Surfactant composition and application thereof in sludge cracking

Abstract

The invention discloses a surfactant composition and an application of the surfactant composition in sludge disintegration. The surfactant composition disclosed by the invention is prepared from 3, 4-didodecyloxy benzylamine and a Gemini surfactant (a Gemini surfactant). When the surfactant composition is used for carrying out cracking treatment on the sludge, the COD content in the liquid phase of the cracked sludge can be obviously improved, and the recovery rate of an available carbon source in the sludge is improved. After the surfactant composition disclosed by the invention is used for carrying out cracking treatment on sludge, filtrate can be recycled in manners such as gravity settling and the like, and the obtained filtrate is reused in a biochemical pool, so that a denitrification carbon source can be effectively supplemented, the use of a commercial carbon source is reduced while the denitrification reaction in the biochemical process is promoted, and the water treatment cost is reduced. The method has important significance on resourceful treatment of the sludge.

Description

Technical Field

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

[0002] Sludge is an extremely complex heterogeneous body composed of organic debris, bacterial cells, inorganic particles, colloids, etc. generated during the sewage treatment process. Its main characteristics are high water content, high organic matter content, and easy to rot and emit odor. In recent years, the sludge production has shown an increasing trend year by year, with astonishing output, but the proportion of sludge properly disposed is still low. Since sludge contains a large amount of organic matter, its resource utilization can not only reduce the adverse impact of sludge on the ecological environment, but also generate additional economic benefits. For example, traditional sewage treatment systems generally suffer from insufficient denitrifying carbon sources, low nitrogen and phosphorus removal efficiency, and need to supplement with external commercial carbon sources. Recycling the available carbon sources in sludge to make up for the shortage of denitrifying carbon sources can reduce the sewage treatment cost and meet the current requirements for sludge reduction, stabilization, harmlessness, and resource utilization.

[0003] Although sludge contains a large amount of organic matter, the presence of extracellular polymers (EPS), etc. makes the organic matter in sludge difficult to be decomposed and utilized, affecting the reduction and resource utilization of sludge. Sludge cracking is an important link in the sludge treatment process, and its purpose is to destroy the cell structure of sludge through physical, chemical, or biological methods, release the organic matter and water inside the cells, thereby improving the dewatering performance and biodegradability of sludge, etc., and promoting the resource utilization of sludge. Existing sludge cracking methods include ultrasonic wave, surfactant treatment, etc. Among them, although the effect of ultrasonic wave in cracking sludge is good, its energy consumption is large and the equipment cost is high, which is not conducive to popularization and use. Surfactants (such as CTAB, etc.) can reduce the liquid surface tension, enhance the interaction between sludge particles, thereby destroying the floc structure of sludge and releasing the organic matter therein. Although using surfactants to crack sludge has advantages such as simple operation, its cracking effect is relatively poor compared with ultrasonic wave cracking, etc. If the cracking rate of surfactants on sludge can be increased and the chemical oxygen demand (COD), etc. in the liquid after cracking can be increased, it will be more beneficial to the resource treatment of sludge. Summary of the Invention

[0004] The present invention aims at the deficiencies existing in the above-mentioned prior art, and provides a surfactant composition and its application in cracking sludge.

[0005] The first object of the present invention is to provide a surfactant composition.

[0006] The second object of the present invention is to provide the application of the said composition in cracking sludge.

[0007] The third object of the present invention is to provide the use of the composition in the preparation of products for cracking sludge.

[0008] The fourth object of the present invention is to provide a method for cracking sludge and recovering utilizable carbon sources.

[0009] The above objects of the present invention are achieved by the following technical solutions:

[0010] In view of the insufficient effect of using surfactants to crack sludge, the present invention provides a surfactant composition composed of 3,4-didodecyloxybenzylamine (DDOBA) and Gemini surfactant. Using the surfactant composition can significantly improve the cracking effect on sludge, significantly increase the COD content in the liquid phase of the cracked sludge, so as to recover more utilizable carbon sources from the sludge. After cracking the sludge with the surfactant composition of the present invention, the filtrate can be recovered by means of gravity sedimentation and the obtained filtrate can be recycled to the biochemical pool, which can effectively supplement the denitrifying carbon source, promote the denitrification reaction in the biochemical process while reducing the use of commercial carbon sources in the biochemical process, and reduce the water treatment cost. Therefore, the present invention claims to protect the surfactant composition and its application in cracking sludge.

