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Determination of acute and early life stage toxicity of fat-plant effluent using zebrafish (Danio rerio).

The present study examines the effects of an effluent from a fat plant (FP) on zebrafish (Danio rerio) embryos and larvae using the whole effluent toxicity testing methods (WET). The method is based on acute toxicity using 96‐h larval mortality and chronic toxicity using endpoints such as the time to hatch, hatching success, deformity, growth rate, swim‐up failure, accumulative mortality, and sex ratio. On the basis of larval mortality the 96‐h LC50 (the concentration was lethal to 50% of newly hatching zebrafish larvae) was 68.9%. In chronic toxicity test, newly fertilized embryos (<5‐h old) were exposed to 1, 6, 12, 25, 50% effluent concentrations in a 24‐h static renewal system at (27 ± 0.5)°C until 15‐day posthatch. The results showed that all chronic endpoints were significantly different from the control at 50% dilution. Embryos began to show lesions on third day at higher concentrations (12, 25, 50% FP effluent concentrations). Treatment group of 25% dilution showed delayed time to hatch. Morphological abnormalities were observed in newly hatched larvae at 25 and 50% FP effluent concentrations. At 25% dilution, sex ratio of larvae was alternated and there was feminization phenomenon. On the basis of the study, the FP effluent tested here may cause increasing embryotoxicity in the zebrafish embryos. We conclude that the test using zebrafish is feasible to evaluate both acute and chronic toxicities of industrial effluents.

Optimization of chemical coagulation of real textile wastewater using Taguchi experimental design method

Abstract In the present study, optimal coagulation conditions, such as pH, coagulant dosage, slow mixing rate, rapid mixing rate, and initial concentration, were determinated using the Taguchi experimental design method. Color and turbidity were considered as performance statistics. An L25 (55) orthogonal array was selected as the experimental plan for the five parameters mentioned above. Performance measure analysis was followed by performing a variance analysis, in order to determine the optimum levels and relative magnitude of the effect of parameters. The obtained results allowed concluding that the optimal conditions in terms of color and turbidity removals were initial pH of the wastewater of 9, coagulant dosage of 200 and 400 mg Al3+/l, slow mixing rate of 15 and 30 rpm, rapid mixing rate of 150, and initial concentration of wastewater of C o/4, respectively. At the end of the experimental studies, obtained color and turbidity removal results for real textile wastewater were 99.43 and 99.22%, respe...

Evaluation of the effect of oxygen on electro-Fenton treatment performance for real textile wastewater using the Taguchi approach

This investigation demonstrates the performance difference of EF reactions conducted in the oxygenated and oxygen-free conditions due to the contribution of hydroxyl radicals in the solution. Additionally, the effects of different operating variables (e.g., current, initial wastewater concentration, and air flow rate) on the decolorization, mineralization, and turbidity removal performance were investigated, and the variables were optimized using the Taguchi method. Under the optimum operation conditions in the EF process, 100% color, 70.4% total organic carbon (TOC), and 98.8% turbidity removals were achieved in the oxygenated solution. However, a decrease was observed in the results of oxygen-free EF reactions, and 91.2, 63.2, and 89.1% removal percentages were obtained for decolorization, mineralization, and turbidity, respectively.

Determination of optimum conditions for color and COD removal of Reactive Blue 19 by Fenton oxidation process

AbstractIn this study, Taguchi method was used to determine the optimum parametric conditions such as initial pH, Fe2+ and H2O2 concentrations, initial dye concentration, slow mixing rate (SMR) and rapid mixing rate (RMR) for Fenton oxidation process performance. The main objective of the study is to provide maximum color and chemical oxygen demand (COD) removals by using optimal levels for Fenton reaction parameters. The orthogonal array L25 was selected as experimental matrix to determine of the optimum parametric levels. It was also, the contribution ratios of each factor were determined by the analysis of variance analysis, separately. Thus, the most effective parameter manages to the process was determined in terms of color and COD removals. Consequently, the optimum color removal conditions for the initial pH, Fe2+ and H2O2 concentrations, initial dye concentration, SMR and RMR are 3, 500 mg/l, 150 mg/l, 250 mg/l, 60 rpm, 90 rpm, respectively, and 3, 400 mg/l, 150 mg/l, 250 mg/l, 60 rpm and 15 rpm f...