阅读说明：本技术 一种人工湿地组合填料及其应用 (Constructed wetland combined filler and application thereof ) 是由 路凤祎 田巧丽 施佳泽 严彦 邢超 高赫廷 于 2021-07-26 设计创作，主要内容包括：本发明涉及污水处理技术领域,提出了一种人工湿地组合填料,包括以下组分：硫铁矿、鸡蛋壳粉末、改性沸石,三者的质量比为3～5:1:1；所述鸡蛋壳粉末为鸡蛋壳与高温煅烧鸡蛋壳质量比为1：1的混合物；还包括聚乙烯醇和PBAT,所述聚乙烯醇、PBAT与所述改性沸石的质量比为1:6:100。通过上述技术方案,解决了现有技术中的湿地填料长期使用时脱氮除磷的效果变差的问题。(The invention relates to the technical field of sewage treatment, and provides a constructed wetland combined filler, which comprises the following components: the weight ratio of pyrite, eggshell powder and modified zeolite is 3-5: 1: 1; the eggshell powder is prepared from eggshells and high-temperature calcined eggshells in a mass ratio of 1: 1; the modified zeolite is characterized by also comprising polyvinyl alcohol and PBAT, wherein the mass ratio of the polyvinyl alcohol to the PBAT to the modified zeolite is 1:6: 100. Through the technical scheme, the problem that the effect of nitrogen and phosphorus removal is poor when the wetland filler in the prior art is used for a long time is solved.)

1. The constructed wetland combined filler is characterized by comprising the following components: the weight ratio of pyrite, eggshell powder and modified zeolite is 3-5: 1: 1;

the eggshell powder is prepared from eggshells and high-temperature calcined eggshells in a mass ratio of 1: 1;

the modified zeolite is characterized by also comprising polyvinyl alcohol and PBAT, wherein the mass ratio of the polyvinyl alcohol to the PBAT to the modified zeolite is 1:6: 100.

2. The constructed wetland combined filler according to claim 1, characterized in that the modified zeolite is prepared by the following steps:

1) adding water with the mass of 100 times into zeolite;

2) adding 0.01mol/L ferric chloride solution until the pH value is 6-7;

3) washing with water, centrifuging and drying to obtain the modified zeolite.

3. The constructed wetland combined filler according to claim 2, wherein the particle size of the modified zeolite is 0.15-0.25 mm.

4. The constructed wetland composite filler according to claim 1, wherein the high-temperature calcined eggshell is prepared by the following steps: heating and calcining the eggshells at 530-550 ℃, and keeping the temperature for 5-6 h; cooling to 380-420 ℃ at the speed of 10 ℃/min, and keeping the temperature for 30 min; cooling to room temperature at 20 deg.C/min, pulverizing, and grinding.

5. The constructed wetland composite filler according to claim 4, wherein the eggshell powder has a particle size of 1-2 mm.

6. The constructed wetland combined filler according to claim 1, wherein the pyrite has a particle size of 0.15-0.25 mm.

7. The constructed wetland combined filler according to claim 1, wherein the alcoholysis degree of the polyvinyl alcohol is 87-89%.

8. The preparation method of the constructed wetland combined filler is characterized by comprising the following steps:

s1, preparing the raw material according to any one of claims 1 to 7;

s2, mixing pyrite, modified zeolite, eggshell powder and polyvinyl alcohol, adding water and stirring to form slurry;

s3, adding PBAT and stirring uniformly to obtain slurry;

and S4, pouring the slurry into a mold, and spraying water on the surface of the mold to solidify the glass to obtain the product.

9. The use of the constructed wetland combined filler according to any one of claims 1 to 7 in sewage treatment.

Technical Field

The invention relates to the technical field of sewage treatment, in particular to an artificial wetland combined filler and application thereof.

Background

Since the 21 st century, the water pollution problem in China is more serious, the problems of red tide in sea areas, eutrophication in lakes and the like appear, and even the water diversion safety of residents and the health of people are threatened. The artificial wetland system has attracted more and more attention for the advantages of good removal effect, low cost and the like. The artificial wetland is a comprehensive ecological system, which applies the principles of species symbiosis and material cycle regeneration in the ecological system and the coordination principle of structure and function, fully exerts the production potential of resources on the premise of promoting the virtuous cycle of pollutants in wastewater, prevents the re-pollution of the environment and obtains the best benefits of sewage treatment and resource utilization.

At present, the wetland filler taking fly ash and zeolite as main fillers has small particle size and is easy to run off along with long-term use, so that the nitrogen and phosphorus removal effect is influenced. Although the wetland filler taking sand as the main filler has low cost, the amount of microorganisms on the wetland filler carrier is small, so that the removal efficiency of phosphorus in sewage is low.

