Treatability of chromite ore processing waste by leaching

Developing treatment and disposal strategies and health-based clean-up standards for chromium containing wastes continues to be an important environmental regulatory issue because of the opposing solubility and toxicity characteristics of chromium species under diverse environmental conditions. In this study, leaching characteristics of total Cr and Cr(VI) were investigated using laboratory column studies. The data obtained from the experimental studies were analysed to assess the treatability of chromite ore processing waste (COPW) by leaching and to identify the leaching strategies that enhance mass removal rates of chromium species. COPW used for laboratory soil column studies was obtained from an industrial plant producing sodium chromate in Mersin, Turkey. Laboratory investigations involved chemical characterisation of waste material and column studies. For waste characterisation, U.S. EPA toxicity characterisation leaching procedure (TCLP) was performed on COPW to determine the concentrations of metal species in the TCLP extract. For column studies, various laboratory columns containing plain COPW material, 1:1 COPW/reducing agent (elemental iron or manure) mixture and different type soils (sand, loam and clay) overlain by COPW were subjected to leaching tests using acidic, neutral and alkaline influent water to deter, mine Cr mass leaching efficiencies. Based on the TCLP analyses, COPW is classified as hazardous waste. As a result of comparing the leaching efficiency data from twelve leaching columns, the maximum removal of total Cr was achieved by leaching COPW/manure mixture using acidic (pH 4.78) influent water. The highest Cr(VI) leaching efficiency was achieved in the columns of plain COPW and COPW/manure mixture using highly alkaline (pH 12.0) influent water. The least effective leaching efficiency for both total Cr and Cr (VI) was obtained by leaching plain COPW with neutral (pH 7.0) influent water. Land-disposal of the treated COPW material by mixing with clayey soils seems to be a viable alternative.


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The potential for groundwater contamination by metals leaching from land-disposed oil field exploration and production (E&P) wastes is an environmental concern. In this study a geochemical transport model is adopted to consider multispecies metal migration. Objectives are to characterize the chemical composition of E&P wastes, to evaluate the mobility and pollution potential of metals in E&P wastes and to investigate the utility of simplified modelling approaches. A chemical transport model coupling a hydro...
Modeling natural attenuation of petroleum hydrocarbons (btex) in heterogeneous aquifers
Uçankuş, Tuğba; Ünlü, Kahraman; Department of Environmental Engineering (2005)
Natural Attenuation can be an effective cleanup option for remediation of Groundwater contamination by BTEX. One of the important aspects of the methodology that has been recognized recently is that mass removal rates, the most important parameters used to determine effectiveness of the methodology, is controlled by groundwater flow regime, which to a large extent controlled by aquifer heterogeneity. Considering this recognition, the primary objective of this research is to quantitatively describe the relat...
Treatability and toxicity of nonylphenol compounds in anaerobic batch reactors
Bozkurt, Hande; Sanin, Faika Dilek; Department of Environmental Engineering (2011)
Nonylphenol (NP) and its ethoxylates are used in formulation of pesticides and detergents, production of personal care products and many industrial sectors such as textile, metal plating, plastic, paper and energy. They are also used in the formulation of household cleaning agents. Industrial uses in the production line make up 55% of the total use; whereas industrial and domestic cleaning processes constitute 30 and 15%, respectively. Since they are widely used in industry and households, NP compounds ente...
Identification of waste management strategies and waste generation factors for thermal power plant sector wastes in Turkey
Demir, Cansu; Yetiş, Ülkü; Ünlü, Kahraman (SAGE Publications, 2019-03-01)
Thermal power plants are of great environmental importance in terms of the huge amounts of wastes that they produce. Although there are process-wise differences among these energy production systems, they all depend on the logic of burning out a fuel and obtaining thermal energy to rotate the turbines. Depending on the process modification and the type of fuel burned, the wastes produced in each step of the overall process may change. In this study, the most expected process and non-process wastes stemming ...
Assessment of PCB contamination, the potential for in situ microbial dechlorination and natural attenuation in an urban watershed at the East Coast of the United States
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Sediment contamination is a major environmental issue in many urban watersheds and coastal areas due to the potential toxic effects of contaminants on biota and human health. Characterizing and delineating areas of sediment contamination and toxicity are important goals of coastal resource management in terms of ecological and economical perspectives. Core and surficial sediment samples were collected from an industrialized urban watershed at the East Coast of the United Stated and analyzed to evaluate the ...
Citation Formats
K. Ünlü, “Treatability of chromite ore processing waste by leaching,” WASTE MANAGEMENT & RESEARCH, pp. 217–228, 2001, Accessed: 00, 2020. [Online]. Available: