CN114538603A

CN114538603A - Composite modified polyurethane biological carrier and preparation method thereof

Info

Publication number: CN114538603A
Application number: CN202210246766.2A
Authority: CN
Inventors: 朱家华; 王皓; 穆立文; 张斌; 陆小华
Original assignee: Nanjing Qingmuyuan Technology Co ltd; Nanjing Tech University
Current assignee: Nanjing Qingmuyuan Technology Co ltd; Nanjing Tech University
Priority date: 2022-03-14
Filing date: 2022-03-14
Publication date: 2022-05-27

Abstract

The invention discloses a composite modified polyurethane biological carrier and a preparation method thereof, belonging to the field of suspension carriers. The carrier molecule organic biological carrier has the advantages that the surface charge of the composite modified biological carrier tends to be electropositive and helps microbial adsorption, the composite modified biological carrier has an excellent ammonia nitrogen adsorption effect, a higher film hanging area and a higher surface roughness can be provided, an electronic exchange way can be provided for a microbial pollutant degradation process, the pollutant degradation effect is enhanced, and the outstanding problem of the carbon material composite carrier is solved.

Description

Composite modified polyurethane biological carrier and preparation method thereof

Technical Field

The invention relates to the field of suspended carriers for sewage treatment, in particular to a composite modified polyurethane biological carrier and a preparation method thereof.

Background

The problem of water pollution is always a prominent problem in China, and simultaneously, with the development of China, the discharge amount of sewage is gradually increased year by year, so that the improvement of a sewage treatment technology is urgently needed, and the problem of water pollution in China is solved. Biological wastewater treatment processes remain the most widely used method for removing organic pollutants and nutrients due to their cost effectiveness and high treatment efficiency. The Moving Bed Biofilm Reactor (MBBR) takes advantage of the traditional activated sludge process and biofilm process and becomes a novel and efficient sewage treatment technology: the high-efficiency organic matter treatment capacity and small occupied area are achieved, and the capacity of a common oxidation pond is only 20% under the same load condition, so that the MBBR is seen to be a trend.

The excellence of the MBBR process depends mainly on the properties of its support. The carrier provides a surface for the microorganisms to attach to and grow on, and provides protection for the microorganisms. The biological film is formed on the surface of the carrier, microorganisms can proliferate while adsorbing and degrading pollutants, and the biological film can grow and update. The carrier can also play a role in disturbing water flow and homogenizing water quality, create good water conservancy conditions, and accelerate the mass transfer speed between the biological membrane and pollutants and dissolved oxygen. Meanwhile, the carrier can also have a certain adsorption and interception effect on suspended matters in water. The carriers used in a biofilm reactor differ in one of the factors that influence the fluctuations in removal efficiency. Furthermore, it is widely believed that the performance of a biofilm system is largely dependent on the formation of a biofilm.

Biological and non-biological factors together affect biofilm formation: 1) microbial community diversity; 2) physical properties of the carrier surface, such as surface hydrophilicity, surface charge properties; 3) topographical properties of the carrier surface (surface roughness); 4) chemically functional groups on the surface of the support; 5) pH, temperature, etc. Among these factors, the physical/chemical properties of the support surface, the surface roughness, the pore structure, the specific area and the type of support material play a decisive role in the formation of biofilms: 1) the hydrophilicity plays a key role in the attachment and growth of microorganisms in the water body; 2) microorganisms are generally negatively charged, and the higher the surface potential of the carrier, the more favorable the attachment of the microorganisms; 3) the nitrification and denitrification of microorganisms involve the conduction of electric charge, and carriers show that the excellent electric charge performance is more beneficial to the process; 4) the higher the surface roughness, the more favorable the attachment of microorganisms on the carrier; 5) the higher the specific surface area is, the richer the pore structure is, the carrier can provide a more sufficient attachment area for bacteria, and the carrier biofilm formation amount is increased; 6) the carrier material plays a multi-aspect role in the attachment of microorganisms, and a proper carrier material can provide a better attachment effect for the microorganisms.

