Abstract
Aquatic toxicity of effluents from five pulp-paper mill was evaluated in an acute toxicity study employing Daphnia bioassay. Toxicity test results revealed 24-h EC50 values > 100, 87.83, 85.69, 78.15, 87.53%, and 48-h EC50 values > 100, 82.84, 46.44, 69.55 and 77.87% for five pulp-paper mill(PP1-PP5), respectively. Toxicity test results showed linear relationship with high degree of confidence(≥ 0.75 R2 ≥ 0.99) between immobility and test concentrations. The general criteria of toxicity classification showed that 4 out of 5 pulp-paper mill effluents tested were minor acutely toxic having 48-h EC50 in between > 46-100% and 1 was not acutely toxic. Toxicity classification based on toxic unit revealed that 4 out of 5 pulp-paper mill effluents were toxic.
