A method for treating farmed white shrimp wastewater

Abstract

This invention provides a method for treating wastewater from Litopenaeus vannamei farming, comprising the following steps: S1, primary filtration of the farming wastewater, followed by aeration with the addition of compound bacteria to the filtered wastewater, controlling the aeration temperature at 30-35℃, dissolved oxygen at 5-10 mg / L, and treatment time at 10-16 h to obtain aerated wastewater; S2, mixing the aerated wastewater with composite activated carbon and treating it at 30-40℃ and ultrasonic power at 300-500 W for 2-3 h, then filtering to obtain filtrate A; S3, circulating filtrate A through a mixed macroporous adsorption resin at a loading flow rate of (3-5) BV / h to obtain filtrate B, followed by sterilization, thus completing the treatment of Litopenaeus vannamei farming wastewater. This invention effectively purifies Litopenaeus vannamei farming wastewater by adding compound bacteria for aeration treatment, combined with activated carbon and macroporous adsorption resin. This effectively reduces the content of pollutants such as total nitrogen, total phosphorus, and suspended solids in the wastewater, resulting in good treatment effect.

Description

Technical Field

[0001] This invention relates to the field of aquaculture wastewater treatment technology, and in particular to a method for treating wastewater from Litopenaeus vannamei aquaculture. Background Technology

[0002] Litopenaeus vannamei is a large-scale farmed shrimp species. During the farming process, factors such as feed input, shrimp feces, animal and plant carcasses, and the use of disinfectants often result in high levels of suspended solids and organic matter in the farming water, along with high ammonia nitrogen levels. This makes the wastewater from Litopenaeus vannamei farming unsuitable for discharge or reuse, necessitating purification treatment. Wastewater treatment typically involves primary filtration, aeration, and plant absorption, a complex and time-consuming process with often unsatisfactory results. Summary of the Invention

[0003] In view of this, the present invention proposes a method for treating wastewater from Litopenaeus vannamei farming, which can effectively improve the treatment efficiency of wastewater from Litopenaeus vannamei farming and shorten the wastewater treatment time.

[0004] The technical solution of this invention is implemented as follows:

[0005] A method for treating wastewater from Litopenaeus vannamei farming includes the following steps:

[0006] S1. The aquaculture wastewater is subjected to primary filtration. The filtered aquaculture wastewater is then aerated with the addition of compound bacteria. The aeration temperature is controlled at 30-35℃, the dissolved oxygen at 5-10 mg / L, and the treatment time is 10-16 h to obtain aerated wastewater. The amount of compound bacteria added is 5-8 g / L. The compound bacteria include Rhodococcus rubrum, Bacillus subtilis, Pseudomonas fluorescens, and photosynthetic bacteria in a mass ratio of (2-5):(3-4):(1-2):(0.5-1).

[0007] S2. The aerated wastewater is mixed with composite activated carbon and treated for 2-3 hours at a temperature of 30-40℃ and an ultrasonic power of 300-500W. Then it is filtered to obtain filtrate A.

[0008] S3. Filter A is passed through a mixed macroporous adsorption resin at a loading flow rate of (3-5) BV / h to obtain Filter B, which is then sterilized to complete the treatment of Litopenaeus vannamei aquaculture wastewater.

[0009] Furthermore, the preparation method of the composite activated carbon is as follows: coconut shell powder and tea seed cake are mixed and then added to an acidic solution for ultrasonic soaking, then washed with water until neutral, calcined, then added to a mixed solution for ultrasonic impregnation, dried, and pulverized to obtain composite activated carbon.

[0010] Furthermore, the mass ratio of coconut shell powder to tea meal is 1:(0.3-0.6); the acidic solution is prepared by mixing citric acid, hydrochloric acid, and water in a mass ratio of (0.5-1):(1-2):(12-15); and the ratio of the total mass of coconut shell powder and tea meal to the liquid content of the acidic solution is (4-5) g / mL.

[0011] Furthermore, the mixed solution is prepared by mixing sodium dodecylbenzenesulfonate, polyglutamic acid, itaconic acid, β-cyclodextrin and water in a mass ratio of (0.3-0.8):(2-3):(1-2):(0.5-1.6):(3-4).

