CN112408592B

CN112408592B - Composite carbon source for water treatment and preparation method and application thereof

Info

Publication number: CN112408592B
Application number: CN201910778906.9A
Authority: CN
Inventors: 唐地源; 徐传伟; 柴磊; 李慧燕; 柴惠南; 刘国超; 侯庆伟
Original assignee: Jinan Shengquan Group Share Holding Co Ltd
Current assignee: Jinan Shengquan Group Share Holding Co Ltd
Priority date: 2019-08-22
Filing date: 2019-08-22
Publication date: 2022-10-21
Anticipated expiration: 2039-08-22
Also published as: CN112408592A

Abstract

The invention provides a composite carbon source for water treatment and a preparation method and application thereof, wherein the composite carbon source comprises the following components in percentage by mass: 10-20% of monosaccharide compound, 8-12% of volatile fatty acid, 10-15% of C1-C5 alcohol compound and 5-10% of saccharomycete thallus; wherein the yeast fungus body can react with monosaccharide compounds to generate volatile fatty acid and alcohol. The composite carbon source for water treatment provided by the invention can stably and long-term release the carbon source through the compounding cooperation of several components, has high denitrification efficiency and long service life, can obviously reduce the total nitrogen content of a water body and improve the sewage treatment efficiency, avoids the output of a large amount of sludge, is convenient and fast to use, and can be directly put into sewage treatment equipment for use; the composite carbon source can be obtained by sugar liquid fermentation, and the preparation method is simple, the raw materials are easy to obtain, the cost is low, and the method has a wide large-scale application prospect.

Description

Composite carbon source for water treatment and preparation method and application thereof

Technical Field

The invention belongs to the technical field of water treatment, and particularly relates to a composite carbon source for water treatment as well as a preparation method and application thereof.

Background

With the rapid development of social economy, the eutrophication phenomenon of surface water bodies is increasingly serious due to excessive discharge of nutrient substances in domestic sewage, industrial wastewater and agricultural non-point source pollution, the research on the efficient and stable sewage nitrogen and phosphorus removal technology has important significance for improving the environmental quality of surface water, and the enhanced biological nitrogen and phosphorus removal by controlling the operation of activated sludge in anaerobic, anoxic and aerobic alternate environments and utilizing the metabolic action of microorganisms is the most widely researched and applied at home and abroad. The biological nitrogen and phosphorus removal performance is greatly influenced by the type and concentration of a carbon source in sewage, and effective carbon source supply is the guarantee for maintaining microbial metabolism and the nitrogen and phosphorus removal effect of the process. Because denitrifying bacteria and dephosphorizing bacteria coexist in activated sludge, the difference of the demand of microorganisms on carbon sources in the denitrifying process and the dephosphorizing process and the shortage or excess of effective carbon sources in sewage cause the unsatisfactory nitrogen and phosphorus removal rate of urban sewage treatment plants, and in the enhanced biological denitrifying and dephosphorizing system, the difference of carbon source types directly influences the denitrification and dephosphorizing rate and removal rate.

The denitrification reaction is a main process for degrading total nitrogen in sewage, and at present, most sewage treatment plants generally face the problem of insufficient denitrification efficiency and low carbon source due to low carbon-nitrogen ratio of inlet water, so that the purification capacity of the system needs to be provided by a carbon source additionally. In order to further improve the denitrification efficiency, researchers have conducted new research and research on the problem of an additional carbon source, and started to turn the attention to the development of a novel additional carbon source.

CN108751423A discloses a high-efficiency liquid sodium acetate carbon source for degrading ammonia nitrogen in wastewater, which is prepared by mixing sodium acetate, glacial acetic acid, sodium carbonate, ethanol, glucose and deionized water. Wherein, sodium acetate is harmless to human body, is easy to be absorbed and utilized by microorganism, and is an ideal external carbon source; glacial acetic acid can be additionally provided with a carbon source, and the pH value can be maintained in the sewage treatment process; sodium carbonate can provide an inorganic carbon source for a portion of the microorganisms.

CN108911131A discloses a composite carbon source medicament for wastewater treatment, which is prepared from the following components by weight: 0.5 to 1.0 percent of sodium formate, 4.5 to 5.5 percent of sodium acetate, 5 to 6 percent of sodium propionate, 40 to 50 percent of carbohydrate and 40 to 45 percent of water; wherein the saccharide is a saccharide mixture with COD of more than 300000 mg/ml. The composite carbon source medicament is an energy-saving, high-quality and efficient environment-friendly water treatment medicament, has the denitrification effect more than 1.5 times that of the traditional water treatment chemicals, and can well adapt to and meet the market demand.

