Advanced treatment of printing and dyeing wastewater by activated coke and thermal regeneration of spent activated coke.

The advanced treatment of printing and dyeing wastewater by adsorption using activated coke was studied. Specifically, the effects of adsorption conditions on wastewater treatment were examined by adsorption experiments. Meanwhile, the adsorption behaviors of organic pollutants by activated coke were investigated by the adsorption kinetics and isotherms. The chemical oxygen demand (COD) removal met the printing and dyeing wastewater discharge requirement under the conditions of initial COD concentration 158 mg/L, adsorption time 360 min, activated coke concentration 30 g/L and adsorption temperature 308 K. After adsorption, 53.86% of COD was removed. The adsorption kinetics of COD by activated coke followed the pseudo-second-order model and the adsorption isotherms could be expressed by the Freundlich model. Moreover, thermal regeneration of spent activated coke was studied. Specifically, the effects of regeneration conditions on the thermal regeneration efficiency of spent activated coke were examined by thermal regeneration experiments. Meanwhile, the reusability of activated coke for organic pollutants removal was evaluated by the successive adsorption-regeneration cycles. 98.13% of thermal regeneration efficiency could be achieved under the conditions of regeneration temperature 1,073 K, regeneration time 30 min and CO₂ flow rate 150 mL/min, and activated coke still maintained 92.54% of regeneration efficiency after ten adsorption-regeneration cycles. [ABSTRACT FROM AUTHOR]