A defoaming agent for biochemical treatment and its preparation method and application

Abstract

The present invention discloses a defoamer for biochemical treatment, its preparation method, and its application, relating to the technical field of biochemical treatment. The defoamer comprises the following components by weight: 60-80% polyether polyol; 5-20% organic solvent; 1-2% sodium carboxymethyl cellulose; and the balance, deionized water. The polyether polyol has a molecular weight of 3000-4000. The defoamer has excellent defoaming and anti-foaming properties, significantly improving defoaming speed. It is suitable for a variety of wastewaters and for biochemical systems with widely varying water quality.

Description

Technical Field

[0001] The present invention relates to the technical field of biochemical treatment, in particular to a defoaming agent special for biochemical treatment, a preparation method and application thereof. Background Art

[0002] Biochemical treatment of wastewater, often referred to as biochemical treatment, is one of the most important processes in wastewater treatment systems. Biochemical treatment utilizes the biological activities of microorganisms to effectively remove soluble and partially insoluble organic matter from wastewater, thereby purifying the water. Biochemical wastewater treatment projects intensify this process under artificial conditions. Countless microorganisms are concentrated in a single pool, creating an environment ideal for their reproduction and growth (e.g., temperature, pH, oxygen, nutrients such as nitrogen and phosphorus). This allows them to multiply rapidly, increasing their speed and efficiency in breaking down organic matter. Wastewater is then pumped into the pool, where the organic matter in the wastewater is oxidized and degraded by the microbial activities, resulting in purification and treatment. Compared to other treatment methods, biochemical treatment offers advantages such as low energy consumption, the absence of chemical additives, high treatment effectiveness, and low costs.

[0003] Sewage aeration is a common biological treatment method. Its principle is to aerate the sewage to accelerate the dissolved oxygen content in the water, promote the metabolic decomposition of microorganisms, accelerate the decomposition of wastewater substances and the oxidation of pollutants such as ammonia and nitrogen, thereby achieving the purpose of purifying water quality. During the sewage treatment process, aeration tanks will produce a large amount of foam. If the foam continues to be produced in large quantities, it may even overflow from the tank, causing pollution to external equipment and tank walls, worsening operating conditions, and seriously affecting the production of water treatment companies. When biochemical sewage treatment encounters foam problems, the foam can be treated by adding defoamers. Currently, the defoamers used in biochemical treatment are mostly polyether defoamers, which have excellent foam suppression capabilities and are not easy to affect the activity of microorganisms in the aeration tank.

[0004] In a biochemical pool, the microorganisms within play a crucial role. They are crucial to the stability of the pool system and the speed of biochemical treatment. Faster microbial growth speeds up the decomposition process, shortening the biochemical treatment time required for wastewater entering the pool. This increases the biochemical rate, allowing the pool to process larger volumes of wastewater.

[0005] At present, the composition of biochemical water in most enterprises is different. Some water is relatively ordinary, and the addition of polyether defoamer has a good defoaming and foaming effect. The biochemical water in some industries is highly oily, and the water quality varies greatly, with high COD, high oil pollution, and strong changes. After the addition of polyether defoamer, the defoaming and foaming performance is suppressed, and the defoaming and foaming ability is poor, which easily causes the foam to be unable to be suppressed. Some foam goes along the pipeline to the next process, affecting the final water output. Summary of the Invention

[0006] The present invention aims to overcome the shortcomings of the prior art by providing a biochemical treatment defoamer, its preparation method, and its application. The biochemical treatment defoamer prepared by the present invention has excellent defoaming and foam suppression properties, significantly improving defoaming speed, and is suitable for a variety of wastewaters and biochemical systems with widely varying water quality.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] In a first aspect, the present invention provides a defoaming agent for biochemical treatment, comprising the following components in percentage by mass:

[0009] 60-80% polyether polyol; 5-20% organic solvent; 1-2% sodium carboxymethyl cellulose; the balance is deionized water; the molecular weight of the polyether polyol is 3000-4000.

