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Title: The influence of sewage sludge-derived organic matter on the mobility and speciation of heavy metals in colliery spoil
Author: Fairley Maureen A., M. A.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1999
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Sewage sludge and colliery spoil can be used in the reclamation of contaminated land. Heavy metals may be present in both spoil and sludge at higher than background levels. The decomposition of sewage sludge produces soluble organic molecules which can form complexes with heavy metals. The object of this thesis was to discover if authigenic metals in colliery spoil would be mobilised as a result of the presence of organic matter derived from sewage sludge. A laboratory experiment was conducted using 24 PVC columns (length 50 cm, diameter 6 cm) filled with colliery spoil (weight 1.8 kg) from the Dechmont Bing near Glasgow, Scotland. This spoil (acid-extractable metal concentrations in mg kg-1: zinc 426, lead 259, copper 60, nickel 42, cadmium 1.8, chromium 22, barium 307, magnesium 3400) has been used to reclaim the contaminated site of the nearby, former Hallside Steelworks. A rural sewage sludge (metal concentrations on dry matter basis in my kg-1: zinc 275, lead 70, copper 165, nickel 12, cadmium 2.2, chromium 12.7) was applied to 16 of the columns at the rate of 300 tonnes per hectare. The columns were irrigated with synthetic rainwater over a period of 15 months at a rate of 900 mm per annum. The leachate was analysed for heavy metals (Zn, Pb, Cu, Ni, Cd, Cr) pH and organic carbon. The concentration of zinc, and also of barium and magnesium, was higher in the leachate from sewage sludge-amended spoil columns (maximum enhancement; zinc 54 μg 1-1, barium 145 μg 1-1 and magnesium 108 μg 1-1) and the pH was lower. The concentration of organic carbon was not directly related to metal concentrations. The results show that the application of sludge to land can lead to enhanced metal levels in drainage water, and that the source of the metals may be authigenic. It was also found that heavy metals can be transported as adsorbed species on fine sediments.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available