CN115636507A - Constructed wetland slow-release filler based on sulfur autotrophic denitrification - Google Patents
Constructed wetland slow-release filler based on sulfur autotrophic denitrification Download PDFInfo
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- CN115636507A CN115636507A CN202211477240.1A CN202211477240A CN115636507A CN 115636507 A CN115636507 A CN 115636507A CN 202211477240 A CN202211477240 A CN 202211477240A CN 115636507 A CN115636507 A CN 115636507A
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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
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- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
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Abstract
The invention discloses a constructed wetland slow release filler based on sulfur autotrophic denitrification, which consists of filler particles and sodium thiosulfate slow release particles, wherein the filling ratio of the filler particles to the sodium thiosulfate slow release particles is 1.8-1.2; the filler particles are composed of the following components: 30 to 50 percent of straws, 10 to 20 percent of calcium hydroxide, 20 to 40 percent of Portland cement and 10 to 20 percent of active carbon. The sodium thiosulfate slow-release particles are cement slow-release particles wrapped with paraffin, and the cement slow-release particles are composed of the following components: 35 to 45 percent of sodium thiosulfate, 15 to 25 percent of stearic acid and 35 to 45 percent of Portland cement. The constructed wetland slow release filler has the advantages of high removal efficiency, high mechanical strength, no need of additional carbon source, resource saving, environmental friendliness and the like, and has good application prospects in the aspects of biological denitrification, sewage treatment and the like.
Description
Technical Field
The invention relates to constructed wetland slow release filler based on sulfur autotrophic denitrification, belonging to the technical field of water treatment.
Background
With the rapid development of economy in China, the urbanization process is accelerated, and the discharge amount of domestic and industrial wastewater is continuously increased, so that the content of nitrogen in the water body exceeds the standard, and the eutrophication of the water body is caused. Eutrophication of water body can cause excessive growth of algae, reduce the transparency and dissolved oxygen of the water body, and even release toxic substances to destroy aquatic ecological environment. Meanwhile, nitrate can be converted into nitrite, and the nitrite can harm human health and even induce cancers. Therefore, the development of a denitrification treatment process which is economical, efficient and has good ecological benefits is urgent.
The conventional denitrification treatment methods include physical methods, biological methods and chemical methods. Physical denitrification methods include gas stripping denitrification and ion exchange methods, but such methods cannot fundamentally solve the problems. The chemical denitrification method comprises a breakpoint chlorination method and an ammonium magnesium phosphate precipitation method, but has high cost, generates a large amount of byproducts and is easy to cause secondary pollution. The biological method is to convert nitrate into nitrogen by using the denitrification of microorganisms, can theoretically completely remove nitrate and has the advantages of high removal efficiency, low operation cost and good ecological effect, so the biological denitrification method is the most mainstream denitrification method at present.
The biological denitrification method can be divided into autotrophic denitrification and heterotrophic denitrification according to the difference of electron donors required by microorganisms. The domestic wastewater generally has the characteristics of high nitrogen and low carbon, the autotrophic denitrification is used for treating the wastewater, no external carbon source is required to be added, the treatment cost can be effectively reduced, the growth period of autotrophic bacteria is long, the sludge yield is low, and the sludge treatment cost can be reduced. Wherein the sulfur autotrophic denitrification process using a sulfur source as a denitrification electron donor is safer.
In biological denitrification, because the traditional activated sludge method has complex operation management, high investment and large energy consumption, the artificial wetland system with simple process, large buffer capacity, low operation cost and good ecological benefit is more and more widely applied. If the artificial wetland method and the sulfur autotrophic denitrification method are combined, the advantages of the artificial wetland method and the sulfur autotrophic denitrification method can be taken into consideration. The artificial wetland filler which can be used as a sulfur source donor has a plurality of substances, wherein the removal efficiency of sodium thiosulfate is highest, but sodium thiosulfate is easily dissolved in water, so that the artificial wetland filler which can realize the slow release of sodium thiosulfate, can release an alkalinity substance for balancing acidity generated in the denitrification process, has porosity to facilitate microorganism attachment and has certain mechanical strength becomes a current research hotspot.
