A method for removing odorous substances

Abstract

The present invention provides a method for removing odorous substances. The present invention combines two means, slightly acidic electrolyzed water treatment and ultraviolet irradiation, to effectively remove not only geosmin and 2-methylisoborneol in water, but also geosmin and 2-methylisoborneol in aquatic organisms. In addition, the removal effect of the inventive method on geosmin and 2-methylisoborneol in water is significantly better than the sum of the effects of using slightly acidic electrolyzed water treatment alone and using ultraviolet irradiation alone, indicating that the two means of slightly acidic electrolyzed water treatment and ultraviolet irradiation of the present invention play a synergistic role in removing geosmin and 2-methylisoborneol.

Description

Technical Field

[0001] The present invention belongs to the field of water treatment technology and more specifically relates to a method for removing odorous substances. Background Art

[0002] Due to agricultural runoff and sewage discharge, flowing water ecosystems such as rivers can become eutrophic, leading to the proliferation of algae such as cyanobacteria. Especially during the hot summer months, outbreaks of cyanobacteria and other algae occur not only in flowing water ecosystems like rivers but also in stagnant water ecosystems such as lakes and reservoirs. The metabolism of algae releases large amounts of geosmin (GSM) and 2-methylisoborneol (2-MIB).

[0003] Excessive presence of geosmin and 2-methylisoborneol in water can have a variety of adverse effects: (1) Geosmin and 2-methylisoborneol may make the water have a rotten earth smell, affecting the sensory indicators and drinkability of the water; (2) Fish may directly absorb geosmin and 2-methylisoborneol in the water through organs such as gills or skin, or ingest geosmin and 2-methylisoborneol by directly preying on algae, which will not only cause the enrichment of odor substances in fish meat, seriously affecting the quality of fish meat, but also may cause dryness. Disrupt the endocrine system of fish and affect their growth and reproduction; (3) Most shellfish are filter-feeding animals and may accumulate geosmin and 2-methylisoborneol through adsorption and ingestion of algae, which will not only seriously affect their meat quality, but may also be passed to organisms at higher trophic levels through the food chain, further expanding the scope of impact; (4) Geosmin and 2-methylisoborneol may stimulate the excessive growth of aquatic vegetation, leading to sediment accumulation and a decrease in dissolved oxygen, destroying the self-purification capacity of the water body and forming a vicious cycle.

[0004] Therefore, it is urgent to find a method that can effectively remove geosmin and 2-methylisoborneol in water. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention aims to provide a method for removing odorous substances. By combining slightly acidic electrolyzed water (SAEW) treatment with ultraviolet (UV-C) irradiation, the two methods can not only effectively remove geosmin and 2-methylisoborneol in water, but also effectively remove geosmin and 2-methylisoborneol in aquatic organisms.

[0006] The first object of the present invention is to provide a method for removing odorous substances in water.

[0007] A second object of the present invention is to provide a method for removing odorous substances from aquatic organisms.

[0008] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0009] The present invention provides a method for removing odorous substances in water, specifically comprising: preparing water containing odorous substances into slightly acidic electrolyzed water containing odorous substances, and then irradiating the water with ultraviolet rays with a wavelength of 222 to 275 nm; wherein the odorous substances include geosmin and / or 2-methylisoborneol.

[0010] Optionally, the concentration of the geosmin in water is below 5 μg / L, for example, it can be 1, 2.5, 3, 5 μg / L or a range between any of the above values.

[0011] Optionally, the concentration of 2-methylisoborneol in water is below 25 μg / L, for example, it can be 2.5, 5, 15, 25 μg / L or a range between any of the above values.

[0012] According to the description of slightly acidic electrolyzed water in GB28234-2020 "Hygiene Requirements for Acidic Electrolyzed Water Generators", slightly acidic electrolyzed water is a colorless, transparent liquid with a slight chlorine smell. The effective chlorine content is 40-80 mg / L (for example, it can be 40, 60, 80 mg / L or a range between any of the above points), and the pH is 5.0-6.5 (for example, it can be 5, 6.5, which can be adjusted with HCl and / or NaOH).

