CN116444845A - Modified biodegradable straw and preparation method and application thereof - Google Patents

Modified biodegradable straw and preparation method and application thereof Download PDF

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Publication number
CN116444845A
CN116444845A CN202310258688.2A CN202310258688A CN116444845A CN 116444845 A CN116444845 A CN 116444845A CN 202310258688 A CN202310258688 A CN 202310258688A CN 116444845 A CN116444845 A CN 116444845A
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biodegradable
straw
biodegradable straw
modified
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周赞民
孟凡刚
陈妍希
陈金灿
刘万里
余志达
周亚梁
欧进浩
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Zhuhai Urban Sewerage And Drainage Co ltd
Sun Yat Sen University
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Zhuhai Urban Sewerage And Drainage Co ltd
Sun Yat Sen University
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    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00Biological treatment of water, waste water, or sewage
    • C02F3/28Anaerobic digestion processes
    • C02F3/2806Anaerobic processes using solid supports for microorganisms
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/006Water distributors either inside a treatment tank or directing the water to several treatment tanks; Water treatment plants incorporating these distributors, with or without chemical or biological tanks
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/12Chemical modification
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/12Chemical modification
    • C08J7/14Chemical modification with acids, their salts or anhydrides
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00Biological treatment of water, waste water, or sewage
    • C02F2003/001Biological treatment of water, waste water, or sewage using granular carriers or supports for the microorganisms
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00Nature of the contaminant
    • C02F2101/10Inorganic compounds
    • C02F2101/16Nitrogen compounds, e.g. ammonia
    • C02F2101/163Nitrates
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2209/00Controlling or monitoring parameters in water treatment
    • C02F2209/15N03-N
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2209/00Controlling or monitoring parameters in water treatment
    • C02F2209/20Total organic carbon [TOC]
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2209/00Controlling or monitoring parameters in water treatment
    • C02F2209/44Time
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2367/00Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
    • C08J2367/04Polyesters derived from hydroxy carboxylic acids, e.g. lactones
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02WCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00Technologies for wastewater treatment
    • Y02W10/10Biological treatment of water, waste water, or sewage

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  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Organic Chemistry (AREA)
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  • Environmental & Geological Engineering (AREA)
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  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Biodiversity & Conservation Biology (AREA)
  • Purification Treatments By Anaerobic Or Anaerobic And Aerobic Bacteria Or Animals (AREA)
  • Biological Treatment Of Waste Water (AREA)

Abstract

The invention belongs to the technical field of recycling of waste materials and wastewater treatment, and particularly relates to a modified biodegradable straw and a preparation method and application thereof. The preparation method of the modified biodegradable straw comprises the steps of modifying the biodegradable straw to obtain the modified biodegradable straw; the biodegradable straw comprises at least one of unused biodegradable straw and waste biodegradable straw; the modification treatment comprises at least one of pyrolysis, acid/alkali solution soaking and yeast extract soaking. The modified biodegradable straw prepared by the method can realize higher carbon release, meanwhile, the modified biodegradable straw prepared by the method is introduced into biological denitrification treatment, a post-treatment technology of the waste biodegradable straw is developed, the operation is simple, the secondary utilization of the waste biodegradable straw can be realized, the problems of resource waste, environmental pollution and the like caused by biodegradable waste can be effectively alleviated, and the reasonable utilization of resources is improved.

Description

Modified biodegradable straw and preparation method and application thereof
Technical Field
The invention belongs to the technical field of recycling of waste materials and wastewater treatment, and particularly relates to a modified biodegradable straw and a preparation method and application thereof.
Background
In recent years, along with the promotion of the national 'double carbon' policy and the implementation of the 'plastic forbidden', the industry of biodegradable plastics has come to a rapid development period. Among them, polylactic acid, polycaprolactone, polybutylene adipate-terephthalate and the like are biodegradable materials with wider application at present, and have been successfully applied in the fields of plastic packaging, textile fibers and the like. However, biodegradable plastics can only be completely degraded under optimal composting conditions, and their size and landfill environment have a large impact on the decomposition time. Under natural landfill conditions, biodegradable plastics may produce more microplastic than non-biodegradable plastics and continue to accumulate in the environment, causing serious pollution.
