Influences of Discharge Waters from Wastewater Treatment Plants on Rice (Oryza sativa L.) Growth and Percolation Water Salinity

Objective of this study was to assess rice growth and percolation water salinity under the irrigation of the discharge waters from the municipal wastewater treatment plant and from the industrial wastewater treatment plant as a alternative water resources during transplanting season. Three kinds of waters were irrigated; the discharge water from an industrial wastewater treatment plant (DIWT), the dischage water from the municipal wastewater treatment plant (DMWT), and groundwater. Concentrations of CODer nh4+-N, Mn2+ and Ni+ in DIWT, SS content and PO4-P concentrations in DMWT were higher than those of reuse water criteria of other country for agricultural irrigation. The plant height in the irrigation of DMWT was shorter by 2 cm than the groundwater irrigation expept for 10 days irrigation. However, the number of tillerings was not significantly different between DMWT and the groundwater. For the harvest index, there were no significant difference between DMWT and DIWT for 20 days irrigation, but slightly higher in DIWT than that of DMWT for 30 days irrigation regardless of soil types.