CN109485157A discloses a composite carbon source for denitrification of wastewater, a preparation method and a use method thereof, wherein the composite carbon source comprises a sodium acetate solution, a glucose solution, a xylitol solution, glycerol, methanol, ethanol, ethylene glycol, glacial acetic acid, active peptide and a composite amino acid solution, wherein the composite amino acid is glycine, serineTyrosine, glutamine and alanine. The compound carbon source is a carbon source product which is easier to be absorbed and utilized by microorganisms, the complex formulation of various raw materials effectively avoids the influence on decarburization caused by microorganism domestication due to a single carbon source, the phenomenon that nutrition absorption of other microorganisms is inhibited due to the fact that certain microorganism is singly propagated in a large quantity is avoided, the negative influence on other strains is avoided while denitrification is promoted, and COD (chemical oxygen demand) to BOD (biochemical oxygen demand) of the compound carbon source ₅ The conversion rate of (D) can reach about 85 percent.

Among the existing external carbon sources, the traditional carbon source methanol has the advantage of economic price, but is easy to cause harm to human bodies due to high toxicity and inconvenient transportation; carbohydrate starch and the like must be hydrolyzed and converted into low molecular organic matters to be utilized by microorganisms, so that the sewage treatment efficiency is reduced. The carboxylate products such as sodium formate, sodium acetate and the like in the novel external carbon source have good denitrification effect, but are expensive, the sludge output rate is high, and the additional sludge treatment problem is increased; amino acid products also suffer from the problems of high price, difficult acquisition of raw materials and the like.

Therefore, the development of a composite carbon source with remarkable denitrification effect, high sewage treatment efficiency, simple use and high cost performance is an urgent problem to be solved in the field.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a composite carbon source for water treatment and a preparation method and application thereof, wherein the composite carbon source comprises monosaccharide compounds, volatile fatty acids, C1-C5 alcohol compounds and saccharomycete thalli, and the saccharomycete thalli and the monosaccharide compounds can further react to generate the volatile fatty acids and micromolecule alcohols, so that the carbon source is stably and permanently released, and the composite carbon source has the characteristics of high denitrification rate, low sludge yield and good denitrification effect.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the invention provides a composite carbon source for water treatment, which comprises the following components in percentage by mass: 10 to 20 percent of monosaccharide compound, 8 to 12 percent of volatile fatty acid, 10 to 15 percent of C1 to C5 (such as C1, C2, C3, C4 or C5) alcohol compound and 5 to 10 percent of yeast cell.

The composite carbon source provided by the invention comprises monosaccharide compounds, volatile fatty acids, C1-C5 alcohol compounds and saccharomycete thalli. The monosaccharide compound is an environment-friendly and efficient external carbon source and can be utilized by microorganisms without a long-time hydrolysis process; the volatile fatty acid is a micromolecular organic acid, is very easy to be utilized by denitrifying bacteria, and has good denitrification effect; the C1-C5 alcohol compound as an external carbon source has the characteristics of low cost and good denitrification effect; the saccharomycete thallus has no denitrogenation effect, but can react with monosaccharide compounds to generate volatile fatty acid and micromolecular alcohols such as methanol, ethanol and the like, so that stable and long-acting release of a carbon source is realized, the release period is long, the service life of a composite carbon source is long, and the denitrogenation efficiency is high; in addition, the yeast contains rich enzyme systems, can promote the degradation of organic matters in the sludge, improve the biodegradability and the digestion rate of the sludge, has a certain sludge treatment function while denitrifying, and avoids the sludge output problem caused by the denitrification process to a certain extent. In conclusion, the composite carbon source provided by the invention can stably and long-term release the carbon source through the compounding and cooperation of several components, has high denitrification efficiency and long service life, can obviously reduce the total nitrogen content of a water body and improve the sewage treatment efficiency, avoids the output of a large amount of sludge, is simple to use, and can be directly put into sewage treatment equipment for use.

The composite carbon source provided by the present invention may comprise the monosaccharide compounds in an amount of 10.5%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 19.5% by mass, and specific values therebetween, for reasons of brevity and conciseness, the present invention is not exhaustive of the specific values included in the range.

The volatile fatty acid may be present in an amount of 8.1%, 8.3%, 8.5%, 8.7%, 9%, 9.2%, 9.4%, 9.5%, 9.7%, 10%, 10.2%, 10.5%, 10.8%, 11%, 11.3%, 11.5%, 11.7%, or 11.9% by weight, and the specific values therebetween are not intended to be exhaustive or to limit the invention to the specific values encompassed by the scope, for reasons of brevity and clarity.

The C1-C5 alcohol compound may be present in an amount of 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14% or 14.5% by weight, and the specific values therebetween are not exhaustive for the sake of brevity and simplicity.

The mass percentage of the yeast strain may be 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9% or 9.5%, and the specific values therebetween are limited by space and for brevity, and the invention is not intended to be exhaustive of the specific values included in the ranges.

When the mass percentage of each component in the composite carbon source provided by the invention is within the limited range, the composite carbon source has high denitrification efficiency and good sewage treatment effect, and if the mass percentage of each component in the composite carbon source is lower than the limited range, the high-efficiency proceeding of denitrification is influenced, so that the denitrification efficiency is reduced; if the content is higher than the above-defined range, the subsequent sludge treatment load of water treatment is increased along with a high sludge yield in the denitrification process.

Preferably, the monosaccharide compounds include pentoses and hexoses.

