The aquaculture industry is rapidly growing as a key method for sustainable food production, but it faces significant challenges in disease management and water quality. As the industry strives to find effective and environmentally friendly solutions, one compound has emerged as the best option: peracetic acid (PAA).
Known for its powerful disinfectant properties, PAA is becoming increasingly popular in aquaculture. In this article, we will explore what peracetic acid is, its structure, formula, and multiple applications, while also addressing critical safety considerations such as exposure limits, decomposition, and material compatibility.
What is Peracetic Acid?
First synthesized in 1902, PAA has a long history as a reliable disinfectant in various industries (Liu et al., 2024). Now, its potential in aquaculture is gaining well-deserved attention. Unlike traditional methods such as formalin (carcinogenic) or chlorine (harmful by-products), PAA offers a safer and more sustainable alternative.
Chemically known as C2H4O3, peracetic acid (PAA) is a colorless liquid with a strong odor, similar to vinegar. Its chemical structure consists of a peroxide bond (-O-O-) between acetic acid and hydrogen peroxide. The formula for peracetic acid is commonly written as CH3CO3H. Due to its potent oxidative capabilities, PAA acts as a broad-spectrum antimicrobial agent effective against bacteria, viruses, and fungi.
PAA as a Disinfectant
The disinfectant properties of peracetic acid make it highly desirable in environments requiring strict microbial control, such as hospitals, food processing facilities, and especially aquaculture systems. Unlike some harsh chemical disinfectants, PAA breaks down into harmless by-products: water, oxygen, and acetic acid, which are environmentally benign.
According to Liu et al. (2024), since 2014, the use of PAA has been approved in the European Union (EU) for organic aquaculture; in the USA, the Environmental Protection Agency (EPA) approved the use of PAA product VigorOx® SP-15 for disinfecting equipment and culture surfaces when no fish are present and for reducing pathogens in recirculating aquaculture systems (RAS) and pond water when fish are present.
The Science Behind PAA
The structure of peracetic acid allows it to penetrate and disrupt microbial cell walls. Its strong oxidative nature leads to the inactivation of pathogens without leaving harmful residues. The decomposition process ensures minimal ecological impact, aligning well with sustainability principles.
Understanding PAA
- Chemical Name: Ethaneperoxoic acid (IUPAC), commonly known as PAA or peroxyacetic acid.
- Composition: Commercial PAA products are mixtures containing acetic acid, hydrogen peroxide, PAA itself, and water. Stabilizers ensure product stability.
- Safety: Unlike formaldehyde, PAA does not pose known carcinogenic risks. Its strong odor discourages prolonged exposure, unlike ozone.
Why is PAA a Good Alternative?
- Safer for People: Unlike formalin, a known carcinogen, PAA poses no cancer risk to humans (Liu et al., 2024). Additionally, Schoeb et al., (2017) indicates that the Environmental Protection Agency, the Occupational Safety and Health Administration, or the National Toxicology Program do not classify peracetic acid as a carcinogen, and it is neither genotoxic nor mutagenic.
- Fish-Friendly: PAA decomposes rapidly, minimizing harm to fish. Studies show strong recovery and physiological adaptation in fish exposed to appropriate concentrations of PAA (generally below 2 mg/L).
- Pathogen Elimination: PAA effectively attacks and eliminates pathogens throughout the culture water, unlike methods like UV radiation or ozone, which only disinfect flowing water.
- Environmentally Responsible: PAA breaks down quickly into harmless by-products, posing minimal environmental risk.
Applications of Peracetic Acid in Aquaculture
The main goal of aquaculture is to maintain healthy, disease-free environments for fish and other aquatic organisms. The uses of peracetic acid in this context are diverse, ranging from water disinfection to pathogen control on equipment and surfaces.
Pathogen Management
One of the most critical uses of peracetic acid in aquaculture is water quality regulation. Fish farms often suffer from high pathogen loads and waterborne diseases. By adding small, controlled amounts of peracetic acid, aquaculturists can significantly reduce microbial populations, ensuring a healthier living environment for aquatic organisms. Good et al., (2022) reported that peracetic acid (PAA) has shown great efficacy against key fish pathogens like Yersinia ruckeri, Weissella ceti, and Flavobacterium columnare.
Liu et al. (2024) report that the effective concentration of PAA against many fish pathogens is usually below 2 mg L−1, which is tolerable for most fish and poses a very low environmental risk due to rapid degradation. Gamal et al., (2024) found that regular application of 1 mg/L PAA and 20 mg/L hydrogen peroxide (H2O2) can temporarily reduce bacterial load in water and fish muscle, regulate stress responses, and improve fish health by reducing A. hydrophila-induced infections and enhancing survival.
