Title: Treatment of waste activated sludge by means of alkaline hydrolysis under 'mild' conditions

Authors: Maria Cristina Collivignarelli; Marco Sordi; Alessandro Abbà; Federico Castagnola; Giorgio Bertanza

Addresses: Department of Civil Engineering and Architecture, University of Pavia, via Ferrata 1, 27100, Pavia, Italy ' Department of Civil Engineering and Architecture, University of Pavia, via Ferrata 1, 27100, Pavia, Italy ' Department of Civil Engineering and Architecture, University of Pavia, via Ferrata 1, 27100, Pavia, Italy ' Department of Civil Engineering and Architecture, University of Pavia, via Ferrata 1, 27100, Pavia, Italy ' Department of Civil, Environmental, Architectural Engineering and Mathematics, University of Brescia, via Branze 43, 25123, Brescia, Italy

Abstract: Proper strategies for reducing the sludge production are a key factor for a correct wastewater treatment plant (WWTP) management. This paper describes an experimental study on sludge thermal alkaline hydrolysis under mild conditions (temperatures from 40 to 70 °C and pH up to 11.5), aimed at sludge minimisation. Tested biological sludge derived from two different WWTPs that treat urban and mixed urban/industrial wastewater, respectively. The experimental results showed: 1) an increase of soluble COD in sludge supernatants; 2) very good biodegradability of the supernatants; 3) improved settleability and dewaterability of treated sludge. The best results were obtained under the following conditions, using lime milk: 70°C, pH 10.0-10.5, contact time 3h.

Keywords: alkaline hydrolysis; thermal treatment; sludge minimisation; COD solubilisation; dewaterability; waste activated sludge; wastewater treatment; soluble COD; chemical oxygen demand; biodegradability; lime milk.

DOI: 10.1504/IJGW.2017.082777

International Journal of Global Warming, 2017 Vol.11 No.3, pp.305 - 316

Received: 01 Dec 2014
Accepted: 26 Jun 2015
Published online: 12 Mar 2017 *

Full-text access for editors Full-text access for subscribers Purchase this article Comment on this article