Enhancing the sludge-based carbon quality via site-occupied and decomposed process

The sequestration of carbon from the sewage sludge to prepare a useful sludge-based carbon (SBC) could be one of the sustainable alternative methods for the solution of sludge in cities. In this work, a novel method of 'site-occupied firstly and decomposed subsequently' was developed to increase the sludge based carbon (SBC) quality. The urea was designed to generate CO2 and NH3 firstly during the decomposition process around 150-250 degrees C, and to form HCNO and g-C3N4 at 360 and 550 degrees C in series. Three times higher BET surface area was observed after 30% urea treated SBC (W-urea/W-sludge = 3/10, SBC30%u), from 97 +/- 4.1 m(2)/g to 300 +/- 7.4 m(2)/g. The point of zero charge (PZC) of SBC30%u, decreased to 3.8 +/- 0.23 from 5.4 +/- 0.20 (PZC of the untreated SBC) due to the generation of acidic groups. The acidic functional groups generated, such as -C=O, -OH, were also confirmed by the FFIR analysis. The SBC obtained was used for the further treatment of leachate effluent, and the corresponding COD removal ratio increased from 21.6% to 50.2% in SBC30%u. It can be concluded that the site-occupied and decomposed process could be a potential process to pyrolysis for the sludge-like complex raw material. (C) 2019 Published by Elsevier Ltd.