Contribution to optimize the biological treatment of synthetic tannery effluent by the sequencing batch reactor

Tanning industries,widespread in the city of fez,release massive amounts of waste (tanned and other wastewater) directly into the sebou river without treatment. faced with this situation,we have tried to study the effect of concentrations (500 and 1000 mg.l-1) of total chromium in synthetic wastewater of tannery by sequencing batch reactor sbr in order to optimize biological treatment process at the laboratory scale. both treatments have proved to be quite effective,and the best one corresponds to a total chromium concentration of 500 mg. l-1,with one cycle per day,and an aeration time of 23 hours. the corresponding results showed a reduction of all chemical parameters with a removal rates for total chromium (100%),cods (100%),total nitrogen (95.6%) and suspended solids (100%). while the synthetic sewage treatment at a total chromium concentration of 1000 mg.l-1 present a lowest performance.