[0012] Furthermore, the ultrasonic immersion is performed for 1.5 to 2 hours at a temperature of 50 to 60°C and a power of 500 to 600W.

[0013] Furthermore, the ultrasonic impregnation is performed at a power of 400-500W for 1-2 hours.

[0014] Furthermore, the calcination is carried out at a rate of 3-5°C / min, with the temperature increased to 600-800°C for 2-3 hours.

[0015] Furthermore, the mixed macroporous adsorption resin includes D-101 macroporous adsorption resin, XAD-8 macroporous adsorption resin, and D3520 macroporous adsorption resin in a mass ratio of (3-4):(1-2):1.

[0016] Furthermore, the sterilization process involves introducing ozone into the filtrate B, with the ozone flow rate controlled at 18–22 mg / min.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] This invention effectively purifies Litopenaeus vannamei farming wastewater by adding compound bacteria for aeration, combined with activated carbon and macroporous adsorption resin. This significantly reduces the levels of pollutants such as total nitrogen, total phosphorus, and suspended solids, resulting in excellent treatment performance. Specifically, the addition of appropriate compound bacteria during aeration effectively decomposes organic matter in the wastewater and adsorbs and degrades ammonia nitrogen and nitrite. The pollutants are then further adsorbed by compound activated carbon, and purified by different types of macroporous adsorption resins, thereby improving the removal efficiency of pollutants in the wastewater.

[0019] In this invention, by using coconut shells and tea seed cakes as raw materials for activated carbon and employing a reasonable preparation method, stable activated carbon with high porosity can be obtained, thereby improving its adsorption, purification, and digestion effects on wastewater. Furthermore, this invention utilizes a suitable composite of macroporous adsorption resins, which effectively enhances the adsorption and purification of pollutants in wastewater.

[0020] The composite activated carbon of the present invention is prepared by ultrasonically soaking coconut shell powder and tea meal in an acidic solution in a suitable ratio. This allows for the formation of better pores in the coconut shell powder and tea meal, which facilitates the formation of a uniform and stable pore structure during subsequent calcination. Then, it is ultrasonically impregnated with a mixed solution containing polyglutamic acid, itaconic acid, β-cyclodextrin, etc., which can improve the adsorption and purification effect of the composite activated carbon. Detailed Implementation

[0021] To better understand the technical content of this invention, specific embodiments are provided below to further illustrate the invention.

[0022] The Rhodococcus used in this embodiment of the invention has the accession number CCTCC NO: M20191008 and is deposited at the China Center for Type Culture Collection.

[0023] The Bacillus subtilis used in this embodiment of the invention has the accession number CCTCC NO: M2020355 and is deposited at the China Center for Type Culture Collection.

[0024] The *Pseudomonas fluorescens* strain used in this embodiment of the invention has the accession number CCTCC NO: M2014274 and is deposited at the China Center for Type Culture Collection.

[0025] The photosynthetic bacteria used in this embodiment of the invention have the accession number CCTCC NO: M 2022251 and are deposited at the China Center for Type Culture Collection.

[0026] Unless otherwise specified, the experimental methods used in the embodiments of this invention are all conventional methods.

[0027] Unless otherwise specified, all materials and reagents used in the embodiments of this invention are commercially available.

[0028] Example 1 - A method for treating water used in Litopenaeus vannamei farming.

[0029] Includes the following steps:

[0030] S1. The aquaculture wastewater is subjected to primary filtration. Compound bacteria are added to the filtered aquaculture wastewater at a dosage of 5g / L. The compound bacteria include Rhodococcus rubrum, Bacillus subtilis, Pseudomonas fluorescens, and photosynthetic bacteria in a mass ratio of 2:3:1:0.8. Then, aeration treatment is carried out, and the aeration temperature is controlled at 30℃ and the dissolved oxygen is 5mg / L. The treatment time is 16h to obtain aerated wastewater.

