CN111547990A - Method for dissolving organic matters and water in municipal sludge by using liquid dimethyl ether and separating and dehydrating - Google Patents
Method for dissolving organic matters and water in municipal sludge by using liquid dimethyl ether and separating and dehydrating Download PDFInfo
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- CN111547990A CN111547990A CN202010411535.3A CN202010411535A CN111547990A CN 111547990 A CN111547990 A CN 111547990A CN 202010411535 A CN202010411535 A CN 202010411535A CN 111547990 A CN111547990 A CN 111547990A
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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
- C02F11/147—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents using organic substances
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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
- C02F11/123—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering using belt or band filters
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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
- C02F11/127—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering by centrifugation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic compounds
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- Life Sciences & Earth Sciences (AREA)
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- Environmental & Geological Engineering (AREA)
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- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Treatment Of Sludge (AREA)
Abstract
The invention discloses a method for dissolving organic matters and water in municipal sludge and separating and dehydrating by liquid dimethyl ether, wherein the organic matters and water in the municipal sludge are dissolved by the liquid dimethyl ether, so that the water in the municipal sludge is changed into free liquid which is easy to separate from particles, and liquid substances enter a separation container in a suction filtration-like mode under the action of pressure difference of high pressure of a reaction kettle and relative low pressure of the separation container. The gas phase product dimethyl ether after the reaction can be recycled, and the solid-liquid phase product can be reused. Compared with the traditional municipal sludge deep dehydration method, the method can reduce the water content of the sludge to 30 percent, has low energy consumption and does not cause secondary pollution.
Description
Technical Field
The invention relates to a method for dissolving municipal sludge organic matters and water by using liquid dimethyl ether (DME) and separating and dehydrating the municipal sludge organic matters and the water, and belongs to the technical field of environmental engineering and sludge treatment.
Background
At present, municipal sludge in China is huge in generation amount, but most of the commonly used co-processing methods such as co-firing or plate-and-frame filter pressing dehydration, mixing and landfill and the like at present need auxiliary measures such as deep dehydration, pre-drying, addition of high-calorific-value substances and the like, so that the problems of high cost, complex rear-end conditions, final path exit and the like seriously trouble the sustainable operation of sludge treatment facilities, and become a great problem of environmental management and urban management. Therefore, the core of the current Chinese sludge treatment technology lies in the deep dehydration problem, and the current deep dehydration and drying technologies all suffer from the problems of cost and subsequent treatment. The liquid Dimethyl Ether has a mass solubility to water of about 6% at room temperature (hollow, fatty, liquid-soluble and solid soluble of Dimethyl Ether of methyl ethyl and liquid soluble of methyl ethyl and water, and Fluid phase Equib, 1988), and has been used in the field of dehydration of subbituminous coals to find dehydration rates of more than 90% (Kanda et al. energy- fi. biological dehydration Using liquid fi. Dimethyl Ether, Fuel, 2010), while the liquid Dimethyl Ether has a mass solubility to lipids (vegetable, organic soluble, fatty, liquid soluble and liquid soluble of fatty acids, solvent Extraction Research and Development, 2017) and water soluble Proteins (Hiroka FURUKAWA et al. Use of liquid dimethyl Ether for the Extraction of Proteins from soluble Tissues, Solvent Extraction Research and Development, 2016). In addition, the Water content of sludge can be simply divided into free Water and bound Water according to studies by researchers (Mikkelsen and Keiding, physical-chemical characteristics of full-scale Water walls with interference to drainage, Water research, 2002), among which bound Water exists mainly in a form bound to organic matter.
Although the researchers mentioned before adopting DME to dewater sludge (Kanda H, Deodorization and dehydration of biochemical by using dimethyl ether, Water Environ Res, 2011), the reaction time and reaction temperature of dewatering are not discussed, and a flow type reaction device is mostly adopted, so that the use amount of dimethyl ether is large.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides the method for dissolving the organic matters and water in the municipal sludge by adopting the liquid dimethyl ether (DME) and separating and dehydrating the organic matters and the water, the organic matters in the sludge are dissolved by the liquid dimethyl ether to release a large amount of sludge-bound water, the dehydration efficiency is obviously improved, the use amount of the dimethyl ether is greatly reduced, and compared with the traditional municipal sludge deep dehydration method, the method can reduce the water content of the sludge to 30 percent.