[0013] Optionally, the preparation method is: using water containing odorous substances as raw material, and preparing it according to the method of GB28234-2020 "Hygiene Requirements for Acidic Electrolyzed Water Generators", that is: adding water containing odorous substances to hydrochloric acid and / or sodium chloride, and electrolyzing it in an electrolytic cell with or without a diaphragm.

[0014] Optionally, the wavelength of the ultraviolet light is 222, 255, 275 nm or a range between any of the above values.

[0015] Optionally, the irradiation time is greater than 0.5 min, for example, it can be 0.5, 1, 1.5, 2, 3, 5, 7 min or a range between any of the above points.

[0016] Optionally, the irradiation intensity of the ultraviolet light is 3 mW / cm 2 above.

[0017] Optionally, the irradiation temperature is 20-30°C, for example, 20, 25, 30°C or any range between the above values.

[0018] Optionally, stirring is performed simultaneously with the irradiation, such as stirring at 800 to 1200 r / min, most preferably 1000 r / min.

[0019] At the same time, the present invention also provides a method for removing odorous substances from aquatic organisms, specifically: immersing aquatic organisms containing odorous substances in slightly acidic electrolyzed water, and then irradiating them with ultraviolet rays with a wavelength of 222 to 275 nm; wherein the odorous substances include geosmin and / or 2-methylisoborneol.

[0020] Optionally, the aquatic organisms are fish and / or shellfish.

[0021] Further optionally, the fish is a freshwater fish, such as one or more of tilapia, grass carp, silver carp, snakehead carp, and carp.

[0022] Further optionally, the shellfish is a freshwater shellfish, such as one or more of Chinese round pond snails, river clams, and river mussels.

[0023] Optionally, the aquatic organism is fish and / or shellfish.

[0024] Optionally, the content of geosmin in aquatic organisms is below 0.40 μg / kg.

[0025] Optionally, the content of 2-methylisoborneol in aquatic organisms is below 4.19 μg / kg.

[0026] Optionally, the usage ratio of the aquatic organisms to the slightly acidic electrolyzed water is 23-27 g:1.5 L, for example, it can be 23 g:1.5 L, 25 g:1.5 L, 27 g:1.5 L or a range between any of the above points.

[0027] Optionally, the wavelength of the ultraviolet light is 222, 255, 275 nm or a range between any of the above values.

[0028] Optionally, the irradiation time is greater than 0.5 min, for example, it can be 0.5, 1, 1.5, 2, 3, 5, 7 min or a range between any of the above points.

[0029] Optionally, the irradiation intensity of the ultraviolet light is 3 mW / cm 2 above.

[0030] Optionally, the irradiation temperature is 20-30° C., for example, 20, 25, 30° C. or any range between the above values.

[0031] Optionally, stirring is performed simultaneously with the irradiation, such as stirring at 800 to 1200 r / min, most preferably 1000 r / min.

[0032] The present invention has the following beneficial effects:

[0033] 1. The present invention combines slightly acidic electrolyzed water treatment with ultraviolet irradiation to effectively remove geosmin and 2-methylisoborneol not only from water but also from aquatic organisms.

[0034] 2. The present invention combines slightly acidic electrolyzed water treatment with ultraviolet irradiation. Its effect on removing geosmin and 2-methylisoborneol in water is significantly better than the sum of the effects of slightly acidic electrolyzed water treatment and ultraviolet irradiation alone, indicating that these two methods play a synergistic role in removing geosmin and 2-methylisoborneol.

[0035] 3. This invention combines slightly acidic electrolyzed water treatment with ultraviolet irradiation. Compared with other methods (such as plasma-activated water treatment, chloramine solution treatment, etc.) combined with ultraviolet irradiation, it is significantly more effective in removing geosmin and 2-methylisoborneol. DETAILED DESCRIPTION

[0036] The present invention is further described below with reference to specific examples, which, however, are not intended to limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0037] Unless otherwise specified, all reagents and materials used in the following examples were commercially available and of analytical grade.

[0038] 1. Reagents

[0039] Geosmin (GSM) standard solution: concentration is 100 μg / mL, purchased from Supelco, USA.

[0040] 2-Methylisoborneol (2-MIB) standard solution: concentration is 100 μg / mL, purchased from Supelco, USA.

[0041] Sodium thiosulfate standard solution: concentration 0.1 mol / L, purchased from Anpu Experimental Technology Co., Ltd.

