Coal Gangue-sludge-based Activated Carbon-mediated Enhanced Anaerobic Digestion of Sewage

Abstract

Coal gangue and waste sludge were used as raw materials for the preparation of composite-based activated carbon. The composition and structural characteristics before and after activation were studied by using experimental devices such as C elemental analyzer, Fourier infrared spectrometer, and scanning electron microscope. The prepared composite-based activated carbon was used in anaerobic digestion process to explore the effect of activated carbon structure on chemical oxygen demand (COD) changes, gas production, and volatile fatty acids(VFAs). The results show that the C contents of sludge and coal gangue were 21.32% and 37.54%, respectively, implying their considerable potential utilization. After activation, rich porous structure was formed on the surface of the composite-based activated carbon, along with increased functional groups, which can significantly increase the cumulative gas production during the anaerobic reaction process and significantly optimize the gas composition. From the change in VFAs and the scanning electron microscopy observations, it was found that the composite-based activated carbon could weaken the instantaneous adsorption of organic matter by activated sludge, but does not affect the degradation pathway of organic matter. It can also effectively slow down the acid stress inside the reactor, and enhance the anaerobic digestion system stability.

Keywords

• coal gangue
• waste sludge
• composite-based activated carbon
• anaerobic digestion
• direct interspecies electron transfer (diet)