Innovative Approaches to Sewage Disposal and Agricultural Reuse in Developing Countries: Challenges and Opportunities

Sewage mismanagement remains a critical constraint to public health, environmental protection, and agricultural sustainability in developing countries. Globally, more than 80% of wastewater is discharged untreated, rising above 95% in low-income settings, while treatment coverage in South Asia and Sub-Saharan Africa remains below 30%. This review synthesizes evidence published between 2010–2024 and evaluates innovative sewage disposal pathways with explicit attention to agricultural reuse, where reported case studies indicate 10–20% crop-yield improvements alongside reduced fertilizer dependence when reuse is implemented safely. Beyond health impacts (including >1.6 million annual deaths linked to waterborne diseases) and economic burdens (approximately USD 260 billion/year in sanitation-related losses), the study provides (i) a comparative evidence base across nine treatment alternatives and (ii) a quantitative multi-criteria prioritization using AHP–TOPSIS. In the pooled descriptive statistics, mean reported performance centers around 85.78% BOD removal, 79.67% COD removal, and 78.67% pathogen reduction, with wide dispersion in cost and resource requirements. The AHP–TOPSIS results identify Trickling Filters as the top-ranked option (Ci = 0.7524), followed by UASB (Ci = 0.6959) and SBR (Ci = 0.6728), supporting robust selection under combined technical, economic, environmental, and social criteria.