Among the various biodegradable products, biodegradable straws have taken the main market place of non-biodegradable straws and paper straws. However, the discarded biodegradable straws have the defects of high brittleness, poor impact resistance and the like, and the recycling and reutilization of the straws are severely limited. In addition, the quality guarantee period of the biodegradable straw is only 1 year, the performance is fast to drop, the rejection rate is high, and the direct landfill of a large number of scrapped straws also causes great resource waste. Therefore, development of post-treatment technology of waste biodegradable straws to realize recycling utilization thereof is of great significance to development of recycling economy.
The biodegradable polymer can be used as a carrier for microorganism adhesion in the treatment of sewage with low carbon nitrogen ratio, and the released decomposition product is used as a carbon source for denitrification microorganisms to remove nitrate in the water, so that the biodegradable polymer has wide application prospect, but has the problem of slow release of the carbon source. The biodegradable polymers commonly used in the present denitrification process are granular, and have the following problems: the filler demand is large and the cost is high; (2) The surface of the particles is smooth, the relative surface area is small, microorganisms are not easy to attach, the attaching area is small, and the like, so that denitrifying bacteria are difficult to enrich in the practical application process, and the process starting time is long. Therefore, there is a need to develop a biodegradable material having a rapid release of carbon source that can be used in denitrification processes.
Disclosure of Invention
The invention aims to provide a modified biodegradable straw, and a preparation method and application thereof. The modified biodegradable straw prepared by the invention can realize higher carbon release, and can realize better sewage purification effect when being applied to a denitrification process.
In order to achieve the above purpose, the present invention adopts the following technical scheme: a preparation method of a modified biodegradable straw comprises the steps of modifying the biodegradable straw to obtain the modified biodegradable straw;
the biodegradable straw comprises at least one of unused biodegradable straw and waste biodegradable straw;
the modification treatment comprises at least one of pyrolysis, acid/alkali solution soaking and yeast extract soaking.
The invention accelerates the breaking and decomposition of the polymer and promotes the release of carbon by heating, alkali liquor soaking, inducer adding and other modes, thereby providing a new direction for the resource utilization of the waste biodegradable straw.
Preferably, the main component of the biodegradable straw is polylactic acid, the biodegradable straw has a diameter of 5-6 mm, a length of 200-210 mm and a density of 1.20-1.25 g/cm 3
Preferably, the preparation method of the modified biodegradable straw at least comprises one of the following (1) to (5):
(1) The pyrolysis is that the biodegradable straw is heated and hydrolyzed for 1-3 hours at the temperature of 60-90 ℃;
(2) The acid/alkali solution soaking is to soak the biodegradable straw in acid solution or alkali solution for 1-3 hours;
(3) The concentration of the acid solution is 1-2 mol/L;
(4) The concentration of the alkali solution is 0.1-1 mol/L;
(5) The adding of the yeast extract is to add the yeast extract into the solution containing the biodegradable straw for soaking for 1-3 hours.
More preferably, the acid solution is hydrochloric acid solution and the alkali solution is sodium hydroxide solution.
More preferably, the concentration of the yeast extract is 5-10mg/L.
The selection of the modification treatment method can be adjusted according to the water quality of the sewage and the scale of the reactor, and the yeast extract inducer can be added to the sewage with low carbon-nitrogen ratio and low carbon demand, so that the release of biodegradable carbon can be promoted and a small amount of carbon source can be supplemented; for sewage with higher carbon demand, higher carbon release can be realized in a shorter time by alkali liquor soaking or heating.
A modified biodegradable straw prepared by the preparation method.