Mota et al., (2022) identified that the no-observed-effect concentration of PAA is below 1.6 mg/L for Atlantic salmon parr and provided insights into its use as a water prophylactic strategy in aquaculture systems with low alkalinity.
Disinfection of Aquatic Species’ Eggs
Peracetic acid is commonly used to sterilize fish eggs, which are vulnerable to bacterial and fungal infections. Its efficacy at low concentrations makes it suitable for protecting sensitive early life stages without causing harm. Redman et al., (2022) determined that the no-observed-effect concentration (NOEC) values for eyed Atlantic salmon eggs treated with peracetic acid for 5 and 10 minutes were 500 and 300 mg/L PAA, respectively. For catfish, Straus (2015) reported safe treatment levels of 2.2 parts per million (ppm) for 2-day-old yolk sac larvae and 1.3 ppm for 7-day-old fry.
Zoral et al., (2024) reported that peracetic acid (PAA) has shown efficacy in inhibiting and eliminating the parasitic copepod Ikanecator primus, both in vitro and in vivo, which infects eggs of the squid Sepioteuthis lessoniana.
Parasite Removal
Peracetic acid (PAA) can also be used to treat parasites in aquaculture species. Farmer et al., (2024) found that a treatment regimen with 2 mg/L PAA can reduce 75% of parasites (Trichodina spp.) in naturally infested juvenile striped bass (Morone saxatilis).
Equipment Sterilization
Another important application is the sterilization of tanks, nets, and other equipment. Sterilization with peracetic acid ensures that all surfaces are pathogen-free, reducing the risk of cross-contamination and disease outbreaks.
Rutala y Weber (2015) reported that peracetic acid inactivates Gram-positive and Gram-negative bacteria, fungi, and yeasts in under 5 minutes at concentrations below 100 ppm. However, in the presence of organic matter, 200 to 500 ppm are required, and for viruses, the dose range is wide (12 to 2250 ppm).
Liu et al., (2018) emphasized that periodic disinfection of culture water in a recirculating aquaculture system (RAS) for mirror carp (Cyprinus carpio) with PAA could temporarily reduce suspended bacterial density, modulate fish stress response, and have long-term beneficial effects on fish health.
Why Choose Peracetic Acid Over Other Disinfectants?
Traditional disinfectants, such as chlorine-based compounds, pose risks both to the environment and to the organisms being farmed. The chemical compatibility of peracetic acid and its non-toxic decomposition make it a safer alternative. Additionally, peracetic acid does not contribute to the development of microbial resistance, which is an increasing concern in aquaculture and public health.
Liu et al. (2024) reported that commercial PAA products are mixtures containing acetic acid (CH3COOH), hydrogen peroxide (H2O2), PAA (CH3COOOH), and water (H2O), and emphasized that PAA is rarely obtained as a pure substance.
An important aspect of peracetic acid is that it does not affect the nitrification processes of biofilters used in RAS. Lepine et al., (2023) found that PAA, when applied at therapeutic concentrations (1.0-2.5 mg/L) to treat opportunistic pathogens, had an insignificant impact on the function of fluidized sand biofilters.
Chemical Compatibility and Safety Data
When implementing peracetic acid, understanding its chemical interactions and safety guidelines is essential. The safety data sheet (SDS) for peracetic acid provides crucial information on handling, storage, and emergency measures.
Chemical Compatibility
Peracetic acid is highly reactive and should be used carefully with specific materials. It can corrode copper, brass, bronze, plain steel, and galvanized iron, though these effects can be mitigated with additives and pH adjustments (Rutala and Weber, 2015). However, it is generally compatible with stainless steel and certain plastics, making it versatile for use in aquaculture infrastructure.
Exposure and Safety Measures
Exposure limits for peracetic acid are defined to prevent adverse health effects for aquaculture farm personnel. Prolonged or high-level exposure can cause irritation to the skin, eyes, and respiratory system. Personal protective equipment (PPE), including gloves and goggles, is essential when handling concentrated solutions.
Handling and Decomposition
Peracetic acid naturally decomposes into non-toxic byproducts. This decomposition is environmentally advantageous but requires careful handling to prevent premature breakdown during storage and application.
Health and Safety Considerations
Despite its benefits, peracetic acid poses certain health risks if mishandled. Direct skin contact can cause peracetic acid burns, characterized by redness, blistering, or severe irritation. Immediate washing and medical attention are required if contact occurs.
Additionally, inhaling vapors can cause respiratory distress, underscoring the importance of proper ventilation and respiratory protection in confined spaces.
Peracetic Acid on Skin
Accidental splashes should be rinsed off immediately with plenty of water. The corrosive nature of the substance makes even brief contact hazardous. Aquaculture workers must adhere to strict safety protocols to prevent injuries.
