Browsing by Author "Centre for Environmental Health Toxicology"
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Publication Metadata only Use of Power Plant Ash to Remove and Solidify Heavy Metals from a Metal-finishing Wastewater(2009-01-01) P. Fongsatitkul; P. Elefsiniotis; N. Khuhasawan; R. Jindal; Mahidol University; Centre for Environmental Health Toxicology; University of Auckland© 2009, Springer Science+Business Media B.V. All Right Reserved. This laboratory-scale study investigated initially the potential of heavy metal removal from a metal-finishing wastewater using fly and bottom ash from a power plant as coagulants. It was found that the maximum heavy metal content in the ash–sludge mix was obtained at a fly ash-to-bottom ash ratio of 1.5:1 and a stirring time of 3 h, which resulted in heavy metal removal (i.e., Cr, Ni, Cu, Zn, Cd, and Pb) in excess of 99%, with effluent concentrations below the corresponding regulatory standards of Thailand. Furthermore, the feasibility of using fly ash as an admixture to stabilize and solidify the ash–sludge mix generated previously was explored. Results indicated that the stabilization/solidification process can achieve a high level of heavy metal removal efficiency from the ash–sludge mix. The optimum ratio regarding chromium leaching was found to be 1:0.75:0.75 (cement:fly ash:ash–sludge). In addition, the compressive strength and the chromium leaching concentration of the solidified sludge were within acceptable levels for secure landfill disposal and/or use as a construction material.Publication Metadata only Use of rice husk ash as an admixture to remove chromium from a tannery waste(2011-09-01) Prayoon Fongsatitkul; Panagiotis Elefsiniotis; Duangta Kitkaew; Chaiwat Rungsipanodorn; Mahidol University; Centre for Environmental Health Toxicology; University of Auckland; Department of Construction ManagementThis laboratory-scale study explored the use of rice husk ash (RHA) as an admixture to stabilize and solidify the waste sludge from a chrome-tanning process. Various ratios of RHA and tannery sludge were used, ranging from 0.25 to 1.0 by weight of the cement content, resulting in an experimental matrix of 16 runs. It was observed that although the compressive strength of solidified sludge improved at longer curing times, the increase was moderate after 7 days of curing. In addition, higher RHA and/or sludge ratios progressively reduced the strength of the samples. On the other hand, curing time had a positive effect on chromium leachability since the leaching concentration decreased considerably with an increase in curing time, up to 28 days. Furthermore, both the RHA and/or sludge content affected leachability, producing acceptable results, from a Thai regulatory perspective, at ratios of 0.50 or lower. Finally, the solidified sludge can be disposed of in a secure landfill and/or used as a construction material in a number of applications. © 2010 Springer Science+Business Media B.V.
