A Multi Expert Decision Support Tool for the Evaluation of Advanced Wastewater Treatment Trains: A Novel Approach to Improve Urban Sustainability

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.Wastewater Treatment (WWT) for water reuse applications has been accepted as a strategic solution in improving water supplies across the globe; however, there are still various challenges that should be overcome. Selection of practical solutions is then required whilst considering technical, environmental, socio-cultural, and financial factors. In this study, a multi expert decision support tool that considers a variety of evaluation criteria is proposed to provide a ranking system for competing advanced WWT technologies in terms of their performance. Two scenarios of water reuse in the contexts of Brazil and Greece are defined, and evaluation is undertaken based on opinions of water reuse experts. The results prove that the tool would successfully facilitate rigorous and methodical analysis in evaluation of WWT technologies for water reuse applications with potential for use under various sets of evaluation criteria, WWT technologies and contexts

Removal of hexavalent chromium of contaminated soil by coupling electrokinetic remediation and permeable reactive biobarriers

PURPOSE: In this study, a novel and ecological alternative have been developed to treat soils contaminated with hexavalent chromium coupling two well-known systems: electrokinetic remediation and permeable reactive biobarriers. The electric field promotes the electromigration of the hexavalent chromium oxyanions towards the anode. The biobarriers were placed before the anode electrode, in order to promote the reduction and retention of the chromium migrating in its direction. Thus, this technology provided a global treatment to soil removal without subsequent treatments of the contaminated effluents. METHODS: The electrokinetic system was coupled with two different permeable reactive biobarriers composed by Arthrobacter viscosus bacteria, supported either in activated carbon or zeolite. An electric field of 10 V was applied and two different treatment times of 9 and 18 days were tested. RESULTS: Removal values of 60% and 79% were obtained when electrokinetic treatment was coupled with zeolite and activated carbon biobarriers, respectively, for a test period of 18 day. The reduction of hexavalent chromium to trivalent chromium was around 45% for both systems. CONCLUSIONS: In this work, two types of biobarriers were efficiently coupled to electrokinetic treatment to decontaminate soil with Cr(VI). Furthermore, the viability of the new coupling technology developed (electrokinetic + biobarriers) to treat low-permeability polluted soils was demonstrated.This work was supported by the Spanish Ministry of Science and Innovation (CTQ2008-03059/PPQ), Xunta de Galicia (08MDS034314PR). The authors are grateful to the Spanish Ministry of Science and Innovation for providing financial support for Marta Pazos under the Ramon y Cajal program and the Fundacao para a Ciencia e Tecnologia, Ministerio da Ciencia e Tecnologia, Portugal through the PhD grant of Bruna Fonseca (SFRH/BD/27780/2006)

effects of zeolite and silica fumes on the mechanical and leaching performance of a cementitious system containing metal nitrates

The objective of this paper is to examine the effect of Cr, Mn, Pb, and Zn, on the mechanical and leaching characteristics of cement-based materials. Three different matrices (i) Portland cement, (ii) Portland cement and silica fume, and (iii) Portland cement and natural zeolites, were investigated. The results of both mechanical and leaching tests showed the importance of the contaminant/matrix pair considered. The setting time was reduced in presence of chromium and delayed in presence of manganese, lead and zinc. Although the early strength development was quite affected in presence of all four contaminants, the long-term strength was comparable to the controls. From 56 days of curing onwards, partial replacement of cement by silica fume was proven to increase the strength of all materials. Conversely, zeolite replacement reduced strength compared to the cement matrix, which was attributed to the high water/binder ratio used. The increased strength and reduced ANC observed in presence of silica fume, are both due to the pozzolanic reaction, which consumes portlandite to form CSH

Effects of foundry dusts on the mechanical, microstructural and leaching characteristics of a cementitious system

The disposal or recycling of industrial wastes has been an important and complex issue for the last 20 years. Hydraulic binders have been widely use to treat and/or reuse waste materials. Synthetic wastes are commonly studied but it does eliminate synergistic waste/binder interference effects that can result from real wastes, which are often composed of complex chemical compounds. The objective of this research was to investigate the possibility of reusing waste from the foundry industry. For this purpose, 3 wastes from foundry plants have been selected based on their common metal contaminants. Therefore, the objective of this paper is to investigate the effects of the major metal contaminants, Pb, Zn and Mn, on the mechanical (setting time, unconfined compressive strength (UCS)) microstructural (X-ray diffractometry (XRD)) and leaching characteristics (acid neutralisation capacity test) of the solidified waste materials. The results showed that the addition of the wastes induced a retardation of the setting time, which is believed to be due to the presence of Zn, which is a known retardant. It was also revealed that, at equal water/cement ratio and after 28 days, the UCS of most waste products is within ±10% of the controls. The mineralogical composition, as depicted by the XRD results, was particularly affected as shown by the clear increase of the non-hydrated products. Finally, the addition of the different wastes was shown to have no effect on the buffering capacity of the solidified products