Preferably, the content of pentose in the complex carbon source is 7-15% by mass, for example 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14% or 14.5%, and the specific values therebetween are not exhaustive, and for the sake of brevity and brevity, the invention is not exhaustive.

Preferably, the pentose is xylose and/or arabinose.

Preferably, the hexose content of the complex carbon source is 2 to 8% by mass, for example 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7% or 7.5% by mass, and the specific values therebetween are not exhaustive for the purpose of brevity and conciseness.

Preferably, the hexose is selected from any one of glucose, galactose or fructose or a combination of at least two thereof.

The monosaccharide compounds in the composite carbon source of the invention include pentoses and hexoses, and can be derived from xylose mother liquor generated by xylose production. Pentose and hexose in the xylose mother liquor are difficult to be effectively separated by the traditional method, so the utilization rate is extremely low; the invention creatively takes monosaccharide compounds as one of the components of the composite carbon source, on one hand, provides a novel environment-friendly high-efficiency water treatment external carbon source, and on the other hand, completes the effective reuse of xylose mother liquor; therefore, the composite carbon source and the preparation method thereof provided by the invention are a real green and environment-friendly product and process.

Preferably, the volatile fatty acid comprises acetic acid.

Preferably, the content of acetic acid in the complex carbon source is 4-10% by mass, such as 4.1%, 4.3%, 4.5%, 4.7%, 5%, 5.2%, 5.5%, 5.8%, 6%, 6.3%, 6.5%, 6.7%, 7%, 7.2%, 7.5%, 7.8%, 8%, 8.3%, 8.5%, 8.7%, 9%, 9.2%, 9.5% or 9.8%, and the specific values therebetween are not intended to be exhaustive or to be brief, and the invention is not intended to include the specific values within the scope.

Preferably, the volatile fatty acid further comprises at least one of formic acid, propionic acid, isobutyric acid, n-butyric acid, or isovaleric acid.

Preferably, the C1-C5 alcohol compounds include methanol and ethanol.

Preferably, the mass percentage of methanol in the composite carbon source is 2-4%, such as 21%, 2.3%, 2.5%, 2.7%, 2.9%, 3%, 3.2%, 3.4%, 3.6%, 3.8%, or 3.9%, and specific values therebetween, including space and simplicity, are not exhaustive, and the invention does not include the specific values included in the range.

Preferably, the content of ethanol in the composite carbon source is 8 to 10% by mass, for example, 8.1%, 8.3%, 8.5%, 8.7%, 8.9%, 9%, 9.2%, 9.4%, 9.6%, 9.8% or 9.9%, and specific values therebetween are not exhaustive, and for brevity and conciseness, the invention is not intended to list the specific values included in the range.

Preferably, the composite carbon source further comprises yeast active metabolites.

Preferably, the mass percentage of the yeast active metabolite in the composite carbon source is 1-5%, for example, 1.3%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 4.9%, and the specific values therebetween are limited by space and for brevity, the invention is not exhaustive of the specific values included in the range.

Preferably, the yeast active metabolite comprises at least one of lactate, pyruvate, or acetaldehyde.

Preferably, the composite carbon source comprises the following components in percentage by mass: 10-20% of monosaccharide compounds, 8-12% of volatile fatty acids, 2-4% of methanol, 8-10% of ethanol, 5-10% of saccharomycete, 1-5% of saccharomycete active metabolites and the balance of water.

Wherein the monosaccharide compounds include pentoses and hexoses; the volatile fatty acid comprises acetic acid and at least one of propionic acid, isobutyric acid, n-butyric acid or isovaleric acid.

Preferably, the pH of the complex carbon source is 4 to 6, for example, 4.1, 4.3, 4.5, 4.7, 4.9, 5, 5.2, 5.4, 5.6, 5.8, or 5.9, etc.

Preferably, the COD of the complex carbon source is more than or equal to 200000 mg/L, such as 203000 mg/L, 205000 mg/L, 208000 mg/L, 210000 mg/L, 213000 mg/L, 215000 mg/L, 217000 mg/L, 220000 mg/L, 223000 mg/L, 225000 mg/L, 228000 mg/L, 230000 mg/L, 232000 mg/L, 235000 mg/L, 238000 mg/L, 240000 mg/L or 250000 mg/L, etc.

In another aspect, the present invention provides a method for preparing the complex carbon source according to the first aspect, the method comprising the steps of:

(1) Mixing the corncobs with water, and hydrolyzing to obtain a sugar mother liquor;

(2) Mixing the sugar mother liquor obtained in the step (1) with yeast, and performing primary fermentation to obtain fermentation liquor;

(3) Mixing the sugar mother liquor obtained in the step (1) with the fermentation liquor obtained in the step (2), and performing secondary fermentation to obtain a mixed liquor;

(4) And (4) filtering the mixed liquid obtained in the step (3) to obtain the composite carbon source.

Preferably, the hydrolysis in step (1) is a cooking hydrolysis at 130-180 ℃ (e.g., 135 ℃, 140 ℃, 145 ℃,150 ℃, 155 ℃,160 ℃, 165 ℃, 170 ℃, 175 ℃ or 178 ℃, etc.).

