NO346187B1 - Method of neutralizing hydrogen peroxide in wastewater from aquaculture delousing treatment - Google Patents
Method of neutralizing hydrogen peroxide in wastewater from aquaculture delousing treatment Download PDFInfo
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- NO346187B1 NO346187B1 NO20200773A NO20200773A NO346187B1 NO 346187 B1 NO346187 B1 NO 346187B1 NO 20200773 A NO20200773 A NO 20200773A NO 20200773 A NO20200773 A NO 20200773A NO 346187 B1 NO346187 B1 NO 346187B1
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- delousing
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- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 title claims description 162
- 238000011282 treatment Methods 0.000 title claims description 37
- 238000000034 method Methods 0.000 title claims description 30
- 239000002351 wastewater Substances 0.000 title claims description 20
- 238000009360 aquaculture Methods 0.000 title claims description 16
- 244000144974 aquaculture Species 0.000 title claims description 16
- 230000003472 neutralizing effect Effects 0.000 title claims description 4
- 239000003795 chemical substances by application Substances 0.000 claims description 27
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 claims description 22
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical group [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 claims description 17
- 241000251468 Actinopterygii Species 0.000 claims description 16
- 235000019688 fish Nutrition 0.000 claims description 16
- 235000010265 sodium sulphite Nutrition 0.000 claims description 16
- 239000003513 alkali Substances 0.000 claims description 12
- 150000003839 salts Chemical class 0.000 claims description 11
- 235000010269 sulphur dioxide Nutrition 0.000 claims description 11
- 239000004291 sulphur dioxide Substances 0.000 claims description 11
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 8
- 239000005864 Sulphur Substances 0.000 claims description 8
- -1 sulphites Chemical compound 0.000 claims description 8
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical class OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 claims description 7
- 238000006386 neutralization reaction Methods 0.000 claims description 7
- 150000004764 thiosulfuric acid derivatives Chemical class 0.000 claims description 7
- HRZFUMHJMZEROT-UHFFFAOYSA-L sodium disulfite Chemical compound [Na+].[Na+].[O-]S(=O)S([O-])(=O)=O HRZFUMHJMZEROT-UHFFFAOYSA-L 0.000 claims description 6
- 235000010262 sodium metabisulphite Nutrition 0.000 claims description 6
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 claims description 5
- 238000003302 UV-light treatment Methods 0.000 claims description 5
- WBZKQQHYRPRKNJ-UHFFFAOYSA-L disulfite Chemical compound [O-]S(=O)S([O-])(=O)=O WBZKQQHYRPRKNJ-UHFFFAOYSA-L 0.000 claims description 5
- LSNNMFCWUKXFEE-UHFFFAOYSA-L sulfite Chemical compound [O-]S([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-L 0.000 claims description 5
- DHCDFWKWKRSZHF-UHFFFAOYSA-L thiosulfate(2-) Chemical compound [O-]S([S-])(=O)=O DHCDFWKWKRSZHF-UHFFFAOYSA-L 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 4
- 150000001447 alkali salts Chemical class 0.000 claims description 3
- AKHNMLFCWUSKQB-UHFFFAOYSA-L sodium thiosulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=S AKHNMLFCWUSKQB-UHFFFAOYSA-L 0.000 claims description 3
- 235000019345 sodium thiosulphate Nutrition 0.000 claims description 3
- 235000010263 potassium metabisulphite Nutrition 0.000 claims description 2
- 235000019252 potassium sulphite Nutrition 0.000 claims description 2
- 229910004879 Na2S2O5 Inorganic materials 0.000 claims 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 22
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 11
- 239000001301 oxygen Substances 0.000 description 11
- 229910052760 oxygen Inorganic materials 0.000 description 11
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 10
- 238000002474 experimental method Methods 0.000 description 10
- 239000000126 substance Substances 0.000 description 10
- 239000003638 chemical reducing agent Substances 0.000 description 7
- 239000000243 solution Substances 0.000 description 7
- 241000238557 Decapoda Species 0.000 description 5
- 230000009467 reduction Effects 0.000 description 5
- 239000013535 sea water Substances 0.000 description 5
- 238000009281 ultraviolet germicidal irradiation Methods 0.000 description 5
- 230000007613 environmental effect Effects 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 241000894007 species Species 0.000 description 4
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 description 3
- 241001674048 Phthiraptera Species 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000006303 photolysis reaction Methods 0.000 description 3
- 230000015843 photosynthesis, light reaction Effects 0.000 description 3
