Sammendrag

There is an increasing interest in plastics, both as a resource and as a pollutant. In Europe, 25.8 million tons of plastic waste are generated each year, and their effects on climate, economy, human and environmental health are major challenges that society needs to address. Although a lot of emphasis is placed on recycling, the use of recycled plastics is still low in the EU. In this context, climate change and environmental concerns have boosted the development of various types of biodegradable plastics. The use of biodegradable plastics spans from disposable containers for food/drink, serviceware and wipes, via waste bags for organic waste collected for biogas production, to agricultural films used to cover soil during vegetable production. However, biodegradable plastics are rarely degraded so quickly and completely that the products disappear in nature, and the label may encourage people think otherwise, enhancing littering. The aim of our study was to describe the fate of biodegradable materials and products during waste treatment, and more specifically during composting. How long does it take these materials to degrade? What are the conditions for degradation, and ultimately, for obtaining plastic-free compost products? To answer these questions, we selected relevant materials, including compostable serviceware, biodegradable plastic bags used for organic waste collection, and biodegradable agricultural mulch films. Composting experiments were performed both at lab-scale (1.5 L containers with externally applied heating) and larger scale (in 140 L insulated compost tumblers, with natural heating from the composting processes, continuously monitored). The endpoints studied were recovery, mass loss, changes in morphology and composition, and microbial analysis of the various composts. In addition, we assessed the applicability of chemical digestion methods used for sample pretreatment of environmental samples containing conventional plastics to biodegradable plastics. Biodegradable plastics is an umbrella term covering materials with diverse polymeric compositions and thus material properties. This was well demonstrated by our selected materials, which displayed distinct degradation behaviors under similar controlled conditions. The time-course of degradation during composting will be presented for all selected materials, together with the main parameters influencing their degradation rates. In addition, some methodological challenges in this research field will be discussed. Finally, experience from a municipal composting facility receiving biodegradable plastic waste will also be presented to put our laboratory-based results into perspective.

Sammendrag

Resirkulering av organisk avfall er et prioritert tema innen sektorene landbruk, klima og avfall, og skal bidra til at organisk materiale og næringsstoffer føres tilbake til jord. Dette kan motvirke en langsiktig trend der moldinnholdet i matjorda gradvis blir lavere, noe som ser ut til å bli et økende problem i forbindelse med klimaendringer og økende behov for mat. Tilbakeføring av næringsstoffene i organisk avfall skal på sin side bidra til å redusere behovet for mineralgjødsel, og dermed minske behovet for energikrevende gjødselproduksjon og uttømming av begrensete ressurser av mineralsk fosfat.

Sammendrag

Organic industrial and household waste is increasingly used in biogas plants to produce bioenergy, generating at the same time extensive amounts of organic residues, called biogas digestates. While agricultural soils can benefit from the organic matter and nutrients, in particular nitrogen and phosphorus, contained in biogas digestates, we need to assess the environmental and health risks associated to the undesirable substances that may come along. Among those, only a few are covered by actual regulations. For instance, the quantity of plastic materials below 4 mm in biogas digestate is currently not limited to any threshold, despite its likely occurrence in organic waste (waste bag remains and wrong waste sorting) and persistence in the environment. The aim of our study was identify and quantify plastic materials in digestates from Norwegian biogas plants, that are using various types of organic waste sources (e.g. sewage sludge, food waste, animal manure). In addition, a lab-scale experiment was set up to assess the physical and chemical transformations undergone during biogas processes by plastic materials commonly found in digestates. The methods used in our study included simultaneous thermal analysis coupled to Fourier transform-Infrared spectroscopy (for analysis of polymer composition), scanning electron microscopy (for assessment of physical transformations), and a range of physical and chemical extractions for recovering plastic materials from biogas digestates. While all digestates complied with current regulations, plastic particles with a size of 0.2-3 mm made up to 1% (on dry mass basis) of the samples analyzed. Analysis of the polymeric composition of the recovered plastic fragments confirmed that they originated both from the waste bags themselves (shredded during the first steps of waste handling) and from wrong waste sorting. In addition, the lab-scale biogas treatment was shown to considerably change the structure of the studied plastic materials, illustrating a pathway for the formation of secondary microplastics. Some analytical challenges linked to the size and aging of the plastic materials, as well as the complex composition of the digestates, will be discussed. From a broader perspective, a few options will be presented to address the presence of plastic materials in biogas digestates, and thereby minimize the risk associated to their use as soil amendment.