Preferably, the volume of the water in the step (1) is 0.5 to 1L, such as 0.6L, 0.7L, 0.8L or 0.9L, etc., based on 1kg of the corn cob in the step (1).

Preferably, the hydrolysis in step (1) further comprises a filtration and separation process.

Preferably, the pH of the sugar mother liquor in step (1) is 6 to 8, for example, the pH is 6.1, 6.3, 6.5, 6.7, 6.9, 7, 7.2, 7.4, 7.6, 7.8 or 7.9, etc.

Preferably, in the step (2), the mass ratio of the sugar mother liquor to the yeast is (200-400) from the following ratio of (205).

Preferably, the temperature of the primary fermentation in step (2) is 30 to 40 ℃, such as 31 ℃, 32 ℃, 33 ℃, 34 ℃,35 ℃, 36 ℃, 37 ℃, 38 ℃ or 39 ℃, etc.

Preferably, the time of the primary fermentation in step (2) is 5-15 h, such as 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h or 14 h.

Preferably, in step (3), the mass ratio of the sugar mother liquor to the fermentation liquor is (5-8) 1, for example, 5.5.

Preferably, the temperature of the secondary fermentation in step (3) is 35 to 45 ℃, such as 36 ℃, 37 ℃, 38 ℃, 39 ℃,40 ℃, 41 ℃, 42 ℃, 43 ℃ or 44 ℃, etc.

Preferably, the time of the secondary fermentation in step (3) is 8-30 h, such as 9h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, 26h, 28h or 29h, etc.

Preferably, the end point of the secondary fermentation in step (3) is 0.1-1 mg/L galactose content in the fermentation system, for example, 0.2mg/L, 0.3mg/L, 0.4mg/L, 0.5mg/L, 0.6mg/L, 0.7mg/L, 0.8mg/L or 0.9mg/L galactose content.

Preferably, the filtering method in the step (4) is as follows: firstly, performing ultrafiltration on the mixed solution to obtain a concentrated solution I and a permeate I; deionized by passing the permeate I through ion exchange resin, and then performing nanofiltration to obtain a concentrated solution II and a permeate II; and mixing and dispersing the concentrated solution I and the concentrated solution II to obtain the composite carbon source.

Preferably, the ultrafiltration membrane has a cut-off molecular weight of 50000 to 300000, e.g. 50000, 70000, 90000, 100000, 120000, 150000, 170000, 200000, 230000, 250000, 270000 or 290000.

Preferably, the nanofiltration membrane has a molecular weight cut-off of 50 to 500, such as 60, 80, 100, 130, 150, 180, 200, 230, 250, 280, 300, 330, 350, 380, 400, 430, 450, 470, 490, and the like.

Preferably, the mass ratio of the concentrated solution I to the concentrated solution II is (3-6): 1, e.g. 3.5.

Preferably, the preparation method specifically comprises the following steps:

(1) Mixing the corncobs with water, cooking and hydrolyzing at 130-180 ℃, filtering, separating and adjusting the pH value to obtain a sugar mother liquor with the pH value of 6-8; wherein, the volume of the water is 0.5-1L based on the mass of the corncobs as 1 kg.

(2) Mixing the sugar mother liquor obtained in the step (1) with yeast according to the mass ratio of (200-400) to 1, and performing primary fermentation for 5-15 h at the temperature of 30-40 ℃ to obtain fermentation liquor.

(3) Mixing the sugar mother liquor obtained in the step (1) with the fermentation liquor obtained in the step (2) according to the mass ratio of (5-8) to 1, performing secondary fermentation for 8-30 h at the temperature of 35-45 ℃, and obtaining a mixed liquor when the content of galactose in a fermentation system reaches an end point when the content of galactose in the fermentation system is 0.1-1 mg/L.

(4) Carrying out ultrafiltration on the mixed solution obtained in the step (3) by using an ultrafiltration membrane with the molecular weight cutoff of 50000-300000 to obtain a concentrated solution I and a permeate I; deionized by ion exchange resin, and then nano-filtering by using a nano-filtration membrane with the molecular weight cut-off of 50-500 to obtain a concentrated solution II and a permeate II; and mixing and dispersing the concentrated solution I and the concentrated solution II according to the mass ratio of (3-6) to 1 to obtain the composite carbon source.

In another aspect, the present invention provides a use of the composite carbon source according to the first aspect in water treatment.

The composite carbon source provided by the invention can be used for treating municipal sewage and industrial wastewater. And diluting the stock solution to a corresponding concentration according to the medicament property of the composite carbon source and the water pollution degree during wastewater treatment, and then adding the diluted stock solution, wherein a mode of directly adding the raw medicament can be selected for wastewater with serious pollution. The adding dosage is mainly determined by the water pollution degree, the adding point and the lab scale condition, generally 100-350 mg of the composite carbon source is added into each liter of wastewater, and the wastewater pollution degree is measured by the total nitrogen index.