- 238000004065 wastewater treatment Methods 0.000 description 3
- 238000009303 advanced oxidation process reaction Methods 0.000 description 2
- 238000006392 deoxygenation reaction Methods 0.000 description 2
- 238000010790 dilution Methods 0.000 description 2
- 239000012895 dilution Substances 0.000 description 2
- 239000003651 drinking water Substances 0.000 description 2
- 235000020188 drinking water Nutrition 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000007800 oxidant agent Substances 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 239000010865 sewage Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- CVOFKRWYWCSDMA-UHFFFAOYSA-N 2-chloro-n-(2,6-diethylphenyl)-n-(methoxymethyl)acetamide;2,6-dinitro-n,n-dipropyl-4-(trifluoromethyl)aniline Chemical compound CCC1=CC=CC(CC)=C1N(COC)C(=O)CCl.CCCN(CCC)C1=C([N+]([O-])=O)C=C(C(F)(F)F)C=C1[N+]([O-])=O CVOFKRWYWCSDMA-UHFFFAOYSA-N 0.000 description 1
- 241000972773 Aulopiformes Species 0.000 description 1
- 241000894006 Bacteria Species 0.000 description 1
- 241001465754 Metazoa Species 0.000 description 1
- 239000007832 Na2SO4 Substances 0.000 description 1
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 1
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 1
- 241000700605 Viruses Species 0.000 description 1
- FUERBINMBLPVRD-UHFFFAOYSA-M [O-]S(O)=O.[Na+].S Chemical compound [O-]S(O)=O.[Na+].S FUERBINMBLPVRD-UHFFFAOYSA-M 0.000 description 1
- 238000002835 absorbance Methods 0.000 description 1
- 238000000862 absorption spectrum Methods 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000002738 chelating agent Substances 0.000 description 1
- 239000013043 chemical agent Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 201000010099 disease Diseases 0.000 description 1
- 208000037265 diseases, disorders, signs and symptoms Diseases 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- TUJKJAMUKRIRHC-UHFFFAOYSA-N hydroxyl Chemical compound [OH] TUJKJAMUKRIRHC-UHFFFAOYSA-N 0.000 description 1
- 150000002484 inorganic compounds Chemical class 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 238000009533 lab test Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 231100000492 no effect concentration Toxicity 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 244000052769 pathogen Species 0.000 description 1
- 230000037361 pathway Effects 0.000 description 1
- 230000002085 persistent effect Effects 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000006862 quantum yield reaction Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000012502 risk assessment Methods 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 239000004296 sodium metabisulphite Substances 0.000 description 1
- 229910052938 sodium sulfate Inorganic materials 0.000 description 1
- 235000011152 sodium sulphate Nutrition 0.000 description 1
- 230000007480 spreading Effects 0.000 description 1
- 238000004659 sterilization and disinfection Methods 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
-
- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01K—ANIMAL HUSBANDRY; AVICULTURE; APICULTURE; PISCICULTURE; FISHING; REARING OR BREEDING ANIMALS, NOT OTHERWISE PROVIDED FOR; NEW BREEDS OF ANIMALS
- A01K61/00—Culture of aquatic animals
- A01K61/10—Culture of aquatic animals of fish
-
- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01K—ANIMAL HUSBANDRY; AVICULTURE; APICULTURE; PISCICULTURE; FISHING; REARING OR BREEDING ANIMALS, NOT OTHERWISE PROVIDED FOR; NEW BREEDS OF ANIMALS
- A01K61/00—Culture of aquatic animals
- A01K61/10—Culture of aquatic animals of fish
- A01K61/13—Prevention or treatment of fish diseases
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/30—Treatment of water, waste water, or sewage by irradiation
- C02F1/32—Treatment of water, waste water, or sewage by irradiation with ultraviolet light
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/58—Treatment of water, waste water, or sewage by removing specified dissolved compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/70—Treatment of water, waste water, or sewage by reduction
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A40/00—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production
- Y02A40/80—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production in fisheries management
- Y02A40/81—Aquaculture, e.g. of fish
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Chemical & Material Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Environmental Sciences (AREA)
- Toxicology (AREA)
- Marine Sciences & Fisheries (AREA)
- Zoology (AREA)
- Animal Husbandry (AREA)
- Biodiversity & Conservation Biology (AREA)
- Health & Medical Sciences (AREA)
- Treatment Of Water By Oxidation Or Reduction (AREA)
Description
Field of the invention
The present invention relates to a method of neutralizing hydrogen peroxide (H2O2) in aquaculture delousing wastewater.