The polymer material is a biological carrier filler which is most widely applied and mainly comprises polyolefins and polyurethanes. In practical application, the simple polymer biological carrier filler has poor hydrophilicity and biological adhesiveness, so that the microorganism film forming speed is low, and the sewage treatment efficiency is reduced.

The existing method for modifying the composite carrier mostly focuses on hydrophilicity and structural modification, for example, montmorillonite is added to improve the net structure of polyurethane and enhance the degradation resistance of the carrier (CN201510932502.2), and for example, the hyperbranched diazonium salt-based polyurethane hydrophilic modification method utilizes the multifunctional property and high reaction activity of the hyperbranched diazonium salt to fix the anionic polyelectrolyte on the surface of polyurethane so as to realize the hydrophilic modification of polyurethane (CN 201510342087.5). On one hand, the methods do not consider the influence of the surface charge of the carrier on the load of the microorganism, the microorganism is more negatively charged, and the electronegativity of the surface of the carrier influences the load of the microorganism; on the other hand, the existing carrier modification method does not consider the improvement of the surface electron conduction capability of the carrier, and the surface electron conduction performance of the carrier influences the degradation reaction of microorganisms in pollutants such as ammonia nitrogen and the like. The patent (CN02141723.7) uses activated carbon to modify a carrier, but has a series of problems, such as poor biological affinity of activated carbon, the electronegativity of the carrier surface caused by the surface functional groups of activated carbon also affects the membrane-hanging effect, and the unmodified activated carbon also has the problems of insufficient hydrophilicity, which results in the problems of poor hydrophilicity and poor microbial compatibility of the carbon material composite carrier, affects the performance of the carrier, and fails to exert the advantages of the carbon material composite carrier.

Disclosure of Invention

The invention provides a composite modified polyurethane biological carrier and a preparation method thereof. Solves the existing problems of the existing carbon material composite carrier and improves the performance of the composite biological carrier. The invention provides a compound modified biological carrier, which has excellent biological loading effect and biological affinity. Compared with the conventional high-molecular organic biological carrier, the surface charge of the composite modified biological carrier tends to be electropositive and helps microbial adsorption, has excellent ammonia nitrogen adsorption effect, can provide higher film coating area and higher surface roughness, can provide an electron exchange path for the pollutant degradation process of microorganisms, enhances the pollutant degradation effect, and solves the outstanding problem of the carbon material composite carrier. The invention provides a preparation method of a compound modified biological carrier.

The purpose of the invention can be realized by the following technical scheme:

a compound modified biological carrier comprises the following components:

the preparation method of the compound modified biological carrier comprises the following steps:

(1) modified charcoal: carrying out modification treatment on the biochar by adopting plasma to obtain modified biochar;

(2) modified charcoal-loaded polyurethane carrier: uniformly mixing the modified biochar, the bonding component, the petroleum ether and the polyurethane sponge; filling the outer surface and the inner hole surface of the polyurethane sponge with biochar modification liquid, and then sequentially carrying out curing and washing to obtain a biochar composite polyurethane carrier;

(3) and preparing a composite modified biological carrier, namely uniformly mixing polyacrylamide and nano-cellulose with the biological carbon composite polyurethane carrier, drying and curing after uniformly mixing to obtain the composite modified biological carrier.

In the preparation method, the modified biochar accounts for 12-16% of the composite modified biological carrier by mass percent; the particle size of the unmodified biochar is 100-200 meshes, and the specific surface area is 20-500 m²The average pore diameter is 0.5-4.0 nm, and the zeta potential of the surface is more than or equal to-60 mV.

In the preparation method, the polyacrylamide accounts for 2-2.5% of the composite modified biological carrier by mass, and is cationic polyacrylamide in white powder form, and the molecular weight of the polyacrylamide is 800-1600 ten thousand Da, preferably 900-1100 ten thousand Da.

In the preparation method, the nano-cellulose raw material is one or more of straw, bagasse, cotton, wood pulp and corn stalks, the length-height-diameter ratio is 10-30, and the length is 80-100 nm.

