cod and color removal from textile wastewater using rosa damascena watering waste ash

aims: several methods have been used for textile wastewater treatment. the aim of this study was to evaluate the efficiency of rosa damascena watering waste ash for cod and color removal from textile wastewater.  materials & methods: rose watering waste was gathered from one of the kashan processing plants. the raw wastewater sample was taken from one of the textile industries in kashan countryside. all experiments were run in the fixed volume (1l) of textile wastewater, contact times (15, 30, 45, 60, 75, and 90min), phs (3, 5, 7, and 9) and different doses of rose watering waste (500, 1000, 2000, and 4000mg) at the room temperature (25°c). moreover, biosorption kinetic studies for cod were done using the pseudo first and pseudo second order models.  findings: the amount of cod and color removal were increased by contact time increasing from 15 to 60min and the maximum removal of cod (50.3%) and color (31.4%) were seen at minute 60. therefore, the contact time of 60min was chosen as the optimum contact time for the first step. the maximum amount of cod (51.9%) and color (32.9%) removal were seen at ph=5 and biosorbent dose of 2000mg. changes at ph and biosorbent dose had significant effects (p<0.05) on amount of cod and color removal.  conclusion: the optimum condition for removing cod and color from textile wastewater is at contact time 60min, ph=5 and biosorbent dose of 2000mg. rosa damascena watering waste ash was more effective on the cod removal than the color.