Recovery of Value-Added Products from Hydrothermal Carbonization of Sewage Sludge

Figure 1

van Krevelen diagram of the sewage sludge (■) and its hydrochars: H-1 (●), H-2 (▲), H-4 (∆), and H-6 (○), including data of cellulose (□), lignite (♦), and subbituminous (◊) coals for comparison. The arrows represent demethanation, dehydration, and decarboxylation pathways.