Compared with the prior art, the invention has the following beneficial effects:

the composite carbon source for water treatment provided by the invention comprises monosaccharide compounds, volatile fatty acids, C1-C5 alcohol compounds and yeast thalli, wherein the monosaccharide compounds, the volatile fatty acids and the C1-C5 alcohol compounds are easy to be utilized by denitrifying bacteria, and the denitrification effect is good; the saccharomycete thallus can react with monosaccharide compounds to generate volatile fatty acid and micromolecule alcohol, so that stable and long-acting release of a carbon source is realized, the release period is long, the service life of a composite carbon source is long, and the denitrification efficiency is high; in addition, the saccharomycetes can also promote the degradation of organic matters in the sludge, improve the biodegradability and the digestion rate of the sludge, have a certain sludge treatment function while denitrifying, and avoid the sludge output problem caused by the denitrification process. Therefore, the composite carbon source for water treatment provided by the invention can stably and long-term release the carbon source through the compounding cooperation of several components, has high denitrification efficiency and long service life, can obviously reduce the total nitrogen content of a water body and improve the sewage treatment efficiency, avoids the output of a large amount of sludge, is convenient to use, and can be directly put into sewage treatment equipment for use; after the water treatment agent is used, the total nitrogen removal rate in water can reach more than 80%, the ammonia nitrogen content is lower than 0.8mg/L, the COD in the water is lower than 12.5mg/L, the pH value is close to neutral, and the water quality requirement after purification is completely met. The composite carbon source can be obtained by fermenting sugar liquor, and the preparation method is simple and environment-friendly, has easily obtained raw materials and low cost, and has wide large-scale application prospect.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitation of the present invention.

The experimental materials used in the following examples and comparative examples of the present invention include:

corncobs and yeasts can be obtained through market approaches, and the sources of the corncobs and the yeasts are not specially limited; the sewage to be treated is derived from urban domestic sewage, the pH value of the sewage is 6.8, the Chemical Oxygen Demand (COD) is 180.53mg/L, the total nitrogen content is 40.8mg/L, and the ammonia nitrogen content is 35.86mg/L.

Example 1

The embodiment provides a composite carbon source for water treatment, and the specific preparation method comprises the following steps:

(1) Mixing corn cobs with water according to a solid-to-liquid ratio of 1;

(2) Mixing the sugar mother liquor obtained in the step (1) with yeast at a mass ratio of 300 to 1, and performing primary fermentation for 10 hours at 35 ℃ to obtain fermentation liquor;

(3) Mixing the sugar mother liquor obtained in the step (1) with the fermentation liquor obtained in the step (2) according to the mass ratio of 7;

(4) Performing ultrafiltration on the mixed solution obtained in the step (3) by using an ultrafiltration membrane with the molecular weight cutoff of 200000 to obtain a concentrated solution I and a permeate I; deionized by passing the permeate I through ion exchange resin, and performing nanofiltration by using a nanofiltration membrane with the molecular weight cut-off of 300 to obtain a concentrated solution II and a permeate II; and mixing and dispersing the concentrated solution I and the concentrated solution II according to a mass ratio of 4.

Example 2

(1) Mixing corn cob with water according to a solid-to-liquid ratio of 1.8 (namely 1kg of corn cob corresponds to 0.8L of water), cooking and hydrolyzing at 160 ℃ for 6h, filtering by a plate-and-frame filter, carrying out chromatographic separation, and adjusting the pH value to obtain a sugar mother liquor with the pH value of 6.9;

(2) Mixing the sugar mother liquor obtained in the step (1) with yeast according to a mass ratio of 310 to 1, and performing primary fermentation for 12 hours at 35 ℃ to obtain fermentation liquor;

(3) Mixing the sugar mother liquor obtained in the step (1) with the fermentation liquor obtained in the step (2) according to the mass ratio of 6;

(4) Performing ultrafiltration on the mixed solution obtained in the step (3) by using an ultrafiltration membrane with the molecular weight cutoff of 150000 to obtain concentrated solution I and permeate I; deionized by passing the permeate I through ion exchange resin, and performing nanofiltration by using a nanofiltration membrane with the molecular weight cut-off of 200 to obtain a concentrated solution II and a permeate II; and mixing and dispersing the concentrated solution I and the concentrated solution II according to a mass ratio of 4.

Example 3

(1) Mixing corn cob with water according to a solid-to-liquid ratio of 1.5 (namely 1kg of corn cob corresponds to 0.5L of water), cooking at 130 ℃ and hydrolyzing for 6h, filtering with a plate-and-frame filter, carrying out chromatographic separation, and adjusting the pH value to obtain a sugar mother liquor with the pH value of 6.3;

(2) Mixing the sugar mother liquor obtained in the step (1) with yeast at a mass ratio of 400:1, and performing primary fermentation for 15h at 30 ℃ to obtain fermentation liquor;

(3) Mixing the sugar mother liquor obtained in the step (1) with the fermentation liquor obtained in the step (2) according to the mass ratio of 5;

(4) Performing ultrafiltration on the mixed solution obtained in the step (3) by using an ultrafiltration membrane with the molecular weight cut-off of 50000 to obtain concentrated solution I and permeate I; deionized by ion exchange resin, and performing nanofiltration by using a nanofiltration membrane with the molecular weight cut-off of 60 to obtain a concentrated solution II and a permeate liquid II; and mixing and dispersing the concentrated solution I and the concentrated solution II according to a mass ratio of 3.