[0031] S2. The aerated wastewater is mixed with composite activated carbon and treated at 30℃ and 300W ultrasonic power for 2 hours, then filtered to obtain filtrate A. The composite activated carbon is prepared by mixing coconut shell powder and tea meal in a mass ratio of 1:0.6 and adding them to an acidic solution (prepared by mixing citric acid, hydrochloric acid, and water in a mass ratio of 0.5:2:12). The total mass of coconut shell powder and tea meal to the acidic solution is 5g / mL. The mixture is then treated at 55℃ and 600W ultrasonic power. The activated carbon was ultrasonically soaked for 1.5 hours under 00W conditions, then washed with water until neutral, and then calcined at 800℃ for 2.5 hours at a rate of 4℃ / min. It was then added to a mixed solution and ultrasonically impregnated for 1 hour at 60℃ and 600W, dried, and pulverized to obtain composite activated carbon. The mixed solution was prepared by mixing sodium dodecylbenzenesulfonate, polyglutamic acid, itaconic acid, β-cyclodextrin, and water in a mass ratio of 0.3:2:1:0.5:3.

[0032] S3. Filter A is passed through macroporous adsorption resin (the macroporous adsorption resin includes D-101 macroporous adsorption resin, XAD-8 macroporous adsorption resin and D3520 macroporous adsorption resin in a mass ratio of 3:2:1) and treated at a loading flow rate of 3 BV / h to obtain filtrate B. Ozone is then introduced into filtrate B for treatment. The ozone flow rate is controlled at 18 mg / min for sterilization, thus completing the treatment of Litopenaeus vannamei aquaculture wastewater.

[0033] Example 2 - A method for treating water used in Litopenaeus vannamei farming

[0034] Includes the following steps:

[0035] S1. The aquaculture wastewater is subjected to primary filtration. Compound bacteria are added to the filtered aquaculture wastewater at a dosage of 8g / L. The compound bacteria include Rhodococcus rubrum, Bacillus subtilis, Pseudomonas fluorescens, and photosynthetic bacteria in a mass ratio of 5:4:2:0.5. Then, aeration treatment is carried out, and the aeration temperature is controlled at 35℃ and the dissolved oxygen is 8mg / L. The treatment time is 14h to obtain aerated wastewater.

[0036] S2. The aerated wastewater is mixed with composite activated carbon and treated at 35℃ and 500W ultrasonic power for 3 hours, then filtered to obtain filtrate A. The composite activated carbon is prepared by mixing coconut shell powder and tea meal at a mass ratio of 1:0.3 and adding them to an acidic solution (prepared by mixing citric acid, hydrochloric acid, and water at a mass ratio of 1:1:15). The total mass of coconut shell powder and tea meal to the acidic solution is 4g / mL. The mixture is then treated at 60℃ and 500W ultrasonic power. The activated carbon was ultrasonically soaked for 2 hours at 550W, then washed with water until neutral, and then calcined at 600℃ for 3 hours at a rate of 5℃ / min. It was then added to a mixed solution and ultrasonically impregnated for 2 hours at 50℃ and 500W. After drying and pulverizing, composite activated carbon was obtained. The mixed solution was prepared by mixing sodium dodecylbenzenesulfonate, polyglutamic acid, itaconic acid, β-cyclodextrin, and water in a mass ratio of 0.5:3:2:1.6:4.

[0037] S3. Filter A is passed through macroporous adsorption resin (the macroporous adsorption resin includes D-101 macroporous adsorption resin, XAD-8 macroporous adsorption resin and D3520 macroporous adsorption resin in a mass ratio of 4:1:1) and treated at a loading flow rate of 5 BV / h to obtain filtrate B. Ozone is then introduced into filtrate B for treatment. The ozone flow rate is controlled at 22 mg / min for sterilization, thus completing the treatment of Litopenaeus vannamei aquaculture wastewater.

[0038] Example 3 - A method for treating water used in Litopenaeus vannamei aquaculture

[0039] Includes the following steps:

[0040] S1. The aquaculture wastewater is subjected to primary filtration. Compound bacteria are added to the filtered aquaculture wastewater at a dosage of 6g / L. The compound bacteria include Rhodococcus rubrum, Bacillus subtilis, Pseudomonas fluorescens, and photosynthetic bacteria in a mass ratio of 4:3:1.5:1. Then, aeration treatment is carried out, and the aeration temperature is controlled at 35℃ and the dissolved oxygen is 10mg / L. The treatment time is 10h to obtain aerated wastewater.

