EVENT REPORT | CIRCULAR WAYS: Promoting circular approaches in wastewater treatment

On 29 June 2023, more than 120 people attended in person or online the seminar that Aqua Publica Europea co-organised with Acque Veronesi and Viveracqua to explore the complex combination of appropriate regulatory framework, new technologies and effective coordination between different sectors and stakeholders needed to achieve a shift to circularity in wastewater treatment.

Adopting circular approaches to wastewater treatment offers real opportunities to achieve societal objectives on waste minimisation, sustainable agriculture and energy generation, and holds clear environmental and geo-political benefits. However, the transition to circularity requires a complex combination of an appropriate regulatory framework, new technologies, and effective coordination between different sectors and stakeholders.

On 29 June 2023, Aqua Publica Europea organised, in partnership with its members Viveracqua and Acque Veronesi, the public seminar "CIRCULAR WAYS: Promoting circular approaches in wastewater treatment" in Verona, Italy, to explore the conditions for accelerating the shift towards a circular approach through insightful contributions from water operators, policymakers and stakeholders.

Following an introductory presentation by Nele-Frederike Rosenstock, Policy Officer at the European Commission’s DG Environment, who summarised the main policy developments on circularity at EU level, with a focus on the ongoing revision of the Urban Wastewater Treatment Directive and on the recent evaluation of the Sewage Sludge Directive, the first part of the seminar was dedicated to exploring concrete examples of circular strategies at regional and local level.

Jon Rathjen, Deputy Director for Water Policy & DECC Operations at the Scottish Government, illustrated Scottish Water’s journey from turning sludge into a resource: thanks to a comprehensive strategy, Scotland’s wastewater sector now produces 3% of the nation’s energy needs.

Gudrun Winkler, Senior Advisor to the Head of the Systems and Technology Department at Hamburg Wasser, shared the approach to neutrality and nutrient recovery of the public operator that manages Germany’s biggest wastewater treatment plant: this approach is based on an incineration plant that produces 62 GWh/year of electricity and 80 GWh/year of heat (an expansion of the plant is currently planned), while a multi-stage flue gas cleaning process ensures that gas emissions remain well below legal limits; phosphorus and other residues are then recovered for use in agriculture and other industrial sectors.

Paolo Giandon, Director of the Environment and Ecological Transition Department at the Veneto Region, presented the “Waste Management Plan” of the Northern Italian region, which provides for different “sludge disposal routes” depending on sludge quality. Giandon also pointed out that, while the Veneto region’s strategy is aligned with the EU’s waste hierarchy, a revision of the Sewage Sludge Directive would be welcome to address some of the emerging controversies surrounding the reuse of sludge in agriculture.

After reviewing existing approaches and strategies, the second session was dedicated to exploring promising research avenues and innovation solutions.

The session was opened by Bertrand Vallet, Policy Officer at the European Commission’s DG Research and Innovation, who provided an insight into the Commission’s research agenda on circularity. He mentioned the implementation of large-scale circular systems for the reuse of water and sludge as one of the research priorities that will be supported under the Horizon Programme.

Vallet’s contribution was followed by the presentation of two innovative projects currently being implemented by APE members. Enrico Pezzoli, President of Como Acqua, presented the plan for a new co-incineration plant, which will be co-financed under the Recovery Fund and which is complemented by nature-based solutions for an integrated approach to circularity. Marco Blazina, Head of Wastewater Operations at MM, presented the results of a pilot plant for thermal valorisation and nutrient recovery which, by integrating the process into the treatment plant rather than into a separate unit, increases efficiency and makes it a suitable solution also for small scale treatment plants.

The seminar then closed with a panel discussion addressing the framework conditions to step up circularity. Veronica Santoro, Brussels Representative of the European Sustainable Phosphorous Platform, emphasised that a plurality of effective approaches to circularity already exists and presented concrete examples to illustrate them; she also stressed the importance of communication and stakeholder engagement to ensure adequate societal support to circularity. David Bolzonella, from the University of Verona, agreed with Santoro that there is a plurality of approaches available, and there is no silver bullet to solve the issue of sludge management. He also argued that society is definitely moving away from an ‘end-of-pipe’ approach to wastewater and that treatment plants are being transformed into ‘bio-refineries’ capable of recovering precious substances; the problem is that the end markets for these substances are not yet stable, due to a lack of quality and regulatory standards and consumers’ mistrust. Regarding the issue of unstable end markets, Vallet also highlighted the lack of a ‘critical mass’ or critical quantity of recovered materials that can underpin investments in supply chains. All panellists agreed that, whilst there is not a one-size-fits-all solution to circularity and approaches can be combined according to contextual conditions, political choices on the appropriate mix must nevertheless be made at national and local level to bolster circularity.