Example 4

(1) Mixing corn cob with water according to a solid-liquid ratio of 1.8 (namely, 1kg of corn cob corresponds to 0.8L of water), cooking and hydrolyzing at 180 ℃ for 6 hours, filtering by a plate-and-frame filter, carrying out chromatographic separation, and adjusting the pH value to obtain a sugar mother liquor with the pH value of 7.9;

(2) Mixing the sugar mother liquor obtained in the step (1) with yeast at a mass ratio of 200;

(3) Mixing the sugar mother liquor obtained in the step (1) with the fermentation liquor obtained in the step (2) according to the mass ratio of 8;

(4) Performing ultrafiltration on the mixed solution obtained in the step (3) by using an ultrafiltration membrane with the molecular weight cutoff of 300000 to obtain concentrated solution I and permeate I; deionized by ion exchange resin, and performing nanofiltration by using a nanofiltration membrane with the molecular weight cut-off of 500 to obtain a concentrated solution II and a permeate liquid II; and mixing and dispersing the concentrated solution I and the concentrated solution II according to a mass ratio of 6.

Comparative example 1

The comparative example is different from example 1 in that the mass ratio of the sugar mother liquor to the yeast in step (2) is 150.

Comparative example 2

The comparative example is different from example 1 in that the mass ratio of the sugar mother liquor to the yeast in step (2) is 430.

Comparative example 3

This comparative example differs from example 1 in that the time for the primary fermentation in step (2) was 4 hours.

Comparative example 4

This comparative example differs from example 1 in that the time for the primary fermentation in step (2) was 17 hours.

Comparative example 5

The difference between the comparative example and example 1 is that the sugar mother liquor and the fermentation liquor in the step (3) are in a mass ratio of 4.

Comparative example 6

The difference between the comparative example and example 1 is that the sugar mother liquor and the fermentation liquor in the step (3) are in a mass ratio of 9.

Comparative example 7

This comparative example differs from example 1 in that the time for the secondary fermentation in step (3) was 6 hours.

Comparative example 8

This comparative example differs from example 1 in that the time for the secondary fermentation in step (3) was 32 hours.

Comparative example 9

This comparative example provides a conventional external carbon source, methanol, for water treatment.

The qualitative and quantitative test method of each component in the composite carbon source comprises the following steps:

(1) Monosaccharide compounds: the determination method is carried out according to national standards, the mass percentage content of xylose (pentose) is tested according to a method specified by GB/T23532-2009 standard, and the mass percentage content of glucose (hexose) is tested according to a method specified by GB/T16285-2008 standard.

(2) Volatile fatty acid: the content of volatile fatty acids was determined by the acidify distillation titration method as specified in DB 34/T2499-2015 standard.

(3) C1-C5 alcohol compounds: and respectively testing the mass percentage of methanol and ethanol in the composite carbon source according to a method specified by GB/T338-2011 standard.

The components of the composite carbon sources provided in examples 1 to 4 and comparative examples 1 to 8 were measured according to the above-described method, and the information on the components is shown in table 1 in terms of mass percent (%):

TABLE 1

By combining the preparation method and the data in table 1, the composite carbon source of the present invention can be obtained according to the preparation method and the fermentation conditions defined in the present invention, wherein the mass percentage of monosaccharide compounds in the composite carbon source is 10-20%, the mass percentage of volatile fatty acids is 8-12%, the mass percentage of C1-C5 alcohol compounds is 10-14%, the composite carbon source further comprises yeast cells, and other active metabolites generated by fermentation of yeast and saccharide compounds. If the mass ratio of yeast to sugar solution in the primary fermentation is out of the range defined in the present invention (comparative examples 1 and 2), the time for the primary fermentation is too short (comparative example 3), the time for the primary fermentation is too long (comparative example 4), the mass ratio of sugar mother liquor to fermentation liquor in the secondary fermentation is out of the range defined in the present invention (comparative examples 5 and 6), the time for the secondary fermentation is too short (comparative example 7) or the time for the secondary fermentation is too long (comparative example 8), the composition and content of the final product are changed, and the content of at least one component of monosaccharide compound, volatile fatty acid or C1-C5 alcohol compound is out of the range defined in the present invention, thereby affecting the sewage treatment performance of the composite carbon source.

Application example

The composite carbon source provided by the embodiments 1 to 4 of the invention is used for treating municipal sewage and industrial wastewater. And diluting the stock solution to a corresponding concentration according to the medicament property of the composite carbon source and the water pollution degree during wastewater treatment, and then adding the diluted stock solution, wherein a mode of directly adding the raw medicament can be selected for wastewater with serious pollution. The adding dosage is mainly determined by the water pollution degree, the adding point and the lab scale condition, generally 100-350 mg of the composite carbon source is added into each liter of wastewater, and the wastewater pollution degree is measured by the total nitrogen index.