[0011] The present invention provides a surfactant composition, which is composed of 3,4-didodecyloxybenzylamine and Gemini surfactant; the mass ratio of 3,4-didodecyloxybenzylamine to Gemini surfactant is 1-2:1-2.

[0012] Preferably, in the surfactant composition, the mass ratio of 3,4-didodecyloxybenzylamine to Gemini surfactant is 1:1-2.

[0013] More preferably, in the surfactant composition, the mass ratio of 3,4-didodecyloxybenzylamine to Gemini surfactant is 1:1-1.5.

[0014] Even more preferably, in the surfactant composition, the mass ratio of 3,4-didodecyloxybenzylamine to Gemini surfactant is 1:1.

[0015] Optionally, the Gemini surfactant is a nonionic Gemini surfactant, a cationic Gemini surfactant and / or an anionic Gemini surfactant.

[0016] Optionally, the non-ionic gemini surfactant is polyethoxydilaurate, polyethoxydipalmitate, and / or polyethoxydioleate; the cationic gemini surfactant is didodecyldimethylammonium bromide, didodecylbenzenesulfonate sodium, and / or N,N-didodecyl-2,6-pyridinedicarboxamidopropionate sodium; the anionic gemini surfactant is 1,4-butanediyl bis(dodecylsulfonate) and / or 1,4-butanediyl bis(hexadecylcarboxylate).

[0017] In a specific embodiment of the present invention, the surfactant composition consists of 3,4-didodecyloxybenzylamine and a cationic gemini surfactant, and the mass ratio of 3,4-didodecyloxybenzylamine to the cationic gemini surfactant is 1-2:1-2.

[0018] Preferably, in the surfactant composition, the mass ratio of 3,4-didodecyloxybenzylamine to the cationic gemini surfactant is 1:1-2.

[0019] More preferably, in the surfactant composition, the mass ratio of 3,4-didodecyloxybenzylamine to the cationic gemini surfactant is 1:1-1.5.

[0020] Even more preferably, in the surfactant composition, the mass ratio of 3,4-didodecyloxybenzylamine to the cationic gemini surfactant is 1:1. When the mass ratio of 3,4-didodecyloxybenzylamine to the cationic gemini surfactant in the surfactant composition is 1:1, after using it to crack the sludge, the COD content in the obtained filtrate is relatively the highest.

[0021] In a specific embodiment of the present invention, 3,4-didodecyloxybenzylamine is prepared from 3,4-dihydroxybenzaldehyde. It is obtained by alkylation reaction with dodecyl bromide to form 3,4-didodecyloxybenzaldehyde, then reacting with hydroxylamine hydrochloride to form 3,4-didodecyloxybenzaldehyde oxime, and finally reducing it with zinc powder. The specific preparation method refers to the method described in the literature (Han Ying, Zhu Lu, Shen Ming, etc. 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.).

[0022] In a specific embodiment of the present invention, the cationic gemini surfactant is didodecyldimethylammonium bromide, and its CAS number is 3282-73-3.

[0023] In view of the fact that the surfactant composition of the present invention can significantly improve the cracking effect on sludge and significantly increase the COD content in the liquid phase of the cracked sludge. Therefore, the present invention claims the application of the surfactant composition in cracking sludge.

[0024] The present invention also claims the application of the surfactant composition in the preparation of a product for cracking sludge.

[0025] Similarly, the application of the surfactant composition in the preparation of a product for cracking sludge and recovering utilizable carbon sources should also be within the protection scope of the present invention.

[0026] Specifically, the sludge is raw sludge.

[0027] More specifically, the sludge is raw sludge generated during domestic sewage or municipal treatment.

[0028] In a specific embodiment of the present invention, the sludge to be treated is thickened sludge generated during municipal sewage treatment. Thickened sludge refers to the sludge obtained after thickening treatment of raw sludge (such as primary sedimentation sludge, etc.).

[0029] The present invention also provides a method for cracking sludge and recovering utilizable carbon sources. The method is as follows: mixing the surfactant composition of the present invention with the sludge to be treated, reacting at 35 - 45 °C for 2 - 6 h and then performing solid-liquid separation, and collecting the liquid; wherein, the dosage of the composition is 0.5% - 5% of the mass of the sludge.

[0030] Preferably, the dosage of the surfactant composition is 1% - 5% of the mass of the sludge.

[0031] More preferably, the dosage of the surfactant composition is 1% - 3% of the mass of the sludge.

[0032] Even more preferably, the dosage of the surfactant composition is 1% of the mass of the sludge.

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

[0034] Specifically, the sludge is raw sludge.