The denitrification reactor comprises a peristaltic pump, a water inlet, a water outlet, a water distribution area, a supporting layer, a filling area and a drainage area, wherein the denitrification reactor sequentially comprises the water distribution area, the supporting layer, the filling area and the drainage area from bottom to top, the water distribution area is connected with the water inlet, and the drainage area is connected with the water outlet;
the filler component selected in the filler zone comprises ceramsite and the modified biodegradable straw.
The denitrification reactor is an up-flow denitrification biological filter.
Preferably, the preparation method of the modified biodegradable straw comprises the following steps: cutting the biodegradable straw with the diameter of 6mm and the length of 210mm, controlling the diameter of the cut biodegradable straw to be 6mm and the length to be 3-5mm, and modifying the cut biodegradable straw to obtain the modified biodegradable straw. The cutting length of the biodegradable straw filler can be adjusted according to the water quality of sewage and the scale of the reactor, and the full filling in the reactor can be ensured within the range of 3-5mm.
Preferably, the denitrification reactor comprises at least one of the following (1) to (2):
(1) The denitrification reactor is of a cylindrical structure, the inner diameter is 80-100 mm, and the height is 400-450 mm;
(2) The inlet water in the denitrification reactor is injected from a water inlet at the bottom end of the reactor through a peristaltic pump, passes through a water distribution area, a bearing layer, a filling area and a drainage area, and is overflowed and discharged through an upper water outlet.
Preferably, the denitrification reactor comprises at least one of the following (1) to (2):
(1) The height of the water distribution area is 50-60 mm, the height of the supporting layer is 10-20 mm, the height of the filling area is 200-250 mm, and the height of the drainage area is 70-80 mm;
(2) The filler selected for the supporting layer is cobblestone.
Preferably, the ratio of the height of the modified biodegradable straw to the effective height of the denitrification reactor is (0.3-0.7): 1. the ratio of the filling height of the modified biodegradable straw to the total height of the filling area of the reactor can be adjusted according to the water quality of sewage and the scale of the reactor, and the modified biodegradable straw can be ensured to have sufficient energy release within the range of 0.3-0.7.
The application of the denitrification reactor in sewage treatment comprises the following steps: and pumping the sewage with low carbon nitrogen ratio into the denitrification reactor through a peristaltic pump in a continuous water inlet mode to perform denitrification treatment.
Preferably, the application of the denitrification reactor in sewage treatment at least comprises one of the following (1) to (2):
(1) The TOC concentration of the sewage with low carbon nitrogen ratio is 13-17mg/L, NO 3 -N concentration is 15mg/L;
(2) The hydraulic retention time of the sewage with the low carbon nitrogen ratio in the denitrification reactor is 2-4 h.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention carries out modification treatment on the biodegradable straw, and the obtained modified biodegradable straw has better carbon release performance, thereby providing a new direction for the post-treatment technology of the waste biodegradable straw.
2. The modified biodegradable straw is introduced into biological denitrification treatment, a post-treatment technology of the waste biodegradable straw is developed, the operation is simple, the secondary utilization of the waste biodegradable straw can be realized, the problems of resource waste, environmental pollution and the like caused by biodegradable waste are effectively alleviated, and the reasonable utilization of resources is improved.
3. The denitrification reactor provided by the invention has the double characteristics of solid slow-release carbon source and biomembrane carrier, and the modified biodegradable straw is used as a filler, so that the carbon source supply and the biological attachment of the denitrification biological filter are realized, the denitrification rate of a denitrification system is improved, and compared with the commercially available biodegradable particles, the denitrification reactor has the advantages of low raw material cost and large microorganism attachment surface area, and has a good development prospect.
Drawings
FIG. 1 is an external view of a modified biodegradable straw according to the present invention.
FIG. 2 is a schematic diagram of the denitrification reactor according to the present invention.
FIG. 3 is a graph showing data of carbon release in test example II of the present invention.
FIG. 4 shows the adhesion of the bio-film of the biodegradable plastic filler according to the test example III of the present invention.
FIG. 5 shows NO in examples and comparative examples of the present invention 3 -N removal rate data plot.
