IVL Swedish Environmental Research Institute

The Swedish Extended Producer Responsibility stipulates recycling rates but does not address the quality of the recycling. This gives an incentive for downcycling, which affects what primary material can be substituted by recycled plastics. To shed light on the climate aspects of high-quality plastics recycling, we compare the climate impacts of (1) no recycling, (2) downcycling and (3) advanced sorting that allows for substantial high-quality mechanical recycling. We discuss the limitations of common approaches to modelling recycling; we then select a basket-of-functions approach with a broad systems perspective. In our model, each tonne of high-quality recyclate replaces 900 kg primary plastics in a closed loop. Downcycled plastics instead compete with wood in railway sleepers that are incinerated with energy recovery at the end of their service life. The model accounts for impacts of recycling and downcycling on both near-term and future Swedish waste incineration, the waste imports, and the waste management and energy systems in the rest of Europe. The basket of functions generated by the system model includes packaging, supply of railway sleepers, treatment of near-term and future European waste, near-term and future European gas supply, and future electricity supply. Our results include no avoided burdens but only the emissions associated with generating the many functions of the system. They indicate that downcycling is better for the climate than no recycling, mainly because the incineration of downcycled material is postponed until after the end of the second use. This allows for a greater near-term import of waste that, in turn, reduces landfill disposal of mixed waste in other countries. The case with advanced sorting has the lowest climate impact because it involves the least primary production of polymers and the least total incineration of waste plastics. Common approaches to model recycling fail to account for key aspects in the assessment. The basket-of-functions approach allows for assessing complex impacts of recycling in a broad systems perspective, although it requires multiple assumptions to be made in the model. High-quality recycling increases the chance that the recycled plastics replace primary plastics. This leads to a greater climate benefit. The basket-of-functions approach should be considered when a decision on a material flow has complex foreseeable system impacts. A plastics-recycling policy generates greater climate benefits if it gives incentives for high-quality recycling.

Plastics play an essential role in modern society, but also lead to significant impacts on the environment and climate. Reducing such impacts while retaining the usefulness of plastics requires a shift towards a more circular and sustainable plastics system. This report tells the story of plastics, and their effect on the environment and climate, and looks at their place in a European circular economy.

Abstract. The annual, accumulated stomatal ozone uptake during the vegetation season, i.e. the species-specific phytotoxic ozone dose above a threshold of 1.0 nmol m−2 s−1 (POD1SPEC), was estimated for European forest tree plant functional types for the years 2008–2012. These POD1SPEC estimates were based on ozone concentrations simulated with the EMEP CTM model in combination with stomatal ozone uptake estimated with the DO3SE (Deposition of Ozone for Stomatal Exchange) model. To consider the impacts of ozone on forest growth rates, POD1SPEC-based dose–response relationships were constructed based on results from multi-year experiments with young trees generated within the framework of the UNECE LRTAP Convention. Official information on forest gross growth rates and on natural and harvest removals for different European countries for the years 2008–2012 was used to estimate annual changes in forest living biomass carbon (C) stocks due to ozone. This was achieved using two different scenarios: with and without the negative impacts of ozone on forest gross growth rates, estimated using the POD1SPEC-based dose–response relationships as they relate to impacts. Results provided an estimate of the annual gap between forest gross growth and the total removals, i.e. the annual forest stock changes, both for current levels of ozone and their associated impacts and in the absence of ozone. Estimates were made by collating species-specific information into broad European coniferous and deciduous forest types for consistency with forest statistics. The default IPCC methodology was used to convert estimates of the impacts of ozone on the annual changes in forest living-biomass C stocks. The results showed that the critical level for negative ozone impacts on forests as suggested by the UNECE LRTAP Convention, based on POD1SPEC, was exceeded in large parts of Europe during 2008–2012, except in inland areas in the Mediterranean and in small parts of continental Europe and the Fennoscandian mountain range. The highest POD1SPEC was estimated for the coastal regions of mid-latitude Europe, including the UK and extending northwards to the middle of Sweden, the south of Norway, and Finland. To the south, lower values for POD1SPEC were estimated for most of the Iberian Peninsula and parts of the Mediterranean coastal regions. It was estimated that reduced ozone exposure, similarly to pre-industrial conditions, would increase European forest stem volume growth rates by 9 %, but this would increase European forest annual net changes in standing stocks by 28 %. The difference in gross forest stem volume growth with and without ozone impacts was relatively similar in, for example, Germany and France. However, since the gap between gross growth and total removals was much smaller for Germany, the enhanced growth in the absence of ozone had a much larger relative impact on the forest standing stock changes in Germany compared to in France. Summarized for all European forests, the C sequestration to the living-biomass C stock was estimated to increase by 31 % in the absence of ozone exposure. A thorough review of the literature resulted in the conclusion that mature trees under field conditions cannot be assumed to be less sensitive to ozone exposure compared to young trees under experimental conditions, strongly suggesting that these results are credible for European forest stands of different age classes.

