CN111560035A - Method for extracting phosphate from algae mud by using dimethyl ether - Google Patents

Method for extracting phosphate from algae mud by using dimethyl ether Download PDF

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CN111560035A
CN111560035A CN202010411570.5A CN202010411570A CN111560035A CN 111560035 A CN111560035 A CN 111560035A CN 202010411570 A CN202010411570 A CN 202010411570A CN 111560035 A CN111560035 A CN 111560035A
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dme
liquid
phosphate
algae
mud
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朱伟
李卓
王辰宇
牟彪
陈乐�
陈思鹏
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Hohai University HHU
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F9/00—Compounds containing elements of Groups 5 or 15 of the Periodic System
    • C07F9/02—Phosphorus compounds
    • C07F9/06—Phosphorus compounds without P—C bonds
    • C07F9/08—Esters of oxyacids of phosphorus
    • C07F9/09—Esters of phosphoric acids
    • C07F9/10—Phosphatides, e.g. lecithin
    • C07F9/103—Extraction or purification by physical or chemical treatment of natural phosphatides; Preparation of compositions containing phosphatides of unknown structure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D11/00—Solvent extraction
    • 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
    • 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
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2303/00—Specific treatment goals
    • C02F2303/06—Sludge reduction, e.g. by lysis

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Hydrology & Water Resources (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • General Health & Medical Sciences (AREA)
  • Molecular Biology (AREA)
  • Biochemistry (AREA)
  • Health & Medical Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Treatment Of Sludge (AREA)

Abstract

The invention relates to a method for extracting phosphate ester from algae mud by using dimethyl ether, which comprises the steps of placing algae mud formed after blue algae are fished in a reaction kettle, converting DME into liquid by an air pressure pump, and adjusting the polarity of the DME to be consistent with that of phosphate ester by adjusting reaction parameters of the reaction kettle, so as to dissolve the phosphate ester. Performing solid-liquid separation on the mixture, wherein the solid phase is dehydrated algae mud, the water content is reduced to 40 percent, and the subsequent landfill incineration requirement is met; separating the obtained liquid phase product, converting liquid DME into a gas state through normal temperature and reduced pressure, collecting and recycling, wherein the residual liquid phase product is rich in phosphate, and further extracting phosphorus element, thereby achieving the purposes of algae mud reduction and resource utilization.