In order to achieve the above object, the present invention adopts the following technical solutions:
the method for dissolving municipal sludge organic matters and water by using liquid dimethyl ether (DME) and separating and dehydrating comprises the following steps of:
(1) and pressurizing and converting gaseous dimethyl ether into liquid dimethyl ether by using a pneumatic pump, and storing the liquid dimethyl ether in a temporary storage tank for later use, wherein the pressure is 0.5-3 MPa.
(2) Putting the sludge dewatered by a belt type dewatering machine or a centrifugal machine adopted in a sewage treatment plant into a pressure-resistant reaction kettle. Withstand voltage reation kettle is equipped with agitating unit and external water bath heating device, and withstand voltage reation kettle's top is equipped with the nitrogen gas filling opening and can changes reaction pressure. The stirring speed of the stirring device is 0-1500 r/min (the endpoint is not taken as 0).
(3) And (3) introducing the liquid dimethyl ether in the temporary storage tank into the pressure-resistant reaction kettle, and controlling the mass ratio of the liquid dimethyl ether to the water content of the sludge to be 0-25 times (not taking an endpoint of 0), preferably 10-13 times. Opening a stirring device of the pressure-resistant reaction kettle and reacting for 0-120 min, preferably, the reaction time is 30-40 min, and the reaction temperature is 20-100 ℃.
(4) After the reaction is finished, a valve at the lower end of the pressure-resistant reaction kettle is opened to carry out solid-liquid separation, the dewatered sludge is left in the reaction kettle to be reused, and the liquid phase enters a gas-liquid separation tank.
In the step, the solid-liquid separation is realized by utilizing the pressure difference between the reaction kettle and the gas-liquid separation tank.
(5) And decompressing the gas-liquid separation tank, gasifying the DME in the liquid phase into a subsequent drying tank, drying, pressurizing and storing for reutilization.
(6) Opening a valve at the lower end of the gas-liquid separation tank to collect the removed liquid-phase product, distilling and separating the obtained liquid-phase product to obtain a water phase and an oil phase, reprocessing the water phase, and utilizing the oil phase.
Has the advantages that:
(1) the water solubility of the liquid dimethyl ether at room temperature is about 6 percent, so the liquid dimethyl ether can dissolve part of water in the sludge in the dehydration process. More importantly, however, the liquid dimethyl ether can dissolve organic matters in the sludge or destroy a structure formed by the combination of the organic matters and water to release a large amount of combined water, so that the water in the sludge is changed into free liquid which is easy to separate from particles, and the liquid substances enter the separation container in a suction filtration-like manner under the action of pressure difference between the high pressure of the reaction kettle and the relatively low pressure of the separation container.
(2) Raw sludge is a colloidal semi-solid material in which water is uniformly combined with particulate matter, but becomes a solid-liquid separated two-phase material after reacting with DME. The flow of liquid in the two-phase materials to the low-pressure container promotes the water to be removed from the sludge, and the total amount of the water to be removed can reach more than 90 percent of the water.
(3) DME is gaseous under normal temperature and normal pressure, and liquid DME after the reaction returns to gaseous state through decompression, easily separates with the product, can recycle, and the energy consumption is little, and can not cause secondary pollution.
Drawings
FIG. 1 is a process flow diagram of the present invention.
Wherein: 1, a pneumatic pump; 2, a temporary storage tank; 3, a pressure gauge; 4, a stirring device; 5, a pressure-resistant reaction kettle; 6, externally connecting a water bath heating device; 7, a gas-liquid separation tank; 8, drying the tank; 9, a DME recovery tank; 10, gaseous DME; 11, liquid DME; 12, municipal sludge; 13, liquid-phase product; 14, DME recovered.
Detailed Description
The principles and features of this invention are described below in conjunction with examples which are set forth to illustrate, but are not to be construed to limit the scope of the invention.