FIG. 6 is a graph showing TN removal rate data of examples of the present invention and comparative examples.
FIG. 7 is an electron scanning microscope image of morphological characteristics of the modified biodegradable pipette of example 15 of the present invention before and after reaction.
Wherein, 1, peristaltic pump; 2. a water inlet; 3. a water outlet; 4. a water distribution area; 5. a support layer; 6. a filler zone (a, ceramsite; b, biodegradable straw); 7. and a drainage area.
Detailed Description
The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the examples and comparative examples, the experimental methods used were conventional methods, and the materials, reagents and the like used were commercially available, unless otherwise specified.
The raw materials used in the examples and comparative examples are described in Table 1.
TABLE 1
Examples 1 to 7
1g of virgin biodegradable straw raw material was weighed and cut to a diameter of 6mm and a length of 3-5mm.
Adding 50mL of deionized water into 2 parts, and respectively carrying out heating hydrolysis at 60 ℃ and 90 ℃;4 parts of a solution is respectively added with 50mL of 1mol/L hydrochloric acid, 2mol/L hydrochloric acid, 0.1mol/L sodium hydroxide and 1mol/L sodium hydroxide at normal temperature for soaking; 50mL of 5mg/L yeast extract was added as inducer in 1 portion.
TABLE 2
Group of Treatment conditions
Example 1 Heating and hydrolyzing at 60deg.C
Example 2 Hydrolysis by heating at 90deg.C
Example 3 Soaking in 1mol/L hydrochloric acid at normal temperature
Example 4 Soaking in 2mol/L hydrochloric acid at normal temperature
Example 5 Soaking in 0.1mol/L sodium hydroxide at normal temperature
Example 6 Soaking in 1mol/L sodium hydroxide at normal temperature
Example 7 Adding 5mg/L yeast extract as inducer
Examples 8 to 14
Examples 8 to 14 differ from examples 1 to 7 only in that the experiments were performed using waste biodegradable pipettes.
TABLE 3 Table 3
Group of Treatment conditions
Example 8 Heating and hydrolyzing at 60deg.C
Example 9 Hydrolysis by heating at 90deg.C
Example 10 Soaking in 1mol/L hydrochloric acid at normal temperature
Example 11 Soaking in 2mol/L hydrochloric acid at normal temperature
Example 12 Soaking in 0.1mol/L sodium hydroxide at normal temperature
Example 13 Soaking in 1mol/L sodium hydroxide at normal temperature
Example 14 Adding 5mg/L yeast extract as inducer
Example 15
Referring to fig. 2, in this embodiment, an up-flow denitrification biological filter is selected as a reaction device, and comprises a water distribution area 4 (50 mm), a supporting layer 5 (10 mm), a filler area 6 (250 mm) and a drainage area 7 (80 mm) from bottom to top; the supporting layer is filled with cobbles with the particle size of 100mm, the filler in the filler area 6 comprises a modified biodegradable straw and ceramsite, the ratio of the filling height of the modified biodegradable straw to the total height of the filler area of the biological filter is 0.7, and the ratio of the filling height of the ceramsite to the total height of the filler area of the biological filter is 0.3. The effective volume of the reaction apparatus was 2L.
Wherein, the modification method of the biodegradable straw is to add 5mg/L yeast extract as inducer to modify the biodegradable straw.
Example 16
Compared with example 15, the difference of this example is only that the filling height of the modified biodegradable straw to the effective height ratio of the biofilter is 0.3, and the filling height of the ceramsite to the effective height ratio of the biofilter is 0.7.
Comparative example 1
The only difference between this comparative example and example 1 is that the temperature of the heated hydrolysis was 30 ℃.
The preparation method is the same as in example 1.
Comparative example 2
The difference between this comparative example and example 3 is that the concentration of the hydrochloric acid solution used was 0.1mol/L.
The preparation method is the same as in example 3.
Comparative example 3
The difference between this comparative example and example 6 is only that the concentration of sodium hydroxide solution selected is 0.001mol/L.
