Phytotoxicity Evaluation of Wastewater from Rice Parboiling

The aim of this study was to evaluate the phytotoxicity of raw and treated effluents from a parboiling rice industry in the south of Brazil. The evaluation included 19 physicochemical parameters and a phytotoxicity test using lettuce and cucumber seeds as bioindicators. The germination index (GI) of both seeds was decreased when in contact with the raw effluent (p<0.05) and with the treated effluent reduced the GI of cucumber seeds (p<0.05) and the root length (RL) of lettuce seeds (p<0.05). For lettuce seeds exposed to the treated effluent there was a negative correlation (p<0.05) between RL and Mn (-0.82) and between GI and Fe (-0.68). For cucumber seeds in the raw effluent, the Fe showed negative correlation (p<0.05) with seed germination (-0.75), but, in the treated effluent, their GI presented positive correlation (0.61) with the ammoniacal-N (p<0.05). The results indicated that both effluents showed phytotoxicity for lettuce and cucumber seeds.