Indicators for resource recovery monitoring within the circular economy model implementation in the wastewater sector.

The European Union is currently in the process of transformation toward a circular economy model in which different areas of activity should be integrated for more efficient management of raw materials and waste. The wastewater sector has a great potential in this regard and therefore is an important element of the transformation process to the circular economy model. The targets of the circular economy policy framework such as resource recovery are tightly connected with the wastewater treatment processes and sewage sludge management. With this in view, the present study aims to review existing indicators on resource recovery that can enable efficient monitoring of the sustainable and circular solutions implemented in the wastewater sector. Within the reviewed indicators, most of them were focused on technological aspects of resource recovery processes such as nutrient removal efficiency, sewage sludge processing methods and environmental aspects as the pollutant share in the sewage sludge or its ashes. Moreover, other wide-scope indicators such as the wastewater service coverage or the production of bio-based fertilizers and hydrochar within the wastewater sector were analyzed. The results were used for the development of recommendations for improving the resources recovery monitoring framework in the wastewater sector and a proposal of a circularity indicator for a wastewater treatment plant highlighting new challenges for further researches and wastewater professionals.

Environmental impact assessment model for substitution of hazardous substances by using life cycle approach.

Regulations that are indirectly driving the substitution of hazardous chemicals, such as the EU REACH regulation, necessitate improvements in chemical alternatives assessment frameworks. In those frameworks, life cycle thinking lacks some important aspects such as systematic and quantitative occupational safety methods and risks from intermediate chemicals that are not released to the environment under normal operating conditions. Concerns of companies about regulatory drivers regarding substances of very high concern often lead to inadequate evaluation of the baseline situation; an issue also overlooked by the frameworks. Moreover, life cycle assessment is optional for assessors with limited resources, such as small and medium enterprises. However, the success of substitution should not be evaluated without life cycle concerns. An environmental impact assessment model has been suggested to overcome these shortcomings of the chemical alternatives assessment frameworks. The model was applied to a case study of primed metal sheet production, where the company was driven to substitute reprotoxic 2-methoxypropanol used in their formulations. The results show that the proposed model is promising for solving the mentioned shortcomings, informing the assessor about substances of very high concern along the life cycle, and it has the potential to be further improved with the help of supporting software and databases. Particularly, in the occupational safety area that concerns risks of accidents at work, improvements to the EU occupational health database can drastically increase the accuracy of the assessments. Besides, the development of methodologies for the quantification of the impacts of reprotoxic, bioaccumulative and endocrine disruptor substances is necessary.