Canteen Effluent Treatment using Phytoremediation Techniques: A Case Study at the University of Vavuniya

Abstract

Canteen wastewater, also known as greywater, primarily contains organic matter such as oils, grease, food particles, and cleaning agents. When discharged untreated into the environment, it can signif icantly affect soil quality, structure, landscape, and vegetation. At the University of Vavuniya (UoV), the discharge of large volumes of effluent from a campus canteen has caused water stagnation and unsanitary conditions. This study evaluates the feasibility of using a laboratory-scale phytoremediation unit to treat canteen wastewater from the UoV. Two constructed wetland setups were developed—one as a control and the other for testing—using Lemna minor as the phytoremediation plant. Effluent collected from the uni versity canteen was fed into the system at a flow rate of 5 mL/min, maintaining a hydraulic retention time (HRT) of 24 hours. The raw effluent was found to contain high levels of contaminants: Turbidity (225±20 NTU), Total Kjeldahl Nitrogen (TKN) (25.21±4 mg/L), Electrical Conductivity (EC) (1249±6 µS/cm), Phosphate (14.23±3 mg/L), Total Dissolved Solids (TDS) (2633±9 mg/L), and Chemical Oxygen Demand (COD) (2400±8 mg/L), with several parameters exceeding Central Environmental Authority (CEA) stan dards. The Lemna minor-based phytoremediation unit showed removal efficiencies of 97% (Turbidity), 59% (TKN), 13% (EC), 59% (Phosphate), 48% (TDS), and 53% (COD) over a continuous four-week experimen tal period. A small sample t-test confirmed that the reductions in Phosphate, TKN, TDS, Turbidity, and COD were statistically significant (p < 0.05). As the treated water met CEA standards for discharge onto land for irrigation, this phytoremediation system is recommended as a cost-effective and environmentally friendly solution for canteen wastewater treatment. Furthermore, the treated water can be safely reused for gardening and irrigation purposes.