Testing the denitrification performance of the sewage:

the sewage to be treated firstly enters a sedimentation tank, colloids and fine suspended matters in the sewage are condensed to form flocculating constituents under the action of a coagulant, and the flocculating constituents are separated and removed and then enter a biological aerated filter for carbonization and nitration reaction; after the effluent of the aeration biological filter tank enters a denitrification filter tank, carrying out denitrification reaction with the assistance of a composite carbon source to remove the total nitrogen in the water; and after the water is discharged from the denitrification filter, the water sequentially enters a sand filter and a catalytic oxidation tank, and finally purified water is obtained.

The composite carbon sources provided in examples 1-4 and comparative examples 1-9 were added to the denitrification filter at a rate of 280mg of composite carbon source per liter of sewage, and the purified water was taken after the treatment to test pH, chemical oxygen demand COD, total nitrogen content, and ammonia nitrogen content. The test method is as follows:

(1) pH value: measuring the pH value of the water according to a glass electrode method specified by GB/T6920-1986 standard;

(2) Chemical oxygen demand COD: determining the Chemical Oxygen Demand (COD) of the water according to a dichromate method specified by an HJ/T828-2017 standard;

(3) Total nitrogen content: measuring the total nitrogen content of the water quality according to a gas phase molecular absorption spectrometry specified by an HJ/T199-2005 standard;

(4) Ammonia nitrogen content: and (3) measuring the ammonia nitrogen content of the water according to a continuous flow-salicylic acid spectrophotometry specified by an HJ/T665-2013 standard.

The test results are shown in table 2:

TABLE 2

As can be seen from the data in Table 1, the composite carbon source provided in the embodiments 1 to 4 of the present invention has high denitrification efficiency when used for sewage treatment, and can reduce the total nitrogen content of sewage from above 40mg/L to below 10.2mg/L, even as low as 8.12mg/L, and the total nitrogen removal rate reaches 80%; the total ammonia nitrogen content of the sewage is reduced from more than 35mg/L to 0.47-0.76 mg/L, the ammonia nitrogen removal rate reaches more than 97%, and the denitrification effect is good. The COD of the water quality treated by the composite carbon source provided by the embodiments 1-4 of the invention is 11-12.5 mg/L, the pH value is close to neutral, and the water quality requirement after purification is completely met.

In the composite carbon sources provided by the comparative examples 1 to 8, the content of at least one of monosaccharide compounds, volatile fatty acids or C1-C5 alcohol compounds exceeds the range defined by the invention, so that the denitrification efficiency is obviously reduced, the total nitrogen removal rate is lower than 68%, and the COD (chemical oxygen demand) of the treated water is higher than 15mg/L and does not meet the ideal water purification requirement. In the comparative example 9, the total nitrogen removal rate and ammonia nitrogen removal rate of the traditional carbon source methanol are lower than those of the examples 1-4, the treated water quality COD is higher, and the methanol has high toxicity and is not beneficial to environmental protection.

The applicant states that the present invention is illustrated by the above examples to the composite carbon source for water treatment and the preparation method and application thereof, but the present invention is not limited to the above process steps, i.e. it does not mean that the present invention must rely on the above process steps to be implemented. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

Claims

1. The composite carbon source for water treatment is characterized by comprising the following components in percentage by mass: 10 to 20% of monosaccharide compounds, 8 to 12% of volatile fatty acids, 10 to 15% of C1-C5 alcohol compounds, and 5 to 10% of yeast cells;

the composite carbon source is prepared by the following method, and the method comprises the following steps:

(1) Mixing the corncobs with water, and hydrolyzing to obtain a sugar mother solution;

2. The composite carbon source of claim 1, wherein the monosaccharide compounds comprise pentoses and hexoses.

3. The composite carbon source according to claim 2, wherein the composite carbon source contains 7 to 15% by mass of pentose.

4. The complex carbon source according to claim 2, characterized in that the pentose is xylose and/or arabinose.

5. The composite carbon source of claim 2, wherein the hexose content in the composite carbon source is 2 to 8% by mass.

6. Composite carbon source according to claim 2, characterized in that the hexose is selected from any one of glucose, galactose or fructose or a combination of at least two thereof.

7. The complex carbon source of claim 1, wherein said volatile fatty acid comprises acetic acid.

8. The composite carbon source as claimed in claim 7, wherein the mass percentage of acetic acid in the composite carbon source is 4 to 10%.

9. The composite carbon source of claim 1, wherein the volatile fatty acid further comprises at least one of formic acid, propionic acid, isobutyric acid, n-butyric acid, or isovaleric acid.

10. The composite carbon source according to claim 1, wherein the C1-C5 alcohol compound comprises methanol and ethanol.

11. The composite carbon source as claimed in claim 10, wherein the mass percentage of methanol in the composite carbon source is 2 to 4%.

12. The composite carbon source of claim 10, wherein the mass percent of ethanol in the composite carbon source is 8-10%.

