The use of water spinach (Ipomoea aquatica) in domestic wastewater treatment

Abstract

The main objective of this study was to examine the efficacy and capacity of using hydroponic systems in municipal pollutant removal at household scale. Three pilot scaled hydroponic systems [dimension for each system: 4.5 m (L) x ɸ 114 mm] were installed to investigate the optimal age of vegetable, planting density and retention time for household wastewater treatment, respectively. Water spinach (Ipomoea aquatica) planted in 27 plastic cups throughout 4.5-m-length and 114-mm-diameter uPVC pipes filled with wastewater was employed as the treating agent of pollutants. The averaged influent contained proximately 32.5 mg/L suspended solids (SS), 76.0 mg/L biological oxygen demand (BOD5), 220.5 mg/L chemical oxygen demand (COD), 26 mg/L NH_4^+, 5.0 mg/L NO_3^- , and 8.5 mg/L PO_4^(3-) at pH 7.3. Results showed that a designed system consisting of 10 plants of 15-day-old water spinach pre-planted in baked clay in each cup could treat 30 L of domestic wastewater meeting the current municipal wastewater discharge standards in Vietnam (column A standards of QCVN 14:2008/BTNMT) after 4 days of wastewater retention time. If operated under conditions of the above parameters, the pilot-plant hydroponic system can achieve the removal of 65% SS, 82% BOD5, 74% COD, 90% NH_4^+, 30% NO_3^- and 86% PO_4^(3-). The result of this study has provided an applicable domestic wastewater treatment system ecofriendly and suitable for small and medium household areas.