[0041] S2. The aerated wastewater is mixed with composite activated carbon and treated at 40℃ and 400W ultrasonic power for 2.5h, then filtered to obtain filtrate A. The composite activated carbon is prepared by mixing coconut shell powder and tea meal in a mass ratio of 1:0.4 and adding the mixture to an acidic solution (prepared by mixing citric acid, hydrochloric acid, and water in a mass ratio of 0.8:1.6:13). The total mass of coconut shell powder and tea meal to the acidic solution is 5g / mL. The mixture is then treated at 50℃ and 400W ultrasonic power for 2.5h. The activated carbon was ultrasonically soaked for 2 hours under 00W conditions, then washed with water until neutral, and then calcined at 700℃ for 2 hours at a rate of 3℃ / min. It was then added to a mixed solution and ultrasonically impregnated for 1.5 hours at 55℃ and 550W. After drying and pulverizing, composite activated carbon was obtained. The mixed solution was prepared by mixing sodium dodecylbenzenesulfonate, polyglutamic acid, itaconic acid, β-cyclodextrin, and water in a mass ratio of 0.8:2.5:1.5:1.2:3.5.

[0042] S3. Filter A is passed through a mixed macroporous adsorption resin (the macroporous adsorption resin includes D-101 macroporous adsorption resin, XAD-8 macroporous adsorption resin, and D3520 macroporous adsorption resin in a mass ratio of 3.5:1.6:1) and treated at a loading flow rate of 4 BV / h to obtain filtrate B. Ozone is then introduced into filtrate B for treatment, with the ozone flow rate controlled at 20 mg / min for sterilization, thus completing the treatment of Litopenaeus vannamei aquaculture wastewater.

[0043] Comparative Example 1

[0044] Compared with Example 3, this embodiment does not add compound bacteria during the aeration process in step S1, but is otherwise the same as Example 3.

[0045] The specific process of S1 in this comparative example is as follows: the aquaculture wastewater is subjected to primary filtration, and then aerated. The aeration temperature is controlled at 35℃ and the dissolved oxygen is 10mg / L. The treatment time is 10h to obtain aerated wastewater.

[0046] Comparative Example 2

[0047] Compared with Example 3, this embodiment changes the bacterial strain ratio during the aeration process, but the rest is the same as Example 3.

[0048] The comparative example of the compound bacteria included Rhodococcus rubrum, Bacillus subtilis, Pseudomonas fluorescens, and photosynthetic bacteria in a mass ratio of 0.1:6:4:0.2.

[0049] Comparative Example 3

[0050] Compared with Example 3, the preparation method of composite activated carbon is different in this embodiment, but the rest is the same as in Example 3.

[0051] The preparation method of the composite activated carbon in this comparative example is as follows: coconut shell powder and tea seed cake with a mass ratio of 1:0.4 are mixed and heated to 700℃ at a rate of 10℃ / min for 2 hours, cooled to room temperature, and pulverized to obtain composite activated carbon.

[0052] Comparative Example 4

[0053] Compared with Example 3, this embodiment uses a stirring method to treat the aerated wastewater and composite activated carbon, while the rest is the same as in Example 3. In this comparative example, the aerated wastewater and composite activated carbon are stirred at a temperature of 40°C and a stirring rate of 200 rpm for 2.5 hours, and then filtered to obtain filtrate A.

[0054] Comparative Example 5

[0055] Compared with Example 3, this embodiment replaces D-101 macroporous adsorption resin with D1400 macroporous adsorption resin, and the rest is the same as Example 3.

[0056] Wastewater from Litopenaeus vannamei farming was treated according to Examples 1-3 and Comparative Example 5. The pH, total nitrogen, total phosphorus, and suspended solids content in the wastewater before and after treatment were measured, and the corresponding removal rates were calculated. Total nitrogen was determined using alkaline potassium persulfate digestion ultraviolet spectrophotometry, total phosphorus was determined using potassium persulfate digestion molybdate spectrophotometry, and suspended solids content was determined using the gravimetric method. The experimental results are shown in Table 1 below.

