Impacto ambiental de los efluentes del proceso de blanqueo de algodón: parámetros químicos y biológicos

Industrial and urban areas make up important focal points for the dumping of all types of toxic substances into the aquatic environment. The textile industry, and more specifically the cotton production sector, also adds its contribution through the various types of effluent in accordance with the type of processing. This paper examines the environmental impact produced by two cotton bleaching processes. The bleaching agents in question are sodium hypochlorite and hydrogen peroxide. Various chemical parameters (COT, DBO5, DQO, AOX, EOX and residual chlorine) were determined in all effluents, together with biological parameters (CL50 in fish, CI50 in micro-algae and CE50 in luminescent bacteria). It was observed that higher values of COT, DQO and DBO5 were obtained from the effluent of the cotton bleaching process when hydrogen peroxide was used than when sodium hypochlorite was used. The values of organohalogenated compounds (AOX and EOX) in the hypochlorite effluent were 24.5 mg/l and 0.98 mg/l respectively. The multi-species toxicological assays that were performed revealed that the effective concentrations for the various species that were examined were very similar for the two effluent types.