The preparation method is the same as in example 7.
Comparative example 4
The only difference of this comparative example compared to example 7 is that biodegradable particles were chosen to replace the biodegradable pipettes.
The preparation method is the same as in example 7.
Comparative example 5
The only difference between this comparative example and example 15 is that the filler in the filler zone is only ceramsite.
The composition and materials of the other reaction apparatus were the same as in example 15.
Comparative example 6
The comparative example was different from example 15 only in that the modified biodegradable particles prepared in comparative example 4 were selected instead of the modified biodegradable straw.
The composition and materials of the other reaction apparatus were the same as in example 15.
Comparative example 7
The comparative example was different from example 15 only in that the filling height of the modified biodegradable straw was 0.8 to the effective height of the biofilter and the filling height of the ceramsite was 0.2 to the effective height of the biofilter.
The composition and materials of the other reaction apparatus were the same as in example 15.
Test example one, carbon Release amount measurement
TOC measurement during carbon release was performed on the soak solutions of samples of examples 1 to 14 and comparative examples 1 to 3 after 3 hours, and the carbon release amounts of the modified biodegradable materials prepared in examples 1 to 14 and comparative examples 1 to 3 at 3 hours were measured. TOC determination methods refer to standard methods (APHA, 1998).
The experimental results are shown in table 4.
TABLE 4 Table 4
As can be seen from the data in Table 4, examples 1 to 14 of the present invention were respectively subjected to acid-base soaking using 60℃and 90℃heating, 1mol/L hydrochloric acid, 0.1mol/L sodium hydroxide and 1mol/L sodium hydroxide, and the addition of yeast extract as an inducer stably increased the carbon release amounts of the biodegradable straws and the waste biodegradable straws, indicating that the above modification methods were applicable to the waste biodegradable straws. The carbon release promoting effect of the yeast extract inducer soaked and added by the alkali solution is better in application to the waste biodegradable straws, which shows that the two methods show better application potential in carbon release of the waste biodegradable straws. The carbon release promoting effect of the alkaline solution soaking is superior to that of other methods, and the waste biodegradable straw added with 1mol/L sodium hydroxide can reach the carbon release amount of 74.48mg/g in 3 hours, which indicates that the alkaline solution soaking treatment can show better application potential of the biodegradable straw in sewage treatment with higher carbon demand. When the yeast extract is used as an inducer, the carbon release of the biodegradable straw is promoted, and the yeast extract can be used as a supplementary carbon source for the growth of microorganisms, so that the method can be applied to the early modification, can be continuously added in the sewage treatment process, does not negatively influence the growth of microorganisms, and shows that the method for adding the yeast extract inducer can be applied to the sewage with low carbon-nitrogen ratio and relatively low carbon requirement.
The treatment method of comparative example 1 in which the temperature of the thermal hydrolysis was 30℃and the treatment method of comparative example 2 in which the 0.1mol/L hydrochloric acid was used did not achieve the promotion of the carbon release amount, and the treatment method of comparative example 3 in which the 0.001mol/L sodium hydroxide was used was inferior to the treatment method in which the promotion effect of the carbon release amount was inferior to the treatment method in which the example was used. Therefore, the carbon release performance of the biodegradable straw can be effectively promoted only by a pretreatment method of heating hydrolysis, acid-base soaking and inducer addition under the condition of specific parameters.
Test example two, determination of carbon Release
The carbon release of the biodegradable straws (example 7) and biodegradable pellets (comparative example 4) in pure water environment after addition of inducer yeast extract was examined. TOC determination reference standard method (APHA, 1998).
The experimental results are shown in figure 3.