[0010] The mechanism of action of the biochemical treatment defoamer described in the present invention is to achieve a defoaming effect by adsorbing on the foam surface and accelerating its drainage rate. The molecular structure of this biochemical treatment defoamer is both hydrophilic and lipophilic, enabling it to quickly disperse in water and oily liquids. This facilitates adsorption on bubbles, separating and merging small bubbles into larger ones, causing them to float to the liquid surface and rupture. For bubbles floating on the liquid surface, the fatty alcohol molecules in the polyether can quickly adhere to and spread at the critical interface between gas and liquid, with the hydrophilic hydroxyl groups pointing toward the water surface and the lipophilic hydrocarbon chains facing the interior of the bubble membrane. This disrupts the initially formed stable interface, thinning the bubble membrane and accelerating the disappearance of the foam. Furthermore, the addition of sodium carboxymethyl cellulose can increase the viscosity of the defoamer, thereby better maintaining the stability of the defoamer.

[0011] As the molecular weight of the polyether increases, the length of the polyether chain segments increases, and these segments have the characteristic of lying flat or spreading on the interface, which in turn increases the space occupied by the defoamer molecules on the interfacial film. Therefore, the defoaming ability is improved with increasing molecular weight. However, if the molecular weight is too high, the molecules will not diffuse to the gas-liquid interface in a timely manner during the foam formation process, and thus will not be able to prevent the gas from forming bubbles, thereby reducing the foam suppression performance. Therefore, the present invention helps to improve the defoaming and foam suppression effects of the defoamer by controlling the molecular weight of the polyether polyol within the above range.

[0012] Preferably, the organic solvent is at least one of methanol and ethylene glycol monobutyl ether.

[0013] Preferably, the organic solvent consists of methanol and ethylene glycol monobutyl ether in a mass ratio of (1-3): (1-5).

[0014] Preferably, the polyether polyol comprises the following components in percentage by mass:

[0015] Ethylene oxide 8-20%; propylene oxide 40-55%; isomeric alcohol 3-7%; fatty alcohol 2-5%; catalyst 1-2%; the balance is deionized water.

[0016] The polyether polyol prepared by the present invention using the above raw materials has high activity, thereby improving the hydrophilicity of the polyether polyol, which is beneficial to further improve the defoaming performance of the defoaming agent specially used for biochemical treatment.

[0017] Preferably, the isomeric alcohol is one of tridecanol and decanol.

[0018] Preferably, the fatty alcohol is one of docosanol and hexadecanol.

[0019] Preferably, the catalyst is a bimetallic DMC catalyst.

[0020] Preferably, the biochemical treatment-specific defoaming agent further comprises 0.5-1% by mass of growth hormone.

[0021] Preferably, the growth hormone is at least one of gibberellins and α-naphthyl acetic acid.

[0022] The addition of growth hormones to the present invention promotes microbial growth in the biochemical pool, increasing the biochemical rate of the pool, thereby shortening the treatment time required for biochemical wastewater and increasing the wastewater treatment capacity. Therefore, the present invention utilizes a specific type of growth hormone, which ensures that the growth hormones involved in the biochemical treatment are completely decomposed by biochemical bacteria after biochemical treatment. The decomposition products do not introduce other substances or interfere with the biochemical system, thus preventing impacts on subsequent processes.

[0023] Preferably, the growth hormone consists of gibberellin and α-naphthyl acetic acid in a mass ratio of 3:2.

[0024] Preferably, the preparation method of the polyether polyol comprises the following steps:

[0025] (1) Add isomeric alcohol, fatty alcohol and catalyst into the reactor, replace with nitrogen in vacuum for 2-3 times, start heating and vacuum dehydration, control the vacuum pressure to be lower than -0.05MPa, control the temperature to be 120-130℃, and the reaction time to be 55-60min;

[0026] (2) Then, the vacuum is turned off, and ethylene oxide and propylene oxide are added to react. The reaction temperature is controlled to be 120-150° C. and the pressure is 0.2-0.4 MPa. The reaction is kept warm and aged for 35-40 minutes. After the reaction is completed, vacuum is drawn to degas, and the temperature is finally lowered and the material is discharged to obtain polyether polyol.

[0027] In a second aspect, the present invention further provides a method for preparing a special defoaming agent for biochemical treatment, comprising the following steps: uniformly mixing the components to obtain the special defoaming agent for biochemical treatment.

[0028] In a third aspect, the present invention also provides an application of a biochemical treatment-specific defoaming agent in biochemical wastewater.

[0029] The defoaming agent for biochemical treatment of the present invention is used for biochemical sewage treatment, which can increase the treatment rate of the biochemical pool, thereby shortening the treatment time required for biochemical sewage, thereby increasing the sewage treatment capacity.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The defoaming agent for biochemical treatment of the present invention has excellent defoaming and antifoaming effects, can significantly improve the defoaming speed, and is applicable to a variety of sewage and biochemical systems with large changes in water quality.

