CN110550735A - Preparation method of coated slow-release carbon source and product thereof - Google Patents
Preparation method of coated slow-release carbon source and product thereof Download PDFInfo
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- CN110550735A CN110550735A CN201910840952.7A CN201910840952A CN110550735A CN 110550735 A CN110550735 A CN 110550735A CN 201910840952 A CN201910840952 A CN 201910840952A CN 110550735 A CN110550735 A CN 110550735A
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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
- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/28—Anaerobic digestion processes
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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
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/16—Nitrogen compounds, e.g. ammonia
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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
- C02F2305/00—Use of specific compounds during water treatment
- C02F2305/06—Nutrients for stimulating the growth of microorganisms
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W10/00—Technologies for wastewater treatment
- Y02W10/10—Biological treatment of water, waste water, or sewage
Abstract
the invention provides a preparation method of an enveloped slow-release carbon source and a product thereof. The coated slow-release carbon source is composed of a film obtained by coating m-phenylenediamine and trimesoyl chloride with a slow-release carbon source core obtained from polyvinyl alcohol and starch through interfacial reaction. The carbon source core prepared by the freezing and thawing circulation method has the advantages of simple operation and easy control in the process, and the prepared carbon source has a more stable structure. An interface polymerization preparation coating method is adopted, and a layer of organic porous membrane is coated outside the coating to form a coated slow-release carbon source, so that the carbon source can be slowly and stably released for a long time, and the released carbon source can be utilized by microorganisms, thereby effectively strengthening the denitrification process. Starch is used as a carbon source, PVA is used as a framework, the source of the starch is wide, the interface polymerization layer is non-toxic, the starch-PVA-. The coated slow-release carbon source belongs to a recyclable material, avoids the problem of secondary pollution in the using process, and has the advantages of energy conservation, environmental protection and great economic and social values.
Description
Technical Field
The invention belongs to the field of sewage treatment, and relates to a controlled-release carbon source composite material for enhancing biological denitrification and a preparation method thereof.
Background
one of the characteristics of water quality in China is that the carbon nitrogen ratio is low and is about 3.3-8.5. The removal rate of TN of the urban sewage with low carbon-nitrogen ratio after biological treatment is very low, and the national first-class A discharge standard is difficult to achieve, so the carbon source becomes a limiting factor of the denitrification process. And the secondary treatment effluent needs to be subjected to advanced treatment frequently because TN cannot reach the primary A standard, and the carbon source in the water is not enough for denitrification, so that an additional carbon source is needed. In the denitrification process, if the carbon source is insufficient, the accumulation of intermediate product nitrite can be caused, and if the carbon source is excessive, the denitrification can be inhibited in turn, and the organic matters in the effluent are excessive, so that the effluent does not reach the standard. Therefore, the method has important significance for seeking a high-efficiency and economic slow-release carbon source for sewage with low carbon-nitrogen ratio.
Many scholars explore the denitrification process by adding liquid carbon sources such as methanol, acetic acid, glucose and the like, and find that the addition of the liquid carbon sources is easy to cause insufficient or excessive addition of the carbon sources, overlong acclimation time of the activated sludge, poor settling property of microorganisms and complex system operation. Based on the defects, many researchers at home and abroad try to adopt various new methods to provide electron donors for the denitrification process so as to develop a more perfect and efficient denitrification process. The technical key of the process is that the supply quantity of the electron donor can adaptively meet the demand quantity of denitrification, and the process has certain fluctuation resistance to the water quantity of treated water. The research of the technology has practical significance for promoting the sewage recycling process and improving the quality of the reclaimed water.
in recent years, many researchers have found a variety of ways to find a novel carbon source that is highly efficient and free of by-products and can replace conventional carbon sources. The novel carbon source mainly comprises natural solid organic matters which are cheap and easy to obtain. The solid carbon source can be used as a carbon source and a biological carrier, so that the problem of the adding amount of the traditional carbon source can be solved, and a safe and stable living environment can be provided for denitrifying flora. The above studies are in the preliminary research stage of the laboratory, and no practical application report is found. Therefore, the development of safe, continuous, stable and efficient artificial preparation of the solid-phase organic carbon source carrier and the exploration of the action mechanism of the solid-phase organic carbon source carrier in the groundwater polluted by the nitrate are the core problems to be further solved by the groundwater biological denitrification technology.
