Development of a wastewater management framework for environmental laboratories in Sri Lanka

Abstract

Laboratories conducting environmental analyses generate highly toxic wastewater containing strong mineral acids, heavy metals, organic solvents, and residual analytical reagents. Yet, no specific national guidelines exist for managing and discharging it. This study assessed wastewater management practices at six major environmental laboratories in Sri Lanka through questionnaire surveys and site assessments, and conducted physicochemical and heavy-metal analyses of effluent from two representative sites. Survey results show that 66.7% of laboratories discharged wastewater without treatment, while 80% were unaware of applicable regulations. Laboratory analyses recorded pH = 3.11 ± 3.68, low biodegradability (BOD/COD <0.3), and heavy-metal concentrations exceeding Central Environmental Authority (CEA) Schedule I inland surface-water discharge standards, with maximum exceedances of 7 times for iron, 5 times for chromium, and 7 times for manganese. The chemical oxygen demand (COD) analysis was identified as the principal source of chromium contamination of laboratory wastewater. Based on the empirical findings of the study, a five-pillar and three-tier wastewater management framework was proposed, incorporating Green Analytical Chemistry, five-stream waste segregation, tiered on-site treatment, documentation of regulatory compliance, and institutional capacity building. The framework is scalable from small-scale academic laboratories to large government institutions and uses locally available materials and existing regulatory infrastructure, offering a practical pathway toward safer and more responsible laboratory wastewater management.