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Plastics in terrestrial ecosystems negatively affect their functioning by altering physical properties and disturbing soil microorganisms. The same could be true for biodegradable plastics entering nature through incomplete degradation in composting plants, and their subsequent application to soil in fertilizer substrate. So far, no standard analysis protocol for biodegradable plastic degradation exist. This Master's thesis has focused on developing methods for the analysis of biodegradable plastic degradation in a compost matrix and lays a foundation which later research can be built upon. Fenton's reagent and hydrogen peroxide were tested as a sample up-concentrating pre-treatment of an organic matter matrix containing biodegradable microplastics. The degradation of four different biodegradable plastics in nylon bags in a compost tumbler and a compost oven incubation were assessed. Samples for pH and phospholipid fatty acids (PLFA) of different treatments were collected to compare their development and interchangeability. Fenton's reagent was the better suited up-concentrating pre-treatment for samples with some uncertainty remaining. Assessing the biodegradable plastic degradation indicated an incomplete process in home composts and (Norwegian) composting plants. pH values coarsely reflected the composting conditions and suggested interchangeability of most treatments. Analysis of pH together with PLFA results would have been optimal, but could not be accomplished as the COVID-19 epidemic hindered the PLFA analysis. While some uncertainties in the developed methods remain, it can be concluded that a basis for establishing biodegradable plastic degradation analysis was created. Subsequent research should continue their development to assess whether biodegradable plastic remains from composting plants contribute to the accumulation of plastics in terrestrial ecosystems.

Sammendrag

At the Norwegian Institute of Bioeconomy Research (NIBIO, formerly Bioforsk), biochar has been a topic of research since 2009 through both laboratory and field studies. Initial results demonstrated that biochar produced from clean biomass is safe to use on agricultural soils, and that pyrolysis temperatures of ≥370 °C are necessary for producing biochar that is resistant to decomposition on a timescale of 100 years. Further work identified the chemical transformations that are responsible for biochar stability and contributed to finding the best indicator of this stability. Throughout the years, we have had close collaboration with industry and farmers in Norway, where now industrial networks are in action and there is financial support for the implementation of biochar technology. Despite the convincing benefits of biochar as a climate mitigation solution, it has only slowly advanced beyond the research stage, notably because its effect on yield are too modest. There is therefore a need for win-win biochar solutions benefiting both food production and climate mitigation. Such a solution is the development of biochar fertilizers, which capitalizes on the capacity of biochar to capture and release nutrients. As biochar properties largely depend on pyrolysis conditions and feedstock properties, our current work contributes to the selective design of biochars for the purpose of improving nutrient use efficiency.

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The aim of this work was to investigate whether the agronomic traits of vermicompost prepared from partially stabilised sewage sludge digestate after thermophilic composting were more favourable than those of conventional compost. The effects of various additives (green waste, spent mushroom compost, wheat straw, biochar) were also tested after 1.5 months precomposting followed by 3 months vermicomposting with Eisenia fetida or by compost maturing. Vermicomposting did not result in significantly more intensive mineralisation than composting; the average organic carbon contents were 21.2 and 22.2% in vermicomposts and composts, respectively. Hence, the average total (N: 2.4%; P: 1.9%; K: 0.9%) and available (N: 160 mg/kg; P: 161 mg/kg; K: 0.8%) macronutrient concentrations were the same in both treatments. The processing method did not influence the organic matter quality (E4/E6) either. However, on average the concentration of the plant growth regulator kinetin was more than twice as high in vermicomposts.

