Helge Liltved

Professor

Department of Engineering Sciences

Email: helge.liltved@uia.no
Phone: +47 37233023
Mobile phone: +4791576029

Office D3104 (Jon Lilletuns vei 9, 4879 Grimstad, Norway)

Research groups

Sustainable built environment

Areas of responsibility

Key qualifications

Water supply and sanitation technology, including water and wastewater characterisation and treatment, specializing in UV- and ozonation for microbial control and oxidation. Long experience and skills in laboratory and pilot scale development and verification of water treatment technologies. Managed several national and international projects. Has published more than 30 papers in scientific journals, and is the author of chapters in several textbooks.

Book chapters

Raa J. and Liltved H. 1991. An assesment of the compatibility between fish farming and the Norwegian coastal environment. In: Aquaculture and the environment, ed. by N. De Pauw and J. Joyce, pp. 51-59, European Aquaculture Society Special Publication No. 16, Gent, Belgium.
Liltved H. and Landfald B. 1993. UV inactivation and photoreactivation of bacterial fish pathogens. In: Fish Farming Technology, ed. by H. Reinertsen, L.A. Dahle, L. Jørgensen & K. Tvinnereim, pp. 77-83, A.A. Balkema, Rotterdam.
Liltved H. 2001. Ozonation and UV-disinfection in intensive fin-fish systems. In: Intensive Fin-Fish Systems and Technologies, p. 57-73. World Aquaculture Society, Lake Buena Vista, Florida.
Bjerknes, V., Liltved, H., Rosseland, B.O, Rosten, T.,Skjelkvåle, B.L.,Stefansson, S. Åtland, Å. 2007. Vannkvalitet og smoltproduksjon. Juul forlag, Bergen.
Bomo, A.M., Tryland, I., Tjomsland, T., Vogelsang, C. og Liltved, H. 2008.Challenges’ facing the water works due to climate change. Management practices in the Nordic countries addressing these challenges,p 17-26. In Proceedings of the6th Nordic Drinking Water Conference, Oslo.
Tryland, I., Fykse, E-M., Bomo, A.M., Jantsch, T.G., Nielsen, A.D. and Liltved, H. 2010. Monitoring of bacteria in ballast water. In: Emerging Ballast Water Management Systems, ed. by N. Bellefointaine, F. Haag, O. Linden, J. Matheickal, p. 219-230. World Maritime University, Malmø, Sweden.
Tryland, I., Bomo, A.B. and Liltved, H. 2011. Impacts of climate changes on surface water quality in relation to drinking water treatment in Norway. In: “Municipalities addressing climate change: A case study of Norway”. pp 49-69. Editor: I. Kelman. Nova publishers. ISBN: 978-1-61324-810-2.
Liltved H. and Summerfelt S. T. 2018. Ozonation and UV-irradiation. In Recirculating Aquaculture (eds. Timmons, M.B., Guerdat T. and Vinci B.J.), p.387-426, NRAC Publication No.401-2018, Cayuga Aqua Ventures, NY, USA.