[0057] Table 1. Wastewater Treatment Status of Litopenaeus vannamei Farming

[0058]

[0059] The above results indicate that the present invention can effectively purify wastewater from Litopenaeus vannamei farming, achieving total nitrogen removal rates of 98.35–99.54%, total phosphorus removal rates of 96.59–97.48%, and suspended solids removal rates of 92.70–93.27%. Compared with Example 3, Comparative Example 1 did not add compound bacteria during aeration treatment; Comparative Example 2 changed the bacterial strain ratio during aeration treatment; Comparative Example 3 used a different method for preparing compound activated carbon; Comparative Example 4 treated aerated wastewater and compound activated carbon by stirring; and Comparative Example 5 replaced D-101 macroporous adsorption resin with D1400 macroporous adsorption resin, resulting in a decrease in the removal efficiency of total nitrogen, total phosphorus, and suspended solids in Litopenaeus vannamei farming wastewater, and a decrease in the purification effect.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for treating wastewater from Litopenaeus vannamei farming, characterized in that, Includes the following steps: S1. The aquaculture wastewater is subjected to primary filtration. The filtered aquaculture wastewater is then aerated with compound bacteria. The aeration temperature is controlled at 30-35℃, the dissolved oxygen is 5-10 mg / L, and the treatment time is 10-16 h to obtain aerated wastewater. The compound bacteria are added at a rate of 5-8 g / L. The compound bacteria include Rhodococcus rubrum, Bacillus subtilis, Pseudomonas fluorescens, and photosynthetic bacteria in a mass ratio of (2-5):(3-4):(1-2):(0.5-1). S2. The aerated wastewater is mixed with composite activated carbon and treated at a temperature of 30~40℃ and an ultrasonic power of 300~500W for 2~3 hours, then filtered to obtain filtrate A; The preparation method of the composite activated carbon is as follows: coconut shell powder and tea seed cake are mixed and added to an acidic solution for ultrasonic soaking, then washed with water until neutral, calcined, then added to the mixed solution for ultrasonic impregnation, dried, and pulverized to obtain composite activated carbon; The mixed solution is prepared by mixing sodium dodecylbenzenesulfonate, polyglutamic acid, itaconic acid, β-cyclodextrin and water in a mass ratio of (0.3~0.8):(2~3):(1~2):(0.5~1.6):(3~4); S3. Filter A is passed through a mixed macroporous adsorption resin and processed at a flow rate of (3~5) BV / h to obtain filtrate B, which is then sterilized to complete the treatment of Litopenaeus vannamei aquaculture wastewater. The mixed macroporous adsorption resin includes D-101 macroporous adsorption resin, XAD-8 macroporous adsorption resin, and D3520 macroporous adsorption resin in a mass ratio of (3~4):(1~2):

1.

2. The method for treating Litopenaeus vannamei aquaculture wastewater according to claim 1, characterized in that, The mass ratio of coconut shell powder to tea meal is 1:(0.3~0.6); the acidic solution is prepared by mixing citric acid, hydrochloric acid and water in a mass ratio of (0.5~1):(1~2):(12~15); the total mass of coconut shell powder and tea meal to the ratio of the acidic solution to the liquid is (4~5) g / mL.

3. The method for treating Litopenaeus vannamei aquaculture wastewater according to claim 1, characterized in that, The ultrasonic immersion is performed at a temperature of 50~60℃ and a power of 500~600W for 1.5~2 hours.

4. The method for treating Litopenaeus vannamei aquaculture wastewater according to claim 1, characterized in that, The ultrasonic impregnation is performed by impregnating for 1 to 2 hours at a power of 400 to 500 W.

5. The method for treating wastewater from Litopenaeus vannamei farming according to claim 1, characterized in that, The calcination is carried out by heating at a rate of 3~5℃ / min to 600~800℃ for 2~3 hours.

6. The method for treating wastewater from Litopenaeus vannamei farming according to claim 1, characterized in that, The sterilization process involves introducing ozone into the filtrate B, with the ozone flow rate controlled at 18-22 mg / min.

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