Description

Method for extracting phosphate from algae mud by using dimethyl ether
Technical Field
The invention belongs to the field of resource environment, and particularly relates to a method for extracting phosphorus element by dissolving phosphate in algae mud by utilizing the dissolving characteristic of state dimethyl ether (DME) to organic matters.
Background
Blue algae is an aquatic organism and is divided into four types: cyanobacteria (Basketbalgae); oscillatoria cyanobacteria cell algae (oscillatorian sp); nostoc (Nostoc); hair weeds (Seaweed). Under the conditions that the lake water is seriously polluted by organic pollution, the nitrogen and phosphorus contents exceed the standards and are in a heavy eutrophication state, the blue algae can grow excessively when the lake water is exposed to a proper temperature (the temperature is about 18 ℃) and the like. Blue algae is green in nature, a large amount of floating algae cover the water surface like a layer of sticky green paint, and a beautiful name, namely blue algae bloom, is obtained by experts. During the blue-green algae outbreak, the dissolved oxygen in the water is consumed by the blue-green algae in large quantity, other aquatic organisms such as fish and the like die due to oxygen deficiency, and the water body not only changes color, but also has odor. For a long time, the lake loses functions and becomes a dead lake. The basic guiding idea of blue algae treatment is as follows: controlling the input of exogenous nutrient substances as much as possible; the load of endogenous nutrients is reduced; emergent algae removal and inhibition before and after the outbreak of hydration. At present, the main emergency treatment method for blue algae in China is blue algae fishing, the fished blue algae enters an algae-water separation station, algae mud is formed after flocculation dehydration, the water content of the dehydrated algae mud still reaches 89-95%, and the dehydrated algae mud is rich in nitrogen, phosphorus and other nutrient elements. The common algae mud disposal methods at present are landfill, composting, fermentation, drying and the like.
In China, if 5000t of algae are obtained from lakes every year, 525t of nitrogen and 62t of phosphorus are removed from the lakes, so that the algae are natural resources for blue-green algae. Among them, the recovery of phosphorus is a direction of much concern at present in China. DME dissolution and desorption technology is a new technology, and has a primary attempt in the fields of coal and sludge dehydration, for example, Simple extraction method of green blue-green micro-algae by dimethyl ether, Fuel90 (2011) 1264-1266, by Hideki Kanda et al, provides a Simple extraction method for extracting green crude oil from blue-green microalgae. The use of dimethyl ether as a biomass organic extraction solvent in biorefineries A user-oriented review, by Manual C.
However, no document is known about a method for extracting phosphorus from algal mud by using DME.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a method for extracting phosphate ester in algae mud by utilizing dimethyl ether, wherein the polarity of liquid DME is adjusted by adjusting reaction parameters, so that the phosphate ester in the algae mud is selectively dissolved and is added into an extraction liquid phase mixture, and then phosphorus element is further extracted, thereby achieving the purposes of reducing the algae mud and recycling the algae mud. And DME in the liquid phase mixture is converted into a gaseous state after being decompressed and then can be recycled after being re-pressurized and liquefied, so that the use loss of the dimethyl ether solvent is greatly reduced.
The invention is realized by the following technical scheme:
a method for extracting phosphate from algae mud by using dimethyl ether comprises the following steps:
placing the algae mud into a reaction kettle, converting DME into liquid by an air pressure pump, pressing the liquid into the reaction kettle, uniformly mixing the liquid with the algae mud, and dissolving phosphate ester of the algae mud by using the DME;
dimethyl ether (DME) is of the formula: h3COCH3Melting point-138.5 deg.C, boiling point-23 deg.C, water solubility 328 g/100 mL (20 deg.C), excellent miscibility, and compatibility with most polar and non-polar organic solvents. Colorless, tasteless, odorless gas at normal temperature and pressure, and liquid under pressure. In this step, gaseous DME is converted to a liquid state using an air-pressure pump.
The using amount of the liquid DME is 15-30 times of the water content of the algae mud, the reaction pressure is 0.5-2 MPa, the reaction temperature is 15-30 ℃, and the reaction time is 20-40 min.
The reaction kettle is provided with a stirrer, so that the DME and the algae mud are uniformly mixed, and the parameters of the stirrer are set as follows: the stirring speed is 60-120 rpm/min, and the stirring time is 20-40 min.
And (2) after the DME is dissolved, performing solid-liquid separation on the mixture, wherein the solid phase is dehydrated algae mud, the water content is reduced to 40%, and the requirements of landfill, incineration and other subsequent treatment are met.
The solid-liquid two phases are filtered and separated by setting the separation pressure difference to be 0.5-2 MPa, and the separation time is 1-2 min.
And (3) separating the obtained liquid-phase product, converting the liquid DME into a gas state at normal temperature and under reduced pressure, collecting and reusing the gas-phase product, wherein the residual liquid-phase product is rich in phosphate and can further recycle phosphorus in the phosphate.
The invention has the following beneficial effects:
(1) the algae mud has the defects of high water content, difficult dehydration and low treatment efficiency. The invention adopts DME wet method to extract phosphate in the algae mud, and has the advantages of easy separation and high efficiency, thereby providing a new idea for reducing the algae mud.
(2) By changing reaction conditions, the polarity of DME is adjusted to be consistent with that of phosphate, and complete dissolution of phosphate in the algae mud is achieved, so that the phosphate extraction rate is high and can reach 70%.
(3) DME is in a gas state at normal temperature and normal pressure, is converted into a liquid state after pressurization, exists in a liquid-phase product after phosphate in algae mud is dissolved, is converted into a gas state after pressure is relieved, and is easy to separate from the liquid-phase product.
(4) And the DME separated from the liquid phase product is pressurized and liquefied again and can be recycled, so that the cost is saved, and the energy utilization efficiency is improved.
Drawings
FIG. 1 is a flow chart of the present invention.
FIG. 2 is a schematic diagram of the connection relationship of the devices used in the present invention.
