Towards Sustainable Wastewater Solutions: Innovations, Challenges, and Economic Opportunities

Dear Colleagues,

In the context of climate change, urbanization, industrialization, and the degradation of water resources, there is a dire need to develop wastewater treatment practices that are compliant with environmental standards, but also ensure public health and achieve economic viability. This Special Issue aims to assess the prospects for the sustainable development of wastewater treatment systems, exploring innovative tools, and the socio-economic prospects for change in the wastewater infrastructure. This collection will bring together cutting-edge research and innovative solutions, addressing the multifaceted challenges of sustainable wastewater management. 
We welcome original research, case studies, reviews, and perspectives that explore the following themes: 

1. Advances in wastewater treatment technologies and practices: 
   • Membrane bioreactors (MBRs) and membrane filtration.
   • Nature-based approaches to decentralized wastewater treatment (e.g. constructed wetlands).
   • Treatment of emerging contaminants (e.g. bioremediation and bioaugmentation).

2.  Resource recovery and circular economy:
   • Nutrient recovery: recovery technologies of phosphorus and nitrogen from wastewaters. 
   • Water–energy nexus: technologies to recover energy from wastewater (e.g. anaerobic digestion and microbial fuel cells).
   • Reuse of treated wastewater for irrigation, industrial processes and urban landscaping.

3. Decentralized and off-grid solutions:
   • Exploring the potential of decentralized treatment systems and on-site wastewater treatment wastewater in areas lacking basic services and infrastructure. 
   • Hybrid systems: integrating decentralized and centralized systems to optimize efficiency, reduce costs, and improve local water security.

4. Challenges in implementation and adoption, and strategies to overcome them:
   • Cost-effectiveness and scalability: addressing the steep capital expenditure in advanced treatment of wastewater and operational level business considerations.
   • Infrastructure limitations, public acceptance, and financial constraints: examining how current infrastructures, societal attitudes, and financial barriers hurdles impact the adoption of sustainable wastewater solutions.
   • Data-driven optimization: applying deep learning, IoT, and big data analytics to optimize monitoring, maintenance, and management of the system.

5. Economic and policy dimensions:
   • Economic opportunities: exploring and providing business analysis towards emerging market for cost effective wastewater technologies and value-added by-products.
   • Public–private partnerships (PPPs): the role of collaboration between government, industry, and communities in promoting sustainable wastewater practices.
   • Policy frameworks and incentives: analysis of successful policy models, subsidies, and tax incentives that drive eco-friendly wastewater innovation and infrastructure investment. 

Dr. Margarida Oliveira
Dr. Luisa Paula Cruz Lopes
Guest Editors

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• decentralized systems
• bioremediation
• membrane bioreactors (MBRs)
• constructed wetlands
• nutrient recovery
• policy frameworks
• public–private partnerships
• circular economy
• sustainable wastewater management
• water–energy nexus