass ratio of 8: 1: 4: 7)2CO3、NaOH、KAl(SO4)2·12H2O and CaSO4(ii) a The mass ratio of the industrial waste residue to the activating agent is 85:10), the addition amount of the conditioner M is 2 wt.% of the sludge amount, and the reaction is carried out for 1h under the stirring condition;
(2) conveying the sludge treated by the conditioning kettle to a hydrothermal modification conditioning kettle by a pump, and adding a modified conditioning medicament FeCl3The adding amount is 2 wt% of the sludge amount, the hydrothermal temperature is 135 ℃, and the stirring reaction is carried out for 0.4 h;
(3) conveying the sludge in the hydrothermal modification conditioning kettle to a diaphragm type filter press by using a screw pump, and performing filter pressing and dehydration to separate water in the sludge;
(4) the sludge enters a diaphragm type filter press for 0.5h, and a diaphragm of the filter press is pressurized by compressed air or pressurized water to obtain dehydrated dry sludge;
(5) and finally, conveying the dewatered mud cakes to a dry mud storehouse through a conveying device.
Comparative example 1
Compared with the example 1, the difference is that no conditioning agent M is added in the step (1), and the rest of pretreatment modes and process parameters are kept unchanged.
Comparative example 2
Compared with the example 2, the difference is only that the modified conditioning agent FeCl is not added in the step (2)3And the other pretreatment modes and process parameters are kept unchanged.
Comparative example 3
Compared with example 3, the difference is that the hydrothermal treatment (i.e. exposure) is not carried out in step (2), and the rest of the pretreatment modes and process parameters are kept unchanged.
Comparative example 4
Compared with the example 1, the difference is only that the modified conditioning agent FeCl is added in the step (1)3In the step (2), a modified conditioning agent FeCl is not added any more3And the other processing modes and process parameters are kept unchanged.
The method is characterized in that the heavy metal content in the sludge dewatered water is measured by referring to the national standard (GB3838-2002) and the water content of the mud cake is measured by referring to the national standard (GB 7172-1987). The water content of the sludge cake and the heavy metal content in the sludge dewatering water in examples 1 to 3 and comparative examples 1 to 4 are shown in fig. 1 and fig. 2, respectively, and the data values are shown in table 1.
TABLE 1
In conclusion, the conditioner M is adopted for pretreatment, and then hydrothermal treatment is carried out under a flocculating agent, so that the dehydration rate of the sludge can be effectively improved, and the heavy metal content of the discharged water can be reduced.
Researches also find that the conditioner M accounts for 8-15% of the weight of the wet sludge, the flocculant accounts for 4-6% of the weight of the wet sludge, and the sludge dehydration rate can be further improved and the heavy metal passivation effect can be further improved under the hydrothermal condition of 105-120 ℃.
Claims (7)
1. A sludge dewatering method is characterized in that sludge and a conditioner M are pre-reacted; adding a flocculating agent into the pre-reaction system, carrying out hydrothermal reaction under a closed condition, and finally carrying out solid-liquid separation to recover water in the pre-reaction system to obtain dry sludge;
the sludge is excess sludge;
the conditioner M comprises industrial waste residue and an activating agent;
the industrial waste residue comprises at least one of slag, phosphorous slag, fly ash liquid slag and fluidized bed furnace slag;
the activating agent is sulfite, triethanolamine, sodium acetate, lignosulfonic acid, Na2CO3、NaOH、KOH、KAl(SO4)2·12H2O、KNO2、NaF、CaSO4At least one of;
in the conditioner M, the weight ratio of the industrial waste residue to the activating agent is 80-100: 5-20 parts of;
the dosage of the conditioner M is 5-15% of the weight of the sludge;
the flocculating agent is FeCl3、FeSO4、Al2(SO4)3、Fe2(SO4)3At least one of;
the dosage of the flocculating agent is 2-8% of the weight of the sludge;
the hydrothermal reaction temperature is 80-185 ℃.
2. The sludge dewatering process according to claim 1, characterized in that the amount of conditioning agent M is 8-15% by weight of the sludge.
3. The sludge dewatering method according to claim 1, characterized in that the pre-reaction is carried out under stirring for a reaction time of 0.5-2 h.
4. The sludge dewatering method of claim 1, wherein the flocculant is used in an amount of 4-6% by weight of the sludge.
5. The sludge dewatering method as claimed in claim 1, wherein the hydrothermal reaction temperature is 105-120 ℃.
6. The sludge dewatering method of claim 1, wherein the hydrothermal reaction time is 0.1-0.5 h.
7. The sludge dewatering method of claim 1, wherein the water content of the sludge is not less than 80%.
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| CN109928593B (en) * | 2019-03-26 | 2022-05-03 | 江苏大学 | Method for deep dehydration of sludge hot water decoupling combined framework material |
| CN109867450B (en) * | 2019-03-30 | 2022-04-22 | 肇庆市珈旺环境技术研究院 | Sludge incineration ash cement and preparation and application thereof |
| CN110981157A (en) * | 2019-12-30 | 2020-04-10 | 肇庆市武大环境技术研究院 | Method for efficiently reducing and harmlessly treating sludge |
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| CN1239085A (en) * | 1998-06-12 | 1999-12-22 | 武汉水利电力大学 | Soil solidifying agent |
| JP2003236593A (en) * | 2002-02-15 | 2003-08-26 | Kurita Water Ind Ltd | Method for treating phosphorus containing organic sludge |
| CN103588365A (en) * | 2012-08-14 | 2014-02-19 | 中国石油化工股份有限公司 | Hydrothermal treatment method of municipal sludge |
| CN108675587A (en) * | 2018-04-27 | 2018-10-19 | 江苏大学 | A kind of method of sludge water heat catalytic oxidation deep dehydration |
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|---|---|---|---|---|
| CN1239085A (en) * | 1998-06-12 | 1999-12-22 | 武汉水利电力大学 | Soil solidifying agent |
| JP2003236593A (en) * | 2002-02-15 | 2003-08-26 | Kurita Water Ind Ltd | Method for treating phosphorus containing organic sludge |
| CN103588365A (en) * | 2012-08-14 | 2014-02-19 | 中国石油化工股份有限公司 | Hydrothermal treatment method of municipal sludge |
| CN108675587A (en) * | 2018-04-27 | 2018-10-19 | 江苏大学 | A kind of method of sludge water heat catalytic oxidation deep dehydration |
Non-Patent Citations (1)
| Title |
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| 《河道底泥重金属浸出毒性分析及其固化/稳定化效果》;侯浩波;《环境工程学报》;20150731;第9卷(第7期);3339-3344 * |
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