Composition and application thereof in sludge hydrolysis treatment

Abstract

The invention discloses a composition and application thereof in sludge hydrolysis treatment. By compounding 3, 4-didodecyloxybenzylamine (DDOBA) with enzymes such as lysozyme which are commonly used for hydrolytic treatment of sludge, and treating concentrated sludge by using the obtained composition, it is found that the hydrolytic treatment efficiency of sludge can be remarkably improved through combined use of DDOBA, lysozyme and other enzymes, and the COD content in hydrolysate obtained by treating raw sludge is remarkably improved. The composition can effectively promote the hydrolysis of raw sludge, so that insoluble substances, such as polysaccharide, in the sludge are hydrolyzed into soluble micromolecular substances, and more available carbon sources are recovered from the sludge. The recycled carbon source can be reused in a biochemical pool, so that denitrification reaction in the biochemical process is effectively promoted, sewage is fully denitrified, the quality of effluent is improved, and meanwhile, the use of commercial carbon sources is reduced. The method is beneficial to resourceful treatment of the sludge, and the operation cost of subsequent water treatment is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of sludge treatment. More specifically, it relates to a composition and its application in hydrolyzing sludge. Background Art

[0002] Sludge is a waste generated in the sewage treatment process, containing abundant resources such as carbon and phosphorus, as well as pollutants such as heavy metals and pathogenic bacteria, having the dual attributes of pollution and resources. Traditional sludge disposal methods, such as landfill and incineration, are prone to causing environmental pollution and are difficult to achieve resource recovery treatment of sludge, and can no longer meet the current requirements for sludge treatment. With the continuous improvement of the urbanization level and the continuous improvement of the urban water supply and drainage system, the amount of sludge generated in the sewage treatment process is also increasing continuously, bringing great pressure to the treatment of sludge.

[0003] Currently, the sewage treatment system generally has the problems of insufficient denitrification carbon source and low efficiency of nitrogen and phosphorus removal. The traditional sewage treatment system makes up for it by adding commercial carbon sources (such as sodium acetate), resulting in an increase in water treatment costs and environmental pollution. Therefore, there is a higher demand for the resource treatment of sludge. The hydrolysis treatment of sludge is a process of hydrolyzing insoluble macromolecular organic matter in sludge into soluble substances, which can improve the resource utilization rate of sludge, mainly including two stages: hydrolysis and acidification. However, the hydrolysis rate of insoluble macromolecular organic matter in sludge is relatively slow, usually taking several days or even longer, resulting in the hydrolysis stage becoming the rate-limiting step of sludge hydrolysis treatment.

[0004] There are many cell wall breaking methods in the sludge hydrolysis treatment process, but physical and chemical treatment methods have the disadvantages of high energy consumption, high treatment costs, and high requirements for treatment equipment, bringing difficulties to practical applications. And biological treatment methods cannot guarantee the safety of microorganisms, and it is difficult for microorganisms to occupy a dominant position. The method of adding hydrolytic enzymes, such as amylase, protease, cellulase, and lysozyme, to sludge has received more and more attention due to its mild reaction conditions, fast onset, and environmental protection. Among them, the main function of lysozyme is to lyse microbial cells by breaking the β-1,4 glycosidic bond connecting N-acetylmuramic acid and N-acetylglucosamine in the cell wall; protease, amylase, and cellulase promote the fragmentation of sludge macromolecules, converting them into smaller molecules with higher biodegradability, thereby improving the hydrolysis effect of sludge. After sludge hydrolysis and cell lysis, the substances in the cells are released into the supernatant, manifested as an increase in the COD concentration of the supernatant. These CODs can be used as available carbon sources and returned to the biochemical section of sewage treatment to provide carbon sources for sewage denitrification and phosphorus removal, making the efficiency of denitrification and phosphorus removal higher.

[0005] However, the sludge system is relatively complex. The microbial cell wall is wrapped by layers of extracellular polymeric substances (EPS) of bacteria, making it difficult for hydrolases to directly contact the cell wall. Moreover, after the hydrolases are added to the sludge system, they are easily captured or trapped by the complex organic substances in the sludge, making it difficult for the enzymes to continuously play a cracking role over time. Although there is currently a method of compounding a complex enzyme composed of a surfactant (such as SDS), protease, and amylase to promote the effluent of sludge, it is not clear whether it can promote the dissolution of insoluble organic substances, and the compounding of the surfactant and the enzyme does not necessarily improve the resource utilization rate of the sludge. That is, there is still a need to develop reagents and methods that can effectively promote the hydrolysis treatment efficiency of sludge, etc. Summary of the Invention

[0006] In view of the deficiencies in the above-mentioned existing technologies, the present invention provides a composition and its application in hydrolyzing sludge. By using the composition, the hydrolysis efficiency of sludge can be accelerated, and its resource utilization rate can be improved.