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

[0036] The present invention has the following beneficial effects:

[0037] In view of the insufficient effect of using surfactants to crack sludge, the present invention provides a surfactant composition composed of 3,4-didodecyloxybenzylamine and Gemini surfactants. Using the surfactant composition to crack sludge can significantly increase the COD content in the liquid phase of the cracked sludge and improve the recovery rate of available carbon sources in the sludge. After using the surfactant composition of the present invention to crack sludge, the filtrate can be recovered by means of gravity sedimentation and the obtained filtrate can be recycled to the biochemical pool, which can effectively supplement the denitrifying carbon source, promote the denitrification reaction in the biochemical process while reducing the use of commercial carbon sources, and reduce the water treatment cost. The present invention is of great significance for the resource treatment of sludge. Description of the Drawings

[0038] Figure 1 The figure shows the COD measurement results in the filtrate obtained after cracking sludge using 3,4-didodecyloxybenzylamine (DDOBA), didodecyldimethylammonium bromide (Gemini), and the surfactant compositions described in Examples 1-5 of the present invention, respectively.

[0039] Figure 2 The figure shows the BOD5 measurement results in the filtrate obtained after cracking sludge using 3,4-didodecyloxybenzylamine (DDOBA), didodecyldimethylammonium bromide (Gemini), and the surfactant compositions described in Examples 1-5 of the present invention, respectively. Detailed Embodiments

[0040] The following further illustrates the present invention in conjunction with the drawings of 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.

[0041] Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0042] In the embodiments of the present invention, 3,4-didodecyloxybenzylamine (DDOBA) is prepared by using 3,4-dihydroxybenzaldehyde as a raw material. Through an alkylation reaction with dodecyl bromide, 3,4-didodecyloxybenzaldehyde is generated, and then it reacts with hydroxylamine hydrochloride to form 3,4-didodecyloxybenzaldehyde oxime, which is then reduced with zinc powder. The specific preparation method refers to the method described in the literature (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.). The manufacturer of the used 3,4-dihydroxybenzaldehyde is Aladdin, and the product number is D130075; the manufacturer of the used dodecyl bromide is Aladdin, and the product number is B105789; the manufacturer of the used hydroxylamine hydrochloride is Aladdin, and the product number is H292538; the manufacturer of the used zinc powder is Aladdin, and the product number is Z683800.

[0043] The Gemini surfactant used in the embodiments of the present invention is a cationic Gemini surfactant didodecyldimethylammonium bromide. Its manufacturer is Aladdin, the product number is D105628, and the CAS number is 3282-73-3.

[0044] Preparation of surfactant composition 1 in Example 1

[0045] The synthesized DDOBA and the Gemini surfactant didodecyldimethylammonium bromide are mixed evenly at a mass ratio of 2:1 to obtain surfactant composition 1.

[0046] Preparation of surfactant composition 2 in Example 2

[0047] The synthesized DDOBA and the Gemini surfactant didodecyldimethylammonium bromide are mixed evenly at a mass ratio of 1:1 to obtain surfactant composition 2.

[0048] Preparation of surfactant composition 3 in Example 3

[0049] The synthesized DDOBA and the Gemini surfactant didodecyldimethylammonium bromide are mixed evenly at a mass ratio of 1:2 to obtain surfactant composition 3.

[0050] Preparation of surfactant composition 4 in Example 4

[0051] The synthesized DDOBA and rhamnolipid are mixed evenly at a mass ratio of 1:1 to obtain surfactant composition 4.

[0052] Preparation of surfactant composition 5 in Example 5

[0053] Mix dodecyl dimethyl ammonium bromide, a Gemini surfactant, and rhamnolipid in a mass ratio of 1:1 to obtain surfactant composition 5.

[0054] Test Example 1 Sludge cracking effect of different compositions

[0055] Take equal amounts of concentrated sludge generated during municipal sewage treatment and place them in different reaction vessels. Mix the above-prepared surfactant compositions 1-5, as well as individual DDOBA and dodecyl dimethyl ammonium bromide, with the concentrated sludge at a dosage of 1% (1% of the sludge mass). React for 2 h at 40 °C and 400 rpm. After the reaction, perform solid-liquid separation by gravity sedimentation. Refer to the "Rapid digestion spectrophotometry HJ / T 399-2007" and the "Dilution and inoculation method HJ 505-2009" to measure the COD and BOD5 in the separated filtrate respectively. The results are as Figure 1 and Figure 2 shown.