Background of the invention
Hydrogen peroxide, H2O2, is widely used in aquaculture as a delousing agent, i.e., for controlling sea lice and amoebic gill disease in fish. It causes release of large quantities of hydrogen peroxide into the environment after a delousing event, which is unfortunate to vulnerable species such as shrimps and zooplankton.
Commercially made hydrogen peroxide solutions (e.g. Paramove® by Solvay and Nemona by AkzoNobel & Performance Chemicals AB, and Aperix Vet by Evonik Resource Efficiency GmbH) are not pure H2O2, but mixtures stabilized by other compounds. They are sold in a 49.5% concentration for veterinary treatments and distributed in large amounts. The pharmaceutical dose recommended by Norwegian Medicines Control Authority guideline is 1.3-1.7 g/L for 20 minutes. The annual usage in Norway varied between 4000 – 43000 tonnes treatment solution in 2015-2019 per year. Treatment of one single pen with a well boat may need 2-4 treatments which has been estimated to be around 1900-3800 m<3 >of medical hydrogen peroxide if a well boat is used. For treatments in the pen itself, the estimate is around 15000 m<3 >for treatment of one pen (Refseth et al., 2019).
At first, it was believed that commercial H2O2 would degrade into water and oxygen very quickly. However, experiments and modelling have proven the opposite and also showed that several non-target species are sensitive to very low concentrations (Bechmann et al., 2019; Refseth et al., 2019).
The predicted no effect concentration (PNEC) level in the marine environment is 11000 times dilution of the treatment solution, i.e. a reduction from 1500 mg/L down to 0.14 mg/L to reach a level that can be considered safe for the marine ecosystem (Refseth et al., 2019). Laboratory experiments have shown high mortality on shrimps at low concentrations, i.e.500-1000 times dilution of the treatment concentration (Bechmann et al., 2019; Frantzen et al., 2019; Refseth et al., 2019).
The delousing event takes place either straight into the fish pen that for the purpose has been sheltered by a tarpaulin during the treatment, or by moving the fish into a well boat where the fish is bathed with H2O2. Once the treatment in the pen is finished, the tarpaulin is removed and the H2O2 flushed out from the pen. When using a well boat, the water is flushed out from the boat at the end of the treatment time, while the fish is kept onboard until they can be transferred back to the pen. Today, delousing wastewater are released into the ocean without any treatment that removes the chemicals used.
Treatment with bath chemicals such as hydrogen peroxide has to be performed more than 500 meters from known shrimp areas and cod spawning areas. If an aquaculture plant is situated within such area, any bath treatment should be done by well boat and discharge of the water has to be conducted outside shrimp and spawning areas. These areas are determined by the Directorate of Fisheries (The Aquaculture Act, Regulation relative to the operation of aquaculture facilities (Section 15)). Nevertheless, in some of the aquaculture areas, sites for discharge of bath delousing chemicals might be small and used by many companies within a short time range, which may add an unnecessary risk to the environment. Concentrations between 1-10 mg/L of hydrogen peroxide after a delousing event can occur kilometres away from the deloused pen, and put vulnerable species such as shrimps and zooplankton in risk. A well boat reduces the horizontal spreading but hydrogen peroxide can still sink quickly in the water mass after a well boat discharge and be present in concentrations well above 0.14 mg/L, which is the PNEC level for the marine environment. Which hydrogen peroxide concentrations that are actually present after a discharge will of course depend on amount released and oceanographic parameters such as depth and currents (Refseth et al., 2019).