Sammendrag

We investigated dissipation, earthworm and plant accumulation of organic contaminants in soil amended with three types of sewage sludge in the presence and absence of plants. After 3 months, soil, plants and earthworms were analyzed for their content of organic contaminants. The results showed that the presence of plant roots did not affect dissipation rates, except for galaxolide. Transfer of galaxolide and triclosan to earthworms was significant, with transfer factors of 10–60 for galaxolide and 140–620 for triclosan in the presence of plants. In the absence of plants, transfer factors were 2–9 times higher. The reduced transfer to worms in the presence of plants was most likely due to roots serving as an alternative food source. Nonylphenol monoethoxylate rapidly dissipated in soil, but initial exposure resulted in uptake in worms, which was detected even 3 months after sewage sludge application. These values were higher than the soil concentration at the start of the exposure period. This indicates that a chemical's short half-life in soil is no guarantee that it poses a minimal environmental risk, as even short-term exposure may cause bioaccumulation and risks for chronic or even transgenerational effects.

Sammendrag

Antallet kunstgressbaner har økt kraftig i Norge de siste 15 årene, og det finnes per i dag 1750 kunstgressbaner i Norge. De oppmalte bildekkene og andre typer granulat fra nyprodusert industrigummi som brukes på kunstgressbaner er nå ansett som en av de største landbaserte kildene til mikroplast. Det viser seg at selv en godt driftet bane sprer granulatet i det ytre miljøet, spesielt baner med vinterdrift. I Vannområde Indre Oslofjord Vest tilsvarer dette mer enn 100 tonn granulat per år, som slippes ut i naturen. Vannområdet ba NIBIO om å ta jordprøver rundt tre av disse fotballbanene med vinterdrift for å bekrefte utlekking fra banene. Jordprøver viste at store mengder – opp til flere kg per kvadratmeter – finnes i nærheten av kunstgressbanene, og analysen av granulatet med simultan termisk analyse og Fourier-transformert infrarød spektroskopi ga oss innsyn i den kjemiske sammensetning av disse granulatpartiklene. Dette blir presentert i foredraget, samt tiltak som kan iverksettes for å redusere tap av granulat rundt kunstgressbaner.

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Green roofs are used increasingly to alleviate peaks of water discharge into the sewage systems in urban areas. Surface runoff from roofs contain pollutants from dry and wet deposition, and green roofs offer a possibility to reduce the amounts of pollutants in the water discharged from roofs by degradation and filtering. These pollutants would otherwise enter wastewater treatments plants and ultimately end up in sewage sludge that is spread on agricultural soils. The most common substrates used in green roofs have limited capacity for filtration and sorption. Also, more sustainable alternatives are sought, due to the high carbon footprint of these materials. Biochar is a carbon-rich material produced by pyrolysis of biomass, and several types of biochar have been described as good sorbents and filter materials. Biochar is also a light and carbon negative material, which may fulfill other desired criteria for new green roof substrates. We here report on an experiment where two types of biochar, produced from olive husks at 450 °C or from forest waste at 850 ° C were mixed with volcanic rock or peat, and tested for retention capacity of phenanthrene and six heavy metals in a column experiment with unsaturated gravimetric water flow lasting for 3 weeks. The results suggest that biochar as a component in green roof substrates perform better than traditional materials, concerning retention of the tested pollutants, and that different types of biochar have different properties in this respect.

Sammendrag

Matching high performing varieties of legumes with effective symbiotic N-fixing bacteria can potentially enhance production volumes and economic returns when cultivating grain legumes. We investigated whether field inoculation with local or introduced Rhizobia to six different varieties of faba bean improved growth, nitrogen (N) fixation and protein content in a field experiment in Southern Norway. In 2016, a full factorial experiment featuring three inoculation treatments (a mixture of four morphotypes of Rhizobia isolated from locally grown faba bean, a mix of two efficient and well documented Rhizobium strains from Latvia, and a non-inoculated control treatment) and six faba bean (Vicia faba) genotypes (Agua Dulce, Bauska, Jõgeva, Gloria, Julia, Lielplatones) was set up in an experimental field with sandy loam soil with no recent legume culture history (>10 years). At late flowering/early pod formation stage we quantified N fixation of the crop using the N-15 natural abundance method, using weeds from the same plots as reference plants. We also assessed morphological and phenological characters, seed yields and protein levels at plant maturity. Clear differences were observed, and detailed results from this study will be presented at the conference (analyses are still pending). This research is a part of the EU FP7 project Eurolegume.