Ghorbani Mooselu, Mehrdad; Liltved, Helge & Akhtar, Naureen (2023). Characterization and treatment of tunneling wastewater using natural and chemical coagulants. Water Science and Technology. ISSN 0273-1223. 88(10), p. 2547–2565. doi: 10.2166/wst.2023.363. Full text in Research Archive Show summary
Particles are a concern regarding tunneling wastewater, but gaps remain in understanding metal(loid)s content and coagulation efficiency. In this research, characterization of the wastewaters before and after treatment was investigated by chemical analysis and various techniques for particle characterization. Then, laboratory work was conducted to evaluate effectiveness of sedimentation and use of coagulants to remove particles and particle-associated contaminants. Both natural (chitosan) and chemical coagulants (ferric chloride sulfates and polyaluminium chloride solution), were applied in a jar test system. The results indicated that short-time sedimentation alone substantially reduced the particle content and particle-associated pollutants, including metal(loid)s, while subsequent chemical coagulation was required to comply with discharge limits. The optimum dosages of chitosan, PIX, and PAX for water 1 after pre-treatment (15 min sedimentation) were 1 mg/L, 3 mg Fe/L, and 3 mg Al/L, respectively, while a dosage of 2 mg Al/L gave the best results in water 3. Furthermore, chemical coagulation significantly decreased the volume density of particles in the diameter range of 1–100 μm, showing that coagulants are efficient for the removal of smaller particles not removed by conventional sedimentation.
Ghorbani Mooselu, Mehrdad; Liltved, Helge; Hindar, Atle & Amiri, Hamid (2022). Current European approaches in highway runoff management: A review. Environmental Challenges. ISSN 2667-0100. 7. doi: 10.1016/j.envc.2022.100464. Full text in Research Archive
Ezziddine, Maha & Liltved, Helge (2021). Quality and yield of lettuce in an open-air rooftop hydroponic system. Agronomy. ISSN 2073-4395. 11(12), p. 1–10. doi: 10.3390/agronomy11122586. Full text in Research Archive
Azadi, Sama; Amiri, Hamid; Ghorbani Mooselu, Mehrdad; Liltved, Helge; Castro-Muñoz, Roberto & Sun, Xun [Show all 7 contributors for this article] (2021). Network design for surface water quality monitoring in a road construction project using Gamma Test theory. Water Resources and Industry. ISSN 2212-3717. 26. doi: 10.1016/j.wri.2021.100162. Full text in Research Archive
Ghorbani Mooselu, Mehrdad; Amiri, Hamid; Azadi, Sama & Liltved, Helge (2021). Spatiotemporal assessment of surface water vulnerability to road construction. Environment, Development and Sustainability. ISSN 1387-585X. doi: 10.1007/s10668-021-01763-9.
Ezziddine, Maha; Liltved, Helge & Seljåsen, Randi (2021). Hydroponic lettuce cultivation using organic nutrient solution from aerobic digested aquacultural sludge. Agronomy. ISSN 2073-4395. 11(8), p. 1–13. doi: 10.3390/agronomy11081484. Full text in Research Archive Show summary
The aim of this study was to demonstrate how aquacultural sludge can be processed and utilized as an organic nutrient solution (ONS) for hydroponic lettuce production. By using a previous developed method, approximately 80% of the processed sludge was reclaimed as a clear, nutrient-rich solution. The performance of the recovered nutrient solution on lettuce growth was assessed in a nutrient film hydroponic system. The results were compared to the results obtained using a conventional nutrient solution (CNS). Yield, fresh weight, water consumption, and nutrient and heavy metal content in leaf tissue were measured. In spite of a 16% lower average fresh weight obtained in ONS compared to the weight obtained in CNS, there was no statistical difference of the yield of lettuce among the two nutrient solutions. After the cultivation period, 90% of the lettuce heads grown in ONS exceeded the marked weight of 150 g. Foliar analysis revealed a similar or higher content of all nutrients, except of magnesium and molybdenum in the leaves of lettuce grown in the ONS compared to lettuce grown in the CNS. This study shows that nutrients recovered from aquacultural sludge can be utilized as fertilizer, thereby reducing the dependency on mineral fertilizer in hydroponic and aquaponic systems.