Considering the high concentrations of the chemical used and large water volumes involved, the removal of residual H2O2 after treatment is important for a sustainable development of aquaculture industry. As of today, there are no known solutions in place for treatment of delousing wastewater.
However, H2O2 is less persistent in the environment and resistance problems among sea lice are lower compared to other delousing chemicals. Therefore, H2O2 is, despite its drawbacks, considered as one of the best treatments where fish health, sea lice resistance and environmental impact can be balanced.
Hence, a tool where H2O2 can continue to be used as a delousing agent, but at the same time protecting the surrounding environment is highly sought after from government, aquaculture, fishing industry and the general public.
Removal of H2O2 at such high concentrations as present in delousing wastewater is challenging.
H2O2 being an oxidant, the use of a reducing agent could be considered as a potential solution for its removal. Ideally, the reducing agent should react selectively and quickly with H2O2 in a way that does not have a large effect on seawater pH or produce toxic biproducts. Sulphur dioxide and easily dissolvable salts of reduced oxyanions of sulphur (including sulphites, metabisulphites and thiosulphates) will reduce H2O2 effectively.
For example, sodium sulphite (Na2SO3) can be used to remove H2O2, but has to be used in very high concentrations (1:1 molar ratio) to neutralize all the H2O2. However, high concentrations of Na2SO3 or another reducing agent as mentioned above deplete the seawater from oxygen, which of course is undesirable.
UV light is in use against unwanted organisms, e.g. in cleaning of ballast water, sewage, etc. UV irradiation is a well-established technology, which is widely used in drinking water and wastewater treatment. While UV alone is widely used to inactivate pathogens including bacteria and viruses in drinking water disinfection, it has wide-ranging applications for the degradation of organics in different water matrices in the presence of oxidants such as H2O2. H2O2 is added in one of the best commercially applicable UV-based advanced oxidation process (AOP) as a part of the wastewater treatment.
UV irradiation photolyzes H2O2 leading to the generation of hydroxyl radicals (·OH) which can non-selectively oxidize a range of organic and inorganic compounds.
Considerably lower levels of H2O2 compared to delousing treatments may be added to e.g. a sewage wastewater matrix where UV light can photolyze it into ·OH radicals.
Photolysis of high concentrations of H2O2 would require longer treatment time as well as high doses of UV radiation, which would incur significant electrical energy demand for operating the UV system making the process prohibitively expensive and unsuitable for treatment of delousing wastewater.
JP 2015130844 A relates to H2O2 treatment for farmed fish in a closed system with seawater where the water to be treated contains 5-650 mg /L H2O2. A method for decomposing H2O2 in such seawater is described by adding a reducing agent at a concentration of 0.1-10 mmol /L to the equimolar equivalent of H2O2 where the reducing agent generates sulphite ions. The use of UV light is not mentioned.
KR 101687389 B describes the use of e.g. Na2S2O3 or Na2SO3 to neutralize H2O2 in land-based fish farms. The concentration of H2O2 in the water is low, typically 10 ppm, and it is recommended to add approx.10 times higher concentration of treatment agent. Nothing is mentioned about treatment with UV light.
CN 103651194 B and WO 2018092831 A1 relate to wastewater treatment wherein H2O2 is added in small amounts with subsequent treatment with UV light as described above as AOP. Treatment of wastewater from fish farms where high concentrations of H2O2 have been added in connection with delousing, is not mentioned.
Now, it has surprisingly been found that by adding an agent selected from sulphur dioxide and easily dissolvable salts of reduced oxyanions of sulphur, including sulphites, metabisulphites and thiosulphates, in low concentration to the delousing wastewater, the time and dose of UV light needed to photolyze and thereby neutralize/remove the high concentrations of H2O2 therein are significantly reduced.
On this basis, the inventors have managed to develop a method for removing H2O2 in delousing wastewater by use of minimal amounts of chemical and UV demand.