First Aid and Emergency Protocols
Refer to the peracetic acid safety data sheet for detailed emergency response measures. In case of skin exposure, thorough rinsing with water is critical, while inhalation incidents require moving the affected person to fresh air.
Environmental Impact and Sustainability
One of the main advantages of peracetic acid is its low environmental footprint. Unlike chlorine-based disinfectants, peracetic acid does not produce harmful byproducts or contribute to eutrophication. Its rapid breakdown into oxygen and acetic acid helps maintain water quality, benefiting the health of ecosystems surrounding aquaculture facilities.
Eco-Friendly Disinfection
The environmental friendliness of peracetic acid lies in its decomposition. As aquaculture facilities face increased scrutiny over environmental impacts, using a sustainable disinfectant like peracetic acid can enhance regulatory compliance and public perception.
Research findings by Pedersen y Lazado (2020) showed that PAA degrades rapidly in seawater, with salinity and temperature significantly affecting PAA decomposition, demonstrating a fourfold faster decomposition rate in seawater compared to freshwater.
Promoting Sustainable Practices
Using peracetic acid in aquaculture represents a shift toward more sustainable aquaculture practices. By reducing the environmental load of chemical treatments, peracetic acid helps ensure that aquaculture remains a viable food source for future generations.
Advantages and Disadvantages of Using Peracetic Acid
Table 01 summarizes the main advantages and disadvantages of using peracetic acid as a disinfectant.
Table 01. Advantages and Disadvantages of Using Peracetic Acid.
| Advantages of Peracetic Acid (PAA) | Disadvantages of Peracetic Acid (PAA) |
|---|---|
| Broad Antimicrobial Spectrum: Effective against bacteria, viruses, fungi, and spores, providing comprehensive disinfection. | Corrosivity: Can damage certain materials, such as non-corrosion-resistant metals, limiting its compatibility. |
| Leaves No Toxic Residues: Breaks down into water, oxygen, and acetic acid, making it environmentally friendly and safe. | Health Hazard: At high concentrations, it is irritating and corrosive to the skin, eyes, and respiratory system, requiring safety precautions. |
| Rapid Action: Acts quickly against microorganisms, making it ideal for disinfection processes where time is critical. | High Cost: Can be more expensive compared to other disinfectants, especially when large volumes are needed. |
| Versatility: Useful in various applications, such as disinfecting equipment, surfaces, and treating water in aquaculture. | Instability: Has a limited shelf life and can decompose rapidly, requiring proper and controlled storage. |
| Low Environmental Impact: Does not contribute to microbial resistance or leave harmful byproducts, supporting sustainable practices. | Requires Protective Equipment: Gloves, goggles, and proper ventilation are needed during handling to prevent exposure-related damage. |
| Effective at Low Temperatures: Maintains efficacy even in cold environments, making it useful under various conditions. | Potential Corrosion of Equipment: Continuous use over time can affect the integrity of metal equipment if non-resistant materials are not used. |
| Minimal Impact on Water Quality: Ideal for aquaculture, as its decomposition does not significantly alter the aquatic environment. | Irritating Odor: Has a strong, pungent smell that can be unpleasant and cause discomfort during application. |
Research and Future Perspectives
Recent studies continue to shed light on the potential of peracetic acid to improve aquaculture systems. Researchers are exploring optimized dosing strategies to maximize microbial control while minimizing costs and adverse effects on aquatic life.
Innovations in Peracetic Acid Delivery Systems
New methods are being developed to enhance the efficacy and precision of peracetic acid application. Automated dosing systems, for instance, can adjust PAA levels in real time based on water quality parameters, ensuring optimal disinfection with minimal waste.
Optimizing PAA application strategies, including considerations of dose, exposure time, and water quality, is essential to maximize its benefits and minimize potential negative impacts. For example, Zhang et al., (2024) reported that calculated PAA concentrations of 0.1 mg/L and 1 mg/L in the pump sump contributed to an increase in bacteria, while no detectable differences were found in the health and welfare of parr salmon.
Comparative Studies
Comparing peracetic acid with other disinfectants highlights its unique advantages and limitations. While PAA is highly effective, it requires careful management to avoid overuse and ensure safety. In this regard, Good et al. (2022) reported that the efficacy of PAA can be influenced by water quality parameters, such as hardness and nutrient levels. Thus, research should consider these aspects to determine appropriate doses based on the cultured species, cultivation system, chemical water parameters, and other factors.
Furthermore, the potential of pathogens to develop resistance to peracetic acid should be investigated to determine the long-term efficacy of the compound.
