Helge Liltved

• Mooselu, Mehrdad Ghorbani; Nikoo, Mohammad Reza; Liltved, Helge; Bjørkenes, Marianne Simonsen; Elnashar, Abdelrazek & Shojaeezadeh, Shahab Aldin [Vis alle 7 forfattere av denne artikkelen] (2024). Assessing road construction effects on turbidity in adjacent water bodies using Sentinel-1 and Sentinel-2. Science of the Total Environment. ISSN 0048-9697. 957, s. 1–18. doi: 10.1016/j.scitotenv.2024.177554. Fulltekst i vitenarkiv Vis sammendrag

  Road construction significantly affects water resources by introducing contaminants, fragmenting habitats, and degrading water quality. This study examines the use of Remote Sensing (RS) data of Sentinel-1 (S1) and Senitnel-2 (S2) in Google Earth Engine (GEE) to do spatio-temporal analysis of turbidity in adjacent water bodies during the construction and operation of the E18 Arendal-Tvedestrand highway in southeastern Norway from 2017 to 2021. S1 radiometric data helped delineate water extents, while S2-Top of Atmosphere (TOA) multispectral data, corrected using the Modified Atmospheric correction for INland waters (MAIN), used to estimate turbidity levels. To ensure a comprehensive time series of RS data, we utilized S2-TOA data corrected with the MAIN algorithm rather than S2-Bottom Of Atmosphere (BOA) data. We validated the MAIN algorithm's accuracy against GLORIA (Global Observatory of Lake Responses to Interventions and Drivers) observations of surface water reflectance in lakes, globally. Subsequently, the corrected S2 data is used to calculate turbidity using the Novoa and Nechad retrieval algorithms and compared with GLORIA turbidity observations. Findings indicate that the MAIN algorithm adequately estimates water-leaving surface reflectance (Pearson correlation > 0.7 for wavelengths between 490 and 705 nm) and turbidity (Pearson correlation > 0.6 for both algorithms), determining Nechad as the more effective algorithm. In this regard, we used S2 corrected images with MIAN to estimate turbidity in the study area and evaluated with local gauge data and observational reports. Results indicate that the proposed framework effectively captures trends and patterns of turbidity variation in the study area. Findings verify that road construction can increase turbidity in adjacent water bodies and emphasis the employing RS data in cloud platforms like GEE can provide insights for effective long-term water quality management strategies during construction and operation phases.

• Mooselu, Mehrdad Ghorbani; 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), s. 2547–2565. doi: 10.2166/wst.2023.363. Fulltekst i vitenarkiv Vis sammendrag

  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.

• Mooselu, Mehrdad Ghorbani; Liltved, Helge; Hindar, Atle & Amiri, Hamid (2022). Current European approaches in highway runoff management: A review. Environmental Challenges. 7. doi: 10.1016/j.envc.2022.100464. Fulltekst i vitenarkiv
• Ezziddine, Maha & Liltved, Helge (2021). Quality and yield of lettuce in an open-air rooftop hydroponic system. Agronomy. 11(12), s. 1–10. doi: 10.3390/agronomy11122586. Fulltekst i vitenarkiv
• Azadi, Sama; Amiri, Hamid; Mooselu, Mehrdad Ghorbani; Liltved, Helge; Castro-Muñoz, Roberto & Sun, Xun [Vis alle 7 forfattere av denne artikkelen] (2021). Network design for surface water quality monitoring in a road construction project using Gamma Test theory. Water Resources and Industry. 26. doi: 10.1016/j.wri.2021.100162. Fulltekst i vitenarkiv Vis sammendrag

  Road construction has a negative environmental impact on the surrounding aquatic environment, requiring the continuous monitoring of surface water quality. Here, optimization of the water quality monitoring network (WQMN) is an essential step in supporting the sustainable development of road construction projects. This study introduces Gamma Test theory (GTT) as a practical method for optimizing the WQMN of surface waters during road construction. The water quality index (WQI) was computed in 48 monitoring stations for six monitoring periods from 2017 to 2019; data was acquired from a primary monitoring network over a new highway in southern Norway. Based on the results, it is possible to reduce the number of stations by 23% in comparison with the original empirical network. The proposed method could be useful to design the monitoring networks of projects with limited construction time and budget, as well as projects lacking enough data.