[0007] The first object of the present invention is to provide a composition.

[0008] The second object of the present invention is to provide the application of the composition in the hydrolysis treatment of sludge.

[0009] The third object of the present invention is to provide the application of the composition in the preparation of hydrolysis treatment products of sludge.

[0010] The fourth object of the present invention is to provide a method for hydrolyzing sludge and recovering utilizable carbon sources.

[0011] The above objects of the present invention are achieved by the following technical solutions:

[0012] When only using hydrolases to hydrolyze sludge, the hydrolases are easily captured by the complex organic substances in the sludge, making it difficult to continuously promote sludge lysis and hydrolysis, resulting in low sludge hydrolysis efficiency, etc. In view of this, the present invention provides a composition composed of 3,4-didodecyloxybenzylamine (DDOBA) and hydrolases. By using the composition of the present invention, sludge hydrolysis and cell cracking can be promoted, further enhancing the sustainable action time of the enzymes, the efficiency of sludge hydrolysis and cell cracking, hydrolyzing insoluble substances in the sludge, such as polysaccharides, into soluble small molecule substances, so as to recover more utilizable carbon sources from the sludge. Recycling the recovered carbon source back to the biochemical pool can effectively promote the denitrification reaction in the biochemical process, fully denitrify the sewage, improve the effluent quality, and reduce the water treatment cost. Therefore, the present invention requests protection for the composition and its application in the hydrolysis treatment of sludge.

[0013] The present invention provides a composition, which is composed of 3,4-didodecyloxybenzylamine and an enzyme; wherein, the mass ratio of 3,4-didodecyloxybenzylamine to the enzyme is 1-2:1-2; the enzyme is one or more of lysozyme, cellulase, amylase, papain, and alkaline protease.

[0014] Preferably, the enzyme is one or more of lysozyme, cellulase, papain, and alkaline protease.

[0015] More preferably, the enzyme is one or more of cellulase, papain, and alkaline protease.

[0016] Even more preferably, the enzyme is papain and / or alkaline protease.

[0017] Even more preferably, the enzyme is alkaline protease.

[0018] The content of COD in the hydrolysis solution obtained by hydrolyzing sludge with the preferably selected enzyme is relatively higher.

[0019] Preferably, the mass ratio of 3,4-didodecyloxybenzylamine to the enzyme is 1-2:1.

[0020] More preferably, the mass ratio of 3,4-didodecyloxybenzylamine to the enzyme is 1-1.5:1.

[0021] Even more preferably, the mass ratio of 3,4-didodecyloxybenzylamine to the enzyme is 1:1.

[0022] In view of the fact that the composition of the present invention can effectively promote the hydrolysis of sludge and the recovery of available carbon sources. Therefore, the present invention claims the application of the composition in the hydrolysis treatment of sludge.

[0023] The present invention also claims the application of the composition in the preparation of hydrolysis treatment products for sludge.

[0024] Correspondingly, the application of the composition in the hydrolysis treatment of sludge and the recovery of available carbon sources should also be within the protection scope of the present invention.

[0025] Similarly, the application of the composition in the preparation of products for the hydrolysis treatment of sludge and the recovery of available carbon sources should also be within the protection scope of the present invention.

[0026] The present invention also provides a method for hydrolyzing sludge and recovering utilizable carbon sources, specifically: mixing the composition of the present invention with the sludge to be treated, reacting at 35-45°C for 2-6 hours, then performing solid-liquid separation, and collecting the liquid. Compared with the sludge before treatment, the COD content in the liquid collected after hydrolysis treatment is significantly increased, which can be used in the denitrification stage of subsequent water treatment, etc., to fully denitrify the sewage and improve the effluent quality.

[0027] Specifically, the dosage of the composition is 0.5%-5% of the sludge mass.

[0028] Preferably, the dosage of the composition is 1%-5% of the sludge mass.

[0029] More preferably, the dosage of the composition is 1%-3% of the sludge mass.

