CN110642338A

CN110642338A - Sewage nitrogen and phosphorus removal filler and preparation method thereof

Info

Publication number: CN110642338A
Application number: CN201911048309.7A
Authority: CN
Inventors: 陈静; 温玉; 陈英
Original assignee: Shenzhen Duer Environmental Technology Co Ltd
Current assignee: Shenzhen Duer Environmental Technology Co Ltd
Priority date: 2019-10-30
Filing date: 2019-10-30
Publication date: 2020-01-03

Abstract

The invention discloses a sewage denitrification and dephosphorization filler and a preparation method thereof. The sewage nitrogen and phosphorus removal filler comprises the following components in parts by weight: 30-50 parts of iron powder, 20-50 parts of carbon powder, 5-10 parts of bentonite, 15-30 parts of cement, 20-50 parts of modified biochar and 20-40 parts of a solid carbon source. The preparation method comprises the steps of modified biochar preparation, solid carbon preparation, mixing, granulation and drying. The sewage nitrogen and phosphorus removal filler has good nitrogen and phosphorus removal efficiency and stable structure, and the preparation method is simple and has low cost and wide application prospect.

Description

Sewage nitrogen and phosphorus removal filler and preparation method thereof

Technical Field

The invention belongs to the field of sewage treatment, and relates to a sewage nitrogen and phosphorus removal filler and a preparation method thereof.

Background

Excessive discharge of nitrogen and phosphorus easily causes eutrophication of water body and deteriorates water quality, and the total nitrogen and total phosphorus concentration of effluent are two important indexes in sewage treatment. The biological nitrogen and phosphorus removal process is increasingly widely applied to sewage treatment because of lower treatment cost and better treatment effect, wherein the most widely applied process is A²O process or its improvement. However, the nitrogen and phosphorus removal effect of the biological nitrogen and phosphorus removal process is affected due to the problems of insufficient concentration of influent organic matters, different ages of denitrifying bacteria and phosphorus removing bacteria and the like. At present, sewage plants can add a large amount of chemical agents such as PAC, iron salt and the like to improve the dephosphorization effect, so that the operation cost is increased, and a large amount of sludge is generated. In addition, the addition of carbon sources such as glucose and sodium acetate improves the denitrification effect, and increases the operation cost and the risk of secondary pollution.

At present, commonly used water treatment fillers such as activated carbon, steel slag, limestone, ceramsite, zeolite, vermiculite, volcanic rock, quartz sand, anthracite and the like mainly remove nitrogen and phosphorus by adsorption, the adsorption capacity is limited, the fillers lose the treatment effect due to easy saturation of adsorption, the service cycle of the fillers is shortened, and the treatment load is reduced. The (modified) biochar can have a good adsorption effect on nitrate, but is lack of denitrification for nitrogen removal, and cannot radically remove nitrogen. The solid carbon source can provide organic matters required by denitrification, but can not adsorb and enrich nitrate, and the treatment rate is influenced. If the filler can release iron ions for a long time and generate precipitates with phosphate, the long-term chemical phosphorus removal effect can be achieved, but the filler is difficult to have the function at present.

In a word, the currently adopted filler has limited nitrogen and phosphorus removal capability, low treatment load and large consumption, and causes the problem of large occupied area.

Disclosure of Invention

The invention aims to overcome the problems of the prior art and provides a sewage denitrification and dephosphorization filler and a preparation method thereof.

In order to achieve the purpose, the technical scheme provided by the invention is as follows:

the sewage nitrogen and phosphorus removal filler comprises the following components in parts by weight: 30-50 parts of iron powder, 20-50 parts of carbon powder, 5-10 parts of bentonite, 15-30 parts of cement, 20-50 parts of modified biochar and 20-40 parts of a solid carbon source.

Preferably, the sewage nitrogen and phosphorus removal filler comprises the following components in parts by weight: 30-50 parts of iron powder, 20-50 parts of carbon powder, 5-10 parts of bentonite, 15-30 parts of cement, 20-50 parts of modified biochar and 20-40 parts of a solid carbon source.

Preferably, the particle sizes of the iron powder, the carbon powder, the kaolin and the solid carbon source are all less than 100 meshes, and the particle size of the modified biochar is less than 50 meshes.

Preferably, the iron powder is a reduced iron powder.

More preferably, the iron content of the iron powder is > 80% by mass.

