Current challenges and future perspectives for the full circular economy of water in European countries

Assessment of European countries' national circular economy policies

The circular economy (CE) has become key to achieving the environmental objectives set by the European Union (EU). This transformative process requires linear production processes to be abandoned and replaced with environmentally-friendly circular models. In this scenario, the present study uses Data Envelopment Analysis and the Sequential Malmquist Index to achieve a twofold objective: (1) to analyse the effectiveness of the national CE policies applied by 19 EU Member States and (2) to identify the items of circularity that need improvement, in order to support decision-makers in the implementation of appropriate CE policies. The results confirm that the measures adopted have had a positive impact, leading to more efficient circular patterns designed to achieve the desired climate neutrality. Policymakers should focus on resilience and international cooperation, without overlooking environmental sustainability and the need to control excessive resource extraction.

Tofu wastewater as a carbon source flowing into municipal wastewater treatment plants for reductions of costs and greenhouse gas emissions

Wastewater treatment processes significantly contribute to greenhouse gas (GHG) emissions. Municipal wastewater treatment also faces challenges related to low strength and a low carbon-to-nitrogen (C/N) ratio. This study investigates the high-carbon tofu wastewater flowing into municipal sewers for co-treatment at a wastewater treatment plant (WWTP) directly, with the goal of enhancing nitrogen removal and reduce GHG emissions. Within the framework of a circular economy for wastewater treatment, tofu wastewater serves as an external carbon source for sustainable solutions. The concentrated tofu wastewater had an average chemical oxygen demand (CODCr) of 21,894 ± 11,485 mg/L, total nitrogen (TN) of 591.8 ± 238.2 mg/L, and a C/N ratio of 36.9 ± 7.4. The denitrification rate reached 3.05 mg NO3--N/(g MLVSS·h). Therefore, tofu wastewater is a suitable alternative carbon source. A full-scale WWTP with a capacity of 20,000 m³/day was monitored from 2017 to 2022 to evaluate the co-treatment effects of municipal wastewater and tofu wastewater. The results showed an increase in 53.3% in the average CODCr concentration of the influent wastewater, while the total nitrogen and total phosphorus removal efficiencies were enhanced to 75.8% and 95.2%, respectively. In addition, the study quantified GHG emissions from tofu wastewater and municipal wastewater treatment. Compared to separate treatment processes, the co-treatment reduced GHG emissions by 337.9 t CO2-eq., approximately 15.8% of the total emissions of WWTP, and achieved a cost saving of 7-10% of the total operational costs. These findings demonstrate the environmental and economic advantages of integrating high-carbon industrial wastewater treatment directly into wastewater treatment plants.

Filling the Knowledge Gap Regarding Microbial Occupational Exposure Assessment in Waste Water Treatment Plants: A Scoping Review

BACKGROUND

Wastewater treatment plants (WWTPs) are crucial in the scope of European Commission circular economy implementation. However, bioaerosol production may be a hazard for occupational and public health. A scoping review regarding microbial contamination exposure assessment in WWTPs was performed.

METHODS

This study was performed through PRISMA methodology in PubMed, Scopus and Web of Science.

RESULTS

28 papers were selected for data extraction. The WWTPs' most common sampled sites are the aeration tank (42.86%), sludge dewatering basin (21.43%) and grit chamber. Air sampling is the preferred sampling technique and culture-based methods were the most frequently employed assays. Staphylococcus sp. (21.43%), Bacillus sp. (7.14%), Clostridium sp. (3.57%), Escherichia sp. (7.14%) and Legionella sp. (3.57%) were the most isolated bacteria and Aspergillus sp. (17.86%), Cladosporium sp. (10.71%) and Alternaria sp. (10.71%) dominated the fungal presence.

CONCLUSIONS

This study allowed the identification of the following needs: (a) common protocol from the field (sampling campaign) to the lab (assays to employ); (b) standardized contextual information to be retrieved allowing a proper risk control and management; (c) the selection of the most suitable microbial targets to serve as indicators of harmful microbial exposure. Filling these gaps with further studies will help to provide robust science to policy makers and stakeholders.

Designing a circular cities declaration for Japan building on the European Union's case study

Japan is progressing towards its circular economy (CE) goals as many of its cities have adopted circular city (CC) policies and programs, although further progress is constrained as a result of the lack of a common framework. A novel framework was proposed with the "European circular cities declaration" (ECCD) (2020), consisting of a list of 10 principles committing to integrate circularity into the city's design, development, and management. As a foremost finding, and building on the authors' previous studies of Japan's CE and CC, this work shaped a circular cities declaration (CCD) for Japan following a triple-axis methodology; It (1) evaluates the ECCD as a baseline, (2) adapts it to Japan's unique socio-economic landscape, and (3) considers the three pillars of sustainable development, offering practical guidance for governments facing similar challenges. This environmental management tool goes beyond the EU one providing a model of hybrid governance and monitoring and evaluation mechanism. The resulting declaration is intended for the government to facilitate a transition from insulated CE policies to holistic CC ones, but also for businesses, academia, and communities; Thus, it may aid in endorsing a cities' common framework and shared vision to harness the potential of CC to address environmental issues, foster innovation and collaboration toward a resilient future in Japan.