In fig. 2: DME gas tank; 2, a flow regulating valve; 3. 17: an air pressure pump; 4, a storage tank inlet valve; 5, a liquid DME temporary storage tank; 6, a storage tank outlet valve; 7, an inlet valve of the reaction kettle; 8, a reaction kettle; 9, a reactor operating parameter regulator; 10, a pressure regulating valve; 11, a gas-liquid separation tank; 12: a liquid flow valve; 13, gas flow valve; 14: a gas inlet valve; 15, a gas drying tank; 16, a gas outlet valve; 18, a recovery tank inlet valve; 19, a recovery tank; 20, a pressure control meter; DME recycle used inlet valve.
Detailed Description
The invention is further explained below with reference to the drawings and the examples.
The algae sludge used in the following examples was obtained from the hong Kong algae water separation station of yellow mud field of Tai lake, with a water content of 95% and a phosphate content of 27% of the dry weight of the algae sludge. The phosphate ester is a polar organic compound and comprises phosphoric acid monoester, diester and triester, is liquid at normal temperature, and has the specific gravity (20 ℃) of 1.165.
Fig. 1 is a flow chart of the present invention, and as shown in fig. 1, a method for extracting phosphate from algae mud by using dimethyl ether comprises the following steps:
step 1, placing algae mud in a reaction kettle 8, converting DME in a DME gas tank 1 into liquid by an air compression pump 3, feeding the liquid DME into a liquid DME temporary storage tank 5 from the gas tank through an output pipeline, injecting the liquid DME into the reaction kettle, dissolving phosphate in the algae mud, adjusting the use amount of the DME to be 15-30 times of the water content of the algae mud by a reaction kettle operation parameter adjuster 9, adjusting the reaction pressure to be 0.5-2 MPa, the reaction temperature to be 15-30 ℃, the reaction time to be 20-40 min, and the stirring speed of the reaction kettle to be 60-120 rpm/min, and the stirring time to be 20-40 min.
And 2, after the algae mud is dissolved by DME, reducing the pressure by a pressure regulating valve 10 of the reaction kettle, and carrying out solid-liquid two-phase separation on the product, wherein the separation pressure difference is set to be 0.5-2 MPa, and the separation time is 1-2 min. After solid-liquid separation, the solid phase is still left in the reaction kettle and is dehydrated algae mud, the water content is reduced from 95 percent to 40 percent, and the requirements of subsequent treatment and disposal such as landfill, incineration and the like can be met; the solid phase product can be taken out for subsequent treatment by opening the reaction vessel 8.
And 3, inputting the liquid-phase product after solid-liquid separation into a gas-liquid separation tank 11, converting DME in the liquid-phase product into a gas state at normal temperature, separating out the gas-phase product, sequentially opening a gas flow valve 13 and a gas inlet valve 14, enabling the DME to enter a drying tank 15 through a second output pipeline of the gas-liquid separation tank 11, performing pressurization liquefaction on the DME after drying by using an air pressure pump 17, enabling the DME to enter a recovery tank 20 from an output pipeline of the drying tank, and after collecting the liquid DME in the recovery tank 20, opening a DME recycling inlet valve 21 and injecting the DME into an output pipeline of a DME gas tank 1 to realize recycling. The liquid phase product after DME separation is a mixture of water, phosphate and other water-soluble products, and the phosphate is liquid at normal temperature and has specific gravity higher than that of water, so the phosphate can be separated after standing and layering.
Examples 1-6 are the results of examining the phosphate extraction under different reaction conditions, and the results are shown in Table 1:
TABLE 1
Figure DEST_PATH_IMAGE001
From examples 1, 2 and 3, it can be seen that the larger the mass ratio of DME to the water content in the algal mud, the higher the dehydration rate of algal mud and the extraction rate of phosphate. From examples 1 and 4, it can be understood that the longer the reaction time, the higher the dehydration rate of algal mud and the higher the extraction rate of phosphate ester. From examples 3 and 5, it can be understood that the higher the stirring speed, the higher the dehydration rate of the algal mud and the extraction rate of the phosphate ester. The viscosity of DME increases with increasing pressure, and generally low solvent viscosity has a beneficial effect on many extraction systems because it facilitates solvent mixing and penetration of the sample matrix. An increase in pressure will therefore result in a reduction in the efficiency of DME extraction, but a change in pressure will not result in a polarity mutation of the DME. To balance the conversion of gaseous DME to the liquid state and the extraction effect, the inventors set the pressure to 0.5 MPa.
Example 7 reaction temperatureExamination of extraction ratio of phosphoric acid ester
Polarity determines the key to solubility becausePhosphoric acid ester is a polar organic compoundAccording to the principle of similarity and compatibility, the method needs to be adjusted DME is a polar solvent, and the larger the dielectric constant, the more polar, whereas the smaller the dielectric constant, the less polar.
Dielectric constant between 0 and 5: non-polar
The dielectric constant is 5-30: medium (or semi-polar)
Dielectric constant > 30: high polarity
The inventors examined the parameters (DME relative dielectric constant) affecting the phosphate extraction rate at different temperatures as shown in Table 2, and found that the temperature increased, the dielectric constant decreased, and the phosphate extraction rate decreased. (phosphate extraction in DME: H2The reaction time was 35min and the stirring speed was 60rpm, measured at 30 times the O mass ratio).
TABLE 2
Figure DEST_PATH_IMAGE003
Example 8
FIG. 2 is a schematic diagram of the connection relationship of the devices used in the present invention. As shown in fig. 2, wherein the output pipeline of the DME gas tank 1 is connected to a liquid DME temporary storage tank 5 through a flow regulating valve 2; an output pipeline of the liquid DME temporary storage tank 5 is connected with an input pipeline of the reaction kettle 8 through a storage tank outlet valve 6 and a reaction kettle inlet valve 7 in sequence; the output pipeline of the reaction kettle 8 is connected with the input pipeline of a gas-liquid separation tank 11 through a pressure regulating valve 10; a first output pipeline of the gas-liquid separation tank 11 outputs liquid rich in phosphate through a liquid flow valve 12, and phosphorus elements in the liquid can be further extracted.
A second output pipeline of the gas-liquid separation tank 11 is connected with an input pipeline of a drying tank 15 through a gas flow valve 13 and a gas inlet valve 14 in sequence; the output duct of the drying tank 15 is connected to a recovery tank 19 through a gas outlet valve 16 and a recovery tank inlet valve 18; the outlet line of the recovery tank is connected to the outlet line of the DME gas tank via a DME recycle inlet valve 21.