Preferably, the carbon powder is conductive activated carbon powder.

Preferably, the raw material of the modified biochar is a pyrolysis product of at least one of crop straws, peanut shells, corn cobs, wood chips and bagasse.

Preferably, the modified biochar is iron-modified biochar.

Preferably, the raw material of the solid carbon source is at least one of crop straws, peanut shells, corncobs, wood chips, bagasse and garden litter.

The preparation method of the sewage denitrification and dephosphorization filler comprises the following steps:

(1) preparing modified biochar: cleaning a raw material of biochar, soaking the biochar in 1.0-2.0 mol/L, preferably 1.5mol/L ferric chloride solution for 8-24 hours, filtering, taking out, drying at 60-120 ℃, carbonizing at 350-500 ℃ for 2.5-3.5 hours, preferably 3 hours, and crushing;

(2) preparing solid carbon: cleaning raw materials of a solid carbon source, drying at 60-120 ℃, and crushing;

(3) mixing: mixing iron powder, carbon powder, bentonite, cement, modified biochar and a solid carbon source to obtain a mixture;

(4) and (3) granulation: preparing the mixture into spherulites with the particle size of 1-2 cm;

(5) drying: and (4) drying the spherulites prepared in the step (4) at 60-120 ℃, and cooling to obtain the sewage nitrogen and phosphorus removal filler.

According to the invention, bentonite and cement are added into the filler, so that the bonding degree and strength of the filler are increased, and the stability is good. The added iron and carbon generate micro-electrolysis to release iron ions and phosphate to form precipitate, thereby improving the dephosphorization effect. The modified charcoal adsorbs nitrate radicals to enrich the nitrate radicals, and the loaded denitrifying bacteria reduce the nitrate radicals into nitrogen by using organic matters provided by a solid carbon source, so that the denitrification effect is improved. The filler provided by the invention has the advantages of simple preparation process, low cost, stable filler structure, long service cycle and strong nitrogen and phosphorus removal capability.

In a word, the sewage nitrogen and phosphorus removal filler has good nitrogen and phosphorus removal efficiency, stable structure, simple preparation method, low cost and wide application prospect.

Drawings

FIG. 1 is a graph showing the results of TP effluent concentrations in examples 1 and 2;

FIG. 2 is a graph showing the TN effluent concentration results of examples 1 and 2;

FIG. 3 is a graph showing the results of TP effluent concentrations for example 1 and comparative example 1;

FIG. 4 is a graph showing the TN effluent concentration results of example 2 and comparative example 2;

FIG. 5 is a graph showing the results of TP effluent concentrations for example 1 and comparative example 3;

FIG. 6 is a graph showing the TN effluent concentration results of example 1 and comparative example 3.

Detailed Description

Example 1

Taking 40 parts of wheat straw, cleaning the wheat straw with distilled water, soaking the wheat straw in 1.5mol/L ferric chloride solution for 12 hours, taking out the wheat straw, putting the wheat straw into a constant-temperature drying oven, drying the wheat straw at 80 ℃, then putting the wheat straw into a muffle furnace, roasting the wheat straw for 3 hours under an anaerobic condition, carbonizing the wheat straw at 400 ℃ for 3 hours, taking out the wheat straw and crushing the wheat straw by a crusher, and obtaining modified biochar particles with the particle size of less than 50 meshes by a screen. 30 parts of wheat straw is taken, washed by distilled water, taken out, put into a constant-temperature drying oven to be dried at 80 ℃, taken out and crushed by a crusher, and solid carbon source particles with the particle size of less than 100 meshes are obtained by a screen mesh. 40 parts of iron powder, 30 parts of carbon powder and 7 parts of bentonite with the particle sizes of less than 100 meshes are mixed with 20 parts of cement, the modified biochar and a solid carbon source, the mixture is wetted by distilled water, a granulator is used for preparing spherical particles with the particle sizes of 1.5cm, a constant-temperature drying box is used for drying at 80 ℃, and the cooling is carried out, so that the sewage nitrogen and phosphorus removal filler is obtained.