As can be seen from FIG. 3, both the biodegradable straw and the biodegradable particles can stably release carbon, and the release rate is rapidly increased for the first 12 hours and is retarded after 12 hours. The results indicate that the biodegradable material has the ability to slow release carbon in pure water. The carbon release rate of the biodegradable straw is stably superior to that of the biodegradable particles, which indicates that the biodegradable straw prepared in the embodiment 7 of the invention has higher relative surface area, can obtain higher carbon release capacity, and is beneficial to the intake and utilization of carbon sources by denitrifying microorganisms. In addition, the carbon release amount of the biodegradable straw when the inducer yeast extract is added is stably better than that of the biodegradable straw without the inducer. The result shows that the method using the yeast extract as the inducer can improve the carbon release amount of the biodegradable straw and provide more available carbon sources for the growth of denitrifying microorganisms.
Test example III biofilm attachment of biodegradable Plastic Filler
The denitrification reaction apparatus prepared in example 15 and comparative example 6 was measured for biofilm attachment of the modified biodegradable plastic filler in the reaction apparatus after 60 days of continuous operation. The reaction apparatus of example 15 and comparative example 6 was continuously fed with 5mg/L yeast extract during the operation.
The method for carrying out the enhanced denitrification by the denitrification reaction device specifically comprises the following steps:
the sewage flows into the reaction device through the water inlet pump in a continuous flow mode, and denitrification treatment is carried out under the condition that the hydraulic retention time is 4h by adopting up-flow water inlet. Wherein the selected sewage with low carbon nitrogen ratio is artificial synthetic wastewater, the TOC concentration of the sewage with low carbon nitrogen ratio is 13-17mg/L (containing 5mg/L yeast extract), and NO 3 The N concentration was 15mg/L.
The experimental results are shown in figure 4.
As can be seen from FIG. 4, the denitrification reaction apparatus prepared in example 15 was operated continuously for 60 days, and a large amount of microorganisms were attached to the surface of the modified biodegradable straw to form an obvious biofilm; while the modified biodegradable particles of comparative example 6 were still smooth in surface, and had little adhesion of microorganisms, no biofilm was formed. The result shows that when the modified biodegradable straw is used as the filler, the growth and adhesion capability of the biological film are better than those of the biodegradable particles, and the film formation of denitrifying microorganisms is facilitated.
Test example four, determination of denitrification Effect
The denitrification effect of the denitrification reaction apparatuses prepared in examples 15 to 16 and comparative examples 5 to 7 was measured. Wherein NO 3 -N、NO 2 -N、NH 4 + -N determination reference Standard method (APHA, 1998), TN determination value of NO 3 -N、NO 2 -N、NH 4 + -N-sum. The specific step of the denitrification reaction device for carrying out the enhanced denitrification is the same as that of the third test example.
The experimental results are shown in figures 5-6.
As can be seen from FIGS. 5 to 6, the TOC and hydraulic retention time of the feed water were changed after the reaction was stabilized, NO in examples 15 to 16 3 Both N and TN removal rates were steadily better than comparative examples 5 and 6, indicating that the modified biodegradable pipettes as fillers can achieve higher denitrification effect relative to the modified biodegradable particles. Comparative example 7 has a relatively low filling ratio of the modified biodegradable straw compared with the example, and is insufficient in carbon source releasing ability, and has no obvious difference in denitrification effect from comparative example 5, and cannot enhance denitrification. In addition, NO of example and comparative example 5 3 The difference of N removal rate can reach 20% at the highest, and the difference of TN removal rate can reach 15% at the highest. Therefore, the modified biodegradable straw prepared by the invention can be used as a denitrification biological filter filler, can slowly release a carbon source and be used as a microorganism adhesion carrier, shows a stable and efficient enhanced denitrification effect in treating sewage with low carbon nitrogen ratio, and simultaneously, the more the carbon release amount which can be taken up and utilized by denitrification microorganisms is along with the increase of the filling proportion of the modified biodegradable straw, the more the denitrification is facilitated, and the removal rate of TN is in a gradually rising trend.
Test example five
Morphological characteristics before and after the reaction of the modified biodegradable pipettes of example 15 were examined using an electron scanning microscope (SEM).
The experimental results are shown in fig. 7.