[0030] Even more preferably, the dosage of the composition is 1% of the sludge mass.

[0031] Specifically, stirring is required during the reaction process.

[0032] Specifically, after reacting at 35-45°C and 300-500 rpm for 2-6 hours, solid-liquid separation is carried out.

[0033] Optionally, in the method, solid-liquid separation is carried out by means of gravity sedimentation, pressure filtration or filtration.

[0034] Specifically, the sludge of the present invention is raw sludge.

[0035] More specifically, the sludge of the present invention is raw sludge generated during the treatment of domestic sewage or municipal sewage.

[0036] In a specific embodiment of the present invention, the sludge to be treated is thickened sludge generated during the treatment of municipal sewage. Thickened sludge refers to the sludge obtained after the concentration treatment of raw sludge (such as primary sedimentation sludge, etc.).

[0037] The present invention has the following beneficial effects:

[0038] The present invention provides a composition which is obtained by compounding 3,4-didodecyloxybenzylamine (DDOBA) with enzymes such as lysozyme commonly used for hydrolyzing sludge. It is found that when the composition of the present invention is used to treat concentrated sludge, the combination of DDOBA and enzymes such as lysozyme can significantly improve the hydrolysis efficiency of sludge and significantly increase the COD content in the hydrolyzate obtained from treating raw sludge. That is, the composition can effectively promote the hydrolysis of raw sludge, hydrolyze insoluble substances in the sludge, such as polysaccharides, into soluble small molecule substances, so as to recover more available carbon sources from the sludge. The recovered carbon source can be recycled to the biochemical pool, effectively promoting the denitrification reaction in the biochemical process, fully denitrifying the sewage, improving the effluent quality while reducing the use of commercial carbon sources. The present invention provides a new method for the resource treatment of sludge, which is not only beneficial to the resource treatment of sludge, but also beneficial to subsequent water treatment processes such as anaerobic digestion and aerobic digestion, reducing the operation cost of subsequent water treatment. Description of the Drawings

[0039] Figure 1 It is the statistical result of the COD content in the liquid obtained after hydrolyzing sludge with DDOBA and different enzyme compositions and enzymes alone.

[0040] Figure 2 It is the statistical result of the BOD5 content in the liquid obtained after hydrolyzing sludge with DDOBA and different enzyme compositions and enzymes alone. Detailed Embodiments

[0041] The present invention will be further described below with reference to the drawings in the specification and specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the technical field.

[0042] Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0043] The 3,4-dihydroxybenzaldehyde used in the embodiments of the present invention is purchased from Aladdin, with the product number D130075; the bromododecane used is also purchased from Aladdin, with the product number B105789; the hydroxylamine hydrochloride used is also purchased from Aladdin, with the product number H292538; the zinc powder used is also purchased from Aladdin, with the product number Z683800; the lysozyme used is also purchased from Aladdin, with the product number L105521; the cellulase used is also purchased from Aladdin, with the product number C757787; the amylase used is also purchased from Aladdin, with the product number A109181; the papain used is also purchased from Aladdin, with the product number P123425; the alkaline protease used is also purchased from Aladdin, with the product number P757698.

[0044] Example 1: Preparation of DDOBA and Different Enzyme Combinations and Their Effects on Sludge Hydrolysis Treatment

[0045] 1. Synthesis of 3,4 - Didodecyloxybenzylamine (DDOBA)

[0046] The DDOBA used in this invention was prepared according to the method described in the reference (Han Ying, Zhu Lu, Shen Ming, et al. Synthesis of a Novel Double - Chain Surfactant DDOBA and Preparation of Highly Monodisperse Hydrophobic Gold Nanoparticles [J]. Acta Physico - Chimica Sinica, 2013, 29(1): 8. DOI: CNKI:SUN:WLHX.0.2013 - 01 - 022.). Using 3,4 - dihydroxybenzaldehyde as the raw material, it undergoes an alkylation reaction with bromododecane to form 3,4 - didodecyloxybenzaldehyde, then reacts with hydroxylamine hydrochloride to form 3,4 - didodecyloxybenzaldehyde oxime, and finally is reduced with zinc powder to obtain 3,4 - didodecyloxybenzylamine.

[0047] 2. Preparation of DDOBA and Different Enzyme Combinations

[0048] The synthesized DDOBA was respectively mixed with the commercially purchased lysozyme, cellulase, amylase, papain, and alkaline protease in a mass ratio of 1:1 to obtain the combinations DDOBA + lysozyme, DDOBA + cellulase, DDOBA + amylase, DDOBA + papain, and DDOBA + alkaline protease.

