Sustainability assessment of organic waste management in three EU Cities: Analysing stakeholder-based solutions.

This study focuses on a comprehensive sustainability assessment of the management of the organic fraction of municipal solid waste in Ghent (Belgium), Hamburg (Germany) and Pécs (Hungary). A sustainability assessment framework has been applied to analyse social, environmental, and economic consequences at the midpoint level (25 impact categories) and at the endpoint level (5 areas-of-protection). For each case study, the reference scenario was analysed, along with three solutions to improve the sustainability performance, which were selected and developed with the collaboration of local stakeholders. The solutions focus on food waste prevention, collection (increasing separate collection and household composting) and/or valorisation treatment (insect breeding, bioplastic production and improvement of centralised treatment). The results show that food waste prevention results in substantial improvements in all areas of protection when a significant quantity of food is saved. Solutions proposing innovative treatments such as insect breeding do not show clear improvements at the endpoint level, given current technology development level, but appear promising for some categories such as Revenues, Ecotoxicity, Land Use or Particulate Matter if the substituted products compensate the impact of the treatment (e.g., energy and water use). Enhancing the separate collection of organic waste can improve sustainability, but trade-offs may arise, e.g., decreased environmental savings from energy recovery at incineration. For this, the influence of the electricity mix (more or less decarbonised) should be carefully considered in future studies. The application of the solutions proposed to other cities should also consider potential bottlenecks such as legislation barriers, public acceptance, or management costs.

On the mode of action of N-phenyl-2-naphthylamine in plants.

N-phenyl-2-naphthylamine, a sediment contaminant previously identified as a major toxicant of site-specific importance was investigated for its mode of toxic action. From short-term bioassays with daphnids, fish eggs, bacteria, and algae it appears that this compound has specific phytotoxic properties at concentrations below 100 microg/L, which cannot be explained assuming an unspecific narcosis type of action in plants. Also, hydroxy-, nitro-, and methylderivatives show clear excess toxicity as compared to baseline toxic effects. Of several plant-specific growth and development processes investigated, only photosynthesis could be demonstrated to be affected at short exposure times and low concentrations. Disturbance of primary photosynthetic reactions such as oxygen evolution and fluorescence quenching, however, becomes only apparent after 2-3 h of exposure, which is in sharp contrast to known specific inhibitors targeting processes such as electron transport or ATP production. This, and concentration-time-effect modeling lead to the suggestion that N-phenyl-2-naphthylamine acts intracellular as a reactive compound in cell membranes producing irreversible, and thus cumulative, damage over time in algae. The effects may become first apparent in membrane-rich compartments such as the algal chloroplast.