Impact of primary treatment methods on sludge characteristics and digestibility, and wastewater treatment plant-wide economics

Impact of primary treatment methods on sludge characteristics and digestibility, and wastewater treatment plant-wide economics

Abdelrahman, Amr Mustafa (Istanbul Technical University; Universiteit Gent)
Kosar, Sadiye (Istanbul Technical University)
Gulhan, Hazal (Istanbul Technical University)
Cicekalan, Busra (Istanbul Technical University)
Ucas, Gulin (ISKI Istanbul Water and Sewerage Administration)
Atli, Ezgi (ISKI Istanbul Water and Sewerage Administration)
Guven, Huseyin (Istanbul Technical University)
Ozgun, Hale (Istanbul Technical University)
van Lier, J.B. (TU Delft Sanitary Engineering)

2023

Biogas production from anaerobic sludge digestion plays a central role for wastewater treatment plants to become more energy-efficient or even energy-neutral. Dedicated configurations have been developed to maximize the diversion of soluble and suspended organic matter to sludge streams for energy production through anaerobic digestion, such as A-stage treatment or chemically enhanced primary treatment (CEPT) instead of primary clarifiers. Still, it remains to be investigated to what extent these different treatment steps affect the sludge characteristics and digestibility, which may also impact the economic feasibility of the integrated systems. In this study, a detailed characterization has been performed for sludge obtained from primary clarification (primary sludge), A-stage treatment (A-sludge) and CEPT. The characteristics of all sludges differed significantly from each other. The organic compounds in primary sludge consisted mainly of 40% of carbohydrates, 23% of lipids, and 21% of proteins. A-sludge was characterized by a high amount of proteins (40%) and a moderate amount of carbohydrates (23%), and lipids (16%), while in CEPT sludge, organic compounds were mainly 26% of proteins, 18% of carbohydrates, 18% of lignin, and 12% of lipids. The highest methane yield was obtained from anaerobic digestion of primary sludge (347 ± 16 mL CH₄/g VS) and A-sludge (333 ± 6 mL CH₄/g VS), while it was lower for CEPT sludge (245 ± 5 mL CH₄/g VS). Furthermore, an economic evaluation has been carried out for the three systems, considering energy consumption and recovery, as well as effluent quality and chemical costs. Energy consumption of A-stage was the highest among the three configurations due to aeration energy demand, while CEPT had the highest operational costs due to chemical use. Energy surplus was the highest by the use of CEPT, resulting from the highest fraction of recovered organic matter. By considering the effluent quality of the three systems, CEPT had the highest benefits, followed by A-stage. Integration of CEPT or A-stage, instead of primary clarification in existing wastewater treatment plants, would potentially improve the effluent quality and energy recovery.

A-stage
Biochemical methane potential
Chemically enhanced primary treatment
Economic evaluation
Physicochemical characteristics
Primary clarification

http://resolver.tudelft.nl/uuid:f7796403-3622-4e09-808b-dea37c70d779

https://doi.org/10.1016/j.watres.2023.119920

2023-09-28

0043-1354

Water Research, 235

Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

Institutional Repository

journal article

© 2023 Amr Mustafa Abdelrahman, Sadiye Kosar, Hazal Gulhan, Busra Cicekalan, Gulin Ucas, Ezgi Atli, Huseyin Guven, Hale Ozgun, J.B. van Lier, More Authors