[0049] 3. Hydrolysis Treatment of Sludge with DDOBA and Different Enzyme Combinations

[0050] Equal amounts of concentrated sludge generated during municipal sewage treatment were placed in different reaction vessels. Each of the above - prepared combinations was mixed with the concentrated sludge at an addition amount of 1% (1% of the mass of the concentrated sludge), and the reaction was carried out at 40 °C and 400 rpm for 2 h; after the reaction, solid - liquid separation was carried out by the gravity sedimentation method, and the filtrate was taken; referring to the "Rapid Digestion Spectrophotometry HJ / T 399 - 2007" and the "Dilution and Inoculation Method HJ 505 - 2009", the COD and BOD5 in the separated filtrate were measured respectively, and the results are as shown in Figure 1 and Figure 2 shown. After the hydrolysis treatment of sludge with DDOBA and different enzyme combinations and individual enzymes, the COD, BOD5 production, and biodegradability (BOD5 / COD) in the separated filtrate are shown in Table 1.

[0051] Table 1 COD and BOD5 Production from Sludge Treated with Different Combinations

[0052]

[0053]

[0054] From Figure 1 and Figure 2 the results shown in Table 1, compared with the sludge treated by enzymatic hydrolysis alone, the combined use of surfactant and hydrolytic enzyme can significantly promote the hydrolysis of sludge and significantly improve the effect of recovering carbon source (COD) from sludge. At the same time, from the results shown in Table 1, the biodegradability (BOD5 / COD) of the sludge cracked by DDOBA + enzyme is higher than 0.5, which is higher than that of the commercial carbon source sodium acetate (the BOD5 / COD of the commercial carbon source sodium acetate is 0.5). That is, the filtrate described in the present invention can replace the commercial carbon source to provide sufficient (high COD value) and highly utilized (high biodegradability) carbon source for the denitrification reaction and the phosphorus release process of polyphosphate-accumulating organisms in the sewage treatment process.

[0055] In addition, the ammonia nitrogen (NH4 + -N) in the filtrate obtained after hydrolyzing the sludge with the composition DDOBA + alkaline protease of the present invention is 325 mg / L, the total nitrogen (TN) is 690 mg / L, and the total phosphorus (TP) is 153 mg / L; the mass fraction of total nitrogen is 0.8%, and the mass fraction of total phosphorus is 0.2%. While the COD concentration of the general untreated municipal sewage in the southern region is about 50 mg / L, the ammonia nitrogen concentration is about 0.5 mg / L, the total nitrogen concentration is about 3 mg / L, and the total phosphorus concentration is about 0.3 mg / L. Its carbon, nitrogen, and phosphorus ratio does not meet the ratio of 100:5:1 and additional carbon source needs to be supplemented. And putting the filtrate obtained by the method of the present invention into the denitrification section can not only effectively improve the carbon-nitrogen ratio of the sewage, but also will not introduce a large amount of nitrogen and phosphorus elements to affect the effluent quality.

[0056] The above results show that by combining the treatment of enzyme and surfactant, the degree of carbon source release from sludge can be greatly improved, and the obtained sludge lysate (filtrate) can be used as a high-quality carbon source to be refluxed to the biochemical pool to increase the carbon-nitrogen ratio of the sewage, improve the efficiency of denitrification, and achieve the effect of deep nitrogen removal of the sewage.

[0057] Example 2 Influence of the dosage ratio of DDOBA to enzyme on the sludge hydrolysis treatment effect

[0058] On the basis of Example 1, taking the combination of DDOBA + alkaline protease as an example, this example tested the influence of the mass ratio of DDOBA to enzyme on the sludge hydrolysis treatment effect. The sludge hydrolysis treatment method was the same as that in Example 1, and the results are shown in Table 2.

[0059] Table 2

[0060]

[0061] As can be seen from the results shown in Table 2, when the mass ratio of DDOBA to the enzyme is 1-2:1-2, the use of the composition for hydrolyzing sludge can improve the biodegradability of the obtained filtrate, that is, it is beneficial to the resource treatment of sludge. Among them, when the mass ratio of DDOBA to the enzyme is 1:1, the COD content in the filtrate obtained by hydrolysis treatment is the highest.

