A comprehensive evaluation method for sludge pyrolysis and adsorption process in the treatment of coking wastewater. (1st April 2019) - Zhou, Hongtao
Abstract: This study proposes a new evaluation method based on expert scoring and data normalization to optimize operational conditions of sludge pyrolysis and assess the comprehensive benefits of the adsorption process in coking wastewater treatment. Pyrolysis temperature, holding time and heating rate were considered as the experimental parameters in sludge pyrolysis. They were optimized by the proposed method, considering raw material cost, net energy consumption, carbon emission and adsorption capacity of sludge-derived bio-char (SB). Two operational modes (cyclic centralized and traditional distributed) were compared to identify a better solution for coking wastewater treatment. The results showed that the optimized operational conditions of coking sludge pyrolysis were that temperature of 550 °C, holding time of 60 min and heating rate of 20 °C/min, using the proposed method. Cyclic centralized mode has been demonstrated as the better mode for wastewater treatment by the proposed method, due to the higher comprehensive score of −0.296. It is a promising technology for sustainable wastewater treatment in terms of sludge recycling, energy saving and carbon emission reduction. Highlights: Sludge-derived bio-char was prepared by pyrolysis and reused in wastewater adsorption. A new comprehensive evaluation method of sludge pyrolysis has been proposed. Pyrolysis conditions of temperature, holding time and heating rate were optimized. Net energy consumption and carbon emission were proved as the main evaluation indexes. Cyclic centralized mode was superior to traditional distribute in adsorption process.