• Mooselu, Mehrdad Ghorbani; 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. Fulltekst i vitenarkiv Vis sammendrag

  Highway construction may pose different pollutants, including suspended solids, metals, and hydrocarbons such as oil and polycyclic aromatic hydrocarbons (PAH's) to water resources and decrease water quality. The principal contribution of this study is developing a practical approach for assessing the spatiotemporal vulnerability of surface water to road construction by using water quality data from the environmental monitoring during construction of a new 22-km-long highway in southern Norway (2017–2019). First, the data were used to assign the relative weights of parameters, and the water quality index (WQI) was computed for all monitoring stations. Then, by defining six time periods, the temporal variation of WQI in various stations was determined, and by classification of WQI in different levels (i.e., excellent water, good water, poor water, very poor water, and unsuitable for drinking), the temporal changes were analyzed. To assess the spatial variation in surface water quality during road construction, the averages of WQI in all monitoring stations of each catchment area were computed, and for each section of the road, the vulnerability map was plotted in all time periods. Besides, evaluating the impact of road construction activities on surface water quality is another innovation of this study. By extracting the activity type in each section of the road over the construction time, the average WQI for each activity was computed for all time periods. The results showed that construction activities such as blasting, area cleaning, and water management have the highest impact on surface water. The results deliver a feasible knowledge to decision-makers for establishing best management practices to control the effects of road construction on surface water bodies.

• Ezziddine, Maha; Liltved, Helge & Seljåsen, Randi (2021). Hydroponic lettuce cultivation using organic nutrient solution from aerobic digested aquacultural sludge. Agronomy. 11(8), s. 1–13. doi: 10.3390/agronomy11081484. Fulltekst i vitenarkiv Vis sammendrag

  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. s. 399–406. doi: 10.17660/ActaHortic.2021.1305.52. Fulltekst i vitenarkiv
• 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, s. 407–414. doi: 10.17660/ActaHortic.2021.1305.53. Fulltekst i vitenarkiv Vis sammendrag

  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.

• Mooselu, Mehrdad Ghorbani; 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. Fulltekst i vitenarkiv Vis sammendrag

  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), s. 81–90. doi: 10.2166/wst.2020.079. Fulltekst i vitenarkiv Vis sammendrag

  The aim of this work was to develop a method that allows the recovery of nutrients from aquaculture sludge, not only to alleviate the disposal problem, but also to address the future scarcity of non-renewable fertilizers. This method includes two steps: Nutrient mobilization using aerobic digestion followed by solids precipitation using chitosan as the flocculant. The aerobic digestion experiments were conducted in aerated batch reactors, while a jar test apparatus was used to assess the capacity of chitosan to remove total suspended solids (TSS) and turbidity. During aerobic digestion, the concentration of soluble N (sum of NH4-N, NO2-N, NO3-N) increased from 181 mg/L at the start to 890 mg/L after three weeks, and to 903 mg/L after four weeks and solids removal by chitosan flocculation. The corresponding concentrations for soluble P were 8.2 mg/L at start, 110 mg/L after three weeks of aerobic digestion, and 160 mg/L after four weeks of aerobic digestion and chitosan flocculation. Other macronutrients (K, Ca, Mg, S) and micronutrients (Fe, Mn, Zn, B, Cu, Mo) were mobilized to concentrations close to or higher than levels recommended for hydroponic growth of vegetables. Chitosan flocculation and precipitation using a dose of 15 mg/L resulted in a reduction of the turbidity by 96% from 156 to 6.5 FNU. After chitosan precipitation, 80% of the sludge could be reclaimed as a nutrient-rich clear phase, low in TSS and turbidity.

