Exergy analysis of cavitation pretreatment of sludge

Abstract

A number of papers present exergy analyses of various wastewater treatment systems. The current development of these systems is mainly aimed at improving their energy efficiency, reducing the share of sludge subject to storage, and reducing their harmfulness. Some of these systems can be supported by the use of the cavitation phenomenon in the processing. The generation of cavitation requires, however, the use of devices or machines and thus additional energy consumption. Therefore, this treatment should be objectively justified, e.g. through exergy analysis, which takes into account not only the amount of energy used in processes, but also its quality. The paper treats the methodology for determining the impact of the use of cavitation in the exergy balance of sewage sludge treatment system. Then, it presents the results of an exemplary analysis comparing sewage sludge treatment systems (with and without application of cavitation phenomenon) in which biogas is produced during the fermentation, then burned in a co-generator, finally receiving useful energy in the form of electric current and hot flue gas stream.

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“…Although the exergy study in wastewater is limited, there is research that supports its potential: as is the case of (Rózẏcki & Banaś2018), who compared two wastewater treatment systems through an exergy analysis, determining energy efficiency in the development of treatments and the reduction of harmfulness; similar case (Vakalis et al 2017) evaluated the chemical exergy in four different methods for the removal of heavy metals from industrial wastewater, determining the removal of more than 96% of two of the metals studied.…”