As can be seen from FIG. 7, the modified biodegradable plastic tubing before the reaction had a few irregular protrusions on the surface, indicating that the modified biodegradable plastic tubing was suitable for microorganism attachment. The modified biodegradable straw after reaction has more folds and holes on the surface, and the phenomenon of microorganism growth and adhesion appears, which indicates that the modified biodegradable straw is corroded under the hydrolysis and microorganism action to release degradation products, and has carrier characteristics, and can be used as filler for microorganism growth and adhesion.
The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.

Claims (10)

1. A preparation method of a modified biodegradable straw is characterized in that the biodegradable straw is modified to prepare the modified biodegradable straw;
the biodegradable straw comprises at least one of unused biodegradable straw and waste biodegradable straw;
the modification treatment comprises at least one of pyrolysis, acid/alkali solution soaking and yeast extract soaking.
2. The preparation method as claimed in claim 1, wherein the main component of the biodegradable straw is polylactic acid, the biodegradable straw has a diameter of 5-6 mm, a length of 200-210 mm, and a density of 1.20-1.25 g/cm 3
3. The method of claim 1, comprising at least one of the following (1) to (5):
(1) The pyrolysis is that the biodegradable straw is heated and hydrolyzed for 1 to 3 hours at the temperature of between 60 and 90 ℃;
(2) The acid/alkali solution soaking is to soak the biodegradable suction tube in acid solution or alkali solution for 1-3 hours;
(3) The concentration of the acid solution is 1-2 mol/L;
(4) The concentration of the alkali solution is 0.1-1 mol/L;
(5) The adding of the yeast extract is to add the yeast extract into the solution containing the biodegradable straw for soaking for 1-3 hours.
4. A modified biodegradable straw produced by the production method according to any one of claims 1 to 3.
5. A denitrification reactor applying the modified biodegradable straw according to claim 4, comprising a peristaltic pump, a water inlet, a water outlet, a water distribution area, a supporting layer, a filler area and a drainage area, wherein the denitrification reactor comprises the water distribution area, the supporting layer, the filler area and the drainage area from bottom to top in sequence, the water distribution area is connected with the water inlet, and the drainage area is connected with the water outlet;
the filler component selected in the filler zone comprises ceramsite and the modified biodegradable straw of claim 4.
6. The denitrification reactor according to claim 5, comprising at least one of the following (1) to (2):
(1) The denitrification reactor is of a cylindrical structure, the inner diameter is 80-100 mm, and the height is 400-450 mm;
(2) The inlet water in the denitrification reactor is injected from a water inlet at the bottom end of the reactor through a peristaltic pump, passes through a water distribution area, a bearing layer, a filling area and a drainage area, and is overflowed and discharged through an upper water outlet.
7. The denitrification reactor according to claim 5, comprising at least one of the following (1) to (2):
(1) The height of the water distribution area is 50-60 mm, the height of the supporting layer is 10-20 mm, the height of the filling area is 200-250 mm, and the height of the drainage area is 70-80 mm;
(2) The filler selected for the supporting layer is cobblestone.
8. The denitrification reactor according to claim 5, wherein the ratio of the height of the modified biodegradable straw to the total height of the packing area of the denitrification reactor is (0.3 to 0.7): 1.
9. use of the denitrification reactor according to any one of claims 5 to 8 in wastewater treatment, wherein the wastewater treatment comprises the steps of: and pumping the sewage with low carbon nitrogen ratio into the denitrification reactor through a peristaltic pump in a continuous water inlet mode to perform denitrification treatment.
10. The use according to claim 9, comprising at least one of the following (1) - (2):
(1) The TOC concentration of the sewage with low carbon nitrogen ratio is 13-17mg/L, NO 3 -N concentration is 15mg/L;
(2) The hydraulic retention time of the sewage with the low carbon nitrogen ratio in the denitrification reactor is 2-4 h.
CN202310258688.2A 2023-03-16 2023-03-16 Modified biodegradable straw and preparation method and application thereof Pending CN116444845A (en)

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