In the preparation method, the polyurethane sponge is polyester polyurethane, and the density: 16 to 28kg/m³，PPI：20～60。

In the preparation method, the specific conditions of the plasma treatment are as follows: treating for 10-30 min by using a plasma enhanced chemical vapor deposition instrument with the radio frequency power of 120-200W, wherein the atmosphere is mixed gas of oxygen and protective gas such as helium.

In the preparation method, the binder is polyisocyanate.

In some preferred embodiments: the polyisocyanate is at least one of toluene diisocyanate and diphenylmethane diisocyanate.

The invention has the beneficial effects that:

the preparation method and the prepared composite biological carrier have the following beneficial effects:

(1) the biochar has a series of uniform pore diameter, high effective specific surface, low mass transfer resistance and the likeThe method has the advantages that the biochar has better biocompatibility than activated carbon, the powdered biomass carbon is loaded on the surface of the porous polyurethane skeleton, and the specific surface area of the modified carrier exceeds 26000m²/m³The surface area is far higher than that of the common commercial polyurethane carrier, so that more surface area can be provided for bacteria attachment, and the number of microorganisms attached to the carrier is greatly increased;

(2) we found through experiments that the biochar has better biological affinity compared with activated carbon, and contributes to the loading of microorganisms;

(3) the biochar modified under the specific plasma condition can effectively adsorb pollutants and toxic substances in a water body, promote the development of microorganisms and protect attached microorganisms;

(4) the biomass carbon is doped, so that the charge conduction efficiency of the surface of the carrier can be improved, the living environment of microorganisms can be improved, and the adsorption and proliferation of electroactive bacteria can be enhanced;

(5) oxygen-containing functional groups are enriched on the surface of the modified biochar, so that the adsorption effect of the biochar on ammonia nitrogen in a water body is improved, and the hydrophilicity of the biochar is improved.

(6) The plasma is selected as a biochar modification method, so that the biochar modification method has more advantages in the aspects of environmental protection and large-scale production, and meanwhile, the biochar is further expanded by the plasma modification, the specific surface area of the biochar is enhanced, and the modification process is shorter in time and easier to regulate.

(7) The surface of the modified biological carbon is electronegative, which is more beneficial to the subsequent load of cationic polyacrylamide.

(8) The surface of the microorganism has a negative charge due to the presence of carboxylic acid and phosphate groups in the cell membrane of the microorganism. The surface of the biochar is enriched with oxygen-containing functional groups, and the surface of the biochar is electronegative. Therefore, the electronegativity of the surface of the single biochar composite carrier is not beneficial to the adsorption of microorganisms. The cationic polyacrylamide is selected to be doped subsequently, the surface potential is improved, and the adhesion of bacteria on the surface of a carrier material is promoted;

(9) the nano-cellulose on the surface of the carrier can effectively improve the surface roughness of the carrier and improve the attachment effect of microorganisms.

(10) The nano-cellulose on the surface of the carrier can be used as a nitrification and denitrification carbon source, so that the growth and the propagation of microorganisms on the surface of the carrier are promoted, the starting time of the reactor is shortened, and the ammonia nitrogen removal effect of sewage is improved.

Drawings

FIG. 1 is the elemental analysis spectrum of biochar in example 1. Wherein: unmodified biochar (a) and modified biochar (b).

FIG. 2 is the elemental ratio analysis chart of biochar in example 1.

FIG. 3 is the infrared analysis spectrum of the biochar of example 1.

FIG. 4 shows the surface morphology of the modified support of example 1, polyurethane sponge (a), composite polyurethane support (b)

FIG. 5 is a flow chart of the MBBR pilot plant of example 1.

FIG. 6 is a graph comparing COD removal effects of the Moving Bed Biofilm Reactor (MBBR) using two carriers of example 1.

FIG. 7 is a graph comparing the ammonia nitrogen removal effect of the Moving Bed Biofilm Reactor (MBBR) using two carriers of example 1.

