A variety of chemical substances used in plastic production may be released throughout the entire life cycle of the plastic, posing risks to human health, the environment, and recycling systems. Only a limited number of these substances have been widely studied. We systematically investigate plastic monomers, additives, and processing aids on the global market based on a review of 63 industrial, scientific, and regulatory data sources. In total, we identify more than 10'000 relevant substances and categorize them based on substance types, use patterns, and hazard classifications wherever possible. Over 2'400 substances are identified as substances of potential concern as they meet one or more of the persistence, bioaccumulation, and toxicity criteria in the European Union. Many of these substances are hardly studied according to SciFinder (266 substances), are not adequately regulated in many parts of the world (1'327 substances), or are even approved for use in food-contact plastics in some jurisdictions (901 substances). Substantial information gaps exist in the public domain, particularly on substance properties and use patterns. To transition to a sustainable circular plastic economy that avoids the use of hazardous chemicals, concerted efforts by all stakeholders are needed, starting by increasing information accessibility.

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Partial nitritation/anammox can provide energy-efficient nitrogen removal from the main stream of municipal wastewater. The main bottleneck is the growth of nitrite oxidizing bacteria (NOB) at low temperatures (<15 °C). To produce effluent suitable for anammox, real municipal wastewater after anaerobic pretreatment was treated by enriched ammonium oxidizing bacteria (AOB) in suspended sludge SBR at 12 °C. NOB were continually washed out using aerobic duration control strategy (ADCS). Solids retention time was set to 9-16 days. Using this approach, average ammonia conversion higher than 57% at high oxidation rate of 0.4 ± 0.1 kg-N kg-VSS d was achieved for more than 100 days. Nitrite accumulation (N-NO/N-NO) of 92% was maintained. Thus, consistently small amounts of present NOB were efficiently suppressed. Our mathematical model explained how ADCS enhanced the inhibition of NOB growth via NH and HNO. This approach will produce effluent suitable for anammox even under winter conditions in mild climates.

When applying partial nitritation (PN) to anaerobically pre-treated sewage, ammonium oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) will be exposed to dissolved sulfide and methane. Both sulfide and methane may inhibit nitrification. To gain knowledge necessary for sustaining PN under these conditions, we exposed an AOB enrichment and a mixed nitrifying culture to dissolved sulfide and methane. In the mixed nitrifying culture, sulfide selectively inhibited NOB activity (K = 150 mg-S L, K = 10 mg-S L) which shows that sulfide may help establish PN. The AOB enrichment showed similar K (130 mg-S L), but nitritation activity lagged longer than the time necessary to remove sulfide from the liquid. This demonstrates that feeding of sulfide into established PN should be avoided. Methane inhibition of AOB enrichment was assessed in batch assays with 10 mg-CH L. As compared to control without methane, AOB enrichment activity was identical. Up to 51% of methane was converted to methanol, thus reducing the greenhouse gas emissions.

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