A subsurface vertical-flow laboratory scale wetland system was designed to investigate the wastewater treatment efficiency by Vetiveria zizanioides Nash, a common grass in Thailand. Diluted pig farm wastewater was fed intermittently. The removal efficiencies in terms of organic carbon, nitrogen and suspended solids were satisfactory under hydraulic and organic loading rates of 36 mm/d and 55 kgCOD/ha.d, respectively.
A comparison of the performance of the systems with Vetiveria zizanioides Nash and Cyperus flabelliformis Rottb. to treat domestic wastewater was made. It was found that both plants are suitable for wastewater treatment by vertical-flow constructed wetlands in tropical areas under hydraulic and organic loading rates within 121 mm/d and 198 kgCOD/ha.d, respectively.