• Liltved, Helge (2018). Ozonation and UV-Irradiation. I Timmons, Michael B.; Guerdat, Todd & Vinci, Brian J. (Red.), Recirculating Aquaculture. Ithaca Press. ISSN 9780971264670. Fulltekst i vitenarkiv
• Liltved, Helge; Vogelsang, Christian & Hindar, Atle (2014). Rensing av partikkelholdig tunnelvann med kitosan. VANN. ISSN 0042-2592. 49(3), s. 327–334. Fulltekst i vitenarkiv
• 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, s. 77–83. doi: 10.1016/j.aquaeng.2014.04.001. Fulltekst i vitenarkiv
• 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), s. 24–36. doi: 10.1016/j.marpolbul.2013.06.014. Fulltekst i vitenarkiv Vis sammendrag

  Since 2005, five different ballast water management systems (BWMS) based on chlorination treatment have been tested by Norwegian Institute for Water Research (NIVA) according to guidelines from the International Maritime Organization (IMO). 25 % and >50 % of all the tested discharge samples exhibited acute and chronic toxic effects on algae, respectively. In most cases this toxicity was plausibly caused by a high free residual oxidant (FRO) level (>0.08 mg Cl/l). Of the 22 disinfection by-products (DBPs) that were identified in treated water at discharge, four compounds were at times found at concentrations that may pose a risk to the local aquatic environment. However, there seemed to be no clear indication that the measured DBP concentrations contributed to the observed algal toxicity. The addition of methylcellulose instead of lignin in the test water to comply with IMO requirements seemed to limit the formation of DBP.

• Skar, Siv; Liltved, Helge & Homme, Jan Morten (2013). Aquaponics - nye muligheter for grøntsektoren? I Fløistad, Erling & Günther, Morten (Red.), Bioforsk-konferansen 2013. Sammendrag og presentasjoner. Bioforsk. ISSN 9788217009986. s. 281–283. Fulltekst i vitenarkiv Vis sammendrag

  Denne boka inneholder sammendrag av 118 av de 134 foredragene som blir holdt under konferansen pluss 30 av 39 vitenskapelige plakater som presenteres.

• 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, s. 10–15. doi: 10.1016/j.marenvres.2012.10.002. Fulltekst i vitenarkiv Vis sammendrag

  In laboratory experiments we added Vibrio cholerae and Vibrio parahaemolyticus to bottles with seawater previously treated by filtration, UV, chlorine or ozone. The purpose was to investigate the influence of different treatment techniques on the growth potential of these bacteria in simulated ballast water tanks. Residual oxidants were removed before inoculation, and the bottles were incubated at 21 ± 1 °C. The growth potential of the vibrios was investigated in two different experimental setups, i.e. in presence and absence of added natural microorganisms. In general, V. cholerae and V. parahaemolyticus rapidly lost their culturability after inoculation and storage in untreated seawater, but showed increased survival or growth in the treated water. Highest growth was observed in water previously exposed to high concentrations of ozone. Addition of natural microorganisms reduced the growth of V. cholerae and V. parahaemolyticus.

• 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), s. 220–226. doi: 10.2166/ws.2012.131. Fulltekst i vitenarkiv Vis sammendrag

  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. I Kelman, Ilan (Red.), Municipalities Addressing Climate Change. A Case Study of Norway. Nova Science Publishers. ISSN 9781613247167. s. 49–69. Fulltekst i vitenarkiv Vis sammendrag

  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), s. 361–373. doi: 10.1108/17568691111175650. Fulltekst i vitenarkiv
• Plosz, Benedek; Vogelsang, Christian; Macrae, Kenneth John; Heiaas, Harald Hasle; Lopez, Antonio & Liltved, Helge [Vis alle 7 forfattere av denne artikkelen] (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), s. 3188–3197. doi: 10.2166/wst.2010.920. Fulltekst i vitenarkiv
• 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), s. 1915–1924. doi: 10.1016/j.scitotenv.2010.01.042. Fulltekst i vitenarkiv
• 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), s. 313–322. doi: 10.1080/01919512.2010.502499. Fulltekst i vitenarkiv
• 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), s. 533–541. doi: 10.2166/wst.2009.386. Fulltekst i vitenarkiv
• 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). Fulltekst i vitenarkiv

