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Abatement of toxicity of effluents containing Cr(VI) by heterogeneous photocatalysis. Toxicity assessment by AMPHITOX assay

Author:
Hojman, Jonatan Y., Meichtry, J. Martín, Litter, Marta I., Pérez Coll, Cristina S.
Source:
Ecotoxicology and environmental safety 2015 v.122 pp. 545-550
ISSN:
0147-6513
Subject:
acute exposure, acute toxicity, bioassays, chromium, effluents, larvae, long term effects, photocatalysis, sublethal effects, titanium dioxide, water conservation
Abstract:
Toxicity of a Cr(VI) solution before and after treatment by TiO2 heterogeneous photocatalysis (HP) was performed with AMPHITOX bioassay. Changes in toxicity on Rhinella arenarum larvae for 10-d were monitored after exposure to an untreated Cr(VI) solution and to the same solution after HP treatment. The HP treatment of a 41.60mgL−1 Cr(VI) solution reduced to 37.5% the concentration of the metal ion. A 10-fold reduction in toxicity at acute exposure (72h) and 150-fold reduction in toxicity after 240h was found. Further, the LOEC value increased from 0.001% for the untreated solution to 0.153% after HP treatment. Moreover, the safe concentration in untreated solution corresponded to 0.0001% sample, and it was 0.01% after the treatment, i.e., 100 times higher. A saving of water of about 100,000L per L of effluent would be possible through dilution to allow safer concentrations for discharge; the saving would reach the highest value (1,000,000L per L) at 240h. Sub-lethal effects were completely absent in larvae exposed to the treated solution. The AMPHITOX test allowed to detect chronic effects at low Cr concentrations, i.e. at environmentally relevant levels.
Agid:
5458727