Summary of the invention
It is a main object of the present invention to provide a sustainable solution for delousing of salmon fish farms. That is, to provide an environmental friendly method where hydrogen peroxide in delousing wastewater is removed or greatly reduced, without being too expensive and chemical intensive, and without deoxygenation of the surrounding water.
Another object of the present invention is to provide a solution to the problem with release of large quantities of hydrogen peroxide into the environment after a delousing event in the aquaculture industry.
These and other objects are obtained by the method as defined in the accompanying claims.
Detailed description of the invention
The present invention provides a method of neutralizing hydrogen peroxide (H2O2) in aquaculture delousing wastewater, comprising addition of at least one agent selected from the group consisting of sulphur dioxide and easily dissolvable salts of reduced oxyanions of sulphur, including sulphites, metabisulphites and thiosulphates to delousing wastewater and subsequent UV light treatment, wherein the amount of said agent is in the range from 0.1 mol to 0.5 mol per mol H2O2.
The said agents enhance the neutralization reaction of H2O2 and are typically reducing agents.
In a preferred embodiment of the invention, the agent is selected from sulphur dioxide (SO2); alkali salts of sulphite (alkali metal2SO3), bisulphite (alkali metal2HSO3), metabisulphite (alkali metal2S2O5) and thiosulphate (alkali metal2S2O3); and alkaline earth salts of sulphite (alkaline earth metalSO3), bisulphite (alkaline earth metalHSO3), metabisulphite (alkaline earth metalS2O5) and thiosulphate (alkaline earth metalS2O3); or any mixtures thereof. These agents may be distributed directly as powder, dissolved in a base such as e.g. potassium hydroxide (KOH) and/or bound by a chelator such as e.g. ethylenediaminetetraacetic acid (EDTA). Use of distribution pathways where KOH and/or EDTA is added together with the agent may facilitate avoidance of sudden drops of pH and/or oxygen.
In a more preferred embodiment of the invention, the agent is selected from alkali salts of sulphite (alkali metal2SO3), bisulphite (alkali metal2HSO3), metabisulphite (alkali metal2S2O5) and thiosulphate (alkali metal2S2O3).
In an even more preferred embodiment of the invention, the agent is selected from Na2SO3, K2SO3, Na2HSO3, K2HSO3, Na2S2O5, K2S2O5, Na2S2O3, and K2S2O3.
Most preferably, the agent is Na2SO3 or Na2S2O5.
The net reaction between H2O2 and e.g. Na2SO3 is as follows:
Na2SO3 (aq) H2O2 (aq) → H2O(l) Na2SO4 (aq)
UV irradiation of H2O2 produces hydroxyl radical:
H2O2+ hv → 2HO•
The hydroxyl radicals are very reactive, and react further to create water and oxygen as endpoint:
2H2O2+ hv → 4HO• => 2 H2O O2
By the present method, the UV irradiation of H2O2 is speeded up by pretreatment with a small amount of reducing agent, resulting in effective decomposition of H2O2, by a combination of the three reactions above.
That is, H2O2 is neutralized into H2O and O2 according to this overall neutralisation reaction:
2 H2O2 → 2 H2O O2
In one embodiment of the invention, the amount of agent added is preferably from 0.1 to 0.35 mol per mol H2O2, and most preferably from 0.1 to 0.25 mol per mol H2O2.
In one embodiment of the invention, the UV treatment lasts/takes place in a range of 30 to 720 minutes, preferably from 60 to 480 minutes, and most preferably from 60 to 360 minutes.
Traditionally, UV light techniques of mostly 254 nm (using mercury lamps) have been used to generate oxidative species. However, UV-LEDs provide much more flexibility and other wavelengths can be explored considering the absorption spectra of H2O2. UV-LEDs provide an opportunity to use other wavelengths including those in the low UVC range. Thus, UV light of wavelengths from low UVC (100-280 nm) to UVB (280-315 nm) range is included in the present invention since the rate of photolysis of hydrogen peroxide ([H2O2]o > 20 mM) follows zero order kinetics with regard to the quantum yield and intensity. Furthermore, the absorbance of UV by H2O2 differs depending on the water quality and also for that reason wavelengths other than 254 nm are possible within this invention. UV wavelength of 254 nm is preferred considering its practical applicability but other wavelengths and their combinations using UV-LEDs could also be used for enhanced photolysis performance.
