Semra Çoruh

Municipal solid waste management strategies in Turkey

Municipal solid waste (MSW) is a major environmental problem in Turkey, as in many developing countries. Problems associated with municipal solid waste are difficult to address, but efforts towards more efficient collection and transportation and environmentally acceptable waste disposal continue in Turkey. Although strict regulations on the management of solid waste are in place, primitive disposal methods such as open dumping and discharge into surface water have been used in various parts of Turkey. This study presents a brief history of the legislative trends in Turkey for MSW management. The study also presents the MSW responsibility and management structure together with the present situation of generation, composition, recycling, and treatment. The results show that approximately 25 million ton of MSW are generated annually in Turkey. About 77% of the population receives MSW services. In spite of efforts to change open dumping areas into sanitary landfills and to build modern recycling and composting facilities, Turkey still has over 2000 open dumps.

Use of fly ash, phosphogypsum and red mud as a liner material for the disposal of hazardous zinc leach residue waste.

Increasing amounts of residues and waste materials coming from industrial activities in different processes have become an increasingly urgent problem for the future. The release of large quantities of heavy metals into the environment has resulted in a number of environmental problems. The present study investigated the safe disposal of the zinc leach residue waste using industrial residues such as fly ash, phosphogypsum and red mud. In the study, leachability of heavy metals from the zinc leach residue has been evaluated by mine water leaching procedure (MWLP) and toxicity characteristic leaching procedure (TCLP). Zinc removal from leachate was studied using fly ash, phosphogypsum and red mud. The adsorption capacities and adsorption efficiencies were determined. The adsorption rate data was analyzed according to the pseudo-second-order kinetic, Elovich kinetic and intra-particle diffusion kinetic models. The pseudo-second-order kinetic was the best fit kinetic model for the experimental data. The results show that addition of fly ash, phosphogypsum and red mud to the zinc leach residue drastically reduces the heavy metal content in the leachate and could be used as liner materials.

A comparison of the properties of natural clinoptilolites and their ion-exchange capacities for silver removal.

The aim of the present study is to investigate the removal of silver ions from aqueous solutions using natural clinoptilolites collected from Cankiri-Corum and Manisa-Gördes regions of Turkey. The optimum conditions for adsorption/ion exchange by using a batch method were evaluated by changing various parameters such as particle size, contact time, initial pH of the solution, adsorbent amount, initial metal concentration and acidic treatment. The Langmuir, Freundlich and Temkin adsorption isotherm equations were derived form the basic empirical equations, and used for calculation of adsorption parameters. The equilibrium data fit well the Freundlich and Langmuir isotherm. The adsorption capacities of Cankiri-Corum and Manisa-Gördes clinoptilolites as obtained from Langmuir isotherm were found to be 31.44 and 22.57 mg/g. The adsorption kinetic rates and metal recoveries were estimated by pseudo-first order, second order and intra-particle models.

Treatment of copper industry waste and production of sintered glass-ceramic

Copper waste is iron-rich hazardous waste containing heavy metals such as Cu, Zn, Co, Pb. The results of leaching tests show that the concentration of these elements exceeds the Turkish and EPA regulatory limits. Consequently, this waste cannot be disposed of in its present form and therefore requires treatment to stabilize it or make it inert prior to disposal. Vitrification was selected as the technology for the treatment of the toxic waste under investigation. During the vitrification process significant amounts of the toxic organic and inorganic chemical compounds could be destroyed, and at the same time, the metal species are immobilized as they become an integral part of the glass matrix. The copper flotation waste samples used in this research were obtained from the Black Sea Copper Works of Samsun, Turkey. The samples were vitrified after being mixed with other inorganic waste and materials. The copper flotation waste and their glass-ceramic products were characterized by X-ray analysis (XRD), scanning electron microscopy and by the toxicity characteristic leaching procedure test. The products showed very good chemical durability. The glass-ceramics fabricated at 850°C/2 h have a large application potential especially as construction and building materials.

Adsorption of basic dye from wastewater using raw and activated red mud

Red mud, an industrial by‐product generated during the processing of bauxite ore, was investigated as an inexpensive and effective adsorbent for the adsorption of methylene blue from aqueous solution. Chemical and heat treatments were applied to the raw red mud. The effects of contact time, adsorbent amount, pH, temperature and initial dye concentration were investigated. The adsorption isotherm and kinetics of the raw and activated red mud were studied. Freundlich, Temkin and Dubinin–Radushkevich isotherms were obtained using concentrations of methylene blue ranging from 10 to 70 mg/L. The results indicated that the Dubinin–Radushkevich model provides the best correlation of the experimental data. The adsorption rate data were analysed according to the pseudo‐first order kinetic, pseudo‐second order kinetic, intraparticle diffusion kinetic and Elovich kinetic models. The pseudo‐second order kinetic was the best fit kinetic model for the experimental data.