[0042] Sodium chloride: purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0043] 2. Instruments

[0044] Rtx-5MS quartz capillary analytical column: specifications are 30 m × 0.25 mm × 0.25 μm, purchased from Shimadzu Corporation, Japan.

[0045] 50 / 30 μm DVB / CAR / PDMS solid phase extraction needle: purchased from Supelco, USA.

[0046] GCMS-TQ8050NX gas chromatography-mass spectrometry: purchased from Shimadzu Corporation, Japan.

[0047] Anywhere-320W slightly acidic electrolyzed water generator: purchased from Beijing Liande Environmental Protection Equipment Co., Ltd.

[0048] DK-98-Ⅱ water bath: purchased from Tianjin Test Instrument Co., Ltd.

[0049] JYL-c50T food processor: purchased from Joyoung Co., Ltd.

[0050] JIDI-UP Basic ultrapure water machine: purchased from Guangzhou Jidi Instrument Co., Ltd.

[0051] 3. Determination of geosmin and 2-methylisoborneol in water

[0052] 5 mL of water, 5 mL of saturated sodium chloride solution, and 2 mL of sodium thiosulfate standard solution were placed in a 40 mL headspace bottle and placed in a 70°C water bath for headspace equilibration for 5 min. The volatile substances in the sample were then adsorbed in the headspace using a 50 / 30 μm DVB / CAR / PDMS solid-phase extraction system for 35 min. The contents of geosmin and 2-methylisoborneol were then determined by GC-MS.

[0053] The GC-MS conditions are:

[0054] A GC / MS-TQ8050NX gas chromatography-mass spectrometry system equipped with an Rtx-5MS quartz capillary analytical column (30 m × 0.25 mm × 0.25 µm) was used. The carrier gas was helium (99.999% purity) at a flow rate of 1.0 mL / min. The column temperature program was as follows: initial temperature at 60°C, held for 2 min, then increased to 120°C at a rate of 10°C / min and held for 3 min, then increased to 150°C at a rate of 3°C / min and held for 1 min, and finally increased to 230°C at a rate of 20°C / min and held for 1 min. The ionization energy was 70 eV, the interface temperature was 250°C, and the ion source temperature was 250°C. The scan mode was selected ion monitoring (MRM). The qualitative and quantitative ion pairs and retention times are shown in Table 1.

[0055] Table 1 Qualitative ion pairs, quantitative ion pairs and retention times

[0056]

[0057] 4. Determination of geosmin and 2-methylisoborneol in fish

[0058] The fish meat was crushed, and 5.0 g of fish meat, 5 mL of saturated sodium chloride solution, and 2 mL of sodium thiosulfate standard solution were placed in a 40 mL headspace bottle. The bottle was placed in a 70 °C water bath for headspace equilibration for 5 min. The volatile substances in the sample were then adsorbed in the headspace using a 50 / 30 μm DVB / CAR / PDMS solid-phase extraction system for 35 min. The contents of geosmin and 2-methylisoborneol were then determined by GC-MS.

[0059] The GC-MS conditions are:

[0060] A GC / MS-TQ8050NX gas chromatography-mass spectrometry system equipped with an Rtx-5MS quartz capillary analytical column (30 m × 0.25 mm × 0.25 µm) was used. The carrier gas was helium (99.999% purity) at a flow rate of 1.0 mL / min. The column temperature program was as follows: initial temperature at 60°C, held for 2 min, then increased to 120°C at a rate of 10°C / min and held for 3 min, then increased to 150°C at a rate of 3°C / min and held for 1 min, and finally increased to 230°C at a rate of 20°C / min and held for 1 min. The ionization energy was 70 eV, the interface temperature was 250°C, and the ion source temperature was 250°C. The scan mode was selected ion monitoring (MRM). The qualitative and quantitative ion pairs and retention times are shown in Table 1.

[0061] Example 1: Effects of different modes of action on the removal of geosmin and 2-methylisoborneol in water

[0062] 1. Test methods

[0063] ① Single slightly acidic electrolyzed water treatment

[0064] S1. Electrolyze water at room temperature (25 ± 5°C) according to the method specified in GB 28234-2020, "Hygienic Requirements for Acidic Electrolyzed Water Generators." Adjust the available chlorine content to 60 mg / L and the pH to 5 by adding water, HCl, or NaOH to obtain slightly acidic electrolyzed water.

