Stimulating effect of hydrostatic pressure on ultrasonic sewage sludge treatment for COD solubilization and methane production

Mohammad Javad Bardi; Ammad Mahmood; Thomas Lippert; Jochen Bandelin; Konrad Koch

doi:10.1016/j.biortech.2022.126785

Stimulating effect of hydrostatic pressure on ultrasonic sewage sludge treatment for COD solubilization and methane production

Bioresour Technol. 2022 Mar:348:126785. doi: 10.1016/j.biortech.2022.126785. Epub 2022 Jan 31.

Authors

Mohammad Javad Bardi¹, Ammad Mahmood¹, Thomas Lippert², Jochen Bandelin³, Konrad Koch⁴

Affiliations

¹ Chair of Urban Water Systems Engineering, Technical University of Munich, Am Coulombwall 3, 85748 Garching, Germany.
² Chair of Urban Water Systems Engineering, Technical University of Munich, Am Coulombwall 3, 85748 Garching, Germany; Department of Civil and Environmental Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA.
³ Chair of Urban Water Systems Engineering, Technical University of Munich, Am Coulombwall 3, 85748 Garching, Germany; BANDELIN Electronic GmbH & Co. KG, Heinrichstraße 3 - 4, 12207 Berlin, Germany.
⁴ Chair of Urban Water Systems Engineering, Technical University of Munich, Am Coulombwall 3, 85748 Garching, Germany. Electronic address: k.koch@tum.de.

PMID: 35114367
DOI: 10.1016/j.biortech.2022.126785

Abstract

The performance of ultrasonic treatment was assessed under different hydrostatic pressures for two different waste activated sludges. The impact of pressurized sonication was evaluated based on the degree of disintegration (DD_COD) and the specific methane yield (SMY). An enhancement of DD_COD was observed at an intermediate pressure level (max. 53% at 1.0 bar), but at higher pressure levels (up to 3.5 bar), the enhancement was not as pronounced as for the intermediate ranges (max. 11%). In contrast to DD_COD, SMY increased with increasing pressure for both sludge samples tested (max 17% at 3.5 bar) so that SMY did not show a notable correlation with DD_COD. A positive energy balance (max. 167%) considering the energy input for ultrasonication and the additional methane generated was only achieved in samples treated under elevated hydrostatic pressure. Since this can be achieved with negligible effort, the enhancement can be considered as "methane for free".

Keywords: Energy-positive sewage sludge pretreatment; Hydrostatic pressure; Sludge disintegration; Specific methane production; Ultrasonic treatment.

MeSH terms

Anaerobiosis
Hydrostatic Pressure
Methane
Sewage*
Sonication
Ultrasonics*
Waste Disposal, Fluid

Substances

Sewage
Methane