Sewage sludge treatment in a thermophilic membrane reactor (TMR): factors affecting foam formation.
Foam formation in the excess sludge treatment facilities of biological wastewater treatment plants (WWTPs) may represent a critical issue as it could lead to several operative problems and reduce the overall plant performance. This trouble also affects a novel technology recently proposed for sludge minimization, the thermophilic membrane reactor (TMR), operating with alternate aeration/non-aeration cycles. This technology, which has proven to be extremely resilient and suitable for treating industrial wastewater of different nature, demonstrated a high potential also as a solution for integrating existing WWTPs, aiming at the "zero sludge production." In this work, an experimental study was conducted with a TMR pilot plant (fed daily with thickened sewage sludge) by adjusting the duration of aeration/non-aeration alternate cycles. Extracellular polymeric substance (EPS) concentration (and its soluble and bound fractions) has been monitored along with foaming power indices. The results highlight that foaming can be correlated to the presence of soluble protein fraction of EPS. Moreover, EPS production seems to be reduced by increasing the duration of the non-aeration cycles: optimal operating conditions resulted 2 h of aeration followed by 6 h of non-aeration. These conditions allow to obtain an EPS concentration of 500 mg L-1with respect to 2300 mg L-1measured at the beginning of experimental work.
Department of Civil Engineering and Architecture, University of Pavia, via Ferrata 1, 27100, Pavia, Italy. mcristina.collivignarelli@unipv.it.
Maria Cristina
http://orcid.org/0000-0002-0497-9354
MC
Collivignarelli
Department of Civil Engineering and Architecture, University of Pavia, via Ferrata 1, 27100, Pavia, Italy.
Federico
F
Castagnola
Department of Civil Engineering and Architecture, University of Pavia, via Ferrata 1, 27100, Pavia, Italy.
Marco
M
Sordi
Department of Civil, Environmental, Architectural Engineering, and Mathematics, University of Brescia, via Branze 43, 25123, Brescia, Italy.
Giorgio
G
Bertanza
D019149:Bioreactors; D011108:Polymers; D012722:Sewage; D014865:Waste Disposal, Fluid; D062065:Wastewater
D011108:Polymers; D012722:Sewage; D062065:Wastewater
EPS; Foaming; MBR; Sludge minimization; Thermophilic treatment