In one embodiment of the invention, UV light of wavelengths from low UVC (100-280 nm) to UVB (280-315 nm) is used. Preferably, UV light of wavelengths from 185 nm to 315 nm, and more preferably from 200 nm to 300 nm, is used. Examples of preferred wavelengths are 210 nm, 254 nm, 265nm and 280nm.
In one embodiment of the invention, the method is carried out in well boat. In this embodiment, an amount of H2O2 is added and adjusted to the recommended delousing treatment dose. Oxygen is continuously added to the water wherein the fish is contained during H2O2 treatment since the water volume is very small compared to the amount of fish and their biological oxygen demand. Once the delousing treatment is finished (H2O2 during maximum 20 minutes), the water with H2O2 is removed from the fish and treated with at least one agent as defined above and UV light before the wastewater is flushed out from the well boat.
In another embodiment of the invention, the method takes place straight into the sea. In this embodiment, the fish pen is sheltered by a tarpaulin or optionally the fish is moved to a mobile treatment pen during the delousing treatment. Thereafter, the wastewater is released from the pen and filled into a moveable frame structure outside the pen where at least one agent as defined above is added followed by UV light treatment to neutralize/remove H2O2 before the wastewater is flushed out in the open sea.
The method of the present invention can be applied in environmental relevant conditions, i.e. sea temperatures <18<o>C, pH ranging 6.5-8.5 and saline water, i.e.9-35 PSU.
The present invention also provides use of at least one agent selected from the group consisting of sulphur dioxide and easily dissolvable salts of reduced oxyanions of sulphur, including sulphites, metabisulphites and thiosulphates wherein the amount of said agent is in the range from 0.1 mol to 0.5 mol per mol H2O2, in combination with UV light treatment in neutralization of hydrogen peroxide (H2O2) in aquaculture delousing wastewater.
The invention is explained in more detail in the examples below. The examples are only meant to be illustrative and shall not be considered as limiting.
Example 1
Experiments carried out in lab-scale have shown that using Na2SO3 is an effective way of reducing the UV doses required for the neutralization of H2O2. The experiments were performed at room temperature and H2O2 measured straight after adding the Na2SO3. As shown in Fig.1, the higher the molar concentration of Na2SO3, the higher the concentration reduction of H2O2. However, since the purpose was to use minimum concentration of Na2SO3, further tests using UV were carried out using 3 different molar ratios for the purpose of comparison (Fig.2).
This experiment was carried out with a UV lamp of 15 W (output power: 3.5 W at 254 nm) in a UV collimated beam system. A stir bar of 25.4 x 7.6 mm was used to ensure sample mixing (330 rpm) during irradiation. The experiment was set up with continuous flow.
Fig.2 shows the kinetics of decay in the concentration of H2O2 when using different H2O2:Na2SO3 molar ratios followed by UV treatment (254 nm) up to 360 min. Due to initial higher removal of H2O2 at the molar ratio of 1:0.5, the greatest reduction was achieved after 300 min when compared with lower molar ratios (1:0.25 and 1:0.16). However, there was very little difference between the lower molar ratios tested throughout the UV treatment process with final reduction values being fairly similar. Although a higher UV irradiation time was needed when using lower concentration of Na2SO3, a trade-off between the higher use of Na2SO3 and resulting deoxygenation vs. UV treatment time had to be considered. The difference in the level of H2O2 removal was comparable for both 1:0.25 and 1:0.16 molar ratios.