Ezziddine, Maha & Liltved, Helge (2021). Nutrients recovery from aquaculture waste for use as fertilizer in soilless growth systems. Acta Horticulturae. ISSN 0567-7572. p. 399–406. doi: 10.17660/ActaHortic.2021.1305.52.
Ezziddine, Maha; Liltved, Helge & Seljåsen, Randi (2021). Nutrient solution dynamics and yield of lettuce (Lactuca sativa) in an EC-controlled recirculating hydroponic system. Acta Horticulturae. ISSN 0567-7572. 1305, p. 407–414. doi: 10.17660/ActaHortic.2021.1305.53. Show summary
In this study, the nutrient dynamic and growth performance of lettuce in a closed recirculating hydroponic system were investigated. Lettuce was grown in three parallel nutrient film technique (NFT) units, illuminated with LED-light. A balanced standard nutrient solution (NS) was used, and the electrical conductivity (EC) and pH were adjusted regularly to constant average values of 1.16 mS cm‑1 and 6.2 with standard deviations of ±0.12 and ±0.5, respectively. The volume of NS in each unit was kept at 20 L by adding refill solution to replace nutrient uptake and transpiration. Lettuce growth during the first six weeks in the NFT-system was normal and stable. After six weeks, a decrease in concentrations of N, P, and K was observed, with a corresponding decline in yield of lettuce. After ten weeks, lettuce weight at harvest was reduced by 56% in average compared to the control, and the concentrations of N, P and K in the NS were reduced by 54.5, 90.5 and 96.6%, respectively. Contrarily, more slowly absorbed nutrients like Ca, S, Zn, Cu, and B experienced increases by factors of 2.2, 2.9, 6.6, 4.9 and 2.5, respectively. The depletion and accumulation of nutrients in the NS were reflected in corresponding deficiency and excess levels of nutrients in leaf tissue compared to norm-values of healthy lettuce. The study showed that after six weeks, corresponding to a yield of 1 kg lettuce per 10 L tank volume of NS, the reduced growth implied that the recirculated NS should have been discharged and replaced, or a “tailor-made” refill solution should have been used to avoid depletion of some nutrients. Based on the foliar analysis and calculations of actual nutrient absorption rates, the composition of such a refill NS was suggested.
Ghorbani Mooselu, Mehrdad; Liltved, Helge; Nikoo, Mohammad Reza; Hindar, Atle & Meland, Sondre (2020). Assessing optimal water quality monitoring network in road construction using integrated information-theoretic techniques. Journal of Hydrology. ISSN 0022-1694. 589. doi: 10.1016/j.jhydrol.2020.125366. Full text in Research Archive Show summary
The environmental impacts of road construction on the aquatic environment necessitate the monitoring of receiving water quality. The main contribution of the paper is developing a feasible methodology for spatial optimization of the water quality monitoring network (WQMN) in surface water during road construction using the field data. First, using the Canadian Council of Ministers of the Environment (CCME) method, the water quality index (WQI) was computed in each potential monitoring station during construction. Then, the integrated form of the information-theoretic techniques consists of the transinformation entropy (TE), and the value of information (VOI) were calculated for the potential stations. To achieve the optimal WQMNs, the