Immobilization of copper flotation waste using red mud and clinoptilolite

The flash smelting process has been used in the copper industry for a number of years and has replaced most of the reverberatory applications, known as conventional copper smelting processes. Copper smelters produce large amounts of copper slag or copper flotation waste and the dumping of these quantities of copper slag causes economic, environmental and space problems. The aim of this study was to perform a laboratory investigation to assess the feasibility of immobilizing the heavy metals contained in copper flotation waste. For this purpose, samples of copper flotation waste were immobilized with relatively small proportions of red mud and large proportions of clinoptilolite. The results of laboratory leaching demonstrate that addition of red mud and clinoptilolite to the copper flotation waste drastically reduced the heavy metal content in the effluent and the red mud performed better than clinoptilolite. This study also compared the leaching behaviour of metals in copper flotation waste by short-time extraction tests such as the toxicity characteristic leaching procedure (TCLP), deionized water (DI) and field leach test (FLT). The results of leach tests showed that the results of the FLT and DI methods were close and generally lower than those of the TCLP methods.

Production of brown and black pigments by using flotation waste from copper slag

One of the major problems in copper-producing countries is the treatment of the large amount of copper slag or copper flotation waste generated from copper slag which contains significant amounts of heavy metals such as Cu, Zn, Pb and Co. Dumping or disposal of such large quantities of flotation waste from copper slag causes environmental and space problems. In this study, the treatment of flotation waste from copper slag by a thermal method and its use as an iron source in the production of inorganic brown and black pigments that are used in the ceramic industry were investigated. The pigments were produced by calcining different amounts of flotation waste and chromite, Cr2O3, ZnO and CoO mixtures. The pigments obtained were added to transparent ceramic glazes and porcelainized tile bodies. Their colours were defined by L*a*b* measurements with a spectrophotometer. The results showed that flotation waste from copper slag could be used as an iron source to produce brown and black pigments in both ceramic body and glazes.

Adsorption of copper (II) ions on montmorillonite and sepiolite clays: equilibrium and kinetic studies

Abstract The removal of Cu(II) with montmorillonite and sepiolite clays in aqueous solutions has been studied. The optimum conditions for adsorption using a batch method were evaluated by changing various parameters such as contact time, adsorbent amount, initial pH of the solution and initial metal concentration. The equilibrium adsorption data were analyzed by Langmuir, Freundlich and Temkin adsorption isotherm models. By comparing the Akaike’s Information Criterion (AIC) and the sum of error squared (SSE) of these models in the three kinetic systems. The Freundlich isotherm best describe the adsorption of Cu(II) on montmorillonite and sepiolite. The adsorption kinetic data were modeled using the Lagergren-fi rst order, pseudo-second order, and Elovich. Adsorption data of the Cu(II) were fi tted well by the Elovich model. The results indicate that montmorillonite and sepiolite are good adsorbents for Cu(II) in aqueous solutions.

Statistical evaluation and optimization of factors affecting the leaching performance of copper flotation waste.

Copper flotation waste is an industrial by-product material produced from the process of manufacturing copper. The main concern with respect to landfilling of copper flotation waste is the release of elements (e.g., salts and heavy metals) when in contact with water, that is, leaching. Copper flotation waste generally contains a significant amount of Cu together with trace elements of other toxic metals, such as Zn, Co, and Pb. The release of heavy metals into the environment has resulted in a number of environmental problems. The aim of this study is to investigate the leaching characteristics of copper flotation waste by use of the Box-Behnken experimental design approach. In order to obtain the optimized condition of leachability, a second-order model was examined. The best leaching conditions achieved were as follows: pH = 9, stirring time = 5 min, and temperature = 41.5°C.

Leaching behaviour and mechanical properties of copper flotation waste in stabilized/solidified products

This research describes the investigation of a cement-based solidification/stabilization process for the safe disposal of copper flotation waste and the effect on cement properties of the addition of copper flotation waste (CW) and clinoptilolite (C). In addition to the reference mixture, 17 different mixtures were prepared using different proportions of CW and C. Physical properties such as setting time, specific surface area and compressive strength were determined and compared to a reference mixture and Turkish standards (TS). Different mixtures with the copper flotation waste portion ranging from 2.5 to 12.5% by weight of the mixture were tested for copper leachability. The results show that as cement replacement materials especially clinoptilolite had clear effects on the mechanical properties. Substitution of 5% copper flotation waste for Portland cement gave a similar strength performance to the reference mixture. Higher copper flotation waste addition such as 12.5% replacement yielded lower strength values. As a result, copper flotation waste and clinoptilolite can be used as cementitious materials, and copper flotation waste also can be safely stabilized/solidified in a cement-based solidification/stabilization system.