[0056] After treating the sludge with the prepared surfactant compositions 1-5 and individual surfactants, the COD, BOD5 production, and biodegradability (BOD5 / COD) in the separated filtrate are shown in Table 1. Gemini in the table refers to dodecyl dimethyl ammonium bromide.

[0057] Table 1 COD and BOD5 production of surfactant compositions 1-5 and individual surfactants for treating sludge

[0058] Reagent name COD (mg / L) <![CDATA[BOD5 (mg / L)]]> <![CDATA[BOD5 / COD]]> Surfactant composition 1 42712 20923 0.49 Surfactant composition 2 84525 48836 0.58 Surfactant composition 3 51048 24662 0.48 Surfactant composition 4 38233 19729 0.52 Surfactant composition 5 36373 20121 0.55 DDOBA 23534 10325 0.44 Gemini 26269 12588 0.48

[0059] Combined Figure 1 , Figure 2 and the results shown in Table 1, it can be seen that compared with treating the sludge with individual surfactants (DDOBA or Gemini surfactant dodecyl dimethyl ammonium bromide), the combination of DDOBA and Gemini surfactant dodecyl dimethyl ammonium bromide can significantly promote the cracking of sludge and can significantly increase the COD value of the filtrate obtained after cracking. Rhamnolipid can damage the cell wall and cell membrane of bacteria, but after its compounding with DDOBA or dodecyl dimethyl ammonium bromide, the sludge cracking effect is significantly weaker than that of the surfactant compositions 1-3 of the present invention. The filtrate obtained after treating the sludge with the surfactant compositions 1-3 of the present invention can replace commercial carbon sources and provide sufficient (high COD value) and highly utilized (high biodegradability) carbon sources for the denitrification reaction and the phosphorus release process of polyphosphate-accumulating bacteria during sewage treatment.

[0060] In addition, the present invention also tested the contents of etc. in the filtrate obtained after cracking the sludge using the surfactant composition described in Example 2. After measurement, the amount of ammonia nitrogen (NH4 + -N) in the obtained filtrate was 117.5 mg / L, the total nitrogen (TN) amount was 1380 mg / L, the total phosphorus (TP) amount was 1027.5 mg / L, the ratio of COD to TN, COD:TN = 61, COD:TP = 82, NH4 +- N:TN = 0.09, the mass fraction of total nitrogen was 1.6%, and the mass fraction of total phosphorus was 1.2%.

[0061] Generally, the COD:TN of untreated influent is 4, and COD:TP is 50. Combining the above results, it can be seen that putting the said filtrate into the denitrification section can effectively increase the carbon-nitrogen ratio of the sewage, and at the same time will not introduce a large amount of nitrogen and phosphorus elements to affect the effluent quality.

[0062] The above results show that using the surfactant composition of the present invention can improve the cracking efficiency of sludge, greatly increase the release degree of soluble organic matter in sludge, and increase its COD production. The obtained sludge cracking liquid (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.

[0063] 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 surfactant composition, characterized in that, The composition consists of 3,4-didodecyloxybenzylamine and a gemini surfactant; the mass ratio of 3,4-didodecyloxybenzylamine to the gemini surfactant is 1-2:1-2.

2. The composition according to claim 1, wherein The mass ratio of 3,4-didodecyloxybenzylamine to the gemini surfactant is 1:1-2.

3. The composition according to claim 2, wherein The gemini surfactant is a nonionic gemini surfactant, a cationic gemini surfactant, and / or an anionic gemini surfactant.

4. The composition according to claim 3, characterized in that, The nonionic gemini surfactant is polyethoxydilaurate, polyethoxydipalmitate, and / or polyethoxydioleate; the cationic gemini surfactant is didodecyldimethylammonium bromide, didodecylanilinesulfonate, and / or N,N-didodecyl-2,6-pyridinedicarboxamidopropionate; the anionic gemini surfactant is 1,4-butanediyl bis(dodecylsulfonate) and / or 1,4-butanediyl bis(hexadecylcarboxylate).

5. Use of the composition according to any one of claims 1-4 in cracking sludge.

6. Use of the composition according to any one of claims 1-4 in preparing a product for cracking sludge.

7. The application according to claim 5 or 6, characterized in that, The sludge is raw sludge.

8. A method for cracking sludge and recovering utilizable carbon sources, characterized in that, Mix the composition according to any one of claims 1-4 with the sludge to be treated, react at 35-45 °C for 2-6 h, then perform solid-liquid separation, and collect the liquid; wherein, the dosage of the composition is 0.5%-5% of the mass of the sludge.

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

10. The method according to claim 9, characterized in that, The sludge is raw sludge.

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