Example 2

Taking 40 parts of wheat straw, cleaning the wheat straw with distilled water, soaking the wheat straw in 1.5mol/L ferric chloride solution for 18h, taking out the wheat straw, putting the wheat straw into a constant-temperature drying oven, drying the wheat straw at 80 ℃, then putting the wheat straw into a muffle furnace, roasting the wheat straw for 3h under an anaerobic condition, carbonizing the wheat straw at 400 ℃ for 3.5h, taking out the wheat straw and crushing the wheat straw by a crusher, and obtaining modified biochar particles with the particle size of less than 50 meshes by a screen. 30 parts of wheat straw is taken, washed by distilled water, taken out, put into a constant-temperature drying oven to be dried at 80 ℃, taken out and crushed by a crusher, and solid carbon source particles with the particle size of less than 100 meshes are obtained by a screen mesh. 40 parts of iron powder, 30 parts of carbon powder and 7 parts of bentonite with the particle sizes of less than 100 meshes are mixed with 25 parts of cement, the modified biochar and a solid carbon source, the mixture is wetted by distilled water, a granulator is adopted to prepare spherical particles with the particle sizes of 2cm, a constant-temperature drying box is adopted to dry the spherical particles at 80 ℃, and the mixture is cooled to obtain the sewage denitrification and dephosphorization filler.

Comparative example 1

Taking 40 parts of wheat straw, cleaning the wheat straw with distilled water, soaking the wheat straw in 1.5mol/L ferric chloride solution for 12 hours, taking out the wheat straw, putting the wheat straw into a constant-temperature drying oven, drying the wheat straw at 80 ℃, then putting the wheat straw into a muffle furnace, roasting the wheat straw for 3 hours under an anaerobic condition, carbonizing the wheat straw at 400 ℃ for 3 hours, taking out the wheat straw and crushing the wheat straw by a crusher, and obtaining modified biochar particles with the particle size of less than 50 meshes by a screen. 30 parts of wheat straw is taken, washed by distilled water, taken out, put into a constant-temperature drying oven to be dried at 80 ℃, taken out and crushed by a crusher, and solid carbon source particles with the particle size of less than 100 meshes are obtained by a screen mesh. Mixing 40 parts of iron powder and 7 parts of bentonite with the grain size of less than 100 meshes with 20 parts of cement, the modified biochar and a solid carbon source, wetting the mixture with distilled water, preparing the mixture into spherical particles with the grain size of 1.5cm by using a granulator, drying the spherical particles by using a constant-temperature drying box at 80 ℃, and cooling the spherical particles to obtain the sewage denitrification and dephosphorization filler.

Comparative example 2

30 parts of wheat straw is taken, washed by distilled water, taken out, put into a constant-temperature drying oven to be dried at 80 ℃, taken out and crushed by a crusher, and solid carbon source particles with the particle size of less than 100 meshes are obtained by a screen mesh. 40 parts of iron powder, 30 parts of carbon powder and 7 parts of bentonite with the particle sizes of less than 100 meshes are mixed with 25 parts of cement, the modified biochar and a solid carbon source, the mixture is wetted by distilled water, a granulator is adopted to prepare spherical particles with the particle sizes of 2cm, a constant-temperature drying box is adopted to dry the spherical particles at 80 ℃, and the mixture is cooled to obtain the sewage denitrification and dephosphorization filler.

Comparative example 3

Taking a common steel slag filler (with the particle size of 1.5-2 cm) as a comparison filler.

The performance of the nitrogen and phosphorus removal filler obtained in the 2 examples and the 3 comparative examples is tested, and the specific test method is as follows.

The reactor was prepared. 5 plexiglass reactors having a diameter of 10cm and a height of 50cm were prepared. 1.2kg of the above 5 fillers of the examples were added to each reactor.

And (5) configuring simulated wastewater. Distilled water is used as a solvent, and the main components are as follows: the COD concentration is 70mg/L (taking glucose as a carbon source), the TP concentration is 4mg/L (taking dipotassium hydrogen phosphate as a phosphorus source), and the nitrate nitrogen concentration is 30mg/L (taking potassium nitrate as a nitrogen source); and additionally preparing a trace element solution: 1.5 g/L FeCl₃·6H₂O，0.15 g/L H3BO₃，0.03 g/L CuSO₄·5H₂O，0.18 g/L KI，0.12 g/L MnCl₂·4H₂O，0.06 g/L Na₂MoO₄·2H₂O，0.12 g/L ZnSO₄·7H₂O，0.15 g/L CoCl₂·6H₂O and 10 g/L EDTA.

