Hydrothermal carbonization of pulp and paper industry wastewater treatment sludges - characterization and potential use of hydrochars and filtrates. (July 2022)

• Record Type: Journal Article
• Authors: Hämäläinen, Anna; Kokko, Marika; Kinnunen, Viljami; Hilli, Tuomo; Rintala, Jukka
• Is Part Of: Bioresource technology. Volume 355(2022)
• Publication Date: 2022-07
• Subjects: Pulp and paper mixed sludge -- Hydrothermal carbonization -- Energy recovery -- Anaerobic digestion -- Carbon sequestration; Biomass -- Periodicals; Biomass energy -- Periodicals; Bioremediation -- Periodicals; Agricultural wastes -- Periodicals; Factory and trade waste -- Periodicals; Organic wastes -- Periodicals; Bioénergie -- Périodiques; Déchets agricoles -- Périodiques; Déchets industriels -- Périodiques; Déchets organiques -- Périodiques; Déchets (Combustible) -- Périodiques; 662.88
• DOI: 10.1016/j.biortech.2022.127258
• Languages: English
• ISSNs: 0960-8524

Abstract

Graphical abstract: Highlights: Mixed sludge from pulp and paper mill wastewater treatment was treated with HTC. HTC enhanced energy recovery in hydrochars having 37% increased heating value. No significant sludge dewaterability improvement was observed after HTC. HTC increased filtrate organics content and volumetric methane production potential. Mixed sludge hydrochars are potential for carbon sequestration. Abstract: The pulp and paper industry's mixed sludge represents waste streams with few other means of disposal than incineration. Hydrothermal carbonization (HTC) could be advantageous for the sludge refinement into value-added products, thus complementing the concept of pulp and paper mills as biorefineries. Laboratory HTC was performed on mixed sludge (at 32% and 15% total solids) at temperatures of 210–250 °C for 30 or 120 min, and the characteristics of the HTC products were evaluated for their potential for energy, carbon, and nutrient recovery. The energy content increased from 14.9 MJ/kg in the mixed sludge up to 20.5 MJ/kg in the hydrochars. The produced filtrates had 12–15-fold higher COD and 3–5-fold higher volumetric methane production than untreated sludge filtrates, even though the methane yield against g-COD was lower. The increased value of the hydrochars in terms of energy content and carbon sequestration potential promote HTC deployment in sludge treatment and upgrading.