Example 2
Neutralisation of H2O2 with sodium metabisulphite (Na2S2O5) in a 1:0.5 molar ratio, 45 L water tank was performed (Fig.3). Two measurements (bottom; 2.13 g/L) and surface (1.44 g/L) were done before the experiment began. This difference was evened out due to constant stirring of the water and controlled measurements from both surface and bottom throughout the experiment. The pH sank quickly throughout the experiment. Oxygen concentrations were measured in a later experiment, where oxygen was quickly depleted. Another experiment where Na2S2O5 was dissolved in seawater and potassium hydroxide (KOH, 10% w/w) was conducted. The pH was kept acceptable (decrease from pH=7.6 at t0 to pH=6.7 at t30 (min) but the oxygen was depleted from 8.6 mg/L to 0.73 mg/L within the same time period. H2O2 was reduced from initial concentration (1.5 g/L) to 0.8 g/L within 5 min.
The present invention is based on a combination of two techniques (chemical agent and UV light) to minimise the chemical usage and at the same time speed up the process and limit the power usage of UV light. An agent selected from the group consisting of sulphur dioxide and easily dissolvable salts of reduced oxyanions of sulphur, including sulphites, metabisulphites and thiosulphates used alone reduces oxygen in the sea. UV light alone would be inefficient in large commercial scale applications. The inventors have found that in combination, these two techniques emphasize and aid each other in a way that was not expect on forehand, particularly for the high H2O2 concentrations used in aquaculture delousing treatments.
The method of the present invention, comprising the combination of an aforementioned agent and UV in a synergistic way speeds up the neutralization process of H2O2 more than if only UV light is used. Hence, the chemical usage is kept as low as possible, providing environmental and economic benefits. The procedure developed here maximizes the animal welfare, since avoids an unnecessary reduction of dissolved oxygen provoked by sulphur dioxide and/or easily dissolvable salts of reduced oxyanions such as sulphur sodium sulphite.
References
Bechmann, R.K., Arnberg, M., Gomiero, A., Westerlund, S., Lyng, E., Berry, M., Agustsson, T., Jager, T., Burridge, L.E., 2019. Gill damage and delayed mortality of Northern shrimp (Pandalus borealis) after short time exposure to anti-parasitic veterinary medicine containing hydrogen peroxide. Ecotoxicology and Environmental Safety 180, 473–482. https://doi.org/10.1016/j.ecoenv.2019.05.045
Frantzen, M., Evenset, A., Bytingsvik, J., Reinardy, H., Tassara, L., Geraudie, P., Watts, E.J., Andrade, H., Torske, L., Refseth, G.H., 2019. Effects of hydrogen peroxide, azamethiphos and deltamethrin on egg-carrying shrimp (Pandalus borealis) (FHF-report No. Akvaplan-niva report 8926-1). Akvaplan-niva, Tromsø.
Refseth, G.H., Nøst, O.A., Evenset, A., Tassara, L., Espenes, H., Drivdal, M., Augustine, S., Samuelsen, O., Agnalt, A.-L., 2019. Risk assessment and risk reducing measures for discharges of hydrogen peroxide (H2O2). Ecotoxicological tests, modelling and SSD curve. Oceanographic modelling. (No. Akvaplan-niva report 8948-1).
Akvaplan-niva.
Claims (11)
1.
A method of neutralizing hydrogen peroxide (H2O2) in aquaculture delousing wastewater, comprising addition of at least one agent selected from the group consisting of sulphur dioxide and easily dissolvable salts of reduced oxyanions of sulphur, including sulphites, metabisulphites and thiosulphates to delousing wastewater and subsequent UV light treatment, wherein the amount of said agent is in the range from 0.1 mol to 0.5 mol per mol H2O2.
2.
The method according to claim 1, wherein the agent is sulphur dioxide; an easily dissolvable salt of reduced oxyanions of sulphur selected from alkali salts of sulphite (alkali metal2SO3), bisulphite (alkali metal2HSO3), metabisulphite (alkali metal2S2O5) and thiosulphate (alkali metal2S2O3) and alkaline earth salts of sulphite (alkaline earth metalSO3), bisulphite (alkaline earth metalHSO3), metabisulphite (alkaline earth metalS2O5) and thiosulphate (alkaline earth metalS2O3); or a mixture thereof.
3.
The method according to claim 1 or 2, wherein the agent is Na2SO3, K2SO3, Na2HSO3, K2HSO3, Na2S2O5, K2S2O5, Na2S2O3, K2S2O3, or a mixture thereof.