13. The composite carbon source of claim 1, further comprising a yeast active metabolite.

14. The composite carbon source of claim 13, wherein the composite carbon source comprises 1 to 5 mass% of yeast active metabolites.

15. The composite carbon source of claim 13, wherein the yeast active metabolite comprises at least one of lactate, pyruvate, or acetaldehyde.

16. The composite carbon source of claim 1, comprising the following components in percentage by mass: 10 to 20 percent of monosaccharide compound, 8 to 12 percent of volatile fatty acid, 2 to 4 percent of methanol, 8 to 10 percent of ethanol, 5 to 10 percent of saccharomycete thallus, 1 to 5 percent of saccharomycete active metabolite and the balance of water;

17. The composite carbon source of claim 1, wherein the pH of the composite carbon source is 4 to 6.

18. The composite carbon source of claim 1, wherein the COD of the composite carbon source is at least 200000 mg/L.

19. A method for preparing the composite carbon source according to any one of claims 1 to 18, comprising the following steps:

(4) And (4) filtering the mixed solution obtained in the step (3) to obtain the composite carbon source.

20. The method according to claim 19, wherein the hydrolysis in step (1) is carried out by cooking at 130 to 180 ℃.

21. The preparation method of claim 19, wherein the volume of the water in the step (1) is 0.5 to 1L, based on 1kg of the corncob in the step (1).

22. The method according to claim 19, wherein the hydrolysis in step (1) further comprises a filtration and separation step.

23. The method according to claim 19, wherein the pH of the molasses of step (1) is 6-8.

24. The preparation method according to claim 19, wherein the mass ratio of the saccharomycetes to the saccharomycetes in the step (2) is (200-400): 1.

25. The method according to claim 24, wherein the mass ratio of the sugar mother liquor to the yeast in the step (2) is 300.

26. The method for preparing the compound of claim 19, wherein the temperature of the primary fermentation in the step (2) is 30 to 40 ℃.

27. The preparation method of claim 19, wherein the time of the primary fermentation in the step (2) is 5 to 15 hours.

28. The preparation method according to claim 19, wherein the mass ratio of the sugar mother liquor to the fermentation liquor in the step (3) is (5 to 8): 1.

29. The method for preparing the compound of the claim 19, wherein the temperature of the secondary fermentation in the step (3) is 35 to 45 ℃.

30. The preparation method of claim 19, wherein the time of the secondary fermentation in the step (3) is 8 to 30 hours.

31. The preparation method of claim 19, wherein the end point of the secondary fermentation in the step (3) is 0.1 to 1mg/L of galactose in the fermentation system.

32. The method for preparing the composite material according to claim 19, wherein the filtering in the step (4) is performed by: firstly, performing ultrafiltration on the mixed solution to obtain a concentrated solution I and a permeate I; deionized by ion exchange resin, and then carrying out nanofiltration on the permeate liquid I to obtain a concentrated liquid II and a permeate liquid II; and mixing and dispersing the concentrated solution I and the concentrated solution II to obtain the composite carbon source.

33. The method for preparing the compound of claim 32, wherein the ultrafiltration membrane has a molecular weight cut-off of 50000 to 300000.

34. The preparation method of claim 32, wherein the nanofiltration membrane has a molecular weight cut-off of 50 to 500.

35. The preparation method according to claim 32, wherein the mass ratio of the concentrated solution I to the concentrated solution II is (3 to 6): 1.

36. The method according to claim 35, wherein the concentrate I and the concentrate II are mixed at a mass ratio of 4.

37. The preparation method according to claim 19, comprising the steps of:

(1) Mixing the corncobs with water, cooking at 130-180 ℃, hydrolyzing, filtering, separating and adjusting the pH value to obtain a sugar mother liquor with the pH value of 6-8; wherein the volume of the water is 0.5 to 1L when the mass of the corncob is 1 kg;

(2) Mixing the saccharomycete mother liquor obtained in the step (1) with saccharomycete in a mass ratio of (200 to 400) to 1, and performing primary fermentation at 30 to 40 ℃ for 5 to 15 hours to obtain a fermentation liquor;

(3) Mixing the sugar mother liquor obtained in the step (1) with the fermentation liquor obtained in the step (2) in a mass ratio of (5-8) to 1, performing secondary fermentation for 8-30 h at the temperature of 35-45 ℃, and reaching an end point when the content of galactose in a fermentation system is 0.1-1 mg/L to obtain a mixed liquor;

(4) Performing ultrafiltration on the mixed solution obtained in the step (3) by using an ultrafiltration membrane with the molecular weight cutoff of 50000-300000 to obtain a concentrated solution I and a permeate I; deionized by passing the permeate I through ion exchange resin, and performing nanofiltration by using a nanofiltration membrane with the molecular weight cut-off of 50-500 to obtain a concentrated solution II and a permeate II; and mixing and dispersing the concentrated solution I and the concentrated solution II according to the mass ratio of (3-6) to 1 to obtain the composite carbon source.

38. Use of the composite carbon source as claimed in any one of claims 1 to 18 in water treatment.