Disclosure of Invention
Aiming at the problem of poor slow release effect of an organic carbon source in the prior enhanced biological denitrification, the invention provides the coated slow release carbon source composite material for enhancing the biological denitrification, which has good carbon source controlled release effect and can not cause secondary pollution in the enhanced denitrification.
the invention also aims to provide a preparation method of the coated slow-release carbon source.
In order to achieve the purpose, the invention adopts the following technical scheme.
A preparation method of an enveloped slow-release carbon source for enhancing biological denitrification nitrogen removal comprises the following steps:
(1) Adding polyvinyl alcohol (PVA) and starch into water, mixing uniformly, heating to dissolve, and standing at room temperature;
(2) pouring the ingredients in the step (1) into a mold, freezing and molding, unfreezing at room temperature, and drying to obtain a slow-release carbon source core;
(3) Immersing the slow-release carbon source core prepared in the step (2) into a 2wt% m-phenylenediamine (MPD) aqueous solution, and airing; then immerging into 0.1% w/v n-hexane solution of trimesoyl chloride (TMC) and drying.
In the step (1), the mass ratio of the polyvinyl alcohol to the starch is 1:1-1: 3. The alcoholysis degree of the polyvinyl alcohol is more than or equal to 99 percent.
in the step (1), the mass ratio of the total mass of the polyvinyl alcohol and the starch to the water is 1: 3-10.
In the step (1), the heating temperature is 95-99 ℃, and the heating time is 1-2 h.
In the step (2), the freezing temperature is-20 ℃. Preferably, the process of freeze-forming-thawing at room temperature is repeated 2-3 times.
In the step (2), the mould is cubic; preferably, the die has a side length of 1-1.5 cm.
In the step (3), the dipping time is 1-4 min.
An enveloped slow-release carbon source obtained by the preparation method. The carbon source core is formed by wrapping an organic porous membrane on the outer layer of a carbon source core formed by starch and polyvinyl alcohol.
An application of the coated slow-release carbon source in sewage enhanced biological denitrification.
The dosage of the coated slow-release carbon source is 3-5 g/L.
The invention has the following advantages:
The preparation method adopts the carbon source prepared by the freezing and thawing cycle method, the process is simple to operate and easy to control, and the prepared carbon source has a more stable structure. An interface polymerization preparation coating method is adopted, and a layer of organic porous membrane is coated outside the coating to form a coated slow-release carbon source, so that the carbon source can be slowly and stably released for a long time, and the released carbon source can be utilized by microorganisms, thereby effectively strengthening the denitrification process. Starch is used as a carbon source, PVA is used as a framework, the source of the starch is wide, the interface polymerization layer is non-toxic, the starch-PVA-. The coated slow-release carbon source belongs to a recyclable material, avoids the problem of secondary pollution in the using process, and has the advantages of energy conservation, environmental protection and great economic and social values.
drawings
FIG. 1 is a schematic structural diagram of an encapsulated slow-release carbon source;
FIG. 2 is the COD and nitrate nitrogen removal for samples 3, 12;
FIG. 3 is the COD and nitrate nitrogen removal for samples 4, 13;
FIG. 4 is the COD and nitrate nitrogen removal for samples 5, 14;
FIG. 5 is the COD and nitrate nitrogen removal for samples 1, 2, 3;
FIG. 6 is the COD and nitrate nitrogen removal for samples 3, 4, 5;
FIG. 7 is the COD and nitrate nitrogen removal for samples 3, 6, 9;
FIG. 8 is the COD and nitrate nitrogen removal for samples 4, 7, 10;
FIG. 9 shows COD and nitrate nitrogen removal for samples 5, 8, 11.
Detailed Description
The present invention will be further described with reference to the following examples and drawings, but the present invention is not limited to the following examples.