Non-dominated Sorting Genetic Algorithm II and III (NSGA-II, and III) based multi-objective optimization models were developed considering three objective functions, including i) minimizing the number of stations, ii) maximizing the VOI in the selected network, and iii) minimizing redundant information for the selected nodes. Finally, three multi-criteria decision-making models, including Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), Preference Ranking Organisation Method for Enrichment Evaluations (PROMETHEE), and Analytical Hierarchy Process (AHP) were utilized for choosing the best alternative among Pareto optimal solutions considering various weighing scenarios assigned to criteria. The applicability of the presented methodology was assessed in a 22 km long road construction site in southern Norway. The results deliver significant knowledge for decision-makers on establishing a robust WQMN in surface water during road construction projects.
Ezziddine, Maha; Liltved, Helge & Homme, Jan Morten (2020). A method for reclaiming nutrients from aquacultural waste for use in soilless growth systems. Water Science and Technology. ISSN 0273-1223. 81(1), p. 81–90. doi: 10.2166/wst.2020.079. Full text in Research Archive
Liltved, Helge (2018). Ozonation and UV-Irradiation. In Timmons, Michael B.; Guerdat, Todd & Vinci, Brian J. (Ed.), Recirculating Aquaculture. Ithaca Press. ISSN 9780971264670.
Liltved, Helge; Vogelsang, Christian & Hindar, Atle (2014). Rensing av partikkelholdig tunnelvann med kitosan. Vann. ISSN 0042-2592. 49(3), p. 327–334.
Pessot, Carlos A.; Åtland, Åse; Liltved, Helge; Lobos, Maria Gabriela & Kristensen, Torstein (2014). Water treatment with crushed marble or sodium silicate mitigates combined copper and aluminium toxicity for the early life stages of Atlantic salmon (Salmo salar L.). Aquacultural Engineering. ISSN 0144-8609. 60, p. 77–83. doi: 10.1016/j.aquaeng.2014.04.001.
Wennberg, Aina Charlotte; Tryland, Ingun; Østensvik, Øyvin; Secic, Indira; Monshaugen, Marte & Liltved, Helge (2013). Effect of water treatment on the growth potential of Vibrio cholerae and Vibrio parahaemolyticus in seawater. Marine Environmental Research. ISSN 0141-1136. 83, p. 10–15. doi: 10.1016/j.marenvres.2012.10.002. Full text in Research Archive
Delacroix, Stephanie; Vogelsang, Christian; Tobiesen, August E.Dessen & Liltved, Helge (2013). Disinfection by-products and ecotoxicity of ballast water after oxidative treatment - Results and experiences from seven years of full-scale testing of ballast water management systems. Marine Pollution Bulletin. ISSN 0025-326X. 73(1), p. 24–36. doi: 10.1016/j.marpolbul.2013.06.014.
Skar, Siv; Liltved, Helge & Homme, Jan Morten (2013). Aquaponics - nye muligheter for grøntsektoren? In Fløistad, Erling & Günther, Morten (Ed.), Bioforsk-konferansen 2013. Sammendrag og presentasjoner. Bioforsk. ISSN 978-82-17-00998-6. p. 281–283. Show summary
Denne boka inneholder sammendrag av 118 av de 134 foredragene som blir holdt under konferansen pluss 30 av 39 vitenskapelige plakater som presenteres.
Hageskal, Gunhild; Tryland, Ingun; Liltved, Helge & Skaar, Ida (2012). No simple solution to waterborne fungi: various responses to water disinfection methods. Water Supply. ISSN 1606-9749. 12(2), p. 220–226. doi: 10.2166/ws.2012.131. Show summary