Conclusion
Peracetic acid stands out as a safe and sustainable disinfectant well-suited to the challenges of modern aquaculture. Its effective pathogen control, minimal environmental impact, and adaptability make it an invaluable tool for fish farmers. However, its benefits come with responsibilities: aquaculturists must stay informed about PAA properties, safety measures, and chemical compatibility. As research progresses, the future of aquaculture looks brighter, with peracetic acid leading the way in safe and eco-friendly disinfection practices.
Fully understanding the potential of PAA requires a commitment to continuous education and adherence to best practices. By embracing these innovations, the aquaculture industry can sustainably meet global food demands while safeguarding aquatic ecosystems.
References
Farmer, B. D., Straus, D. L., Deshotel, M. B., Fuller, S. A., Reading, B. J., & Meinelt, T. (2024). Antiparasitic effects of peracetic acid on Striped Bass infested with Trichodina spp. North American Journal of Aquaculture, 86(3), 287-294. https://doi.org/10.1002/naaq.10332
Gamal, A., A., D., Morsi, A. S., Malak, N. M., Ali, A. M., & Khalefa, H. S. (2024). In-vitro and in-vivo assessment of the bactericidal potential of peracetic acid and hydrogen peroxide disinfectants against A. Hydrophila infection in Nile tilapia and their effect on water quality indices and fish stress biomarkers. Scientific Reports, 14(1), 1-15. https://doi.org/10.1038/s41598-024-76036-2
Good, C., Redman, N., Murray, M., Straus, D. L., & Welch, T. J. (2022). Bactericidal activity of peracetic acid to selected fish pathogens in recirculation aquaculture system water. Aquaculture Research, 53(16), 5731-5736. https://doi.org/10.1111/are.16031
Lepine, C., Redman, N., Murray, M., Lazado, C. C., Johansen, H., Espmark, Å. M., Davidson, J., & Good, C. (2023). Assessing Peracetic Acid Application Methodology and Impacts on Fluidized Sand Biofilter Performance. Aquaculture Research, 2023(1), 6294325. https://doi.org/10.1155/2023/6294325
Liu, D., Straus, D. L., Pedersen, L., & Meinelt, T. (2018). Periodic bacterial control with peracetic acid in a recirculating aquaculture system and its long-term beneficial effect on fish health. Aquaculture, 485, 154-159. https://doi.org/10.1016/j.aquaculture.2017.11.050
Liu, D., Straus, D. L., Pedersen, F., Good, C., Lazado, C. C., & Meinelt, T. 2024. Towards sustainable water disinfection with peracetic acid in aquaculture: A review. Reviews in Aquaculture. https://doi.org/10.1111/raq.12915
Mota, V. C., Eggen, M. L., & Lazado, C. C. (2022). Acute dose-response exposure of a peracetic acid-based disinfectant to Atlantic salmon parr reared in recirculating aquaculture systems. Aquaculture, 554, 738142. https://doi.org/10.1016/j.aquaculture.2022.738142
Pedersen LF, Lazado CC (2020) Decay of peracetic acid in seawater and implications for its chemotherapeutic potential in aquaculture. Aquacult Environ Interact 12:153-165. https://doi.org/10.3354/aei00354
Schoeb, T. R., Rahija, R. J., Boyd, C., Orcutt, R. P., & Eaton, K. A. (2017). Principles of Establishing and Operating a Gnotobiotic Facility. Gnotobiotics, 21-63. https://doi.org/10.1016/B978-0-12-804561-9.00002-5
Redman, N., Straus, D. L., Annis, E. R., Murray, M., & Good, C. (2022). Assessing the toxicity of peracetic acid to early Atlantic salmon Salmo salar life-stages. Aquaculture Research, 53, 5097– 5104. https://doi.org/10.1111/are.15997
Rutala, W. A., & Weber, D. J. (2015). Disinfection, Sterilization, and Control of Hospital Waste. Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases (Eighth Edition), 3294-3309.e4. https://doi.org/10.1016/B978-1-4557-4801-3.00301-5
Zhang, J., Eggen, M., Peruzzi, S., Klokkerengen, R., Sundfør, E., Odei, D. K., Timmerhaus, G., Asimakopoulos, A. G., Flaten, T. P., Lazado, C. C., & Mota, V. C. (2024). Effects of prolonged application of peracetic acid-based disinfectant on recirculating aquaculture systems stocked with Atlantic salmon parr. Science of The Total Environment, 942, 173762. https://doi.org/10.1016/j.scitotenv.2024.173762
Zoral, M. A., Lajbner, Z., Zifcakova, L., & Miller, J. (2024). Peracetic acid treatment of squid eggs infected with parasitic copepod (Ikanecator primus gen. Et sp. Nov.). Scientific Reports, 14(1), 1-18. https://doi.org/10.1038/s41598-024-65290-z
