Effluent Quality Trends of a Vocational School WWTP (2021–2024) and Performance of a Mini Water Hyacinth Wetland as a Polishing Unit

Desrita Gevia (Environmental Studies Program, Universitas UPGRISBA, Padang)
Erismar Amri (Environmental Studies Program, Universitas UPGRISBA, Padang)
Nefilinda (Environmental Studies Program, Universitas UPGRISBA, Padang)

Formosa Journal of Science and Technology (FJST)
Vol. 5 No. 2 (2026): February 2026

This study evaluates whether effluent compliance also implies ecological safety in a vocational-school WWTP in Padang, Indonesia. We analyzed semester effluent data (2021–2024) and an influent–effluent snapshot (October 2025), then tested a mini water hyacinth wetland as a polishing unit (Eichhornia crassipes; 13 L; ~8-day HRT). Variables included pH, BOD, COD, NH3-N, and selected metals. COD and BOD consistently met the national effluent standard, whereas pH showed episodic extremes. Snapshot removal was high for organics (BOD 98.9%; COD 90.4) but moderate for NH3-N (47.1%) under acidic influent. The wetland raised pH and improved Fe/Cu removal yet increased COD and NH3-N, indicating a need for better pH control, nitrification, and polishing design