Authors: Maria Cristina Collivignarelli Federico Castagnola Marco Sordi Giorgio Bertanza
Publish Date: 2016/11/04
Volume: 24, Issue: 3, Pages: 2316-2325
Abstract
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/nonaeration 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/nonaeration 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 nonaeration cycles optimal operating conditions resulted 2 h of aeration followed by 6 h of nonaeration These conditions allow to obtain an EPS concentration of 500 mg L−1 with respect to 2300 mg L−1 measured at the beginning of experimental work
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