[0032] (2) The biochemical treatment-specific defoaming agent of the present invention can be completely decomposed by biochemical bacteria after being added to the biochemical pool to participate in the biochemical treatment. The decomposed product will not bring other substances and interference to the biochemical system, thus avoiding the impact on the next process. DETAILED DESCRIPTION

[0033] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below with reference to specific embodiments, but the protection scope and implementation methods of the present invention are not limited thereto.

[0034] Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0035] name factory model Sodium carboxymethyl cellulose Aladdin C304951 Gibberellic acid Merck G7645 α-Naphthylacetic acid Merck N0640 Tridecanol Maclean F906407 Isomeric decanol Maclean I922339 C12-D2O Maclean D807563 Hexadecanol Maclean H810872

[0036] Preparation Example 1

[0037] A polyether polyol comprising the following components in percentage by mass:

[0038] 8% ethylene oxide; 55% propylene oxide; 3% tridecanol; 2% dodecyl alcohol; 1% bimetallic DMC catalyst; the balance is deionized water.

[0039] A method for preparing a polyether polyol comprises the following steps:

[0040] (1) Tridecanol, dodecyl alcohol, and bimetallic DMC catalyst were placed in a 2L stainless steel high-pressure polymerization reactor, and the atmosphere was replaced with nitrogen three times under vacuum. The temperature was then raised to vacuum dehydration. The vacuum pressure was controlled below -0.05 MPa, the temperature was controlled at 120°C, and the reaction time was 60 min.

[0041] (2) Then, the vacuum is turned off, and propylene oxide is first added to induce the reaction. The temperature during the induction period is 120°C and the pressure is 0.2 MPa. After the reaction pressure is significantly reduced, ethylene oxide and propylene oxide (in a ratio of 2:8) are added for end-capping. The reaction temperature is controlled to 130°C and the pressure is 0.3 MPa. The mixture is kept warm and aged for 40 minutes. After the reaction is completed, vacuum degassing is carried out, and the temperature is finally lowered to below 80°C. The material is discharged to obtain polyether polyol.

[0042] Preparation Example 2

[0043] A polyether polyol comprising the following components in percentage by mass:

[0044] Ethylene oxide 20%; propylene oxide 40%; isodecanol 7%; hexadecanol 5%; bimetallic DMC catalyst 1%; the balance is deionized water.

[0045] A method for preparing a polyether polyol comprises the following steps:

[0046] (1) Isomeric decanol, hexadecanol, and bimetallic DMC catalyst were placed in a 2L stainless steel high-pressure polymerization reactor, and the atmosphere was replaced with nitrogen three times under vacuum. The temperature was then raised to vacuum dehydration. The vacuum pressure was controlled below -0.05 MPa, the temperature was controlled at 130°C, and the reaction time was 60 min.

[0047] (2) Then, the vacuum is turned off, and propylene oxide is first added to induce the reaction. The temperature during the induction period is 130°C and the pressure is 0.3 MPa. After the reaction pressure is significantly reduced, ethylene oxide and propylene oxide (in a ratio of 2:8) are added for end-capping. The reaction temperature is controlled to 150°C and the pressure is 0.4 MPa. The mixture is kept warm and aged for 40 minutes. After the reaction is completed, vacuum degassing is carried out, and the temperature is finally lowered to below 80°C. The material is discharged to obtain polyether polyol.

[0048] Example 1

[0049] A defoaming agent for biochemical treatment, comprising the following components in percentage by mass:

[0050] Polyether polyol 70%; methanol 20%; gibberellin 0.6%; α-naphthaleneacetic acid 0.4%; sodium carboxymethyl cellulose 1%; the balance is deionized water. The molecular weight of the polyether polyol is 3000.

[0051] In this embodiment, the model of the polyether polyol is VORANOL 3010.

[0052] A method for preparing a special defoaming agent for biochemical treatment comprises the following steps:

[0053] Add polyether polyol, methanol, gibberellin and deionized water into a beaker, start the stirrer and stir evenly, then add sodium carboxymethyl cellulose and mix evenly to obtain a defoaming agent for biochemical treatment.