The operation method comprises the following steps: 2L of activated sludge of 2.1g/L is inoculated in each of 5 reactors. The simulated wastewater is used as inlet water, water is uniformly distributed from the upper part of the reactor, and water is discharged from the bottom of the reactor. The water outlet pipe is lifted to be flush with the surface of the filler in the reactor, so that the sewage in the reactor just submerges all the filler. The peristaltic pump is used as water inlet power, and the flow is adjusted to ensure that the hydraulic retention time is 20 h. The microelement solution was added manually in 0.5 mL to 5 reactors per day. After the acclimation is carried out for 25 days, the nitrogen and phosphorus concentration of the effluent is measured every several days. The results of the 121 day runs are shown in fig. 1-6.

It is clear from fig. 1 and 2 that both examples 1 and 2 achieve good TP and TN removal effects. From fig. 3, it can be seen that the effluent TP concentration in the late stage operation is lower in example 1 than in comparative example 1, i.e. better phosphorus removal capability is obtained. The difference between the comparative example 1 and the example 1 is that carbon powder is not added in the former, so that an iron-carbon micro-electrolysis system cannot be formed, iron ions cannot be released to react with phosphorus to form a precipitate, and phosphorus is mainly removed by adsorption. With operation, the limited adsorption capacity of the packing decreases the phosphorus removal capacity. From FIG. 4, it can be seen that the concentration of TN in the effluent of example 2 is lower than that of comparative example 2, i.e., better denitrification capability is obtained. Comparative example 2 differs from example 2 in that the former did not incorporate modified biochar. The improved biochar has good adsorption capacity on nitrate nitrogen in water, plays a role in enrichment, and then denitrifies and denitrifies nitrogen through the loaded denitrifying bacteria by utilizing organic carbon provided by a solid carbon source. When this component is absent, nitrate nitrogen cannot be enriched on the filler, resulting in a decrease in denitrification efficiency. From fig. 5, it can be seen that the effluent TP concentration of example 1 is lower than that of comparative example 3, i.e. the filler provided by the present invention has better phosphorus removal capability than the conventional steel slag. As can be seen from FIG. 6, the TN concentration of the effluent of example 1 is lower than that of comparative example 3, that is, the filler provided by the invention has better denitrification capability than the conventional steel slag.

Claims

1. The sewage nitrogen and phosphorus removal filler is characterized by comprising the following components in parts by weight: 30-50 parts of iron powder, 20-50 parts of carbon powder, 5-10 parts of bentonite, 15-30 parts of cement, 20-50 parts of modified biochar and 20-40 parts of a solid carbon source.

2. The sewage nitrogen and phosphorus removal filler of claim 1, wherein the sewage nitrogen and phosphorus removal filler comprises the following components in parts by weight: 30-50 parts of iron powder, 20-50 parts of carbon powder, 5-10 parts of bentonite, 15-30 parts of cement, 20-50 parts of modified biochar and 20-40 parts of a solid carbon source.

3. The sewage nitrogen and phosphorus removal filler of claim 2, wherein the particle sizes of the iron powder, the carbon powder, the kaolin and the solid carbon source are all less than 100 meshes, and the particle size of the modified biochar is less than 50 meshes.

4. The sewage nitrogen and phosphorus removal filler of claim 2, wherein the iron powder is a reducing iron powder.

5. The sewage nitrogen and phosphorus removal filler of claim 4, wherein the iron powder contains more than 80% of iron by mass.

6. The sewage nitrogen and phosphorus removal filler of claim 1, wherein the carbon powder is conductive activated carbon powder.

7. The sewage denitrification and dephosphorization filler according to claim 1, wherein the raw material of the modified biochar is a pyrolysis product of at least one of crop straws, peanut shells, corn cobs, wood chips and bagasse.

8. The sewage nitrogen and phosphorus removal filler of claim 1, wherein the modified biochar is iron-modified biochar.

9. The sewage denitrification and dephosphorization filler according to claim 1, wherein the solid carbon source is at least one of crop straw, peanut shell, corn cob, wood chip, bagasse and garden litter.

10. The method for preparing the sewage nitrogen and phosphorus removal filler according to any one of claims 1 to 9, wherein the method comprises the following steps:

(1) preparing modified biochar: cleaning raw materials of biochar, soaking the biochar in 1.0-2.0 mol/L ferric chloride solution for 8-24 hours, filtering and taking out the biochar, drying the biochar at 60-120 ℃, carbonizing the biochar for 2.5-3.5 hours at 350-500 ℃, and crushing the biochar;