Se alle arbeider i NVA

• Liltved, Helge & Beferull-Lozano, Baltasar (2020). Hydroponic systems for crop growth. Fulltekst i vitenarkiv
• Ezziddine, Maha & Liltved, Helge (2019). Nutrients Recovery from Aquaculture Waste for Use as Fertilizer in Soilless Growth Systems. Fulltekst i vitenarkiv
• Ezziddine, Maha & Liltved, Helge (2019). A method to reclaim nutrients from aquaculture waste. Fulltekst i vitenarkiv
• Liltved, Helge (2019). Use of aquacultural waste for crop production in aquaponic and hydroponic systems. Fulltekst i vitenarkiv
• Liltved, Helge (2019). Hydroponi - vannbaserte dyrkingsteknikker. Fulltekst i vitenarkiv
• Liltved, Helge & Ezziddine, Maha (2019). Declining growth rate of lettuce (Lactuca sativa L.) due to nutrient imbalance in an EC-controlled recirculating hydroponic system. Fulltekst i vitenarkiv
• Liltved, Helge (2018). Klimaeffekter i VA-sektoren med eksempler på tilpasninger fra UiA-prosjekter. Fulltekst i vitenarkiv
• Liltved, Helge (2018). Miljøutfordringer knyttet til ekstremvær. Fulltekst i vitenarkiv
• Liltved, Helge (2017). Impacts of climate change on water supply and storm water management in municipalities in Norway. Fulltekst i vitenarkiv
• Liltved, Helge (2016). The global water crisis and possible technical solutions. Fulltekst i vitenarkiv
• Liltved, Helge & Delacroix, Stephanie (2014). UV Technologies - Possibilities and Challenges for Compliance. Fulltekst i vitenarkiv
• Liltved, Helge (2014). Sludge treatment in aquaponics systems. Fulltekst i vitenarkiv
• Åtland, Åse; Liltved, Helge; Rosseland, Bjørn Olav; Salbu, Brit; Teien, Hans-Christian & Kristensen, Torstein [Vis alle 7 forfattere av denne artikkelen] (2013). Vannkvalitet i akvakultur. Tilbakeblikk på noen viktige samarbeidsprosjekter NIVA, UMB og Nofima – videre muligheter? Fulltekst i vitenarkiv
• Ezziddine, Maha; Liltved, Helge; Seljåsen, Randi & Homme, Jan Morten (2023). Reuse of Water and Nutrients in Soilless Plant Culture. Universitetet i Agder. ISSN 9788284271163. Fulltekst i vitenarkiv Vis sammendrag

  This dissertation proposes two approaches to mitigating the dependency of soilless culture on scarce mineral fertilisers. The first approach aims to increase the lifetime of the NS used in recirculating hydroponic systems, while the second approach presents a holistic method for the treatment and use of aquacultural sludge as NS for soilless growth systems. This method includes two steps: nutrient mobilisation using aerobic digestion (AD), followed by solids precipitation using the biopolymer chitosan as the flocculant. The recovered NS was used to grow lettuce in a recirculating hydroponic system. The outcome of the first approach showed that NS can be used for several weeks before discharge, even though many growers discard recycling NS at weekly intervals. In this study, NS was reused for 6 weeks, corresponding to a production of 1 kg lettuce per 10 litres tank volume of NS, in a closed hydroponic system without compromising the yield and apparent quality of lettuce. The results from the second approach indicated that AD is an efficient method to mobilise nutrients in aquacultural waste to concentrations close to or exceeding the mineral levels recommended for soilless growth systems. In addition, the biopolymer chitosan proved to be an efficient and safe alternative for solids removal from aerobically digested aquacultural waste. The recovered NS was successfully used for lettuce production in a closed hydroponic system, with yield and quality comparable to those of lettuce grown with conventional NS. The results obtained clearly show the possibility of substituting synthetic fertilisers with recovered NS from aquaculture waste, which can be considered an alternative and resource-efficient fertilisation strategy for soilless culture systems. Both approaches are described in this dissertation, while detailed explanations of the materials and methods used, as well as the obtained results, can be found in the appended papers.

• Mooselu, Mehrdad Ghorbani; Liltved, Helge; Meland, Sondre; Hindar, Atle & Bjørkenes, Marianne Simonsen (2022). Sustainable Approaches for Highway Runoff Management During Construction and Operation. Universitetet i Agder. ISSN 9788284270746. Fulltekst i vitenarkiv
• 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 9788271179472. Fulltekst i vitenarkiv Vis sammendrag

  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 (NIVA). ISSN 9788257763640. Fulltekst i vitenarkiv Vis sammendrag

  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. ISSN 9788272514951. Fulltekst i vitenarkiv Vis sammendrag

  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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