Sabina Kolbl Repinc , Gašper Rak , Blaž Stres , Uroš Novak , Blaž Likozar , Anže Prašnikar , Marko Blagojevič , Benjamin Bizjan
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Pretreatment of waste activated sludge by rotational generator of hydraulic shock
This study investigates hydrodynamic performance of a novel sludge pretreatment device based on periodic shock wave generation by a hydraulic hammer mechanism. A falling circular jet of thickened waste activated sludge was repeatedly impacted by a rotating blade, resulting in occurrence of hydraulic shock waves within the liquid region adjacent to the impact. The rotational generator of hydraulic shock (RGHS) treating 10 L of waste activated sludge was operated for 30 liquid passes and at two different rotational speeds producing blade impact velocities of 44 m/s and 70 m/s, respectively. At 70 m/s impact velocity and 30 passes, the device was able to achieve 41.3 % disintegration degree (DD), specific energy consumption (SEC) of 10.4 kWh/kg sCOD released and 9.0 % improvement of produced methane volume over unprocessed sample. Corresponding values for 44 m/s impact regime were DD = 18.7 %, SEC = 8.03 kWh/kg sCOD released and 33.1 % improvement in methane production. In both pretreatment regimes, sludge shear-dependent viscosity was reduced by about 60 %, while physicochemical analysis, FTIR spectra revealed substantial structural changes in WAS, namely median particle size reduction, degradation of proteins and polysaccharides, and microbial cell wall damage, what was notable also on SEM images. Compared to other rotary devices, the novel RGHS can achieve relatively high degree of sludge disintegration while consuming significantly less energy for sludge solubilization, and for methane production enhancement.
期刊介绍:
Ultrasonics Sonochemistry stands as a premier international journal dedicated to the publication of high-quality research articles primarily focusing on chemical reactions and reactors induced by ultrasonic waves, known as sonochemistry. Beyond chemical reactions, the journal also welcomes contributions related to cavitation-induced events and processing, including sonoluminescence, and the transformation of materials on chemical, physical, and biological levels.
Since its inception in 1994, Ultrasonics Sonochemistry has consistently maintained a top ranking in the "Acoustics" category, reflecting its esteemed reputation in the field. The journal publishes exceptional papers covering various areas of ultrasonics and sonochemistry. Its contributions are highly regarded by both academia and industry stakeholders, demonstrating its relevance and impact in advancing research and innovation.