FIG. 8 is the change of ammonia nitrogen concentration in the carrier for 12 h.

Figure 9 is the ammonia nitrogen concentration of the MBBR reactor effluent with four carriers (four carrier test).

Figure 10 is the MBBR reactor ammonia nitrogen degradation rate (four carrier test).

Detailed Description

The invention is further illustrated by the following examples, without limiting the scope of the invention:

example 1

A compound modified biological carrier is prepared by the following steps: s1, preparing modified biochar, S2, loading the modified biochar by polyurethane sponge, and S3, preparing a composite modified biological carrier.

S1, preparing modified biomass charcoal: selecting fruit tree biochar (LUCK/Artocarpus chinensis fruit tree carbon FT4DM) with specific surface area of 103m²The average pore diameter is 0.67nm, the zeta potential on the surface is more than or equal to-42 mV, the granularity of the charcoal powder is selected from 100-200 meshes, and the charcoal powder is placed in plasma equipment (RTL1200-PECVD-ALD)Www.njbytyq.com Nyjingbo Technology Co., Ltd.) area with the strongest glow, processing at a radio frequency power of 150W for 20min in pure oxygen atmosphere, and drying after modification.

S2, polyurethane sponge-loaded modified biochar:

1) 70 sponge blocks 1 x 1cm, a Macro foam product Co., Ltd, of Dongguan having a density of 28kg/m were prepared³Sponge per square inch (PPI: 60, sponge dried at 60 ℃ for 0.5 h).

2) Preparing 15 parts of modified biochar, adding 300 parts of petroleum ether, stirring for 10min, adding a polyurethane sponge block, and stirring for 20 min.

3) 4 parts of diphenylmethane diisocyanate (MDI) were added dropwise to the reaction system in a fume hood with stirring for 40 min. The sponge block was removed and dried in an oven at 80 ℃ for 20 minutes.

4) The cubes were washed with petroleum ether to remove particles that had just become trapped in the pores and did not react with the surface, and dried in an oven at 80 ℃ for 60 minutes to give biochar-loaded polyurethane sponges.

S3, preparing a compound modified biological carrier:

1) adding 2.5 parts of PAM and 4 parts of nanocellulose into 200 parts of deionized water, stirring for 10min, adding the polyurethane sponge loaded with the biochar, adding ultrapure water, and performing ultrasonic stirring for 30 min. The polyacrylamide is cationic polyacrylamide, white powder, and has a molecular weight of 900-1000 Da. The nano-cellulose raw material is bagasse, the length-height-diameter ratio is 25, and the length is 80 nm.

2) And taking out the carrier, filtering to remove water, putting in a 60 ℃ oven for 1h, taking out, cleaning by using a Buchner funnel, and then putting in an 80 ℃ oven for drying for 2 h.

Characterization test

The element analysis of the modified and unmodified biochar shows that the oxygen element content of the modified biochar is greatly improved, and meanwhile, the surface of the modified biochar has rich oxygen-containing functional groups according to an infrared spectrogram.

TABLE 1 content of surface acidic functional groups before and after biochar modification

The specific surface area of the compound modified carrier reaches 27000m²/m³Far superior to unmodified polyurethane sponges. Meanwhile, the surface roughness of the carrier loaded with the biochar and the nanocellulose is greatly improved through the shooting of an electron microscope, and the attachment of microorganisms is facilitated.

TABLE 2 comparison of specific surface area of polyurethane sponge and composite modified Carrier

Carrier	Composite modified carrier	Polyurethane sponge
			Specific surface area (m)²/m³)	27000	2800