Disclosure of Invention

The invention provides an artificial wetland combined filler and application thereof, and solves the problem that the effect of nitrogen and phosphorus removal is poor when the wetland filler in the prior art is used for a long time.

The technical scheme of the invention is as follows:

the constructed wetland combined filler comprises the following components: the weight ratio of pyrite, eggshell powder and modified zeolite is 3-5: 1: 1;

the eggshell powder is prepared from eggshells and high-temperature calcined eggshells in a mass ratio of 1: 1;

the modified zeolite is characterized by also comprising polyvinyl alcohol and PBAT, wherein the mass ratio of the polyvinyl alcohol to the PBAT to the modified zeolite is 1:6: 100.

As a further technical scheme, the modified zeolite is prepared by the following steps:

1) adding water with the mass of 100 times into zeolite;

2) adding 0.01mol/L ferric chloride solution until the pH value is 6-7;

3) washing with water, centrifuging and drying to obtain the modified zeolite.

As a further technical scheme, the particle size of the modified zeolite is 0.15-0.25 mm.

As a further technical scheme, the high-temperature calcined egg shell is prepared by the following steps: heating and calcining the eggshells at 530-550 ℃, and keeping the temperature for 5-6 h; cooling to 380-420 ℃ at the speed of 10 ℃/min, and keeping the temperature for 30 min; cooling to room temperature at 20 deg.C/min, pulverizing, and grinding.

As a further technical scheme, the particle size of the eggshell powder is 1-2 mm.

As a further technical scheme, the particle size of the pyrite is 0.15-0.25 mm.

According to a further technical scheme, the alcoholysis degree of the polyvinyl alcohol is 87-89%.

The invention also provides a preparation method of the constructed wetland combined filler, which comprises the following steps:

s1, mixing the raw materials according to the above steps;

s2, mixing pyrite, modified zeolite, eggshell powder and polyvinyl alcohol, adding water and stirring to form slurry;

s3, adding PBAT and stirring uniformly to obtain slurry;

and S4, pouring the slurry into a mold, and spraying water on the surface of the mold to solidify the glass to obtain the product.

The artificial wetland combined filler is applied to sewage treatment.

The invention has the beneficial effects that:

1. the pyrite is one of the most abundant minerals on the earth, and the S element in the pyrite can be used as an electron donor to promote the autotrophic denitrification process of the pyrite. Fe produced by biological oxidation of pyrite during denitrification³⁺And Fe (OH)₃So as to achieve the purpose of removing phosphorus while removing nitrogen.

2. The zeolite of the invention belongs to inert substances, can absorb nutrient substances in sewage, and can also be used as a microbial carrier, but the performance of the zeolite for absorbing phosphorus is poorer.

3. The eggshell belongs to kitchen waste, generates about 400 million tons each year in China, and tends to increase year by year, and needs to be reasonably disposed. The chemical components of the egg shell basically comprise calcium carbonate (93-95%, w/w), magnesium carbonate (1%, w/w), calcium phosphate (1%, w/w) and organic substances (4%, w/w) (Shu Lu et al, 2008). Because the eggshell contains a large amount of calcium carbonate, on one hand, the eggshell can provide an inorganic carbon source for pyrite autotrophic denitrification, and on the other hand, the eggshell can be used as a buffer agent to adjust the pH value in an artificial wetland system. Because the eggshell also contains some organic matters, the heterotrophic denitrification process can be promoted to occur, thereby improving the denitrification efficiency. According to the invention, a part of eggshells are calcined at high temperature, the original organic substances in the eggshells are retained, calcium carbonate in the eggshells reacts to generate calcium oxide and carbon dioxide, the carbon dioxide can increase the number of pores of the eggshells which are not large in number originally, so that the porosity is improved, the mass transfer efficiency of a system is improved, and on the other hand, the calcium oxide generated by the generated calcium oxide and water can adjust the pH value of the system which is weakly acidic after being treated by ferric chloride. After the eggshell is calcined, the temperature reduction process is divided into two steps, and the generated pores can be well protected. The primary cooling speed is lower, so that the generated pores are more uniformly distributed, the rate can be increased during secondary cooling, and the time cost is saved. In addition, the eggshells are recycled, so that the resource utilization of waste is realized.

4. The invention adds the high molecular polymer polyvinyl alcohol and poly adipic acid/butylene terephthalate (PBAT for short), the bonding property between the calcined eggshell and other fillers is poor, in addition, the particle size of the zeolite is small, and the calcined eggshell can run off with water after long-term use. The PBTA is biodegradable, no additional environmental pressure is brought, a carbon source can be provided for nitrobacteria, the denitrification effect is promoted, and on the other hand, carboxyl is introduced into the system, so that the adsorption of microorganisms is facilitated, a stable biological membrane is formed, and the long-term use is improved.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any inventive step, are intended to be within the scope of the present invention.

