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Bergamo, Italy

Bertanza G.,University of Brescia | Zanaboni S.,University of Pavia | Canato M.,University of Pavia | Laera G.,CNR Water Research Institute | Galessi R.,3V Green Eagle SpA
International Journal of Global Warming | Year: 2014

Today, several technologies and management strategies are proposed and applied in WWTPs to minimise sludge production and contamination and their techno-economic feasibility has to be carefully evaluated. In this work (which is being conducted within the European Union project 'ROUTES), based on bench results, a mass balance was drawn for a WWTP (500,000 PE), where it was supposed to install a wet oxidation (WO) stage for sludge minimisation. The design of treatment units and the estimation of capital and operation costs were then performed. Subsequently, a procedure for technical-economic assessment was developed. Basically, this procedure consists in the definition and ranking of several technical (e.g., reliability of the technology, complexity and integration with the existing facilities, amount of residues to be disposed of or recovered, etc.) and economic aspects. Preliminary results have shown WO to be a suitable solution for sludge minimisation. Copyright © 2014 Inderscience Enterprises Ltd. Source

Slavik E.,3V Green Eagle SpA | Galessi R.,3V Green Eagle SpA | Rapisardi A.,3V Green Eagle SpA | Salvetti R.,3V Green Eagle SpA | And 5 more authors.
Drying Technology | Year: 2015

In this article, the effectiveness of an advanced sludge treatment technology (Wet Oxidation, WO) is presented by analyzing experimental studies at the lab scale and data collected during years of industrial-scale activities. The data showed good performances of WO on COD and VSS removal efficiencies—about 65–70% and 95–98%, respectively—and the effect of operating parameters (i.e., temperature and reaction time) on process efficiencies was highlighted. The energy balance of the WO systems indicated that about 90% of the energy entering the system may be recovered. Finally, a techno-economic assessment showed that WO can be a suitable solution for sludge treatment and minimization. © 2015, Copyright © Taylor & Francis Group, LLC. Source

Bertanza G.,University of Brescia | Canato M.,University of Brescia | Heimersson S.,Chalmers University of Technology | Laera G.,stituto di Ricerca sulle Acque | And 3 more authors.
Environmental Science and Pollution Research | Year: 2015

Today, several technologies and management strategies are proposed and applied in wastewater treatment plants (WWTPs) to minimise sludge production and contamination. In order to avoid a shifting of burdens between different areas, their techno-economic and environmental performance has to be carefully evaluated. Wet oxidation (WO) is an alternative solution to incineration for recovering energy in sewage sludge while converting it to mostly inorganic residues. This paper deals with an experimentation carried out within the EU project “ROUTES”. A mass balance was made for a WWTP (500,000 person equivalents) in which a WO stage for sludge minimisation was considered to be installed. Both bench- and full-scale test results were used. Design of treatment units and estimation of capital and operational costs were then performed. Subsequently, technical and economic aspects were evaluated by means of a detailed methodology which was developed within the ROUTES project. Finally, an assessment of environmental impacts from a life cycle perspective was performed. The integrated assessment showed that for the specific upgrade considered in this study, WO technology, although requiring a certain increase of technical complexity at the WWTP, may contribute to environmental and economic advantages. The paper provides guidance in terms of which aspects need a more thorough evaluation in relation to the specific case in which an upgrade with WO is considered. © 2014, Springer-Verlag Berlin Heidelberg. Source

Bertanza G.,University of Brescia | Galessi R.,3V Green Eagle SpA | Menoni L.,University of Brescia | Pedrazzani R.,University of Brescia | And 2 more authors.
Environmental Science and Pollution Research | Year: 2015

Wet Oxidation (WO) of sewage sludge is a chemical oxidation of sludge at high temperatures and pressures by means of an oxygen-containing gas. The liquid stream originated by WO is easily biodegradable, and therefore, the recirculation to the biological Waste Water Treatment Plant (WWTP) may be a feasible solution. However, the WO effluent has a residual organic and nitrogen content so that its treatment may be required when the receiving WWTP has no surplus treatment capacity left. The aim of this research was the assessment of the anaerobic treatability of the WO liquid residue, in order to reduce the organic load to be recirculated to the WWTP, simultaneously promoting energy recovery. For this purpose, the liquid residue obtained during full scale WO tests on two different types of sludge was submitted to anaerobic digestion in a continuous flow pilot reactor (V = 5 L). Furthermore, batch tests were carried out in order to evaluate possible inhibition factors. Experimental results showed that, after the start-up/acclimation period (~130 days), Chemical Oxygen Demand (COD) removal efficiency was stably around 60 % for about 120 days, despite the change in operating conditions. In the last phase of the experimental activity, COD removal reached 70 % under the following treatment conditions: Hydraulic Retention Time (HRT) = 20 days, Volumetric Organic Loading Rate (VOLR) = 0.868 kg COD/m3/day, Organic Loading Rate per Volatile Suspended Solids (OLRvss) = 0.078 kg COD/kg VSS/day, temperature (T) = 36.5 °C, pH = 8. Energy balance calculation demonstrated anaerobic treatment sustainability. © 2014, Springer-Verlag Berlin Heidelberg. Source

Bertanza G.,University of Brescia | Galessi R.,3V Green Eagle SpA | Menoni L.,University of Pavia | Zanaboni S.,University of Pavia
Desalination and Water Treatment | Year: 2016

In the last years, sewage sludge management turned out to be a topic of great interest due to the increasing sludge production and the high cost of sludge treatment and disposal. In this context, several methods are being studied for sewage sludge minimization: among them, wet oxidation (WO) was proposed as an effective hydrothermal oxidation based technology. The aim of this work, carried out within the European project “ROUTES,” was the assessment of the influence of sludge composition on process performance: for this purpose, seven different types of sewage sludge were submitted to WO tests at lab scale. Moreover, each operating condition (temperature, reaction time, and initial oxygen pressure) was varied so as to highlight the effect of process parameters on oxidation efficiency; this was essentially evaluated in terms of chemical oxygen demand (COD), volatile suspended solid (VSS) and total suspended solid (TSS) reduction. COD and VSS abatement varied in the ranges 44–85%, 71–99% depending on reaction time (15–120 min) and 22–79%, 54–99% as a function of temperature (200–250°C), respectively. Furthermore, by comparing WO tests results of the seven types of sludge obtained under the same treatment conditions (temperature = 250°C and reaction time = 60 min), it was highlighted that VSS and COD removal efficiency can be correlated to the initial VSS/TSS ratio. © 2015 Balaban Desalination Publications. All rights reserved. Source

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