The test was carried out in a moving bed biofilm reactor set up in the laboratory, and the flow chart is shown in fig. 5. 30% of polyurethane sponge block (1 x 1cm) is added into one 4L MBBR experimental device, and 30% of compound modified biological carrier (1 x 1cm) is added into the other 4L MBBR experimental device. The two devices are inoculated with activated sludge, and the mixed liquid of the activated sludge and the artificially synthesized wastewater is 1: 1 mixing, immersing the filler in the mixed liquid, controlling the temperature of the mixed liquid to be about 25 ℃, controlling the temperature of the mixed liquid to be about 8 hours per aeration, closing an aeration device, precipitating the reactor for 0.5 hour, removing supernatant and bottom sludge on the upper part of the reactor, supplementing the simulated sewage to the original water level, and continuing to add the simulated sewage to the original water levelAeration is continued. And after 48h of continuous aeration, emptying the sewage and sludge mixed liquor in the reactor, adding simulated sewage and entering continuous flow. The dissolved oxygen in the reactor is adjusted to be 2-4mg/L by adjusting the air input. The water quality of the inlet water (artificially synthesized wastewater, configured as shown in table 3) of the two MBBR experimental devices is as follows: COD 300mg/L, NH₃ ⁺-N60 mg/L. The hydraulic retention time was 12h and the reactor temperature was constant at 30 ℃. The data are measured after 20 days of acclimation, and the test results of 2 carriers are shown in tables 4 and 5 respectively, wherein the unit of COD and ammonia nitrogen is mg/L.

Table 3: artificial wastewater configuration scheme

Table 4: MBBR (moving bed biofilm reactor) water inlet and outlet condition by using polyurethane sponge as carrier

Table 5: example 1MBBR Water in and out Using Complex modified organisms

According to the comparative test, the composite modified polyurethane biological carrier disclosed by the invention is applied to an MBBR experimental device, and has an excellent treatment effect on common pollutants in a water body.

Example 2

The effect test is carried out on the carriers compounded in different proportions, a series of tests are carried out, and the main tests are mainly used for testing the ammonia nitrogen removal effect and the biofilm formation effect. The preparation method of the carrier comprises the following steps:

1) preparing modified biomass charcoal:placing fruit tree biochar in quartz boat, placing in the region with strongest glow of plasma equipment, treating for 20min with radio frequency power of 150W, selecting pure oxygen in atmosphere, modifying, and drying for use, wherein the fruit tree biochar is litchi fruit charcoal with specific surface area of 103m²(iv)/g, mean pore diameter of 0.67nm, surface zeta potential of not less than-42 mV, plasma equipment (RTL1200-PECVD-ALD) custom made by Nanjing Bo Nenton instruments science and technology Limited www.njbytyq.com.

2) 70 parts of sponge blocks were prepared and dried at 60 ℃ for 0.5 hour, wherein the sponge blocks were obtained from Macro-metallocene foam products Co., Ltd, Dongguan, and had a density of 28kg/m³And a spongy mass per square inch (PPI) of 60.

3) Adding 10, 15 or 20 parts of modified biochar into sufficient 300 parts of petroleum ether, stirring for 10min, adding a polyurethane sponge block, and stirring for 20 min.

4) 4 parts of diphenylmethane diisocyanate (MDI) were added dropwise to the reaction system in a fume hood with stirring for 40 min. Removed and dried in an oven at 80 ℃ for 20 minutes.

5) The cubes were washed with petroleum ether to remove particles that had just become trapped in the pores and not reacted with the surface and dried in an oven at 80 ℃ for 60 minutes to give a biochar-loaded polyurethane sponge.

6) Adding 1, 2.5 or 6 parts of PAM and 4 parts of nanocellulose into 200 parts of deionized water, stirring for 10min, adding a polyurethane sponge loaded with biochar, and performing ultrasonic stirring for 30min at the same time, wherein Polyacrylamide (PAM) is cationic polyacrylamide, is white powder and has a molecular weight of 900-1000 Da, and the nanocellulose raw material is bagasse, and has a length-to-height-diameter ratio of 25 and a length of 80 nm.

7) And taking out the carrier, filtering to remove water, putting the carrier in a 60 ℃ oven for 1h, taking out the carrier, cleaning the carrier by using a Buchner funnel, and then putting the carrier in an 80 ℃ oven for drying for 2 h.