EXAMPLE 1 preparation of Slow-Release carbon Source
Preparing different slow-release carbon sources or enveloped slow-release carbon sources according to different raw material quality and parameter controls in the table 1:
TABLE 1 raw material proportioning and parameter control of slow-release carbon source
samples 1-11 were prepared as follows:
(1) Weighing starch and PVA, adding deionized water, mixing completely, heating in water bath to gradually raise the temperature of water from room temperature to 95 ℃, and stirring in 95 ℃ water bath for 1h to obtain a blend;
(2) Pouring the blend into a cubic grinding tool with the side length of 1.3cm, freezing for 20h in a refrigerator with the temperature of-20 ℃, unfreezing for 4h at room temperature, circulating for 3 times of freezing and unfreezing, drying for 24h at the temperature of 60 ℃ after demolding, and storing in an oxygen-isolated manner for later use;
(3) dissolving 2g of m-phenylenediamine in 98g of water to prepare a 2wt% MPD solution; 0.1g of trimesoyl chloride is dissolved in 100mL of n-hexane to prepare TMC solution with the mass concentration of 0.1% w/v; putting the slow-release carbon source core obtained in the step (2) into MPD solution, fully soaking, putting into an oven, and drying for 5min at 60 ℃; and then putting the dried slow-release carbon source into a TMC solution, fully soaking, putting into an oven, drying at 60 ℃ for 5min to obtain the coated slow-release carbon source, and storing in an oxygen-isolated manner for later use.
Samples 12-14 were prepared by the above steps (1) - (2).
EXAMPLE 2 Effect of adding different carbon sources on removal of nitrate Nitrogen
the nitrate nitrogen removal rate of the different samples prepared in example 1 on the wastewater was tested:
(1) Preparing simulated wastewater, namely adding potassium nitrate, monopotassium phosphate and hydrochloric acid into tap water which is placed for one day to ensure that the concentration of NO 3- -N is 50mg/L, the concentration of TP is 1mg/L and the pH value is 7.5;
(2) respectively weighing 5.0g of different samples and 100mL of inoculated sludge, and adding 400mL of simulated wastewater to finally obtain 500mL of biological denitrification and denitrification system;
(3) Carrying out shake culture on a biological denitrification and denitrification system at 25 +/-1 ℃, replacing new simulated wastewater (inlet water) every day, filtering the treated wastewater (outlet water) by a 0.45-micrometer filter membrane, and measuring NO 3 - -N, NO 2 - -N, COD cr;
Referring to the Water and wastewater monitoring and analyzing method (Water and wastewater monitoring and analyzing method, ed. Committee of the State environmental protection administration, Water and wastewater monitoring and analyzing method [ M ]. 4 edition, Beijing: Chinese environmental science Press, 2002), NO 3 - -N was measured at 220nm and 275nm with an ultraviolet spectrophotometer (Shimadzu UV-3100), and COD (mg/L) of effluent and removal rate of nitrate nitrogen at 1 to 15 days of each of NO 2 - -N and CODcr were measured by a hydrochloride naphthylethylenediamine spectrophotometry and a potassium dichromate method, as shown in FIGS. 2 to 9.
In FIGS. 2-4, at the same time point, the COD released by the coated carbon source was nearly doubled compared to the non-coated carbon source, with little difference in the effluent nitrate nitrogen, most stabilized below 5 mg/L. In the initial stage, the COD release amount of the two is high, and the COD release amount tends to be stable about day 6. The reason is that when starch and PVA are blended at high temperature, some easily degradable small molecular substances are generated and are easily released into water, and meanwhile, starch molecules on the surface layer of the carbon source after blending are more easily decomposed by hydrolytic enzyme released by microorganisms. When the surface starch molecules are decomposed, a microcrystalline region is formed in the starch PVA material and serves as a physical cross-linking point, and the starch molecules can be wrapped and wound by the obtained three-dimensional network structure through hydrogen bonds and cross-linking effects, so that the blended carbon source is good in curing property and not easy to disintegrate in water, and the release of the starch is controlled. Therefore, the carbon source released by the coated carbon source can be utilized by the microorganism, and the problem of excessive release of the carbon source is avoided.
