Quantification and characterisation of activated carbon in activated sludge by thermogravimetric and evolved gas analyses. Issue 2 (April 2018)

• Record Type: Journal Article
• Authors: Dittmann, Daniel; Braun, Ulrike; Jekel, Martin; Ruhl, Aki Sebastian
• Is Part Of: Journal of environmental chemical engineering. Volume 6:Issue 2(2018)
• Page Start: 2222
• Page End: 2231
• Publication Date: 2018-04
• Subjects: TGA thermogravimetric analysis -- DTG derivative thermogravimetry -- EGA evolved gas analysis -- SGP specific gas profile -- FGP functional group profile; Advanced wastewater treatment -- Powdered activated carbon -- Sewage treatment plant -- Thermoanalysis -- Thermogravimetry -- Fourier transform -- Infrared spectroscopy; Chemical engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; Chemical engineering -- Environmental aspects; Environmental engineering; Periodicals; 660.0286
• DOI: 10.1016/j.jece.2018.03.010
• Languages: English
• ISSNs: 2213-2929

Abstract

Highlights: Method proposed for direct quantification of PAC in activated sludge with 1.2% LOD. Valuable insights on activated sludge gained by hyphenated technique TGA-FTIR. DTG profiles indicate aged activated sludge. Revealed interaction mechanisms of PAC and activated sludge via aliphatic compounds. Abstract: Advanced wastewater treatment with powdered activated carbon (PAC) leads to a spread of PAC into different purification stages of wastewater treatment plants (WWTP) due to recirculation and filter back-wash. Currently, no methods for quantification of PAC in activated sludge are available. In this study, PAC containing activated sludge from four WWTP were examined by two-step thermogravimetric analysis (TGA) with heating up to 600°C in N2 and subsequently in synthetic air. Direct quantification of PAC according to temperature specific weight losses was possible for one WWTP. Quantification by combining specific mass losses was found to be an alternative direct method, with a detection limit of 1.2% PAC in dry sample mass. Additionally, evolved gas analysis (EGA) by infrared-spectroscopy (FTIR) during TGA revealed interaction mechanisms between PAC and activated sludge. Aliphatic compounds from activated sludge were identified as major substances influenced by PAC. In derivative thermogravimetry (DTG), a typical double peak at approximately 300°C was found to be related to carbonylic species with increased evolution of acetic acid in aged activated sludge. TGA and EGA are promising tools to understand, control and optimise the application of PAC in advanced wastewater treatment.