Disclosure of Invention
Aiming at the prior art, the invention provides a constructed wetland slow-release filler based on sulfur autotrophic denitrification. The constructed wetland slow-release filler has the advantages of high removal efficiency, high mechanical strength, no need of an external carbon source, resource saving, environmental friendliness and the like, and has good application prospects in the aspects of biological denitrification, sewage treatment and the like.
The invention is realized by the following technical scheme:
the constructed wetland slow release filler based on the sulfur autotrophic denitrification comprises filler particles and sodium thiosulfate slow release particles, wherein the filling ratio of the filler particles to the sodium thiosulfate slow release particles is 1.8-1.2, and the filler particles and the sodium thiosulfate slow release particles are calculated according to the weight ratio.
The particle diameters of the filler particles and the sodium thiosulfate slow-release particles are both 4-8 mm, and preferably 6mm.
The filler particles are composed of the following components: 30-50% of straw, 10-20% of calcium hydroxide, 20-40% of portland cement and 10-20% of activated carbon by weight percentage.
The sodium thiosulfate slow-release granules are cement slow-release granules wrapped with paraffin, and the cement slow-release granules are composed of the following components: 35 to 45 percent of sodium thiosulfate, 15 to 25 percent of stearic acid and 35 to 45 percent of Portland cement by weight percentage; the paraffin accounts for 15 to 25 percent of the weight of the cement slow-release particles, and the thickness of the wrapped paraffin layer is 0.8 to 1.2 mm.
Further, the filler particles are prepared by the following method: mixing straw powder, calcium hydroxide, cement, activated carbon and water, wherein the material-water ratio is 1; and pouring the mixed slurry into a spherical mold, and drying to obtain filler particles. Covering a layer of linen on the filler particles, keeping the linen moist by a watering can, and continuously maintaining for one week to improve the mechanical strength of the filler. The straw powder is prepared by the following method: crushing the straws (by using a crusher), and sieving by using a sieve with 80-120 meshes to obtain straw powder.
Further, the straws are selected from wheat straws, corn straws, sorghum straws, rice straws and the like.
Further, the sodium thiosulfate slow-release granules are prepared by the following method:
(1) Mixing stearic acid and absolute ethyl alcohol, heating to 70-80 ℃ in a water bath, stirring until the stearic acid is completely melted, adding sodium thiosulfate, fully stirring to uniformly disperse the stearic acid, naturally cooling to 30-35 ℃ in the stirring process, and completely separating out solids; drying the precipitated solid (the absolute ethyl alcohol is completely volatilized), and sieving by a sieve of 80-120 meshes to obtain the sustained-release capsule;
the weight ratio of stearic acid, absolute ethyl alcohol and sodium thiosulfate is 1:1: (2-3);
(2) Mixing the sustained-release capsule, the cement and a proper amount of water (the material-water ratio is 1; pouring the mixed slurry into a spherical mould, and drying to obtain cement slow-release particles;
(3) Heating the solid paraffin to 65-75 ℃ in a water bath, soaking the cement slow-release granules in the paraffin for 5-10 seconds after the paraffin is completely melted, taking out the cement slow-release granules, and cooling the cement slow-release granules to room temperature to obtain the sodium thiosulfate slow-release granules wrapped with a layer of paraffin.
The constructed wetland slow-release filler based on the sulfur autotrophic denitrification is used as a filler for biological denitrification and sewage treatment.
The constructed wetland slow release filler based on the sulfur autotrophic denitrification is composed of filler particles and sodium thiosulfate slow release particles. When the filler particles are used alone, the growth rate of bacteria is slow due to the lack of a sulfur source; when the sodium thiosulfate slow-release particles are used alone, the surfaces of the slow-release particles are smooth, so that the slow-release particles are not beneficial to microorganism attachment. Therefore, when the two particles are used independently, the denitrification effect is poor. The two fillers are coupled according to a certain proportion (the proportion of the sodium thiosulfate and the hydrated lime is controlled), so that the hydrated lime in the filler particles can perfectly neutralize the alkalinity of microorganisms generated by degrading the sulfur source in the sodium thiosulfate slow-release particles, and a neutral environment required by the growth of the microorganisms is maintained; the two complement each other and cooperate with each other.
