María Auxiliadora Vázquez

Stabilization of fly ash using cementing bacteria. Assessment of cementation and trace element mobilization

Fly ash from municipal solid waste incineration (MSWI) was treated with microorganisms (Sporosarcina pasteurii and Myxococcus xanthus) to assess their capacity for cementing this waste material. Leaching tests on the samples treated with bacteria were also performed to assess the possibility of recovering and recycling trace elements from the fly ash. Sequential extractions combined with mineralogical studies demonstrated that Pb is mobile in water when associated with portlandite. Also, Cd, Pb, and Zn are primarily associated with carbonates and are mobile in acidic environments (up to 4.8, 13.9 and 248mg/l of Cd, Pb and Zn, respectively, extracted with acetic acid). Microbial treatment of the fly ash, especially with Sporosarcina pasteurii, led to its cementation and stabilization, preventing its dispersion into the environment. But samples treated with bacteria exhibited a higher capacity for trace element leaching than did untreated fly ash. The ability of these bacteria to mobilize metals can be applied to recover those of economic interest. The use of low cost biotechnologies can be an alternative to chemical treatments currently utilized for the recovery and reuse of these wastes.

Real-Time Diagnosis of Historical Artworks by Laser-Induced Fluorescence

Laser-induced fluorescence (LIF) is a powerful remote analysis tool that has been successfully applied to the real-time diagnosis of historical artworks, allowing the observation of features invisible to the naked eye, as pigment composition, biological attack and restoration technique. This paper presents a LIF-based optical radar and reports on the results of its deployment during a field campaign conducted in February 2010 in Seville, Spain.

A new approach to the assessment of flooding and dampness hazards in cultural heritage, applied to the historic centre of Seville (Spain)

Flooding and dampness have caused considerable damage to historic towns and cities and have become more frequent in recent years. The aim of this paper is to analyse the hazards of flooding and dampness in historic cities to establish a methodology that prioritises preventive conservation actions and restorations. The case study concerns the historic centre of Seville (Spain) and parish churches built between the 13th and 18th centuries. Geographic information system (GIS) software has been used to assess hazards caused by flooding and dampness along with a Delphi consultation process surveying a multidisciplinary group of seven experts-archaeologists, geologists, chemists, architects, engineers and environmentalists-to gain a general overview of the hazards affecting each area of the city. Currently, the historic centre of Seville is at a very low risk of flooding due to the engineering works being undertaken to divert the river course. For flooding to occur, water levels would need to rise over 6 to 12m along the different sections of the defensive walls; as a result, the historic centre has not been flooded since 1961, when these defences broke. However, there is a continual presence of dampness due to the proximity of the river, the presence of underground water and the permeability of the subsoil, resulting in continual damage to the lower sections of the monuments studied. Hence, hazard maps of flooding and dampness need to be dovetailed. This new approach provides tools for decision-makers in the current crisis, allowing them to prioritise strategies that will minimise damage in a town, as the urban unit where territorial policies could be applied.