FIG. 1 is a process flow diagram of the present invention, referring to FIG. 1, a method for dissolving municipal sludge organic matter and water by liquid dimethyl ether (DME) and performing separation and dehydration comprises the following steps:
(1) the gas dimethyl ether is pressurized and converted into liquid dimethyl ether by using the pneumatic pump 1 and stored in the temporary storage tank 2 for later use, and the pressure is 0.5-3 MPa.
(2) Sludge obtained after dehydration by a belt dehydrator or a centrifugal machine in a sewage treatment plant is put into a pressure-resistant reaction kettle 5. Withstand voltage reation kettle is equipped with agitating unit 4 and external water bath heating device 6, and withstand voltage reation kettle's top is equipped with the nitrogen gas filling opening and can changes reaction pressure. The stirring speed of the stirring device 4 is 0 to 1500r/min (the endpoint 0 is not selected).
(3) And (3) introducing the liquid dimethyl ether in the temporary storage tank into the pressure-resistant reaction kettle, and controlling the mass ratio of the liquid dimethyl ether to the water content of the sludge to be 0-25 times (not taking an endpoint of 0), preferably 10-13 times. Opening a stirring device of the pressure-resistant reaction kettle and reacting for 0-120 min, preferably, the reaction time is 30-40 min, and the reaction temperature is 20-100 ℃.
(4) After the reaction is finished, a valve at the lower end of the pressure-resistant reaction kettle is opened to carry out solid-liquid separation, the dewatered sludge is left in the reaction kettle to be reused, and the liquid-phase product 13 enters a gas-liquid separation tank 7. In the step, the solid-liquid separation is realized by utilizing the pressure difference between the reaction kettle and the gas-liquid separation tank.
(5) Decompressing the gas-liquid separation tank 7, gasifying DME in the liquid phase, feeding the gasified DME into a subsequent drying tank 8, drying the DME by calcium chloride 15, pressurizing the DME for storage for reuse, opening a valve at the lower end of the gas-liquid separation tank 7 to collect the removed liquid-phase product, distilling and separating the obtained liquid-phase product to obtain a water phase and an oil phase, reprocessing the water phase and utilizing the oil phase.
The process conditions for examples 1-6 are shown in Table 1:
50g of municipal dewatered sludge (with water content of 85%) of a sewage plant is taken and put into a reaction kettle, then liquid dimethyl ether is introduced, the mass ratio of the liquid dimethyl ether to the water content of the sludge, the reaction time and the reaction temperature are controlled, the stirring speed is 750r/min, and the water content of the sludge is measured by adopting a drying method after the reaction is finished.
TABLE 1
In Table 1, DME: H2And O is the mass ratio of the liquid dimethyl ether to the water content of the municipal sludge.
As is apparent from table 1, the larger the amount of liquid dimethyl ether (mass ratio), the longer the reaction time, and the higher the reaction temperature, the lower the water content of the sludge, and the larger the dehydration rate, the more preferable amount of liquid dimethyl ether (mass ratio) is 13 times, and the more preferable reaction time is 40 min. When the mass ratio is 13 times and the reaction time is 40min at room temperature, the water content of the sludge is 35%, and the amount of the removed water is far higher than that of the water removed when the dissolution rate of the liquid dimethyl ether to the water is 6% at room temperature, because the liquid dimethyl ether not only dissolves the water but also dissolves organic matters in the sludge to cause a large amount of combined water to be released, the water in the sludge is changed into free liquid which is easy to separate from particles.
Comparative example 1
5kg of municipal dewatered sludge (water content 85%) from a sewage plant was taken, treated without adding liquid dimethyl ether, subjected to plate-and-frame filter-pressing dewatering at the same pressure as that used in the solid-liquid separation in example 1, and the water content of the sludge after the reaction was measured to be 68% according to the test method in example 1.
Comparative example 2
50 municipal dewatered sludge (water content 85%) of a sewage plant is diluted with water until the water content is 95%, liquid dimethyl ether is not added for treatment, vacuum filtration dewatering is performed by the same pressure difference as that in solid-liquid separation in example 1, and the water content of the sludge after reaction is 83% according to the test method in example 1.