The test is carried out in the moving bed biofilm reactor built in the laboratory, the reactor adopts cylindrical reactor, the material is acrylic glass, the capacity is 10L, the top is equipped with the sample connection, and the bottom is equipped with the mud discharging port. The reactor was loaded with 396 carriers and tested at a fill rate of 30%. Inoculating activated sludge and activating in the initial stageSludge mixed liquor and synthetic wastewater 1: 1, mixing, immersing the filler in the mixed solution, controlling the temperature of the mixed solution to be about 25 ℃, controlling the temperature of the mixed solution to be maintained at about 8 hours for aeration, closing an aeration device, precipitating the reactor for 0.5 hour, removing supernatant and bottom sludge on the upper part of the reactor, supplementing the simulated sewage to the original water level, and continuing aeration. And after 48h of continuous aeration, emptying the sewage and sludge mixed liquor in the reactor, adding simulated sewage and entering continuous flow. The dissolved oxygen in the reactor is adjusted to be 2-4mg/L by adjusting the air input. The water inlet of the experimental device (the water quality of the artificial synthetic wastewater is 400mg/L of COD and NH3⁺-N40 mg/L. The hydraulic retention time is 8h, and the reactor temperature is constant at 25 ℃. The test results of the carriers are shown in Table 8, wherein the unit of ammonia nitrogen is mg/L.

Table 6: the component ratio of different composite carriers

Carrier	A	B	C	D	E	F	G	H	I
										Charcoal parts	10	10	10	15	15	15	20	20	20
PAM parts	1	2.5	6	1	2.5	6	1	2.5	6

Table 7: biofilm thickness after maturation of different composite Carrier biofilms

Carrier	A	B	C	D	E	F	G	H	I
										Biofilm thickness (μm)	210.3	221.8	198.6	216.3	235.6	206.1	204.5	219.2	211.8

Table 8: ammonia nitrogen and total nitrogen degradation performance tests of different composite carriers (35 day)

Carrier	A	B	C	D	E	F	G	H	I
										Degradation rate of Ammonia Nitrogen (%)	85.36	87.14	86.12	90.19	93.2	82.57	89.17	89.38	90.23
Total nitrogen degradation rate (%)	74.58	73.21	67.88	80.1	83.1	83.54	78.11	80.16	76.32

Example 3

To test the effect of the novel bio-carrier on hypoxic MBBR performance, a series of batch experiments were performed when MBBR reached steady state. From the experiment of example 1, at 30 days, 6 pieces of composite modified polyurethane biological carriers were taken and respectively filled into 250mL serum bottles, and the filling rate was kept at 30%, which contained the artificial wastewater prepared in example 1. All serum bottles were incubated in a constant temperature shaker at 25 ℃ and a rotational speed of 150 r/min. And (4) collecting the suspended water sample by using a needle and an injector at regular intervals of 2 hours, and determining the ammonia nitrogen concentration. The results are shown in FIG. 8.

Under the anoxic condition, the MBBR reactor loaded with the composite modified polyurethane biological carrier has good ammonia nitrogen degradation effect.

Example 4

The following carrier preparation procedure involved the same materials and equipment as in example 1, plasma was tailored for RTL1200-PECVD-ALD by Nanjing Bo Nento Instrument science and technology, Inc.; the sponge was purchased from Hongmao foam products Co., Ltd, of Dongguan, and had a density of 28kg/m ³60 spongy mass per square inch (PPI); the fruit wood charcoal is litchi fruit charcoal with a specific surface area of 103m²The volume/g, the average pore diameter is 0.67nm, and the zeta potential of the surface is more than or equal to-42 mV; the polyacrylamide is cationic polyacrylamide, white powder, and has a molecular weight of 900-1000 Da. The nano-cellulose raw material is bagasse, the length-height-diameter ratio is 25, and the length is 80 nm. .

The biochar composite carrier (carrier A-reactor A) is prepared by the following steps:

i. 70 parts of sponge blocks are prepared and dried for 0.5 hour at 60 ℃.

ii.15 parts of modified biochar, adding sufficient 300 parts of petroleum ether, stirring for 10min, adding a polyurethane sponge block, and stirring for 20 min.

