Cost Effective Nature Based Solutions for Urban Water Quality Improvement in Lahore, A Comparative Review

Abstract

Rapid urbanization and inadequate wastewater management have intensified water quality degradation in major cities of developing countries, particularly in Lahore, Paki-stan. Conventional centralized treatment systems often fail to deliver sustainable perfor-mance due to high capital costs, energy dependence and institutional constraints. This study presents a systematic narrative review of cost-effective and sustainable urban water quality improvement methods, with a primary focus on Lahore while maintaining broad-er applicability across Pakistan. The review evaluates nature-based solutions, low-cost technological interventions, decentralized treatment systems and policy-oriented ap-proaches using a multi-criteria framework encompassing treatment efficiency, cost-effectiveness, environmental sustainability, scalability and contextual suitability. Comparative analysis indicates that constructed wetlands, biochar-based adsorption sys-tems, solar and photocatalytic disinfection technologies and community-based decentral-ized systems consistently outperform conventional centralized treatment plants under local socio-economic and environmental conditions. Constructed wetlands show high reclamation rates for organic pollutants, biochar systems demonstrate strong heavy-metal removal efficiency and solar-based disinfection offers effective pathogen control under fa-vorable climatic conditions. The findings highlight that no single technology is universal-ly optimal; instead, integrated hybrid treatment configurations aligned with Integrated Urban Water Management principles provide the most viable pathway for sustainable urban water quality improvement. This review offers practical insights for urban plan-ners, policymakers, and water managers seeking resilient, low-cost solutions for rapidly growing cities such as Lahore.