4.
The method according to any one of claims 1 to 3, wherein the amount of agent is in the range from 0.1 to 0.35 mol per mol H2O2, and preferably from 0.1 to 0.25 mol per mol H2O2.
5.
The method according to any one of claims 1 to 4, wherein the UV treatment lasts/takes place in a range of 30 to 720 minutes, preferably from 60 to 480 minutes, and most preferably from 60 to 360 minutes.
6.
The method according to any one of claims 1 to 5, wherein UV light of wavelengths from low UVC (100-280 nm) to UVB (280-315 nm) is used.
7.The method according to any one of claims 1 to 6, wherein UV light of wavelengths from 185 nm to 315 nm, and preferably from 200 nm to 300 nm, is used.
The method according to any one of claims 1 to 7, wherein UV light of 210 nm, 254 nm, 265 nm or 280 nm wavelength is used.
9.
The method according to any one of claims 1 to 8, wherein it is carried out in wellboat or other infrastructure used for delousing fishes in aquaculture.
10.
The method according to any one of claims 1 to 8, wherein it takes place straight into the sea in connection with the fish pen.
11.
Use of an agent selected from the group consisting of sulphur dioxide and easily dissolvable salts of reduced oxyanions of sulphur, including sulphites, metabisulphites and thiosulphates wherein the amount of said agent is in the range from 0.1 mol to 0.5 mol per mol H2O2, in combination with UV light treatment in neutralization of hydrogen peroxide (H2O2) in aquaculture delousing wastewater.
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| PCT/NO2021/050154 WO2022005297A1 (en) | 2020-07-01 | 2021-06-25 | Method of lowering concentrations of strong oxidants in wastewater from aquaculture |
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| US20130327718A1 (en) * | 2011-01-26 | 2013-12-12 | Katayama Chemical, Inc. | Device and method for reducing the hydrogen peroxide and peracetic acid content in a water flow |
| JP2015130844A (en) * | 2014-01-15 | 2015-07-23 | 株式会社片山化学工業研究所 | Decomposition treatment method for hydrogen peroxide |
| CN103651194B (en) * | 2013-11-18 | 2016-03-02 | 苏州依科曼生物农业科技有限公司 | A kind of method improving aquaculture products quality |
| KR101687389B1 (en) * | 2016-06-16 | 2016-12-21 | 대한민국 | Apparatus for removal of red tide flagellate using hydrogen peroxide on shore aquaculture place |
| WO2018092831A1 (en) * | 2016-11-18 | 2018-05-24 | オルガノ株式会社 | Water treatment method and device |
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| US9254400B2 (en) * | 2010-03-02 | 2016-02-09 | Ecolab Usa Inc. | Method for processing peroxygen solutions |
| FR2994174B1 (en) * | 2012-08-01 | 2015-08-07 | Degremont | METHOD AND INSTALLATION FOR PROCESSING SHIP BALLAST WATER |
| CN108996653A (en) * | 2018-07-03 | 2018-12-14 | 江苏开放大学（江苏城市职业学院） | It is a kind of to utilize UV/Na2SO3The method that collaboration system carries out reduction dechlorination to 4- chlorophenol |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US20130327718A1 (en) * | 2011-01-26 | 2013-12-12 | Katayama Chemical, Inc. | Device and method for reducing the hydrogen peroxide and peracetic acid content in a water flow |
| CN103651194B (en) * | 2013-11-18 | 2016-03-02 | 苏州依科曼生物农业科技有限公司 | A kind of method improving aquaculture products quality |
| JP2015130844A (en) * | 2014-01-15 | 2015-07-23 | 株式会社片山化学工業研究所 | Decomposition treatment method for hydrogen peroxide |
| KR101687389B1 (en) * | 2016-06-16 | 2016-12-21 | 대한민국 | Apparatus for removal of red tide flagellate using hydrogen peroxide on shore aquaculture place |
| WO2018092831A1 (en) * | 2016-11-18 | 2018-05-24 | オルガノ株式会社 | Water treatment method and device |
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