The constructed wetland slow-release filler based on the sulfur autotrophic denitrification has the following beneficial effects:
(1) The invention selects the sodium thiosulfate as a sulfur source providing substance, and the treatment efficiency is higher than that of the current mainstream artificial wetland filler using sulfur as a sulfur source.
(2) According to the invention, the activated carbon is added into the raw materials of the artificial wetland filler, and the activated carbon can adsorb nitrate in water, so that the hydraulic retention time is prolonged, and the treatment effect is improved.
(3) The invention uses hydrated lime as alkalinity providing substance and silicate cement as binder, the mechanical strength is higher after the hydrated lime and the silicate cement are mixed, and simultaneously, the silicate cement has alkalescence and can neutralize part of acid generated by sulfur autotrophic denitrification. And the calcium ions can also be combined with phosphate radicals in water to form insoluble substances, so that the filler has a phosphorus removal function.
(4) Sintering is not needed, and the method is low-carbon and environment-friendly.
(5) The invention adds the straws in the raw materials of the artificial wetland filler, which not only can make the filler present porosity and increase the biological attachment area, but also can release carbon sources, improve the efficiency of sulfur autotrophic and heterotrophic denitrification and increase new ways of utilizing the straws.
Drawings
FIG. 1: photograph of the filler particles.
FIG. 2 is a schematic diagram: photographs of sodium thiosulfate slow release granules.
FIG. 3: the slow release performance of the slow release granules prepared by different slow release processes is compared.
FIG. 4 is a schematic view of: schematic diagram of removal of nitric acid nitrogen in continuous experiment.
Detailed Description
The present invention will be further described with reference to the following examples. However, the scope of the present invention is not limited to the following examples. It will be understood by those skilled in the art that various changes and modifications may be made to the present invention without departing from the spirit and scope of the invention.
The instruments, reagents and materials used in the following examples are conventional instruments, reagents and materials known in the art and are commercially available. Unless otherwise specified, the experimental methods and detection methods described in the following examples are conventional experimental methods and detection methods known in the art.
The cement used in the present invention is portland cement po42.5 available from the mountain and water group. The active carbon adopted by the invention is purchased from Kande brand powder active carbon. The straw adopted by the invention is wheat straw.
Example 1 constructed wetland slow release filler based on sulfur autotrophic denitrification
The sodium thiosulfate slow-release granule is composed of filler granules and sodium thiosulfate slow-release granules, wherein the filling ratio of the filler granules to the sodium thiosulfate slow-release granules is 1. The particle sizes of the filler particles and the sodium thiosulfate slow-release particles are both 6mm.
The preparation method comprises the following steps:
preparing filler particles:
(1) Crushing the straws in a crusher for 5min, and screening out straw powder by using a 100-mesh screen for later use;
(2) Mixing 40 g of straw powder, 15 g of hydrated lime, 30 g of cement, 15 g of activated carbon and 100 ml of water, and stirring for 30 minutes to obtain mixed slurry; the mixed slurry was poured into a spherical mold (diameter 6 mm), and dried to obtain filler particles. Covering a layer of linen on the filler particles, keeping the linen moist by using a watering can, and continuously maintaining for one week. The photograph of the obtained filler particles is shown in figure 1, and it is detected that the specific surface area is 0.0048 square meters per gram, the porosity is 47%, the particle size is 6mm, the density is 0.78g/cm for harvesting, and the stacking density is 0.368g/cm for harvesting.