Control strategies against waterborne fungi have been studied only to a small degree. In order to increase knowledge of the effect of water treatment on waterborne fungi, the dose–response effect of four commonly used drinking water disinfection methods was tested on selected fungal species: Aspergillus calidoustus, Penicillium spinulosum, Trichoderma viride and Fusarium solani. These species are all common in Norwegian drinking water, and are regarded as emerging pathogens, toxigenic and/or food contaminants. Spore suspensions were treated with ultraviolet (UV) irradiation, ozone, chlorine and chloramine. Three different doses were tested for each disinfectant and all doses were repeated three times. Bacillus subtilis was included as a control for the disinfection processes and to compare the resistance. P. spinulosum and T. viride were resistant to chlorine and chloramine. They were also very tolerant to UV-irradiation and ozone, although the highest doses of ozone had a small inactivation effect, especially on T. viride. Ozone was found to be most effective against fungi in general. It is apparent that fungal species may have very different properties when it comes to tolerance to water disinfection, and the inactivation of B. subtilis spores cannot be used as an indicator of fungal spore inactivation after water treatment.
Tryland, Ingun; Bomo, Anne-Marie & Liltved, Helge (2011). Impacts of climate change on surface water quality in relation to drinking water treatment in Norway. In Kelman, Ilan (Eds.), Municipalities Addressing Climate Change. A Case Study of Norway. Nova Science Publishers. ISSN 978-1-61324-716-7. p. 49–69. Show summary
Today's world is changing rapidly - technologically, socially, and environmentally. One of the main challenges is climate change which is accompanied by an explosion of scientific and policy material. This volume provides 'usable science' based on cutting edge research regarding the impact of climate change on specific sectors in municipalities in Norway. Topics covered include climate change's expected impacts on Norway; agricultural runoff and drinking water quality under climate change scenarios; managing cultural heritage sites, including monuments and building façades, facing climate change difficulties; local floodplain management and how municipalities need to approach climate change for decision-making.
Tryland, Ingun; Robertson, Lucy J; Blankenberg, Anne-Grete; Lindholm, Markus; Rohrlack, Thomas & Liltved, Helge (2011). Impact of rainfall on microbial contamination of surface water. International Journal of Climate Change Strategies and Management. ISSN 1756-8692. 3(4), p. 361–373. doi: 10.1108/17568691111175650.
Plosz, Benedek; Vogelsang, Christian; Macrae, Kenneth John; Heiaas, Harald Hasle; Lopez, Antonio & Liltved, Helge [Show all 7 contributors for this article] (2010). The BIOZO process - a biofilm system combined with ozonation: occurrence of xenobiotic organic micro-pollutants in and removal of polycyclic aromatic hydrocarbons and nitrogen from landfill leachate. Water Science and Technology. ISSN 0273-1223. 61(12), p. 3188–3197. doi: 10.2166/wst.2010.920.
Plosz, Benedek; Ried, Achim; Lopez, Antonio; Liltved, Helge & Vogelsang, Christian (2010). Ozonation as a Means to Optimize Biological Nitrogen Removal from Landfill Leachate. Ozone : Science & engineering. ISSN 0191-9512. 32(5), p. 313–322. doi: 10.1080/01919512.2010.502499.
Plosz, Benedek; Leknes, Henriette; Liltved, Helge & Thomas, Kevin V (2010). Diurnal variations in the occurrence and the fate of hormones and antibiotics in activated sludge wastewater treatment in Oslo, Norway. Science of the Total Environment. ISSN 0048-9697. 408(8), p. 1915–1924. doi: 10.1016/j.scitotenv.2010.01.042.
Plosz, Benedek; Liltved, Helge & Ratnaweera, Harsha Chandima (2009). Climate change impacts on activated sludge wastewater treatment: a case study from Norway. Water Science and Technology. ISSN 0273-1223. 60(2), p. 533–541. doi: 10.2166/wst.2009.386.
Vogelsand, Christian; Grung, Merete; Jantsch, Tor Gunnar; Tollefsen, Knut Erik & Liltved, Helge (2006). Occurrence and removal of selected organic micropollutants at mechanical, chemical and advanced wastewater treatment plants in Norway. Water Research. ISSN 0043-1354. 3559(3570).