Example 1

A preparation method of the constructed wetland combined filler comprises the following steps:

s1, adding water with the mass being 100 times of that of the zeolite;

s2, adding 0.01mol/L ferric chloride solution to pH 6;

s3, washing with water, centrifuging and drying to obtain modified zeolite for later use;

s4, heating and calcining the eggshells to 530 ℃, and keeping the temperature for 6 h; cooling to 380 deg.C at a rate of 10 deg.C/min, and maintaining for 30 min; cooling to room temperature at the speed of 20 ℃/min, and grinding to obtain high-temperature calcined eggshells with the particle size of 1-2 mm for later use;

s5, mixing pyrite, modified zeolite, eggshell powder (mixing high-temperature calcined eggshells and eggshells according to a mass ratio of 1: 1) and polyvinyl alcohol, adding water, and stirring into slurry, wherein the amount of the added water is the minimum amount capable of stirring solid materials into slurry, and the mass ratio of the pyrite, the eggshell powder and the modified zeolite is 3:1: 1;

s6, adding PBAT and uniformly stirring to obtain slurry, wherein the mass ratio of the polyvinyl alcohol to the PBAT to the modified zeolite is 1:6: 100;

and S7, pouring the slurry into a mold, and spraying water on the surface of the mold to solidify the glass to obtain the product.

Example 2

A preparation method of the constructed wetland combined filler comprises the following steps:

s1, adding water with the mass being 100 times of that of the zeolite;

s2, adding 0.01mol/L ferric chloride solution to pH 6.4;

s3, washing with water, centrifuging and drying to obtain modified zeolite for later use;

s4, heating and calcining the eggshells to 550 ℃, and keeping the temperature for 5 hours; cooling to 420 deg.C at a rate of 10 deg.C/min, and maintaining for 30 min; cooling to room temperature at the speed of 20 ℃/min, and grinding to obtain high-temperature calcined eggshells with the particle size of 1-2 mm for later use;

s5, mixing pyrite, modified zeolite, eggshell powder (mixing high-temperature calcined eggshells and eggshells according to a mass ratio of 1: 1) and polyvinyl alcohol, adding water, and stirring into slurry, wherein the amount of the added water is the minimum amount capable of stirring solid materials into slurry, and the mass ratio of the pyrite, the eggshell powder and the modified zeolite is 5:1: 1;

s6, adding PBAT and uniformly stirring to obtain slurry, wherein the mass ratio of the polyvinyl alcohol to the PBAT to the modified zeolite is 1:6: 100;

and S7, pouring the slurry into a mold, and spraying water on the surface of the mold to solidify the glass to obtain the product.

Example 3

A preparation method of the constructed wetland combined filler comprises the following steps:

s1, adding water with the mass being 100 times of that of the zeolite;

s2, adding 0.01mol/L ferric chloride solution to pH 6.7;

s3, washing with water, centrifuging and drying to obtain modified zeolite for later use;

s4, heating and calcining the eggshells to 540 ℃, and keeping the temperature for 5 hours; cooling to 400 deg.C at a rate of 10 deg.C/min, and maintaining for 30 min; cooling to room temperature at the speed of 20 ℃/min, and grinding to obtain high-temperature calcined eggshells with the particle size of 1-2 mm for later use;

s5, mixing pyrite, modified zeolite, eggshell powder (mixing high-temperature calcined eggshells and eggshells according to a mass ratio of 1: 1) and polyvinyl alcohol, adding water, and stirring into slurry, wherein the amount of the added water is the minimum amount capable of stirring solid materials into slurry, and the mass ratio of the pyrite, the eggshell powder and the modified zeolite is 5:1: 1;

s6, adding PBAT and uniformly stirring to obtain slurry, wherein the mass ratio of the polyvinyl alcohol to the PBAT to the modified zeolite is 1:6: 100;

and S7, pouring the slurry into a mold, and spraying water on the surface of the mold to solidify the glass to obtain the product.