BackgroundWithin systems as dynamic as the aquatic environment, it is crucial to address the impacts of an ever-growing network of emerging pollutants at their intersection. With previous research having demonstrated the capacity of microplastics (MPs) to sorb persistent organic pollutants, we ask in our study how different plastic polymers that are found throughout aquatic systems interact with polycyclic aromatic hydrocarbons (PAHs) and how this intersection of pollutants might impact the bacterial communities that form on MP surfaces. We performed an in situ incubation experiment at different sites along the Baltic Sea coast and through a PAH and 16S amplicon analysis, we investigated the sorption patterns of different substrates and their potential impacts on associated biofilm communities.ResultsPAH sorption patterns of polyethylene (PE), polystyrene (PS), and aquaria stone were found to be dictated predominantly by substrate type and secondly by incubation site. While PE showed a general positive trend of sorption, stone rather leached PAHs into the environment, whereas the PAH levels of PS remained relatively unchanged following incubation. These sorption patterns correlated significantly with the composition of biofilm communities observed on all three substrate types after a 6-week incubation period. Strong correlations between specific PAHs and bacterial taxa indicate a direct relationship between these factors. Elevated levels of specific 3- and 4-ring PAHs on PE and PS coincided with higher proportions of specific taxa reportedly capable of hydrocarbon utilisation as well as a reduced diversity among biofilm communities.ConclusionThe findings in our study highlight the importance of investigating contaminants such as MPs holistically, including any associated substances, to fully understand how they impact surrounding ecological systems as they traverse the different compartments of the aquatic ecosystem.

To meet future nitrogen removal targets, Henriksdal wastewater treatment plant (WWTP) will require external carbon addition, estimated at 8 tons COD/day by 2040, due to low influent BOD/TN ratios, precipitation chemical use, and low temperatures. Methanol, the projected option, is fossil-based and contributes to indirect greenhouse gas emissions. This study evaluated a volatile fatty acid (VFA)-based fermentate produced from primary sludge and food waste in a 2 m3 mesophilic fermenter as a carbon source for denitrification. The filtrated fermentate was tested as carbon source in both batch denitrification tests and pilot-scale MBR (4.5 m3/h), where it was dosed for 70 days, replacing glycerol currently used at Henriksdal and Henriksdals WWTP. In batch tests, the fermentate achieved a 40% higher denitrification rate than glycerol. Pilot trials showed a 30% higher denitrification rate and 50% lower carbon consumption while maintaining effluent concentration below 3 mg NO3- -N/L. Microbial analysis revealed no significant community changes with the carbon source transition, indicating effective VFA uptake by existing microorganisms. Full-scale projections suggested that replacing methanol would require 10% of the plant's primary sludge plus food waste. Although this sludge use would reduce biogas production, methane potential tests showed that recycling of the fermentate solid fraction would result in only 2% lower biogas production, representing a minor trade-off.

Detta kapitel ger en omfattande översikt av de viktigaste datadrivna metoderna för kvalitetsbedömning av givardata som kan vara ett stöd för drift och processoptimering. Begreppet datadrivna metoder används här som ett samlingsnamn för de beräkningsmetoder och algoritmer (maskininlärning, mekanistiska modeller etc.) som på olika sätt kan användas för att tolka data. Kapitlet introducerar begreppet redundanta mätningar som ligger till grund för själva kvalitetsbedömningen i de flesta metoderna. Kapitlet går också igenom det typiska dataflödet som består av en inledande analys, förbehandling av data och metodspecifika beräkningssteg. Vart och ett av dessa tre delsteg beskrivs i tre separata avsnitt. Utöver detta så ges även riktlinjer för att välja den lämpligaste metoden och de viktigaste prestandamåtten som används för att utvärdera dem samt en förklaring av hur man samlar in metadata utifrån datadrivna valideringsmetoder.