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Liltved, Helge & Beferull-Lozano, Baltasar (2020). Hydroponic systems for crop growth.
Ezziddine, Maha & Liltved, Helge (2019). A method to reclaim nutrients from aquaculture waste.
Ezziddine, Maha & Liltved, Helge (2019). Nutrients Recovery from Aquaculture Waste for Use as Fertilizer in Soilless Growth Systems .
Liltved, Helge (2019). Hydroponi - vannbaserte dyrkingsteknikker.
Liltved, Helge (2019). Use of aquacultural waste for crop production in aquaponic and hydroponic systems .
Liltved, Helge & Ezziddine, Maha (2019). Declining growth rate of lettuce (Lactuca sativa L.) due to nutrient imbalance in an EC-controlled recirculating hydroponic system.
Liltved, Helge (2018). Miljøutfordringer knyttet til ekstremvær.
Liltved, Helge (2018). Klimaeffekter i VA-sektoren med eksempler på tilpasninger fra UiA-prosjekter.
Liltved, Helge (2017). Impacts of climate change on water supply and storm water management in municipalities in Norway.
Liltved, Helge (2016). The global water crisis and possible technical solutions.
Liltved, Helge (2014). Sludge treatment in aquaponics systems.
Liltved, Helge & Delacroix, Stephanie (2014). UV Technologies - Possibilities and Challenges for Compliance.
Åtland, Åse; Liltved, Helge; Rosseland, Bjørn Olav; Salbu, Brit; Teien, Hans-Christian & Kristensen, Torstein [Show all 7 contributors for this article] (2013). Vannkvalitet i akvakultur. Tilbakeblikk på noen viktige samarbeidsprosjekter NIVA, UMB og Nofima – videre muligheter?
Ezziddine, Maha; Liltved, Helge; Seljåsen, Randi & Homme, Jan Morten (2023). Reuse of Water and Nutrients in Soilless Plant Culture. University of Agder. ISSN 978-82-8427-116-3. Full text in Research Archive
Ghorbani Mooselu, Mehrdad; Liltved, Helge; Meland, Sondre; Hindar, Atle & Simonsen Bjørkenes, Marianne (2022). Sustainable Approaches for Highway Runoff Management During Construction and Operation. Universitetet i Agder. ISSN 978-82-8427-074-6. Full text in Research Archive Show summary
Environmentally friendly approaches for highway runoff management during construction and operation are considered in this project. First, the state of the art in runoff management in terms of characterization, treatment, and modeling approaches were surveyed, and knowledge gaps were identified. Then, the characterization and treatment of tunneling wastewater (by natural and chemical coagulants) was investigated. In the next stage, the vulnerability of water quality to road construction activities was investigated by analyzing field monitoring data. In addition, two different approaches, involving information theory and gamma test theory, were suggested to optimize the water quality monitoring network during road construction. Lastly, the application of satellite data (i.e., Sentinel-2 Multi-Spectral Imager satellite imagery products) for water quality monitoring was examined. Based on the results, it can be shown that site-specific parameters (e.g., climate, traffic load) cause spatiotemporal variation in the characterization of highway runoff and performance of best management practices (BMP) to protect water quality. There is a knowledge gap regarding the characterization of highway runoff under different climatic scenarios, as well as the continuous monitoring and assessment of roadside water bodies. Analysis of the field monitoring data indicates that blasting, area cleaning, and construction of water management measures have the highest impact on surface water quality during road construction. Additionally, the application of information theory and gamma test theory indicate that the primary monitoring network assessed here is not optimally designed. The number and spatial distribution of monitoring stations could be modified and reduced, as the construction activities vary over time. Additionally, the suggested remote sensing techniques applied in this project are able to estimate water quality parameters (i.e., turbidity and chlorophyll-a) in roadside water bodies with a reliability consistent with field observations, reflecting the spatiotemporal effects of road construction and operations on water quality. Finally, an efficient two-step treatment strategy (15 min sedimentation followed by chemical coagulation and 45 min sedimentation) is suggested for the treatment of tunneling wastewater. The optimum coagulant dosages in the jar test exhibit high treatment efficiency (92-99%) for both turbidity and suspended solids (SS), especially for particle removal in the range of 10-100 μm, which is hard to remove by sedimentation ponds and may pose serious threats to the aquatic ecosystem. It is hoped the knowledge generated by this project will help decision-makers with management strategies and support UN Sustainable Development Goals (SDGs). The proposed approaches directly contribute to managing highway runoff and achieving SDG 6 (clean water and sanitation) and especially target 6.3 (water quality).