(II) preparing sodium thiosulfate slow-release granules:
(1) Putting 20 g of stearic acid into a beaker, adding 20 ml of absolute ethyl alcohol, heating the stearic acid in a constant-temperature water bath kettle in a water bath manner to 75 ℃, stirring the stearic acid until the stearic acid is completely melted, adding 40 g of sodium thiosulfate, fully stirring the mixture to uniformly disperse the stearic acid, and naturally cooling the mixture to 30 ℃ in the stirring process until the solid is completely separated out; drying the precipitated solid in an oven (at 40 deg.C), and sieving with 100 mesh sieve to obtain sustained-release capsule;
(2) Mixing 60 g of sustained-release capsules, 40 g of cement and 100 ml of water, and uniformly stirring to obtain mixed slurry; pouring the mixed slurry into a spherical mould (diameter is 6 mm), and drying to obtain cement slow-release particles;
(3) 20 g of solid paraffin, heating the solid paraffin to 70 ℃ in a water bath at a constant temperature, soaking the cement slow-release particles in the paraffin after the paraffin is completely melted for 8 seconds, taking out the cement slow-release particles, and cooling the cement slow-release particles to room temperature to obtain the sodium thiosulfate slow-release particles (the thickness of the paraffin layer is about 1.0 mm) coated with a layer of paraffin on the surface (the weight of the coated paraffin is calculated to be 18 percent of that of the cement slow-release particles, 20 g of paraffin is adopted here, so that the melted paraffin can completely coat the cement slow-release particles), and the picture is shown in figure 2.
Control 1: the preparation method of the slow-release granules prepared by adding the paraffin and the cement (the paraffin and the cement for short) is the same as the second step, and the difference is that: step (1) is not carried out, and sodium thiosulfate is adopted to replace the sustained-release capsule in step (2).
Control 2: the preparation method of the slow-release granules prepared by adding the stearic acid and the cement (stearic acid and cement for short) is the same as that of the second step, and the difference is that: and (4) not performing the step (3), wherein the cement sustained-release particles obtained in the step (2) are the final product.
Two sodium thiosulfate sustained-release granules prepared above were taken and soaked in 250 ml of water, and the sustained-release rate thereof is shown in table 1. Meanwhile, the sustained release granules prepared by paraffin wax and cement, and the sustained release granules prepared by stearic acid and cement were used as controls, and the results are shown in fig. 3. As can be seen from table 1 and fig. 3, the sodium thiosulfate sustained-release particles of the present invention have good sustained-release effect; when no paraffin or stearic acid is added, the slow release effect is obviously different.
TABLE 1
Filling the prepared filler particles and sodium thiosulfate slow-release particles into an upflow anaerobic sludge reactor (the filling weight ratio of the filler particles to the sodium thiosulfate slow-release particles is 1), and carrying out stable and continuous water inflow by a peristaltic pump, wherein the HRT is 9.6h, and the nitrate nitrogen concentration of the inflow water is 130mg/L. The nitrate nitrogen removal efficiency is shown in table 2 and fig. 4. As can be seen from table 2 and fig. 4, the constructed wetland slow-release filler based on sulfur autotrophic denitrification of the present invention has a good denitrification effect.
TABLE 2
The above examples are provided to those of ordinary skill in the art to fully disclose and describe how to make and use the claimed embodiments, and are not intended to limit the scope of the disclosure herein. Modifications apparent to those skilled in the art are intended to be within the scope of the appended claims.
Claims (10)
1. The constructed wetland slow-release filler based on the sulfur autotrophic denitrification is characterized in that: the filler particles and the sodium thiosulfate slow-release particles are mixed, and the filling ratio of the filler particles to the sodium thiosulfate slow-release particles is 1;
the particle sizes of the filler particles and the sodium thiosulfate slow-release particles are both 4-8 mm;
the filler particles are composed of the following components: 30-50% of straw, 10-20% of calcium hydroxide, 20-40% of portland cement and 10-20% of active carbon by weight percentage;
the sodium thiosulfate slow-release particles are cement slow-release particles wrapped with paraffin, and the cement slow-release particles are composed of the following components: 35-45% of sodium thiosulfate, 15-25% of stearic acid and 35-45% of portland cement by weight percentage; the paraffin accounts for 15 to 25 percent of the weight of the cement slow-release particles, and the thickness of the wrapped paraffin layer is 0.8 to 1.2 mm.
2. The constructed wetland slow-release filler based on sulfur autotrophic denitrification according to claim 1, characterized in that the filler particles are composed of the following components: 40% of straws, 15% of calcium hydroxide, 30% of portland cement and 15% of activated carbon.
3. The constructed wetland slow-release filler based on the sulfur autotrophic denitrification as claimed in claim 1, is characterized in that: the cement slow-release particles are composed of the following components: 40% of sodium thiosulfate, 20% of stearic acid and 40% of portland cement; the thickness of the wrapped paraffin layer was 1.0mm.
