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Barcelona, Spain

Coma M.,University of Girona | Coma M.,Ghent University | Rovira S.,GS Inima | Canals J.,GS Inima | Colprim J.,University of Girona
Water Science and Technology | Year: 2015

Integrated processes to reduce in situ the sludge production in wastewater treatment plants are gaining attention in order to facilitate excess sludge management. In contrast to post-treatments, such as anaerobic digestion which is placed between the activated sludge system and dewatering processes, integrated technologies are placed in the sludge return line. This study evaluates the application of an anoxic side-stream reactor (SSR) which creates a physiological shock and uncouples the biomass metabolism and diverts the activity from assimilation for biosynthesis to non-growth activities. The effect of this system in biological nutrient removal for both nitrogen and phosphorus was evaluated for the anaerobic, anoxic and aerobic reactors. The RedOx potential within the SSR was maintained at - 150 mV while the sludge loading rate was modified by increasing the percentage of recycled activated sludge feed to the SSR (0 and 40% at laboratory scale and 0, 10, 50 and 100% at pilot scale). The use of the SSR presented a slight reduction of phosphorus removal but maintained the effluent quality to the required discharge values. Nitrogen removal efficiency increased from 75 to 86% while reducing the sludge production rate by 18.3%. © IWA Publishing 2015. Source


Coma M.,University of Girona | Rovira S.,GS Inima | Canals J.,GS Inima | Colprim J.,University of Girona
Bioresource Technology | Year: 2013

This study evaluates the application of an anoxic side-stream reactor in the sludge return line of a conventional activated sludge system for the reduction of biomass production. The oxidation-reduction potential was maintained at -150mV while the applied sludge loading rate was modified by changing the percentage of return sludge treated in this reactor. The observed yield from the conventional system (0.513kg VSSkg-1 COD) was continuously reduced when the portion of return sludge treated was increased. A maximum reduction of 18.3% of the observed yield was obtained treating the whole sludge return line. The sludge age maintained through the experiment. The organic matter removal was not deteriorated, even improved, by the proposed plant modification. Thus, simply applying an anoxic side-stream reactor would decrease the final volume of waste sludge while maintaining the sludge retention time and would, in fact, decrease the economic costs in terms of sludge handling. © 2012 Elsevier Ltd. Source

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