Tratabilidad del efluente de una tenería con presencia de cromo usando un reactor por carga secuencial

tannery wastewater are highly pollutant for the high concentrations of organic matter, nitrogen and heavy metals as chrome that they contain. sequential batch reactors (sbr) have demonstrated to be a good option of treatment of these effluents due to their flexibility and efficiency in presence of inhibiting substances (chrome). the aim of this investigation was to determine the best conditions for removal of organic matter, nutrients and heavy metals of the residual water of a tannery using a sbr fed on a mixture of tanning-dyeing effluent. the efficiencies of removal were compared when using dilute and concentrated influents, under 8 and 12 hour of hydraulic residence time. during the reaction phases anoxics and oxics phases were combined. the removal of pollutants were significantly higher when dilute influent was used (dqo￡1000 mg/l and [cr3+]￡10 mg/l), independently of the retention time, being achieved the major elimination during the anoxic phase. the removals fluctuated between 82.5 and 84.45% of dqo, 58.0 and 73.9% of p-po43- and 51.2 and 53.9% of cr. the elimination of nitrogen was achieved by assimilation, due to the fact that nitrifying bacteria were more sensitive and their activity was inhibited by the presence of chrome and high concentrations of organic matter. the removal of chrome was achieved by precipitation and/or adsorption on the sludge, being necessary to control the ph between 7.5 - 8.5 in the reactors.