According to comparative examples 1 and 2, the water in the municipal sludge cannot be removed only by adopting the pressure difference during solid-liquid separation in example 1 without adding liquid dimethyl ether for treatment, and the water in the municipal sludge is changed into free liquid which is easy to separate from particles by dissolving organic matters and water after adding the liquid dimethyl ether, so that liquid substances are separated into a separation container in a suction filtration-like manner under the action of the pressure difference between the high pressure of a reaction kettle and the relatively low pressure of the separation container.
Although the present application has been described with reference to a few embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.
Claims (8)
1. The method for dissolving organic matters and water in municipal sludge and separating and dehydrating by using liquid dimethyl ether is characterized by comprising the following steps of:
(1) pressurizing gaseous dimethyl ether into liquid dimethyl ether by using a gas pressurizing pump, and storing the liquid dimethyl ether in a temporary storage tank for later use;
(2) directly selecting municipal sludge and putting the sludge into a pressure-resistant reaction kettle;
(3) introducing liquid dimethyl ether into a pressure-resistant reaction kettle, opening a stirring device of the pressure-resistant reaction kettle for reaction, dissolving organic matters in municipal sludge or destroying the combination of the organic matters and water to cause the release of combined water while dissolving the water in the municipal sludge, so that the combined water in the municipal sludge is changed into free liquid which is easy to separate from particles, and after the reaction with the liquid dimethyl ether, the sludge is changed into a solid-liquid separated two-phase substance from a colloidal semi-solid substance which is formed by uniformly combining water and particle substances;
(4) after the reaction is finished, opening a valve at the lower end of the pressure-resistant reaction kettle, carrying out solid-liquid separation, leaving the dehydrated sludge in the reaction kettle for reuse, and allowing the separated liquid to enter a gas-liquid separation tank;
(5) decompressing the gas-liquid separation tank, gasifying DME in the separation liquid into a subsequent drying tank, drying, pressurizing, storing for reuse, and opening a valve at the lower end of the gas-liquid separation tank to collect the removed liquid-phase product; the resulting liquid phase is used by distillation of the oil phase and the aqueous phase is worked up again.
2. The method for dissolving organic matters and water in municipal sludge and performing separation and dehydration according to claim 1, wherein in step (2), the municipal sludge is sludge dewatered by a belt dewaterer or a centrifuge of a sewage treatment plant.
3. The method for dissolving organic matters and water in municipal sludge and separating and dehydrating by using liquid dimethyl ether according to claim 1, wherein in the step (3), a nitrogen injection port is arranged at the top of the pressure-resistant reaction kettle, and the reaction pressure is adjusted to be 0.5-3 MPa by adjusting the content of nitrogen.
4. The method for dissolving organic matters and water in municipal sludge and separating and dehydrating by using liquid dimethyl ether according to claim 1, wherein in the step (3), the reaction time is 0-120 min; the reaction temperature is 20-100 ℃.
5. The method for dissolving organic matters and water in municipal sludge and separating and dehydrating by using liquid dimethyl ether according to claim 1, wherein in the step (3), the mass ratio of the liquid dimethyl ether to the water content in the municipal sludge is controlled to be 0-25 times.
6. The method for dissolving organic matters and water in municipal sludge and separating and dehydrating by using liquid dimethyl ether according to claim 1, characterized in that in step (5), the solid-liquid separation is mainly realized by the pressure difference between the reaction kettle and the gas-liquid separation tank.
7. The method for dissolving organic matters and water in municipal sludge and separating and dehydrating by using liquid dimethyl ether according to claim 1, wherein in the step (3), the reaction time is 30-40 min; the reaction temperature is 20-100 ℃.
8. The method for dissolving organic matters and water in municipal sludge and separating and dehydrating by using liquid dimethyl ether according to claim 1, wherein in the step (3), the mass ratio of the liquid dimethyl ether to the water content in the municipal sludge is controlled to be 10-13 times.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113652256A (en) * | 2021-08-02 | 2021-11-16 | 南京信息工程大学 | Process for synchronously preparing biological oil with low nitrogen content in sludge and hydrothermal carbon |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113652256A (en) * | 2021-08-02 | 2021-11-16 | 南京信息工程大学 | Process for synchronously preparing biological oil with low nitrogen content in sludge and hydrothermal carbon |
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Application publication date: 20200818 |