Building resilience through smart hybrid systems: sustainable textile wastewater remediation in Bangladesh

Bangladesh's textile industry, a cornerstone of the national economy, faces persistent challenges in achieving effluent compliance, particularly for salinity-driven total dissolved solids. A synoptic survey of eight facilities in Dhaka EPZ-2 (<i>n</i> = 24 grab samples) revealed near-universal TDS non-compliance (seven of eight facilities), with outlet concentrations of 1,800-2,950 mg L^-1 exceeding the ECR-2023 limit of 2,100 mg L^-1; one facility (Paddocks Jeans) maintained TDS ≈ 980 mg L^-1. The ecological risk assessment indicated that maximum TDS levels (2,950 mg L^-1) exceeded the LC₅₀ for local aquatic species, aligning with elevated ecological and public health risks. Compliance was evaluated using a normalized <i>Z</i>-score framework, and ecological risks were screened via a locally adjusted risk-quotient approach. Modular reverse osmosis and sludge pyrolysis performance is presented from documented pilots and literature (e.g., RO 85-92% TDS rejection; pyrolysis yielding metal-rich char). Integrating these findings, we propose a staged, SME-feasible pathway: Phase 1 - digital dosing and solar aeration with continuous monitoring; Phase 2 - piloting modular RO or electrodialysis reversal for salinity control and water reuse; and Phase 3 - shared sludge valorization facilities to offset costs and promote circularity. This study provides an actionable roadmap and advanced resource recovery, directly contributing to SDGs 6, 9, and 12 in Bangladesh's textile sector.