4. The constructed wetland slow-release filler based on sulfur autotrophic denitrification according to claim 1, characterized in that the filler particles are prepared by the following method: mixing straw, calcium hydroxide, cement, activated carbon and water, wherein the material-water ratio is 1: 0.8-1.2, and uniformly stirring to obtain mixed slurry; and pouring the mixed slurry into a spherical mold, and drying to obtain filler particles.
5. The constructed wetland slow-release filler based on the sulfur autotrophic denitrification is characterized in that: covering a layer of linen on the filler particles, keeping the linen moist by using a watering can, and continuously maintaining for one week.
6. The constructed wetland slow-release filler based on sulfur autotrophic denitrification according to claim 1, characterized in that the sodium thiosulfate slow-release particles are prepared by the following method:
(1) Mixing stearic acid and absolute ethyl alcohol, heating water to 70-80 ℃, stirring until the stearic acid is completely melted, adding sodium thiosulfate, fully stirring to uniformly disperse the stearic acid, naturally cooling to 30-35 ℃ in stirring, and completely separating out solids; drying the precipitated solid to obtain the sustained-release capsule;
(2) Mixing the sustained-release capsule, cement and a proper amount of water to obtain mixed slurry; pouring the mixed slurry into a spherical mould, and drying to obtain cement slow-release particles;
(3) Heating the solid paraffin to 65-75 ℃, soaking the cement slow-release granules in the paraffin for 5-10 seconds after the paraffin is completely melted, taking out the cement slow-release granules, and cooling the cement slow-release granules to room temperature to obtain the sodium thiosulfate slow-release granules wrapped with a layer of paraffin.
7. The constructed wetland slow-release filler based on sulfur autotrophic denitrification according to claim 6 is characterized in that: the weight ratio of stearic acid, absolute ethyl alcohol and sodium thiosulfate is 1:1: (2-3).
8. The constructed wetland slow-release filler based on the sulfur autotrophic denitrification as claimed in claim 1, is characterized in that: the filling ratio of the filler particles to the sodium thiosulfate slow-release particles is 1; the particle sizes of the filler particles and the sodium thiosulfate slow-release particles are both 6mm.
9. The constructed wetland slow-release filler based on the sulfur autotrophic denitrification as claimed in claim 1, is characterized in that: the straw is selected from wheat straw, corn straw, sorghum straw and rice straw.
10. Use of the constructed wetland slow release filler based on sulfur autotrophic denitrification as claimed in any one of claims 1 to 9 in biological denitrification and sewage treatment.
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| CN114524511A (en) * | 2022-01-28 | 2022-05-24 | 大连理工大学 | Alkalinity slow-release porous spherical shell suspended filler based on sulfur autotrophic nitrogen removal of low C/N sewage |
| CN114524513A (en) * | 2022-01-28 | 2022-05-24 | 大连理工大学 | Method for treating low C/N sewage by anaerobic-aerobic-anoxic-moving bed autotrophic denitrification process |
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- 2022-11-23 CN CN202211477240.1A patent/CN115636507B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20050032269A (en) * | 2003-10-01 | 2005-04-07 | 광주과학기술원 | Method of high-rate denitrification using two reactors in series |
| CN104591384A (en) * | 2015-01-31 | 2015-05-06 | 淄博正邦知识产权企划有限公司 | Slow-release sewage processing material and preparation method thereof |
| CN107522286A (en) * | 2017-10-17 | 2017-12-29 | 浙江深德环境技术有限公司 | A kind of tail water processing method based on sulphur/oyster shell |
| CN109650539A (en) * | 2019-02-21 | 2019-04-19 | 天津友爱环保科技有限公司 | Biologic packing material and its preparation method and application for removing groundwater azotate |
| CN114524511A (en) * | 2022-01-28 | 2022-05-24 | 大连理工大学 | Alkalinity slow-release porous spherical shell suspended filler based on sulfur autotrophic nitrogen removal of low C/N sewage |
| CN114524513A (en) * | 2022-01-28 | 2022-05-24 | 大连理工大学 | Method for treating low C/N sewage by anaerobic-aerobic-anoxic-moving bed autotrophic denitrification process |
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