[0065] S2. Adding geosmin and 2-methylisoborneol to the slightly acidic electrolyzed water obtained in S1 to a final concentration of 2.5 μg / L for geosmin and 2.5 μg / L for 2-methylisoborneol, thereby obtaining slightly acidic electrolyzed water containing odorous substances.

[0066] S3. Magnetic stirring at 1000 r / min for 5 min.

[0067] ② Ultraviolet irradiation alone

[0068] S1. At room temperature (25 ± 5°C), add geosmin and 2-methylisoborneol to water to a final concentration of 2.5 μg / L for geosmin and 2.5 μg / L for 2-methylisoborneol, to obtain odor-containing water.

[0069] S2. Irradiate with ultraviolet light at wavelengths of 222, 255, and 275 nm for 5 min while magnetically stirring at 1000 r / min; wherein the ultraviolet light intensity is 3 mW / cm 2 .

[0070] ③Combination of slightly acidic electrolyzed water treatment and ultraviolet irradiation

[0071] S1. Electrolyze water at room temperature (25 ± 5°C) according to the method specified in GB 28234-2020, "Hygienic Requirements for Acidic Electrolyzed Water Generators." Adjust the available chlorine content to 60 mg / L and the pH to 5 by adding water, HCl, or NaOH to obtain slightly acidic electrolyzed water.

[0072] S2. Adding geosmin and 2-methylisoborneol to the slightly acidic electrolyzed water obtained in S1 to a final concentration of 2.5 μg / L for geosmin and 2.5 μg / L for 2-methylisoborneol, thereby obtaining slightly acidic electrolyzed water containing odorous substances.

[0073] S3. Irradiate with ultraviolet light at wavelengths of 222, 255, and 275 nm for 5 min while magnetically stirring at 1000 r / min; wherein the ultraviolet irradiation intensity is 3 mW / cm 2 .

[0074] ④ Plasma activated water treatment combined with ultraviolet irradiation;

[0075] S1. At room temperature (25 ± 5°C), geosmin and 2-methylisoborneol were added to plasma-activated water to a final concentration of 2.5 μg / L for geosmin and 2.5 μg / L for 2-methylisoborneol, respectively, to obtain plasma-activated water containing odorous substances. The plasma-activated water was prepared by discharging 500 mL of pure water at 200 W for 15 minutes. The pH and redox potential of the water were 4.72 and 374 mV, respectively.

[0076] S2. Irradiate with ultraviolet light at a wavelength of 222 nm for 5 min while magnetically stirring at 1000 r / min; wherein the ultraviolet irradiation intensity is 3 mW / cm 2 .

[0077] ⑤ Chloramine solution treatment combined with ultraviolet irradiation

[0078] S1. At room temperature (25 ± 5°C), add water, HCl, or NaOH to adjust the available chlorine content of chloramine to 60 mg / L and the pH to 5 to obtain a chloramine solution.

[0079] S2. Add geosmin and 2-methylisoborneol to the chloramine solution to obtain a final concentration of 2.5 μg / L for geosmin and 2.5 μg / L for 2-methylisoborneol, thereby obtaining a chloramine solution containing odorous substances.

[0080] S3. Irradiation with ultraviolet light at a wavelength of 222 nm for 5 min while magnetically stirring at 1000 r / min; wherein the ultraviolet irradiation intensity is 3 mW / cm 2 .

[0081] 2. Test results

[0082] The contents of geosmin and 2-methylisoborneol in water were measured at 0.5, 1, 1.5, 2, and 5 minutes under magnetic stirring at S2 or S3, respectively. The clearance rates of geosmin and 2-methylisoborneol under different action modes were calculated according to "clearance rate (%) = (content before treatment - content after treatment) / content before treatment × 100%". The results are shown in Tables 2 to 4.