4 parts of diphenylmethane diisocyanate (MDI) was added dropwise to the reaction system in a fume hood with stirring for 40 min. Removed and dried in an oven at 80 ℃ for 20 minutes.

Washing the cubes with petroleum ether to remove particles that have just become trapped in the pores and not reacted with the surface, and drying in an oven at 80 ℃ for 60 minutes to obtain biochar-loaded polyurethane sponge.

(II) a plasma modified biochar composite carrier (carrier B-reactor B), which is prepared by the following method steps:

i. placing the biochar in a quartz boat, placing the quartz boat in a plasma device with the strongest glow area, treating for 20min at the radio frequency power of 150W, selecting pure oxygen in the atmosphere, and drying for later use after modification;

preparing 70 parts of sponge blocks, and drying at 60 ℃ for 0.5 h.

iii.15 parts of modified biochar (same as in example 1), adding sufficient 300 parts of petroleum ether, stirring for 10min, adding a polyurethane sponge block, and stirring for 20 min.

v. washing the cubes with petroleum ether to remove particles that have just become trapped in the pores and not reacted with the surface, and drying in an oven at 80 ℃ for 60 minutes to obtain modified biochar loaded polyurethane sponge.

(III) a biochar compound type modified biological carrier (carrier C-reactor C) which is prepared by the following method steps:

i. 70 parts of sponge blocks are prepared and dried for 0.5h at 60 ℃.

ii.15 parts of biochar, adding sufficient 300 parts of petroleum ether, stirring for 10min, adding a polyurethane sponge block, and stirring for 20 min.

v, adding 2.5 parts of PAM and 4 parts of nanocellulose into 200 parts of deionized water, stirring for 10min, adding the polyurethane sponge loaded with the biochar, and performing ultrasonic stirring for 30min simultaneously.

And vi, taking out the carrier, filtering to remove water, putting the carrier in a 60 ℃ oven for 1h, taking out the carrier, cleaning the carrier by using a Buchner funnel, and then putting the carrier in an 80 ℃ oven for drying for 2 h.

(IV) a modified biochar compound type modified biological carrier (carrier D-reactor D), which is prepared by the following method steps:

i. and (3) placing the biochar in a quartz boat, placing the quartz boat in a strongest glow area of plasma equipment, and treating for 20min at the radio frequency power of 150W. Pure oxygen is selected as the atmosphere, and the modified product is dried for standby;

preparing 70 parts of sponge blocks, and drying at 60 ℃ for 0.5 h.

And iii.15 parts of modified biochar, adding sufficient 300 parts of petroleum ether, stirring for 10min, adding a polyurethane sponge block, and stirring for 20 min.

4 parts of diphenylmethane diisocyanate (MDI) was added dropwise to the reaction system in a fume hood with stirring for 40 min.

v. removed and dried in an oven at 80 ℃ for 20 minutes.

Washing the cubes with petroleum ether to remove particles that have just become trapped in the pores and do not react with the surface, and drying in an oven at 80 ℃ for 60 minutes to obtain biochar-loaded polyurethane sponge.

And vii, adding 2.5 parts of PAM and 4 parts of nanocellulose into 200 parts of deionized water, stirring for 10min, adding the polyurethane sponge loaded with the biochar, and performing ultrasonic stirring for 30min simultaneously.

And viii, taking out the carrier, filtering to remove water, putting the carrier in a 60 ℃ oven for 1h, taking out the carrier, cleaning the carrier by using a Buchner funnel, and then putting the carrier in an 80 ℃ oven for drying for 2 h.

