Comparative techno-economic performance of wastewater treatment technologies in ethiopia: Insights from ten case studies

Sustainable wastewater management is vital for environmental protection and public health, yet treatment performance in developing regions remains inconsistent. The study assessed how combined technical performance, economic viability, energy efficiency, and cost-effectiveness under real operating conditions influence the sustainability of wastewater treatment plants. Technical efficiency was evaluated using chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total suspended solids (TSS) removal, while economic performance was assessed through specific energy consumption and unit treatment cost. Membrane bioreactors achieved excellent removal efficiencies (99.12% TSS, 98.94% COD) but were economically unsustainable under low loading conditions (€0.54 m⁻³ and 5.83×10⁶ J m⁻³). In contrast, nature-based and hybrid systems, including Waste stabilisation ponds and upflow anaerobic sludge blanket combined with Trickling Filters, exhibited stable performance with low energy demand ((2.16–5.04)×10⁵ J m⁻³) and minimal treatment cost ( €0.0073–€0.013 m⁻³) when operated near design capacity. National Alcohol Factory sequencing batch reactor, operating at 95% capacity, achieved high efficiency (99.78% COD, 99.66% BOD) at a moderate cost (€0.091 m⁻³). Centralised systems such as Kality sewage treatment plant generated the highest economic returns (>€467 500 yr⁻¹). These findings highlight the importance of capacity utilisation, energy efficiency, and context-specific technologies for resilient wastewater management. • MBRs achieved >99% removal but had high unit costs at low loading • UASB+TF and WSP systems improved energy use and operational stability • Nature-based WSPs and hybrids stayed cost-stable at high utilisation • AANAF SBR reached 99.7% BOD/COD removal at moderate treatment cost • WSPs and hybrids ranked most cost-effective per kg BOD removed