[0083] Table 2 Geosmin removal rates of ①~③

[0084]

[0085] Table 3 2-Methylisoborneol clearance rates of ① to ③

[0086]

[0087] Table 4 Odor substance removal rates of ④~⑤

[0088]

[0089] Analysis of the results of the effects of ① to ③ shows that the removal rate of geosmin and 2-methylisoborneol, two odorous substances in water, by combining the two means of slightly acidic electrolyzed water treatment and ultraviolet irradiation, ③ is higher than the sum of the removal rates of the corresponding odorous substances by ① using slightly acidic electrolyzed water alone and ② using ultraviolet irradiation alone. This shows that the present invention combines the two means of slightly acidic electrolyzed water treatment and ultraviolet irradiation, and its removal effect on geosmin and 2-methylisoborneol in water is significantly better than the sum of the effects of using slightly acidic electrolyzed water treatment alone and using ultraviolet irradiation alone, that is, the two means play a synergistic role in removing geosmin and 2-methylisoborneol.

[0090] Analysis of the results of ③ to ⑤ shows that the removal rate of geosmin and 2-methylisoborneol, two odorous substances in water, by ③, which combines the two methods of slightly acidic electrolyzed water treatment and ultraviolet irradiation, is higher than that by ④ to ⑤, which combine other methods (such as plasma activated water treatment, chloramine solution treatment, etc.) with ultraviolet irradiation. This shows that it is precisely because the present invention specifically selects the method of slightly acidic electrolyzed water treatment and combines it with ultraviolet irradiation that such excellent geosmin and 2-methylisoborneol removal effects can be achieved.

[0091] Example 2: Effect of slightly acidic electrolyzed water with different available chlorine contents on the removal of geosmin and 2-methylisoborneol in water

[0092] 1. Test methods

[0093] S1. Electrolyze water at room temperature (25 ± 5°C) according to the method specified in GB 28234-2020, "Hygienic Requirements for Acidic Electrolyzed Water Generators." Adjust the available chlorine content to 40, 60, or 80 mg / L, and the pH to 5 by adding water, HCl, or NaOH to obtain slightly acidic electrolyzed water.

[0094] S2. Adding geosmin and 2-methylisoborneol to the slightly acidic electrolyzed water obtained in S1 to a final concentration of 2.5 μg / L for geosmin and 2.5 μg / L for 2-methylisoborneol, thereby obtaining slightly acidic electrolyzed water containing odorous substances.

[0095] S3. Irradiation with ultraviolet light at a wavelength of 255 nm for 5 min while magnetically stirring at 1000 r / min; wherein the ultraviolet irradiation intensity is 3 mW / cm 2 .

[0096] 2. Test results

[0097] The contents of geosmin and 2-methylisoborneol in water were measured at 0.5, 1, 1.5, 2, and 5 minutes of S3 magnetic stirring, respectively. The removal rates of geosmin and 2-methylisoborneol by slightly acidic electrolyzed water with different available chlorine contents were calculated according to "removal rate (%) = (content before treatment - content after treatment) / content before treatment × 100%". The results are shown in Table 5.

[0098] Table 5 Odor substance removal rate

[0099]

[0100] It can be seen that in the method of the present invention, the combination of slightly acidic electrolyzed water treatment with different available chlorine contents and ultraviolet irradiation can effectively eliminate geosmin and 2-methylisoborneol in water, and with the increase of available chlorine content, the elimination rate of geosmin and 2-methylisoborneol in water also shows an overall increasing trend.

[0101] Example 3: Effects of slightly acidic electrolyzed water with different pH values ​​on the removal of geosmin and 2-methylisoborneol in water

[0102] 1. Test methods

[0103] S1. Electrolyze water at room temperature (25 ± 5°C) according to the method specified in GB 28234-2020, "Hygienic Requirements for Acidic Electrolyzed Water Generators." Adjust the available chlorine content to 80 mg / L and the pH to 5 or 6.5 by adding water, HCl, or NaOH to produce slightly acidic electrolyzed water.

[0104] S2. Adding geosmin and 2-methylisoborneol to the slightly acidic electrolyzed water obtained in S1 to a final concentration of 2.5 μg / L for geosmin and 2.5 μg / L for 2-methylisoborneol, thereby obtaining slightly acidic electrolyzed water containing odorous substances.

[0105] S3. Irradiation with ultraviolet light at a wavelength of 255 nm for 5 min while magnetically stirring at 1000 r / min; wherein the ultraviolet irradiation intensity is 3 mW / cm 2 .