The experimental process comprises the following steps:

the test was carried out in a moving bed biofilm reactor set up in the laboratory, and the flow chart is shown in fig. 5. The 4 reactors (reactor A, reactor B, reactor C and reactor D are the same reactor) all adopt cylindrical reactors, the material is acrylic glass, the capacity is 10L, the top is equipped with the sample connection, and the bottom is equipped with the mud discharging port. The reactor was loaded with 396 carriers and tested at a fill rate of 30%. Inoculating activated sludge in the initial stage, wherein the mixed solution of the activated sludge and artificially synthesized wastewater is 1: 1, mixing, immersing the filler in the mixed solution, controlling the temperature of the mixed solution to be about 25 ℃,and (3) closing the aeration device every time of aeration for 8 hours, precipitating the reactor for 0.5 hour, removing supernatant and bottom sludge on the upper part of the reactor, supplementing the reactor to the original water level by using simulated sewage, and continuing aeration. And after 48h of continuous aeration, emptying the sewage and sludge mixed liquor in the reactor, adding simulated sewage and entering continuous flow. The dissolved oxygen in the reactor is adjusted to be 2-4mg/L by adjusting the air input. The water inlet of the experimental device (the water quality of the artificial synthetic wastewater is 400mg/L of COD and NH3⁺-N40 mg/L. The hydraulic retention time is 8h, and the reactor temperature is constant at 25 ℃. The test results of the carrier are shown in FIG. 9 and FIG. 10, respectively, wherein the unit of ammonia nitrogen is mg/L.

The ammonia nitrogen degradation efficiency of the reactor using the carrier A is 81.53%, the ammonia nitrogen degradation efficiency of the reactor using the carrier B is 76.95%, compared with the carrier which is not modified by biochar, the carrier which is modified by biochar and compounded by biochar has reduced ammonia nitrogen treatment effect, and the modified biochar has more negative charge groups and is not beneficial to the load of microorganisms on the carrier. And after PAM is added for surface charge modification, the ammonia nitrogen degradation effect is obviously enhanced. The ammonia nitrogen degradation efficiency of the reactors C and D using the carriers C and D is respectively 84.4 percent and 95.05 percent, and simultaneously the performance of the modified biochar loaded carrier is further improved after PAM modification.

Claims

1. A compound modified biological carrier is characterized in that: the carrier comprises the following components in parts by weight:

2. a method for preparing the composite modified biological carrier of claim 1, which is characterized in that: the method comprises the following steps:

3. The preparation method of the compound modified biological carrier according to claim 2, wherein the modified biological carbon accounts for 12-16% of the compound modified biological carrier by mass; the particle size of the unmodified biochar is 100-200 meshes, and the specific surface area is 20-500 m²The average pore diameter is 0.5-4.0 nm, and the zeta potential of the surface is more than or equal to-60 mV.

4. The method for preparing the modified polyurethane support according to claim 2, wherein: the mass percentage of the polyacrylamide in the composite modified biological carrier is 2-2.5%, the polyacrylamide is cationic polyacrylamide and white powder, and the molecular weight of the polyacrylamide is 800-1600 ten thousand Da, preferably 900-1100 ten thousand Da.

5. The method for preparing the composite modified biological carrier according to claim 2, wherein the method comprises the following steps: the nano-cellulose raw material is one or more of straw, bagasse, cotton, wood pulp and corn stalks, the length-height-diameter ratio is 10-30, and the length is 80-100 nm.

6. The method for preparing the composite modified biological carrier according to claim 2, wherein the method comprises the following steps: the polyurethane sponge is polyester polyurethane, and the density is as follows: 16 to 28kg/m³，PPI：20～60。

7. The method for preparing the composite modified biological carrier according to claim 2, wherein the method comprises the following steps: specific conditions of the plasma treatment are: treating for 10-30 min by using a plasma enhanced chemical vapor deposition instrument with the radio frequency power of 120-200W, wherein the atmosphere is mixed gas of oxygen and protective gas such as helium.

8. The method for preparing the composite modified biological carrier according to claim 2, wherein the method comprises the following steps: the binding component is a polyisocyanate.

9. The method for preparing the composite modified biological carrier according to claim 8, wherein the method comprises the following steps: the polyisocyanate is at least one of toluene diisocyanate and diphenylmethane diisocyanate.