Example 4

A preparation method of the constructed wetland combined filler comprises the following steps:

s1, adding water with the mass being 100 times of that of the zeolite;

s2, adding 0.01mol/L ferric chloride solution to pH 6.5;

s3, washing with water, centrifuging and drying to obtain modified zeolite for later use;

s4, heating and calcining the eggshells to 540 ℃, and keeping the temperature for 5 hours; cooling to 410 deg.C at a rate of 10 deg.C/min, and maintaining for 30 min; cooling to room temperature at the speed of 20 ℃/min, and grinding to obtain high-temperature calcined eggshells with the particle size of 1-2 mm for later use;

s5, mixing pyrite, modified zeolite, eggshell powder (mixing high-temperature calcined eggshells and eggshells according to a mass ratio of 1: 1) and polyvinyl alcohol, adding water, and stirring into slurry, wherein the amount of the added water is the minimum amount capable of stirring solid materials into slurry, and the mass ratio of the pyrite, the eggshell powder and the modified zeolite is 4:1: 1;

s6, adding PBAT and uniformly stirring to obtain slurry, wherein the mass ratio of the polyvinyl alcohol to the PBAT to the modified zeolite is 1:6: 100;

and S7, pouring the slurry into a mold, and spraying water on the surface of the mold to solidify the glass to obtain the product.

Comparative example 1

In comparison with example 4, untreated egg shells were used instead of high temperature calcined egg shells, and the rest was the same as example 4.

Comparative example 2

Compared with the example 4, the preparation process of the high-temperature calcined egg shell comprises the following steps: heating and calcining the eggshells to 540 ℃, and keeping the temperature for 5 hours; cooling to room temperature at a speed of 20 ℃/min, grinding to a particle size of 1-2 mm to obtain the high-temperature calcined eggshell, and the rest is the same as the example 4.

Comparative example 3

The zeolite was not modified as compared with example 4, and the rest was the same as example 4.

Comparative example 4

The same procedure as in example 4 was repeated except that polyvinyl alcohol was not added as in example 4.

Comparative example 5

Compared with example 4, PBTA was not added, and the rest was the same as example 4.

Examples of the experiments

The filler obtained in the embodiment and the comparative example is the filler of the artificial wetland, the reed and the acorus calamus are used as wetland plants to construct a small artificial wetland, the small artificial wetland is filled into a container, the upper end and the bottom of the small artificial wetland are provided with a water inlet and a water outlet, two descending and ascending composite vertical flow series devices are adopted, a constant flow pump continuously feeds water, the hydraulic retention time is 20 hours, and the hydraulic load is 0.3m³/(m²·d)。

And (3) measuring the concentrations of nitrate nitrogen, ammonia nitrogen and total nitrogen in the sewage before treatment, respectively measuring the concentrations of nitrate nitrogen, ammonia nitrogen and total nitrogen in the sewage after the sewage is treated in the system for 10 days and 30 days, and calculating the removal rate of nitrogen.

Removal rate is (concentration before treatment-concentration after treatment)/concentration before treatment × 100%.

Wherein, the total nitrogen is determined by alkaline potassium persulfate digestion ultraviolet spectrophotometry, the ammonia nitrogen is determined by a distilled Nashin reagent colorimetry, the nitrate nitrogen is determined by the spectrophotometry, and the total phosphorus concentration is determined by ammonium molybdate spectrophotometry. The results are shown in tables 1 to 4 below.

TABLE 1 conditions of removing nitrate and nitrogen from sewage by different artificial wetland fillers

TABLE 2 conditions of removing ammonia nitrogen from sewage by different artificial wetland fillers

TABLE 3 Total nitrogen removal from sewage by different artificial wetland fillers

TABLE 4 Total phosphorus removal by different constructed wetlands

From the experimental data of the experimental examples, it was found that example 4 of the present invention is the best example in terms of overall performance. In comparative example 1, calcined eggshells were not added, and the obtained filler further treated in an artificial wetland system, the treatment effect on nitrogen and phosphorus was reduced, because the calcined eggshells can improve the porosity of the filler, which is beneficial to improving the mass transfer efficiency of the system. The preparation method of the calcined eggshell in the comparative example 2 does not have two steps of temperature reduction, and is improved compared with the comparative example 1, but the adsorption capacity of the calcined eggshell to nitrogen and phosphorus is still poor compared with the embodiment of the invention, and the inventor thinks that the formed pores can be more sufficient and the adsorption capacity can be improved probably due to the secondary temperature reduction in the embodiment. In the comparative example 3, the adsorption capacity of the unmodified zeolite to nitrogen and phosphorus is poor, while in the embodiment of the invention, iron ions are introduced after the zeolite is treated by ferric chloride, so that the effects of nitrogen and phosphorus removal can be achieved simultaneously, and compared with other anions, the inventor finds that the effect of nitrogen and phosphorus adsorption of the filler cannot be influenced by the introduction of the chloride ions. In comparative example 4, polyvinyl alcohol was not added, and in comparative example 5, PBTA was not added, and the obtained filler was poor in effect when subjected to artificial wetland treatment, and after long-term use for 30 days, the nitrogen and phosphorus removal ability hardly increased, indicating that the filler may have run off.

The present invention is not limited to the above preferred embodiments, and any modifications, equivalent substitutions, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.