Anaerobic and aerobic degradation of wastewater from hydrothermal carbonization (HTC) in a continuous, three-stage and semi-industrial system. Issue 1 (February 2019)

• Record Type: Journal Article
• Authors: Weide, Tobias; Brügging, Elmar; Wetter, Christof
• Is Part Of: Journal of environmental chemical engineering. Volume 7:Issue 1(2019)
• Publication Date: 2019-02
• Subjects: AD anaerobic digestion -- COD chemical oxygen demand -- CSTR continuous stirred-tank reactor -- DM dry matter -- EGSB expanded granular sludge bed -- HTC hydrothermal carbonization -- HTL hydrothermal liquefaction -- IEP Institute for Energy and Process -- IWARU institute for water·resources·environment -- TIC total inorganic carbon -- TOC total organic carbon -- VOA volatile organic acids; Hydrothermal carbonization -- Wastewater treatment -- Anaerobic treatment -- Aerobic treatment -- Sewage sludge -- Expanded granular sludge bed (EGSB); Chemical engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; Chemical engineering -- Environmental aspects; Environmental engineering; Periodicals; 660.0286
• DOI: 10.1016/j.jece.2019.102912
• Languages: English
• ISSNs: 2213-2929

Abstract

Highlights: Continuous and anaerobic COD reduction of HTC-wastewater by 58%. The final continuous and aerobic digestion step led to a total COD reduction of 78%. Two volumetric loadings, namely 0.44 and 0.88 gCOD ·l −1 ·d −1, yielded 254 and 296 l N·kgoDM −1 of methane. Abstract: Wastewater produced by the hydrothermal carbonization (HTC) of various wood and sewage sludge mixtures was subjected to anaerobic and aerobic digestion. Previous studies have analyzed the batch digestion of wastewater with a chemical oxygen demand (COD) of 15 g·l −1, yielding 406 lN biogas per kg of organic dry matter (oDM) with a methane concentration of 77%. The wastewater was continuously digested in a pilot plant with two anaerobic stages followed by one aerobic stage over 500 days, in a continuous stirred-tank reactor (CSTR) with sludge recirculation and an expanded granular sludge bed (EGSB). The aim was to investigate the process's long-term behavior and stability, as well as to determine the maximum possible COD degradation; therefore, the wastewater was treated in its original state via a separate mono-digestion process. Two volumetric loadings, namely 0.44 and 0.88 gCOD ·l −1 ·d −1, yielded 254 and 296 lN ·kgoDM −1 of methane, respectively, as well as 58% and 55% reductions in the COD. The final aerobic digestion step then led to total reductions of 78% and 71%, meaning that the increased volumetric loading caused the final COD to rise from 3.1 to 4.9 g·l −1 . Trials attempting to reduce the COD further by ozone treatment, precipitation, and flocculation have been done.