Hybrid smart bio-reactor and modular wetland system for blackwater treatment in tidal coastal settlements

• Proposes the first hybrid sanitation network for stilt villages over shallow seas. • Integrates Smart Bio-Reactor and Modular Wetlands in a single adaptive system. • Functions as a dual ecological–engineering solution for blackwater treatment. • Designed for floating and semi-floating clusters with limited land availability. • Offers a scalable, SDG-aligned model for resilient coastal water settlements. Tidal coastal settlements experience critical sanitation challenges arising from blackwater discharge, recurrent tidal flooding, and limited land for wastewater treatment. This study develops a hybrid conceptual model of a blackwater sanitation network that integrates Smart Bio-Reactor (SBR) technology with a Modular Wetland System (MWS) to strengthen the socio-ecological resilience of vulnerable coastal communities. The Smart Bio-Reactor ensures high-efficiency biological treatment of concentrated blackwater, while the Modular Wetland provides natural filtration, nutrient absorption, and ecological enhancement. A decentralized, cluster-based network design is proposed to accommodate dense settlement morphology and dynamic tidal conditions, linking SBR units with interconnected wetland modules for optimized treatment and spatial adaptability. The model employs a participatory and adaptive planning framework, combining spatial analysis, environmental assessment, and community engagement to ensure technical feasibility, policy relevance, and local acceptance. Expected outcomes include improved coastal water quality, reduced pollution risks, enhanced public health, and the creation of multifunctional ecological corridors that support economic co-benefits. The proposed hybrid model, drawing from established performance ranges in the literature, is expected to achieve 85–95% BOD removal, 70–90% COD removal, 60–85% nitrogen reduction, 50–80% phosphate reduction, and 2–4 log pathogen removal, indicating its potential for high-efficiency blackwater treatment in tidal coastal environments. This hybrid system aligns with multiple Sustainable Development Goals (SDGs), particularly SDG 6 (clean water and sanitation), SDG 11 (sustainable cities and communities), and SDG 13 (climate action), offering a scalable, replicable, and context-sensitive framework for sustainable sanitation in tidal coastal environments.