Sammendrag

Sewage sludge is an important amendment that enriches soils with organic matter and provides plants with nutrients such asnitrogenandphosphorus.However,knowledgeonthe fateandeffectsof organic pollutants presentin the sludge on soilorganisms is limited.In the present study, the uptake of triclosan, galaxolide, and tonalide in the earthworm Dendrobaena veneta was measured 1 wk afteramendment of agricultural soil with sewage sludge, while elimination kinetics were assessed over a 21-d period after transferring worms toclean soil. After 1-wk exposure, earthworms had accumulated 2.6  0.6 mgg1galaxolide, 0.04  0.02 mgg1tonalide, and0.6  0.2 mgg1triclosan. Both synthetic musks were efficiently excreted and below the limit of quantification after 3 and 14 d ofdepuration for tonalide and galaxolide, respectively. Triclosan concentrations, on the other hand, did not decrease significantly over thedepuration period, which may lead to the transfer of triclosan in the food web.

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A szennyvíziszap hasznosításának perspektivikus lehetősége hazánkban a mezőgazdasági célú felhasználás. Lehetőség van a víztelenített szennyvíziszap ún. injektálására, illetve a komposztálás utáni hasznosításra. A komposztálás egyik speciális válfaja a vermikomposztálás, amikor a kiindulási alapanyagokat gilisztákkal, vagy gilisztákban gazdag humusszal keverik, így a lebontás hatékonyságát a giliszták keverő hatásával, illetve lebontó tevékenységükkel növelik. A különböző életformatípusokba sorolt fajok közt szélsőséges körülményekhez alkalmazkodott, kizárólag trágya-, illetve komposztlakók is megtalálhatók, vagyis azok a fajok, amelyek bomlásban lévő szervesanyagok további feltárásában vesznek részt. Így a vermikomposztálás szempontjából jelentős fajok Eisenia sp., Eudrilus eugeniae, és Perionyx excavatus. A vermikomposztálás szerepének, lehetőségeinek vizsgálatakor a hagyományos komposztálással való összehasonlítás elkerülhetetlen. A vermikomposzt előállításának legfontosabb szempontja a giliszták optimális életkörülményeinek biztosítása, elsősorban a hőmérséklet, nedvességtartalom, levegőzöttség tekintetében. Ez többlet odafigyelést igényel. A hagyományos komposztálás egyik fontos jellemzője a termofil fázis, mely során a szennyvíziszapban található patogén szervezetek elpusztulnak. A vermikomposztálás során a földigiliszták hőérzékenysége miatt, kimarad a termofil fázis, azonban a földigiliszták tevékenységének, jelenlétének köszönhetően hasonló sterilitás érhető el. Tápanyagtartalom vonatkozásában a vermikomposzt nagyobb mennyiségben tartalmaz összes és felvehető makrotápelemet a hagyományos komposztokhoz képest. A vermikomposztálás további előnye a földigiliszták által kiválasztott növényi hormonhatású anyagok jelenléte. Környezetvédelmi szempontból a földigiliszták nehézfém akkumulációs képessége, valamint a speciális bélflóra által biztosított szerves szennyezők lebontásában való szerepük hozzájárulhat a szennyvíziszapok vermikomposztálásának jövőbeni terjedéséhez. Miközben a vermikomposzt számos előnnyel rendelkezik, hazánkban való elterjedéséhez még jó néhány akadályt le kell győznie. A földtulajdonosok sok esetben a szennyvíziszap komposztra nem tápanyag- és talajjavító anyagként gondolnak, hanem sokkal inkább kockázatos hulladékként, amelyek használatával elszennyezhetik talajaikat és a rajta termő növényeket. Habár számtalan szennyvíziszappal kapcsolatos ismeretanyag létezik, a hazai körülmények közötti Vermikomposztálás, mint a szennyvíziszap-komposztálás alternatív megoldása: Szemle 409 hosszú távú hatások vizsgálatáról szóló, a jelenkor aggályait is taglaló eredmények még hiányoznak. A vermikomposztálás tehát perspektivikus, innovatív technológia a szennyvíziszap hasznosítás terén. Azok a szennyvíziszapok, szennyvíziszap komposztok, amelyek szennyező anyag tartalmuk miatt nem felelnek meg az 50/2001. (IV. 3.) Korm. rendelet alapján a mezőgazdasági felhasználásra, a vermikomposztálás révén arra alkalmassá tehetőek.