As can be seen from fig. 5: when the mass ratio of starch to PVA is 30:30, coating for 2min, the COD released by the carbon source is increased along with the increase of the water content; when the water adding amount is 200mL, the COD is basically maintained at about 30mg/L, but the removal rate is lower; the COD of the added water amount of 400mL and 600mL basically exceeds 50mg/L, and the removal rate is basically more than 95%.
The coating time is 2min, the water adding amount is 200mL, and the removal rates of COD and nitrate nitrogen in effluent after treatment by carbon sources with different starch and PVA ratios are shown in figure 6: the COD of the effluent at the ratio of 55:5 is higher, the COD of the effluent at the ratio of 30:30 and the COD of the effluent at the ratio of 45:15 are mostly maintained below 50mg/L, and the removal rates of nitrate nitrogen of the effluent at the ratio of 30:30 and the effluent at the ratio of 45:15 are higher.
FIGS. 7-9 reflect the effect of different coating times on COD and nitrate nitrogen removal at different starch and PVA ratios: coating for 2min and 4min under the condition that the ratio of starch to PVA is 30:30, wherein the difference of COD of effluent is small; under the condition of coating for 1min, compared with 2min and 4min, the COD of effluent is higher, mostly about 50mg/L, the removal rate of the coating for 1min is the best, basically about 80%, and the removal rates of the coating for 2min and 4min show a descending trend. The ratio of starch to PVA is 45:15, and the nitrate nitrogen removal rate in different coating time is over 80 percent; coating for 2min and 4min, and the difference of COD of the effluent is small; the COD of the effluent after 1min of coating exceeds 50 mg/L. The ratio of starch to PVA is 55:5, the removal rate of nitrate nitrogen of the carbon source obtained within 1-4min of the coating time is over 90 percent, but the mechanical property of the coating material is biased due to the internal disintegration of the carbon source, the film material is broken due to the internal disintegration of the carbon source, and the COD of effluent of the three is high.
Claims (8)
1. A preparation method of an enveloped slow-release carbon source for enhancing biological denitrification is characterized by comprising the following steps:
(1) Adding polyvinyl alcohol and starch into water, mixing uniformly, heating to dissolve, and standing at room temperature;
(2) Pouring the ingredients in the step (1) into a mold, freezing and molding, unfreezing at room temperature, and drying to obtain a slow-release carbon source core;
(3) Immersing the slow-release carbon source core prepared in the step (2) into a 2wt% m-phenylenediamine aqueous solution, and airing; then immerging into 0.1% w/v n-hexane solution of trimesoyl chloride, and drying.
2. The preparation method according to claim 1, wherein in the step (1), the mass ratio of the polyvinyl alcohol to the starch is 1:1 to 1: 3; the mass ratio of the total mass of the polyvinyl alcohol and the starch to the water is 1: 3-10.
3. The preparation method according to claim 1, wherein in the step (1), the heating temperature is 95-99 ℃ and the heating time is 1-2 h; in the step (2), the freezing temperature is-20 ℃.
4. the method according to claim 1, wherein in the step (2), the process of freeze molding-thawing at room temperature is repeated 2 to 3 times.
5. The production method according to claim 1, wherein in the step (3), the dipping time is 1 to 4 min.
6. an encapsulated slow-release carbon source obtainable by the process as claimed in any one of claims 1 to 5.
7. the use of the coated slow-release carbon source of claim 6 in enhanced biological denitrification of wastewater.
8. The use of claim 7, wherein the amount of the coated slow-release carbon source is 3-5 g/L.
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| CN113754051A (en) * | 2021-01-13 | 2021-12-07 | 上海大学 | Biological denitrification slow-release carbon source composite material and preparation method and application thereof |
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| CN113754051A (en) * | 2021-01-13 | 2021-12-07 | 上海大学 | Biological denitrification slow-release carbon source composite material and preparation method and application thereof |
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