Publications

NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.

2021

Abstract

Denne rapporten gir en oversikt over teknologier og systemer for slambehandling som brukes med gode erfaringer rundt om i verden i dag, samt forurensinger som kan forekomme i slam. Vi går også gjennom de mest brukte regulative rammeverkene for slamhåndtering, spesielt EUs slamdirektiv og den amerikanske standarden kjent som US EPA “Part 503 Rule”. Hensikten med rapporten er å gi et kunnskapsgrunnlag for forbedringer av håndtering av slam (behandling og disponering) i det urbane India.

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Abstract

Bicarbonate was evaluated as an alternative carbon source for a green microalga, Tetradesmus wisconsinensis, isolated from Lake Norsjø in Norway. Photosynthesis, growth, and lipid production were studied using four inorganic carbon regimes: (1) aeration only, (2) 20 mM NaHCO3, (3) 5% (v/v) CO2 gas, and (4) combination of 20 mM NaHCO3 and 5% CO2. Variable chlorophyll a fluorescence analysis revealed that the bicarbonate treatment supported effective photosynthesis, while the CO2 treatment led to inefficient photosynthetic activity with a PSII maximum quantum yield as low as 0.31. Conversely, bicarbonate and CO2 treatments gave similar biomass and fatty acid production. The maximum growth rate, the final cell dry weight, and total fatty acids under the bicarbonate-only treatment were 0.33 (± 0.06) day−1, 673 (± 124) mg L−1 and 75 (± 5) mg g−1 dry biomass, respectively. The most abundant fatty acid components were α-linolenic acid and polyunsaturated fatty acids constituting 69% of the total fatty acids. The fatty acid profile eventuated in unsuitable biodiesel fuel properties such as high degree of unsaturation and low cetane number; however, it would be relevant for food and feed applications. We concluded that bicarbonate could give healthy growth and comparative product yields as CO2.

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Abstract

Power-to-methane technology is a promising solution to facilitate the use of excess variable renewable energy for biomethane production. In this approach, hydrogen produced via electrolysis is used to upgrade raw biogas, which can be subsequently used as fuel or stored in the gas grid. Ex-situ biomethanation is an emerging technology that could potentially replace conventional energy-intensive biogas upgrading methods and allow CO2 utilization for biomethane production. This work provides a comprehensive overview on the current status of ex-situ biomethanation with particular attention to trickle bed reactor. The review includes description of ex-situ biomethanation and summarizes previous works on this topic. The key elements related to operational conditions, efficiency, and microbiology of ex-situ biomethanation using trickle bed reactor are described here. Additionally, the review highlights the technical and economic issues that have to be addressed for future development and large-scale implementation of ex-situ biomethanation.

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Abstract

This study attempted to enhance sulfidogenic activity via sulfate-reducing bacteria (SRB) enrichment and minimize organic carbon loss by methanogen inhibition in the sulfidogenic stage of a two-stage anaerobic digestion system (TSADS). To enrich SRB in the sulfidogenic stage, batch tests were performed with various granular sludge pretreatments. Starvation was the most effective pretreatment, increasing SO42− removal and minimizing chemical oxygen demand (COD) loss by inhibiting methanogen activity. Microbial community analysis showed that Desulfovibrio, Desulfotomaculum, and Syntrophobacter were the dominant SRB in the sulfidogenic stage (5.0%, 3.1%, and 2.4%, respectively). This enabled SO42− reduction (86%) and volatile fatty acid production (55% of fed COD) at a hydraulic retention time (HRT) of 4 h. Conversely, biogas with a reduced H2S content (110 ppmv) was produced in the methanogenic stage (HRT = 6 h). A granular sludge comparison revealed differences in their ecology, structure, and extracellular polymeric substance characteristics. Economic feasibility analysis demonstrated that TSADS can lead to a cost reduction of $80–90/1,000 m3 CH4 compared to single-stage anaerobic digestion.

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Abstract

Plastic pollution is a widespread environmental problem that is currently one of the most discussed issues by scientists, policymakers and society at large. The potential ecotoxicological effects of plastic particles in a wide range of organisms have been investigated in a growing number of exposure studies over the past years. Nonetheless, many questions still remain regarding the overall effects of microplastics and nanoplastics on organisms from different ecosystem compartments, as well as the underlying mechanisms behind the observed toxicity. This chapter provides a comprehensive literature review on the ecotoxicological impacts of microplastics and nanoplastics in terrestrial and aquatic organisms in the context of particle characteristics, interactive toxicological effects, taxonomic gradients and with a focus on synergies with associated chemicals. Overall, a total of 220 references were reviewed for their fulfilment of specific quality criteria (e.g. experimental design, particle characteristics, ecotoxicological endpoints and findings), after which 175 were included in our assessment. The analysis of the reviewed studies revealed that organisms’ responses were overall influenced by the physicochemical heterogeneity of the plastic particles used, for which distinct differences were attributed to polymer type, size, morphology and surface alterations. On the other hand, little attention has been paid to the role of additive chemicals in the overall toxicity. There is still little consistency regarding the biological impacts posed by plastic particles, with observed ecotoxicological effects being highly dependent on the environmental compartment assessed and specific morphological, physiological and behavioural traits of the species used. Nonetheless, evidence exists of impacts across successive levels of biological organization, covering effects from the subcellular level up to the ecosystem level. This review presents the important research gaps concerning the ecotoxicological impacts of plastic particles in different taxonomical groups, as well as recommendations on future research priorities needed to better understand the ecological risks of plastic particles in terrestrial and aquatic environments.