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Effects of hydrodynamic cavitation, low-level thermal and low-level alkaline pre-treatments on sludge solubilisation

TitoloEffects of hydrodynamic cavitation, low-level thermal and low-level alkaline pre-treatments on sludge solubilisation
Tipo di pubblicazioneArticolo su Rivista peer-reviewed
Anno di Pubblicazione2019
AutoriMancuso, G., Langone M., Andreottola G., and Bruni L.
RivistaUltrasonics Sonochemistry
Parole chiaveAlkaline treatment, alkalinity, Anaerobic digestion, article, calcium hydroxide, Cavitation, Chemical consumption, Combined pre treatments, cytolysis, Cytometric analysis, Disintegration, energy efficiency, hazardous waste, health hazard, Health risks, Human health risks, Hydrated lime, Hydrodynamic cavitations, hydrodynamics, pH, Potassium hydroxide, priority journal, Sludge digestion, Sludge stabilization, sludge treatment, Sodium hydroxide, Solubilisation, Solubility, Temperature, Wastewater treatment

WAS is a polluting and hazardous waste generated in WWTPs that must be treated to prevent pollution and human health risks. Anaerobic digestion is the most used process for sludge stabilization. However, it must be improved in terms of both speed and extend of degradation. With the purpose of reducing the energy and chemical consumption linked to sludge treatment, in this study, different anaerobic digestion pre-treatments such as low-level mechanical (hydrodynamic cavitation, 2 bar), low-level thermal (50 °C) and low-level alkaline (NaOH, KOH and Ca(OH)2, pH 10) methods, and a combination thereof, were tested as strategies to improve sludge solubilisation. When the pre-treatments were used alone, the alkaline pre-treatment showed the highest sludge solubilisation. Among the alkaline reagents tested, NaOH and KOH led to higher DDPCOD (41.6 and 39.4%), while only 8.4% was achieved by using Ca(OH)2. However, the low-level hydrodynamic cavitation assisted thermo-alkaline pre-treatment was the most efficient in terms of both sludge solubilisation (DDPCOD = 53.0%) and energy efficiency (EE = 64.5 mgΔSCOD kJ−1). The synergetic effects of the combined pre-treatment were also confirmed by the highest release of EPS. Furthermore, cytometric analyses showed that the main mechanism involved in sludge solubilisation for the investigated pre-treatments was flocs disintegration rather than cell lysis. © 2019 Elsevier B.V.


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Citation KeyMancuso2019