[0106] 2. Test results

[0107] The contents of geosmin and 2-methylisoborneol in water were measured at 1.5, 2, and 5 minutes of S3 magnetic stirring, respectively. The clearance rates of geosmin and 2-methylisoborneol by slightly acidic electrolyzed water with different pH values ​​were calculated according to the formula “clearance rate (%) = (content before treatment - content after treatment) / content before treatment × 100%”. The results are shown in Table 6.

[0108] Table 6 Odor substance clearance rate

[0109]

[0110] It can be seen that in the method of the present invention, the combination of slightly acidic electrolyzed water treatment with different pH values ​​and ultraviolet irradiation can effectively eliminate geosmin and 2-methylisoborneol in water, and as the pH decreases, the elimination rate of geosmin and 2-methylisoborneol in water also increases significantly.

[0111] Example 4: Effects of Ultraviolet Light of Different Wavelengths on the Removal of Geosmin and 2-Methylisoborneol in Water

[0112] 1. Test methods

[0113] S1. Electrolyze water at room temperature (25 ± 5°C) according to the method specified in GB 28234-2020, "Hygienic Requirements for Acidic Electrolyzed Water Generators." Adjust the available chlorine content to 80 mg / L and the pH to 5 by adding water, HCl, or NaOH to obtain slightly acidic electrolyzed water.

[0114] S2. Adding geosmin and 2-methylisoborneol to the slightly acidic electrolyzed water obtained in S1 to a final concentration of 2.5 μg / L for geosmin and 2.5 μg / L for 2-methylisoborneol, thereby obtaining slightly acidic electrolyzed water containing odorous substances.

[0115] S3. Irradiate with ultraviolet light at wavelengths of 222, 255, and 275 nm for 5 min while magnetically stirring at 1000 r / min; wherein the ultraviolet irradiation intensity is 3 mW / cm 2 .

[0116] 2. Test results

[0117] The contents of geosmin and 2-methylisoborneol in water were measured at 0.5, 1, 1.5, 2, and 5 minutes of S3 magnetic stirring, respectively. The scavenging rates of geosmin and 2-methylisoborneol under ultraviolet light of different wavelengths were calculated according to the formula “scavenging rate (%) = (content before treatment - content after treatment) / content before treatment × 100%”. The results are shown in Table 7.

[0118] Table 7 Odor substance removal rate

[0119]

[0120] It can be seen that in the method of the present invention, ultraviolet irradiation with a wavelength of 222 to 275 nm combined with slightly acidic electrolyzed water treatment can effectively eliminate geosmin and 2-methylisoborneol in water, and as the wavelength of ultraviolet irradiation decreases, the elimination rate of geosmin and 2-methylisoborneol in water also tends to increase overall.

[0121] Example 5: Effects of different substrate concentrations on the removal of geosmin and 2-methylisoborneol in water

[0122] 1. Test methods

[0123] S1. Electrolyze water at room temperature (25 ± 5°C) according to the method specified in GB 28234-2020, "Hygienic Requirements for Acidic Electrolyzed Water Generators." Adjust the available chlorine content to 80 mg / L and the pH to 5 by adding water, HCl, or NaOH to obtain slightly acidic electrolyzed water.

[0124] S2. Add geosmin and 2-methylisoborneol to the slightly acidic electrolyzed water obtained in S1 to obtain slightly acidic electrolyzed water containing odorous substances ① to ③; wherein, in ①, the final concentration of geosmin is 1 μg / L, and the final concentration of 2-methylisoborneol is 5 μg / L; in ②, the final concentration of geosmin is 3 μg / L, and the final concentration of 2-methylisoborneol is 15 μg / L; in ③, the final concentration of geosmin is 5 μg / L, and the final concentration of 2-methylisoborneol is 25 μg / L;

[0125] S3. Irradiation with ultraviolet light at a wavelength of 222 nm for 5 min while magnetically stirring at 1000 r / min; wherein the ultraviolet irradiation intensity is 3 mW / cm 2 .

[0126] 2. Test results

[0127] The contents of geosmin and 2-methylisoborneol in water were measured at 0.5, 1, 1.5, 2, and 5 minutes of S3 magnetic stirring, and the clearance rates of geosmin and 2-methylisoborneol at different substrate concentrations were calculated according to "clearance rate (%) = (content before treatment - content after treatment) / content before treatment × 100%". The results are shown in Table 8.

