Search results for "recirculating"
showing 10 items of 24 documents
Filtration of Nordic recirculating aquaculture system wastewater : Effects on microalgal growth, nutrient removal, and nutritional value
2021
Microalgal bioremediation of recirculating aquaculture system (RAS) wastewater represents an alternative for wastewater treatment with the potential to generate valuable biomass. This study evaluated the effects of removing biological contamination and suspended solids from Nordic area RAS wastewater through filtration with 0.45 μm filters on the performance and nutritional value of microalgae. All three tested green microalgae (Haematococcus pluvialis, Monoraphidium griffithii, and Selenastrum sp.) were able to grow in raw (unfiltered) and filtered RAS wastewater. Cultivation in raw RAS wastewater decreased the ω-3 and ω-6 fatty acid content of H. pluvialis as compared to filtered wastewat…
Filtration of Nordic recirculating aquaculture system wastewater: Effects on microalgal growth, nutrient removal, and nutritional value
2021
Abstract Microalgal bioremediation of recirculating aquaculture system (RAS) wastewater represents an alternative for wastewater treatment with the potential to generate valuable biomass. This study evaluated the effects of removing biological contamination and suspended solids from Nordic area RAS wastewater through filtration with 0.45 μm filters on the performance and nutritional value of microalgae. All three tested green microalgae (Haematococcus pluvialis, Monoraphidium griffithii, and Selenastrum sp.) were able to grow in raw (unfiltered) and filtered RAS wastewater. Cultivation in raw RAS wastewater decreased the ω-3 and ω-6 fatty acid content of H. pluvialis as compared to filtered…
Biochemical profiling of temperate zone freshwater green microalgae grown in filtered and unfiltered recirculating aquaculture systems effluent and m…
2020
Viljelemällä mikroleviä kalojen kiertovesiviljelyn jätevedessä siitä voidaan poistaa ravinteita ja tuottaa niistä biomassaa. Menetelmää voidaan käyttää korvaamaan perinteistä jäteveden käsittelyä ja kehittämään vesiviljelyn kannattavuutta. Tässä työssä verrattiin kolmen eri viherlevälajin (Haematococcus pluvialis, Monoraphidium griffithii and Selenastrum sp.) kasvua, ravinteiden poistoa, sekä rasvahappo- ja aminohappoprofiileja, kun leviä kasvatettiin suodatetussa tai suodattamattomassa kiertovedessä tai levien elatusaineessa. Monoraphidium ja Selenastrum -lajien kasvunopeudet olivat pienemmät kiertovedessä (0.64 vrk-1 ja 0.50 vrk-1) kuin levien elatusaineessa (0.72 ja 0.59 vrk-1), mutta Ha…
The effect of plants on microbes, water quality, and fish performance in an aquaponic system
2023
Aquaponics is a way to utilize the nutrient-rich effluents from recirculating aquaculture systems (RAS) by combining hydroponics, i.e. soilless plant farming, with RAS. The plants in aquaponics can be grown as a single or mixed plant species together with fish. In this dissertation, I investigated if plant growth is affected in aquaponics compared to hydroponics and if the plants affected the growth and microbial communities in rainbow trout (Oncorhynchus mykiss) or water quality in aquaponics compared to RAS. The first experiment was conducted by pairing lettuce (Lactuca sativa) with mint (Mentha spicata), rucola (Diplotaxis tenuifolia), or wormwood (Artemisia absinthium) and growing them …
Controlling of geosmin and 2‐methylisoborneol induced off‐flavours in recirculating aquaculture system farmed fish—A review
2018
Salinity affects nitrate removal and microbial composition of denitrifying woodchip bioreactors treating recirculating aquaculture system effluents
2019
Abstract This study investigated the effect of salinity on microbial composition and denitrification capacity of woodchip bioreactors treating recirculating aquaculture system (RAS) effluents. Twelve laboratory-scale woodchip bioreactors were run in triplicates at 0, 15, 25, and 35 ppt salinities, and water chemistry was monitored every third day during the first 39 days of operation. Microbial communities of the woodchips bioreactors were analyzed at the start, after one week, and at the end of the trial. Woodchip bioreactors removed nitrate at all salinities tested. The highest NO3-N removal rate of 22.0 ± 6.9 g NO3-N/m3/d was obtained at 0 ppt, while 15.3 ± 4.9, 12.5 ± 5.4 and 11.8 ± 4.0…
Enhanced nitrogen removal of low carbon wastewater in denitrification bioreactors by utilizing industrial waste toward circular economy
2020
Aquaculture needs practical solutions for nutrient removal to achieve sustainable fish production. Passive denitrifying bioreactors may provide an ecological, low-cost and low-maintenance approach for wastewater nitrogen removal. However, innovative organic materials are needed to enhance nitrate removal from the low carbon effluents in intensive recirculating aquaculture systems (RAS). In this study, we tested three additional carbon sources, including biochar, dried Sphagnum sp. moss and industrial potato residues, to enhance the performance of woodchip bioreactors treating the low carbon RAS wastewater. We assessed nitrate (NO3−) removal and microbial community composition during a one-y…
Salinity affects nitrate removal and microbial composition of denitrifying woodchip bioreactors treating recirculating aquaculture system effluents
2019
This study investigated the effect of salinity on microbial composition and denitrification capacity of woodchip bioreactors treating recirculating aquaculture system (RAS) effluents. Twelve laboratory-scale woodchip bioreactors were run in triplicates at 0, 15, 25, and 35 ppt salinities, and water chemistry was monitored every third day during the first 39 days of operation. Microbial communities of the woodchips bioreactors were analyzed at the start, after one week, and at the end of the trial. Woodchip bioreactors removed nitrate at all salinities tested. The highest NO3-N removal rate of 22.0 ± 6.9 g NO3-N/m3/d was obtained at 0 ppt, while 15.3 ± 4.9, 12.5 ± 5.4 and 11.8 ± 4.0 g NO3-N/…
Microbial communities in full-scale woodchip bioreactors treating aquaculture effluents.
2021
Woodchip bioreactors are being successfully applied to remove nitrate from commercial land-based recirculating aquaculture system (RAS) effluents. In order to understand and optimize the overall function of these bioreactors, knowledge on the microbial communities, especially on the microbes with potential for production or mitigation of harmful substances (e.g. hydrogen sulfide; H2S) is needed. In this study, we quantified and characterized bacterial and fungal communities, including potential H2S producers and consumers, using qPCR and high throughput sequencing of 16S rRNA gene. We took water samples from bioreactors and their inlet and outlet, and sampled biofilms growing on woodchips a…
Effect of ozone and hydrogen peroxide on off-flavor compounds and water quality in a recirculating aquaculture system
2022
The recirculating aquaculture system (RAS) is an ever-developing technology for producing fish with a low environmental impact. However, off-flavors can be a major problem in RAS fish production. Off-flavor compounds are of microbial origin and are accumulated in fish flesh. They typically cause a musty and earthy taste and odor, which consumers find unacceptable. Here we hypothesized that oxidizing compounds such as ozone (O3), hydrogen peroxide (H2O2), and their combinations, referred to as advanced oxidation processes (AOP)s, can remove or decrease these compounds in water and prevent their accumulation in fish. In this study, four different oxidative treatments (O3 low (0.4 mg O3 L−1), …