[0054] Example 2

[0055] A defoaming agent for biochemical treatment, comprising the following components in percentage by mass:

[0056] Polyether polyol 60%; methanol 10%; α-naphthaleneacetic acid 1%; sodium carboxymethyl cellulose 2%; the balance is deionized water. The molecular weight of the polyether polyol is 4000.

[0057] In this embodiment, the model of the polyether polyol is VORANOL 3010.

[0058] The preparation method of the defoaming agent for biochemical treatment is the same as that in Example 1.

[0059] Example 3

[0060] A defoaming agent for biochemical treatment, comprising the following components in percentage by mass:

[0061] Polyether polyol 80%; ethylene glycol monobutyl ether 5%; gibberellin 0.6%; α-naphthaleneacetic acid 0.4%; sodium carboxymethyl cellulose 1%; the balance is deionized water. The molecular weight of the polyether polyol is 4000.

[0062] In this embodiment, the model of the polyether polyol is VORANOL 3010.

[0063] The preparation method of the defoaming agent for biochemical treatment is the same as that in Example 1.

[0064] Example 4

[0065] A defoaming agent for biochemical treatment, comprising the following components in percentage by mass:

[0066] Polyether polyol 70%; methanol 10%; ethylene glycol monobutyl ether 10%; gibberellin 0.6%; α-naphthaleneacetic acid 0.4%; sodium carboxymethyl cellulose 1%; the balance is deionized water. The molecular weight of the polyether polyol is 3000.

[0067] In this embodiment, the model of the polyether polyol is VORANOL 3010.

[0068] Example 5

[0069] A defoaming agent for biochemical treatment, comprising the following components in percentage by mass:

[0070] Polyether polyol 70%; methanol 8%; ethylene glycol monobutyl ether 12%; gibberellin 0.6%; α-naphthaleneacetic acid 0.4%; sodium carboxymethyl cellulose 1%; the balance is deionized water. The molecular weight of the polyether polyol is 3000.

[0071] In this embodiment, the model of the polyether polyol is VORANOL 3010.

[0072] Example 6

[0073] A defoaming agent for biochemical treatment, comprising the following components in percentage by mass:

[0074] Polyether polyol 70%; methanol 8%; ethylene glycol monobutyl ether 12%; gibberellin 0.6%; α-naphthaleneacetic acid 0.4%; sodium carboxymethyl cellulose 1%; the balance is deionized water.

[0075] The difference between this embodiment and embodiment 5 is that the polyether polyol used is the polyether polyol prepared in preparation example 1.

[0076] Example 7

[0077] A defoaming agent for biochemical treatment, comprising the following components in percentage by mass:

[0078] Polyether polyol 70%; methanol 8%; ethylene glycol monobutyl ether 12%; gibberellin 0.6%; α-naphthaleneacetic acid 0.4%; sodium carboxymethyl cellulose 1%; the balance is deionized water.

[0079] The difference between this embodiment and embodiment 5 is that the polyether polyol is the polyether polyol prepared in preparation example 2.

[0080] Comparative Example 1

[0081] The difference from Example 1 is that the molecular weight of the polyether polyol in the biochemical treatment defoamer is 2000, and the other components are the same as those in Example 1.

[0082] Comparative Example 2

[0083] The difference from Example 1 is that the molecular weight of the polyether polyol in the biochemical treatment defoamer is 5000, and the other components are the same as those in Example 1.

[0084] Comparative Example 3

[0085] The difference from Example 1 is that the percentage of polyether polyol in the biochemical treatment special defoamer is 50%, and the other components are the same as those in Example 1.

[0086] Comparative Example 4

[0087] The difference from Example 1 is that the percentage of polyether polyol in the biochemical treatment special defoamer is 85%, and the other components are the same as those in Example 1.

[0088] Comparative Example 5

[0089] A defoaming agent A, manufactured by Ashland 4600EG.

[0090] Comparative Example 6

[0091] A defoamer B, manufactured by BASF FoamStar SI2210.

[0092] Comparative Example 7

[0093] A defoaming agent C, manufactured by Dow Corning AFE-7610.

[0094] experiment

[0095] 1. Foaming suppression test: 200 mL of the biochemical waste liquid brought back from the site was taken with a 500 mL graduated cylinder. The graduated cylinder was placed in a constant temperature and heated to 30°C. The air stone was placed in the biochemical liquid and bubbling was started. When the bubbling reached a height of 500 mL, 10 ppm of the biochemical treatment defoamer prepared by Examples 1-7 and Comparative Examples 1-7 were added respectively. The time and height required for defoaming to the lowest height were recorded (the shorter the defoaming time, the better the defoaming agent effect). The bubbling was continued, and the timing was started. The corresponding height under the foam suppression time was recorded every period of time until the bubbling height reached 500 mL. The experimental results are shown in Table 1.