[0128] Table 8 Odor substance removal rate

[0129]

[0130] It can be seen that the present invention combines slightly acidic electrolyzed water treatment with ultraviolet irradiation to effectively eliminate geosmin and 2-methylisoborneol at different concentrations in water, and as the substrate concentration decreases, the elimination rate generally increases.

[0131] Example 6: Effect of Slightly Acidic Electrolyzed Water Treatment Combined with Ultraviolet Irradiation on the Removal of Geosmin and 2-Methylisoborneol from Fish

[0132] 1. Test methods

[0133] S1. Live tilapia (1.50 ± 0.31 kg) purchased from Huguang Market were killed by sudden death on crushed ice. The dorsal meat of the tilapia was removed and cut into 3.5 mm thick fillets for later use.

[0134] S2. Dissolve geosmin in distilled water to obtain soaking solution 1 with a final concentration of 5 ng / mL; dissolve 2-methylisoborneol in distilled water to obtain soaking solution 2 with a final concentration of 25 ng / mL;

[0135] S3. Soak 150 g of fish fillets in 500 mL of soaking solution 1 for 1 hour, remove and drain, to obtain a fish fillet containing 0.40 μg / kg of geosmin. Soak 150 g of fish fillets in 500 mL of soaking solution 2 for 1 hour, remove and drain, to obtain a fish fillet containing 4.19 μg / kg of 2-methylisoborneol.

[0136] S4. Electrolyze water at room temperature (25 ± 5°C) according to the method specified in GB 28234-2020, "Hygienic Requirements for Acidic Electrolyzed Water Generators." Adjust the available chlorine content to 80 mg / L and the pH to 5 by adding water, HCl, or NaOH to produce slightly acidic electrolyzed water.

[0137] S5. 25 g of fish fillets containing odorous substances were soaked in 1.5 L of slightly acidic electrolyzed water and then irradiated with ultraviolet light of 222 nm wavelength for 7 min while magnetically stirring at 1000 r / min; wherein the irradiation intensity of the ultraviolet light was 3 mW / cm 2 .

[0138] 2. Test results

[0139] The contents of geosmin and 2-methylisoborneol in fish meat were measured at 0.5, 1, 1.5, 2, 3, 5, and 7 min of S5 magnetic stirring, and the clearance rates of geosmin and 2-methylisoborneol were calculated according to "clearance rate (%) = (content before treatment - content after treatment) / content before treatment × 100%". The results are shown in Table 9.

[0140] Table 9 Odor substance removal rate

[0141]

[0142] It can be seen that the present invention combines the slightly acidic electrolyzed water treatment with ultraviolet irradiation to effectively eliminate geosmin and 2-methylisoborneol in fish meat.

[0143] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for removing odorous substances in water, characterized in that: Water containing odorous substances is prepared into slightly acidic electrolyzed water containing odorous substances, and then irradiated with ultraviolet rays with a wavelength of 222 to 275 nm; wherein the odorous substances include geosmin and / or 2-methylisoborneol, the concentration of the geosmin in the water is less than 5 μg / L, and the concentration of the 2-methylisoborneol in the water is less than 25 μg / L; the effective chlorine content of the slightly acidic electrolyzed water is 40 to 80 mg / L.

2. A method for removing odorous substances from aquatic organisms, characterized in that: Aquatic organisms containing odorous substances are immersed in slightly acidic electrolyzed water and then irradiated with ultraviolet rays with a wavelength of 222 to 275 nm; wherein the odorous substances include geosmin and / or 2-methylisoborneol, the content of the geosmin in the aquatic organisms is less than 0.40 μg / kg, and the content of the 2-methylisoborneol in the aquatic organisms is less than 4.19 μg / kg; the effective chlorine content of the slightly acidic electrolyzed water is 40 to 80 mg / L.

3. The method according to claim 2, wherein The usage ratio of the aquatic organisms to the slightly acidic electrolyzed water is 23-27 g:1.5 L.

4. The method according to claim 2, characterized in that The aquatic organisms are fish and / or shellfish.

5. The method according to claim 4, characterized in that: The fish is a freshwater fish.

6. The method according to claim 4, characterized in that: The shellfish are freshwater shellfish.

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