Feasibility study of treated sewage irrigation on paddy rice culture

A feasibility study was performed to examine the agronomic application of t he treated sewage on paddy rice culture through field experiment. The domes tic sewage was treated using a constructed wetland system, a subsurface flo w type consisting of sand and macrophyte. The effluent of the wetland syste m was diluted to maintain the total nitrogen concentration below 25 mg/L an d was used as irrigation water. Addition of the treated sewage to the irrig ation water showed no adverse effect on the paddy rice culture; in fact som e enhancement was noticed in both growth and yield. Irrigation with the tre ated sewage after the concentration was adjusted accompanied by conventiona l fertilization showed a better result, with the yield exceeding that of th e control where clean water was used, thus suggesting that reuse of the tre ated sewage as supplemental irrigation water could be a feasible and practi cal alternative. For a full-scale application, however, further study is re commended on the specific guideline for controlling the major water quality components in the treated sewage.