• Design-centric ecological engineering integrates ecological constraints directly into engineering design, fostering constraint-aware architectures, system-wide optimization, and scalable urban implementations. [1], [2], [7], [13].

• Wastewater treatment is a core testbed for ecological engineering, combining constructed wetlands, phytoremediation, and plant–microbe interactions to achieve nutrient removal and sustainable treatment. [5], [9], [10], [12], [14].

• Modelling and theoretical framing underpin ecological engineering, enabling design, scalability, and understanding of system complexity through ecological modelling, thermodynamic perspectives, and constraint-based approaches. [2], [15], [16], [17].

• Restoration ecology and ecosystem restoration constitute primary application domains for ecological engineering, linking practices to river, wetland, and broader ecosystem recovery and remediation. [4], [6], [18].

• Bioremediation and microbial–ecological processes drive remediation outcomes in ecological engineering, illustrated by oil-spill bioremediation, PAO-driven nutrient removal, denitrification, and algae-based remediation. [8], [14], [19], [20].