Tertiary Hospital Wastewater Treatment using Reed Bed Technology Planted with Vetiveria nigritana benth and Phragmites karka retz

Abstract

Tertiary hospital wastewater in Nigeria constitutes a risk to public health due to inadequate treatment. Reed bed technology using locally available macrophytes holds tremendous potentials for biological wastewater treatment. The use of Vetiveria nigritana and Phragmites karka in CW for the removal of organic and inorganic pollutants from tertiary hospital was therefore investigated. Characteristics of wastewater such as pH, Nitrates (NO₃^-), Phosphates (PO₄^3-) and Ammonia (NH₃) contents, Suspended Solids (SS), Biochemical Oxygen Demand (BOD), Dissolved Oxygen (DO) from the University College Hospital, Ibadan were evaluated using American Public Health Association’s (APHA) methods. The optimal dilution ratio of wastewater was determined by varying wastewater concentration (3:1, 1:3, 1:1, 4:0 and 0:4 wastewater to water) while monitoring growth rate of the macrophytes. Four 3.1 x 3.4 x 0.7 m Reed bed prototypes with Vetiveria nigritana and Phragmites karka planted on 0.2 m deep, 10-15 mm sized granite overlaid by 0.2m washed sand and control bed were evaluated. Composition of wastewater displayed considerable variability (pH 7.5 ± 0.3, NO₃^- 2 ± 0.1mg/L, 3 PO₄^3- 3.9 ± 2.5mg/L, NH₃ 19.5 ± 6.3mg/L, SS 204.1 ± 23.9mg/L, DO 0.9 ± 0.8 mg/L and BOD 310.6 ± 29.9 mg/L). The 1:3 waste water to water dilution ratios supported the most rapid growth of macrophytes. The prototype reed bed showed reduction of BOD 82.0% and 85.0%, TDS 72.0% and 73.0%, PO₄^3- 78.0% and 81.0%, NO₃^- 61.0% and 65.0% for V. nigritana and P. karka respectively. Vetiveria nigritana and Phragmites karka were found to be efficient in wastewater treatment using Reed bed Technology.