[0096] The foam height indicates the time required for the foam volume to rise to the required height (280 mL), which reflects the strength of the defoaming agent's ability to suppress foam (the longer the foam suppression time, the better the defoaming agent effect).

[0097] 2. Biochemical sewage treatment experiment

[0098] Measure 500mL of biochemical liquid into a beaker, test the COD and total nitrogen parameters of the biochemical liquid before the experiment, record them as COD0 and TN0 (COD0:TN0 needs to be approximately equal to 4:1. If the ratio is insufficient, carbon source needs to be added to increase the COD concentration). Put the air stone into the biochemical liquid and start bubbling. Continue bubbling for 1 day. After the time is up, test the COD and total nitrogen of the biochemical water, record them as COD1 and TN1. Compare the COD and total nitrogen before and after the experiment, and calculate the COD and total nitrogen removal rates, that is, the biochemical treatment efficiency.

[0099] COD treatment efficiency = (COD0-COD1) / COD0

[0100] Total nitrogen treatment efficiency = (TN0-TN1) / TN0

[0101] Table 1

[0102]

[0103] Comparing Comparative Examples 1-2 with Example 1 in Table 1, it can be seen that the molecular weight of the polyether polyols described in Comparative Examples 1-2 is not within the range specified in the present invention. The defoaming time of the defoaming agent for biochemical treatment is longer than that of Example 1, and the foam suppression time is shorter than that of Example 1. This indicates that the molecular weight of the polyether polyol affects the performance of the defoaming agent. Therefore, the present invention improves the defoaming and foam suppression effects of the defoaming agent for biochemical treatment by controlling the molecular weight of the polyether polyol within the range specified in the present invention.

[0104] According to the comparison of Comparative Examples 3-4 with Example 1, the defoaming time of the biochemical treatment defoamer in Comparative Examples 3-4 is longer than that in Example 1, and the foam suppression time is shorter than that in Example 1, indicating that too much or too little content of polyether polyol will also affect the performance of the defoamer.

[0105] According to the comparison of Comparative Examples 5-7 with Example 7, Comparative Examples 5-7 were tested using commercially available defoaming agents. The defoaming time of the commercially available defoaming agents was greater than that of Example 7, and the foam suppression time was less than that of Example 7. This shows that the special defoaming agent for biochemical treatment prepared by the present invention has high defoaming and foam suppression properties, can significantly improve the defoaming speed, is suitable for a variety of sewage and is suitable for biochemical systems with large changes in water quality.

[0106] According to the comparison of Examples 6-7 with Example 5 in Table 1, the polyether polyols described in Examples 6-7 are prepared by the method of the present invention, and the defoaming time of the defoaming agent for biochemical treatment is shorter than that of Example 5, indicating that the polyether polyols prepared by the method of the present invention can improve the defoaming performance of the defoaming agent for biochemical treatment.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A defoaming agent for biochemical treatment, characterized in that: The following components are included in mass percentage: Polyether polyol 60-80%; organic solvent 5-20%; sodium carboxymethyl cellulose 1-2%; the balance is deionized water; the molecular weight of the polyether polyol is 3000-4000; The polyether polyol comprises the following components in percentage by mass: Ethylene oxide 8-20%; Propylene oxide 40-55%; Isomeric alcohol 3-7%; fatty alcohol 2-5%; Catalyst 1-2%; the balance is deionized water; The isomeric alcohol is one of tridecanol and decanol; the fatty alcohol is one of docosanol and hexadecanol; The organic solvent is composed of methanol and ethylene glycol monobutyl ether in a mass ratio of 2:3; The biochemical treatment special defoamer also includes 0.5-1% by mass of growth hormone; the growth hormone is composed of gibberellin and α-naphthyl acetic acid in a mass ratio of 3:

2.

2. The method for preparing a special defoamer for biochemical treatment according to claim 1, wherein The following steps are involved: The components are mixed evenly to obtain a defoaming agent specially used for biochemical treatment.

3. Use of the special defoamer for biochemical treatment as claimed in claim 1 in biochemical sewage.

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