Repurposing pre-pasteurization as an in situ thermal hydrolysis pretreatment process for enhancing anaerobic digestion of municipal sludge: a horizontal comparison between temperature-phased and standalone thermophilic or mesophilic anaerobic digestion

This study evaluated the effect of pre-pasteurization (70 °C for 45 min) on the performance of temperature-phased anaerobic digestion (TPAD) in horizontal comparison with standalone mesophilic and thermophilic anaerobic digestion (AD). The results suggested that existing pre-pasteurization system in...

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Bibliographic Details
Published in:Environmental science water research & technology 2020-12, Vol.6 (12), p.3316-3325
Main Authors: Zhang, Dian, Santha, Hari, Pallansch, Karen, Novak, John T., Wang, Zhi-Wu
Format: Article
Language:English
Subjects:
Anaerobic digestion
Anaerobic processes
Anaerobic treatment
Biodegradability
Biodegradation
Biosolids
Carbohydrates
Chemical oxygen demand
Digestion
Hydrolysis
Methane
Municipal wastes
Odor control
Odors
Odour
Organic matter
Pasteurization
Pathogens
Pretreatment
Process intensification
Reduction
Refuse as fuel
Sludge
Sludge digestion
Temperature
Utilities
Volatile solids
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Summary:This study evaluated the effect of pre-pasteurization (70 °C for 45 min) on the performance of temperature-phased anaerobic digestion (TPAD) in horizontal comparison with standalone mesophilic and thermophilic anaerobic digestion (AD). The results suggested that existing pre-pasteurization system installed in utilities for the purpose of pathogen reduction can function in a similar way as the thermal hydrolysis pretreatment being implemented across the world for AD process intensification. For this reason, pre-pasteurization substantially increased soluble organic matter concentrations in terms of soluble chemical oxygen demand, protein, and carbohydrate by 22, 59, and 43%, respectively, and thus improved methane production, solids reduction, sludge dewaterability, and biosolids odor reduction. However, also because of the sludge biodegradability improvement by pre-pasteurization, high-rate AD such as the thermophilic phase of TPAD was subjected to extensive souring problem during startup which can be remedied by slow pace of SRT reduction and buffer addition. In spite of this challenge, upon arriving at steady state, the TPAD system fed with pre-pasteurized sludge outperformed all other AD processes, leading to at least 21% higher normalized methane production rate and 10% more volatile solids reduction.
ISSN:2053-1400
2053-1419
DOI:10.1039/D0EW00633E