O'Born, Reyn Joseph; Liltved, Helge & Fredriksen, Karl Sigurd (2019). Strategies and solutions for including life cycle emissions in planning Norwegian road infrastructure. 07 Gruppen. ISSN 978-82-7117-947-2. Show summary
In response to increasing environmental pressure due to climate change, the global community and the Norwegian government have agreed to reduce emissions of greenhouse gases. The government-run Norwegian Public Roads Administration (NPRA) have been tasked with finding ways to drastically reduce their carbon dioxide emissions from road construction and maintenance by the year 2030. In response, NPRA has invested in research and begun the process of developing policy to promote the uptake of cleaner technologies, fuels, materials and processes. This thesis will discuss the solutions and strategies that NPRA can follow to reduce their emissions by presenting a series of articles that focus on the use of life cycle assessment models to calculate emissions of road infrastructure in the early planning phases and by discussing the implementation of emissions reductions policies. The results of this study have shown the use of models can be helpful for calculating emissions but that these models must be sufficiently robust and simple to use in order to be useful during road planning.
Liltved, Helge (2014). Oppfølgende undersøkelse av sigevann i forbindelse med masseuttak ved Møretrømoen i Aust-Agder i 2011-2013. Norsk institutt for vannforskning. ISSN 978-82-577-6364-0. Full text in Research Archive Show summary
I sandtaket ved Møretrømoen i Reddal, Grimstad kommune, tas det ut masser nært opptil en nedlagt fyllplass. Fylkesmannen i Aust-Agder har pålagt operatøren av sandtaket å iverksette avbøtende tiltak for å hindre spredning av forurensninger fra fyllplassen i forbindelse med masseuttakene. I en undesøkelse som ble gjennomført i 2004 ble status med hensyn på forurensninger fra det nedlagte deponiet kartlagt. I den oppfølgende undersøkelsen som er gjennomført i 2011-2013 ble det tatt nye vannprøver på samme stasjoner som i 2004. Det er gjort en vurdering av forurensningssituasjonen basert på de nye analyseresultatene.
Sørensen, Nils Kristian; Højgaard, Samson & Liltved, Helge (2002). Effekter av ozon i kjølt sjøvann. En utredning for bruk av ozon i fiskerinæringen. Nofima AS (tidligere Fiskeriforskning). ISSN 82-7251-495-8. Full text in Research Archive Show summary
RSW (Refrigerated Sea Water) brukes som kjølemedium ved fangst av sild og makrell. Høyt innhold av bakterier og organisk materiale i vannet skaper både hygieniske og tekniske problemer i anleggene. Ozoneringsutstyr er tilpasset RSW anlegg og løser ifølge skippere problemene med rengjøring og desinfeksjon. Slik bruk er nå tillatt forutsatt at fisk ikke kommer i kontakt med ozonert vann. Effekter for fiskelasten er diskutert og det er vist at ozon påvirker fiskekvaliteten, positivt gjennom redusert bakterietall, negativt ved harskning og misfarging. Ozon kan også danne potensielt giftige forbindelser i sjøvannet. Sikkerhetsmessige sider ved drift av ozonanlegg er omtalt og det foreslås at dette område vies større oppmerksomhet ved praktisk bruk. Drift av ozonanlegg krever nøye oppfølging for å tilpasse ozontilsats og derved kontrollere kostnader ved bruk. Fiskeridirektoratet samarbeider med Folkehelsa og SNT for å gi fiskerinæringa retningslinjer for bruk av ozon. Rapporten viser at ved lagring i RSW vil ozon gi økt harskning av kjølt, iset sild. Effekten er mindre etter 2,5 mnd fryselagring, mer ved –18° enn – 30°C. Det registreres rask reduksjon av kvalitet gjennom bleiking, misfarging og skjelltap, men forskjellene mellom behandlet og ikke behandlet sild er ikke stor. Ozon gir effektiv dreping av bakterier i sjøvann og effekten er bedre når vannet har lavt innhold av organisk materiale, som vist i blødetank vs kjøletank etter spyling, i et lakseslakteri. Forsøkene har blitt utført ved Fiskeriforskning i et modell RSW-anlegg. Den praktiske gjennomføring har vært krevende og ikke tilfredsstillende da vi måtte starte med råstoff som allerede var RSW-ført i et/to døgn.

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Published Apr. 16, 2024 11:38 AM