Acute toxicity tests of a textile mill wastewater effluent and a

Abstract

Bioassay tests were conducted with wastewater effluents from a textile mili and a detergent packing plant using the hermit crab. Clibinarius africanus. (Aurivillus) as experimental animal. LC50 values were evaluated using static testing procedures for 24, 48 and 96 hour. For the textile effluent, means of 79.0, 50.24 and 51.81 percentage effluent by volume were obtained in respect of crabs in the “medium” weight range (0.3 – 0.7grams) for the test periods. For the “detergent wash”, 95.16, 85.00 and 82.33 percentage effluent by volume represented means of values obtained for “small” size crabs (weight range 0.08–0.24 grams) and 96.0, and 81.50 percentage effluent by volume for ‘medium’ size crabs for 24, 48 and 96 hour respectively. Spearman’s Rank correlation coefficient showed no relationship between the variable weight and survival rate within the weight range used (p>0.05 for the two-wastewater effluents. For the textile mill effluent, a two-way analysis of variance showed no significant differences between aerated and unaerated test solutions within a 96 hour period. Presumable safe concentrations have been compound using 0.1–0,05 and 0.1–0.01 as arbitrary application factors for the textile mill and “detergent wash” respectively. Some cost benefit recommendations are suggested based on observed plant processing activities