[0062] Effect of the dosing ratio of the composition in Example 3 on the sludge hydrolysis treatment effect

[0063] On the basis of Example 1, in this example, taking the combination of DDOBA + alkaline protease as an example, the effect of the dosage of the composition of DDOBA and the enzyme on the sludge hydrolysis treatment effect was tested. The sludge hydrolysis treatment method was the same as that in Example 1, and the results are shown in Table 3.

[0064] Table 3

[0065]

[0066] As can be seen from the results shown in Table 3, although the COD obtained increases with the increase of the dosage, it is not advantageous in terms of economic benefits. Considering all the data, a dosage of 1% is more appropriate.

[0067] Comparative Example 1

[0068] The difference between this comparative example and Example 1 is that the surfactant used is rhamnolipid.

[0069] Referring to the method described in Example 1, after hydrolyzing the same sludge with the composition described in this comparative example, the yields of COD and BOD5 in the obtained filtrate are shown in Table 4.

[0070] Table 4

[0071] Composition Name COD (mg / L) <![CDATA[BOD5 (mg / L)]]> <![CDATA[BOD5 / COD]]> Rhamnolipid + Lysozyme 12233 5381 0.440 Rhamnolipid + Cellulase 13657 5862 0.429 Rhamnolipid + Amylase 11431 4987 0.436 Rhamnolipid + Papain 14522 6243 0.430 Rhamnolipid + Alkaline Protease 17916 7825 0.437

[0072] As can be seen from the results shown in Table 4, after mixing rhamnolipid with lysozyme, cellulase, amylase, papain and alkaline protease respectively at a mass ratio of 1:1 and hydrolyzing the sludge, the COD content in the obtained filtrate cannot be significantly increased, and its biodegradability decreases compared with the use of the enzyme alone (see Table 1).

[0073] Comparative Example 2

[0074] The difference between this comparative example and Example 1 is that the surfactant used is SDS.

[0075] After hydrolyzing the sludge with the composition described in this comparative example, the yields of COD and BOD5 in the obtained filtrate are shown in Table 5.

[0076] Table 5

[0077] Composition Name COD (mg / L) <![CDATA[BOD5 (mg / L)]]> <![CDATA[BOD5 / COD]]> SDS + Lysozyme 14235 6251 0.439 SDS + Cellulase 12484 4869 0.390 SDS + Amylase 11721 4374 0.373 SDS + Papain 15665 7608 0.486 SDS + Alkaline Protease 18837 9612 0.510

[0078] As can be seen from the results shown in Table 5, when SDS is mixed with lysozyme, cellulase, amylase, papain and alkaline protease respectively at a mass ratio of 1:1 and the sludge is hydrolyzed, it cannot significantly increase the COD content in the hydrolyzed filtrate. Moreover, except for the combination of SDS + alkaline protease, the biodegradability of the filtrate obtained by the treatment of the other combinations decreases compared with the use of enzymes alone (see Table 1); among them, the biodegradability of SDS + cellulase and SDS + amylase decreases significantly.

[0079] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A composition, characterized in that, It consists of 3,4-didodecyloxybenzylamine and an enzyme; the mass ratio of 3,4-didodecyloxybenzylamine to the enzyme is 1-2:1-2; The enzyme is one or more of lysozyme, cellulase, amylase, papain, and alkaline protease.

2. The composition according to claim 1, wherein The enzyme is one or more of lysozyme, cellulase, papain, and alkaline protease.

3. The composition according to claim 1, wherein The enzyme is one or more of cellulase, papain, and alkaline protease.

4. The composition according to claim 3, wherein The enzyme is papain and / or alkaline protease.

5. The composition according to claim 4, characterized in that, The enzyme is alkaline protease.

6. Use of the composition according to any one of claims 1-5 in the hydrolysis treatment of sludge.

7. Use of the composition according to any one of claims 1-5 in the preparation of a hydrolysis treatment product of sludge.

8. A method for hydrolyzing sludge and recovering utilizable carbon sources, characterized in that, Mix the composition according to any one of claims 1-5 with the sludge to be treated, react at 35-45 °C for 2-6 h, then perform solid-liquid separation, and collect the liquid.

9. The method according to claim 8, wherein The dosage of the composition is 0.5%-5% of the mass of the sludge.

10. The method according to claim 8, wherein Perform solid-liquid separation by means of gravity sedimentation, pressure filtration, or filtration.

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