Claims (6)

1. A method for extracting phosphate from algae mud by using dimethyl ether is characterized by comprising the following steps:
placing the algae mud into a reaction kettle, converting DME into liquid by an air pressure pump, pressing the liquid into the reaction kettle, uniformly mixing the liquid with the algae mud, and dissolving phosphate ester of the algae mud by using the DME;
step (2), after dissolving phosphate ester by DME, carrying out solid-liquid separation on the mixture, wherein the solid phase is dehydrated algae mud, the water content is reduced to 40%, and the requirement of subsequent landfill incineration is met;
and (3) separating the obtained liquid-phase product, converting the liquid DME into a gas state at normal temperature and under reduced pressure, collecting the gas-phase product for reuse, and further extracting the residual liquid-phase product rich in phosphate to obtain the phosphorus element.
2. The method for extracting phosphate from algal mud by using dimethyl ether according to claim 1, wherein in the step (1), the amount of the liquid DME is 15-30 times of the water content of the algal mud.
3. The method for extracting phosphate from algal mud by using dimethyl ether according to claim 1, wherein in the step (2), the pressure of a reaction kettle for dissolving phosphate by DME is 0.5-2 MPa, the temperature is 15-30 ℃, and the reaction time is 20-40 min.
4. The method for extracting phosphate from algal mud by using dimethyl ether according to claim 1, wherein in the step (2), the solid-liquid two phases are separated by filtration by setting a separation pressure difference, the separation pressure difference is set to be 0.5-2 MPa, and the separation time is 1-2 min.
5. The method for extracting phosphate from algal mud by using dimethyl ether according to claim 3, wherein in the step (2), the polarity of DME is adjusted to be consistent with that of phosphate by adjusting the pressure and temperature of the reaction kettle, so as to dissolve the phosphate.
6. The method for extracting phosphate from algae mud by using dimethyl ether as claimed in claim 1, wherein in the step (1), the algae mud is waste biomass formed by flocculating and dewatering through an algae-water separation station after the blue algae is salvaged, and is rich in phosphorus element, and the water content is 89% -95%.
CN202010411570.5A 2020-05-15 2020-05-15 Method for extracting phosphate from algae mud by using dimethyl ether Pending CN111560035A (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011053867A1 (en) * 2009-10-30 2011-05-05 Aurora Algae, Inc. Systems and methods for extracting lipids from and dehydrating wet algal biomass
CN102559375A (en) * 2010-11-30 2012-07-11 新奥科技发展有限公司 Method for extracting greasy from microalgae
CN108129420A (en) * 2016-12-01 2018-06-08 云南爱尔康生物技术有限公司 A kind of method of dimethyl ether fluid extraction Phaeodactylum tricornutum fucoxanthin

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011053867A1 (en) * 2009-10-30 2011-05-05 Aurora Algae, Inc. Systems and methods for extracting lipids from and dehydrating wet algal biomass
CN102559375A (en) * 2010-11-30 2012-07-11 新奥科技发展有限公司 Method for extracting greasy from microalgae
CN108129420A (en) * 2016-12-01 2018-06-08 云南爱尔康生物技术有限公司 A kind of method of dimethyl ether fluid extraction Phaeodactylum tricornutum fucoxanthin

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Application publication date: 20200821