Publications2009

ÇEVRE BİLİM VE TEKNOLOJİ DERGİSİ 3 (2009) 15-36

Title: Türkiye’nin Poliklorlu Bifeniller Kaynaklı Kirlilik Durumuyla İlgili Çalışmalar
Authors: İpek İMAMOĞLU, Kadir GEDİK, Filiz DEMİRCİOĞLU, Nazan AKDUMAN
Abstract:-Poliklorlu bifeniller (PCB'ler) yüksek kimyasal ve termal kararlılıkları ile gelişen sanayinin ihtiyaçları doğrultusunda üretilerek yaygın olarak kullanılmış, ancak aynı özellikleri sebebiyle toprak, sediman ve canlılarda halen birikmekte, atmosferde uzun mesafelere taşınabilmekte ve dolayısıyla çok yaygın kirlenmeye sebep olmaktadır. Türkiye'de bu kimyasallar üretilmemiştir, ancak bazı ulusal ve uluslararası çalışmalar Türkiye'yi çevreleyen deniz suları, sedimanlar, sucul fauna ve hatta anne sütünde ölçülebilir miktarda PCB'lerin bulunduğunu göstermektedir. Bu çalışmanın amacı, PCB'lerle ilgili Türk Çevre Mevzuatı'nı da gözönüne alarak, sözkonusu çalışmaları derlemek ve Türkiye'nin PCB'ler kaynaklı kirlilik durumunun bir değerlendirmesini yapmaktır.

CHEMOSPHERE 77 (2009) 1137-1142

Title: Recovery of acids from anaerobic acidification broth by liquid–liquid extraction
Authors: Emrah Alkaya, Serkan Kaptan, Leyla Ozkan, Sibel Uludag-Demirer and Göksel N. Demirer
Abstract:In this study, anaerobic acidification of sugar beet processing wastes and subsequent liquid–liquid extraction of produced fermentation metabolites were investigated. The aim of extraction experiments was to asses the influence of pH and extractant (trioctylphosphine oxide (TOPO) in kerosene) concentrations on the recovery of volatile fatty acids (VFAs) from fermentation broth. The effect of TOPO in kerosene concentration was as crucial as the effect of pH on the recovery of VFAs via extraction. Consequently, pH 2.5 was determined as optimum. At this pH, percent recoveries of VFAs were changed from 43% to 98%, depending on the type of the acid extracted (acetic, butyric, propionic and valeric acids) and the concentration of TOPO in kerosene (5–20%). As the concentration of TOPO in kerosene was increased, efficiency of extraction was increased. As a result, highest VFA recoveries (61–98%) were observed at 20% TOPO in kerosene with distribution ratio values ranging between 1.54 and 40.79. At pH 2.5, the increase in TOPO concentration directly increased the chemical oxygen demand (COD) removal efficiencies, as it does for total VFA recovery. Up to 72% COD removals were achieved, at 20% TOPO in kerosene at pH 2.5, while the removal efficiencies remained between 19% and 22% at pH 5.5.

CLEAN TECHNOLOGIES AND ENVIRONMENTAL POLICY

Title: Investigation of Co-Combustion of Coal and Olive Cake in a Bubbling Fluidized Bed With Secondary Air Injection
Authors: Aysel T. Atimtay
Abstract:In this study, a review of the studies done on the co-combustion of some agro-waste in a bubbling fluidized bed combustor (BFBC) having an inside diameter of 102 mm and a height of 900 mm is given. The agro-waste used to investigate the co-combustion characteristics were peach and apricot stones produced as a waste from the fruit juice industry, and olive cake produced as a waste from the olive oil industry. These are typical wastes for a Mediterranean country. A lignite coal was used for co-combustion. On-line concentrations of O2, CO, CO2, SO2, NO x and total hydrocarbons (C m H n ) were measured in the flue gas during combustion experiments. Variations of emissions of various pollutants were studied by changing the operating parameters (excess air ratio, fluidization velocity and fuel feed rate). Temperature distribution along the bed was measured with thermocouples. Emissions were also monitored from the exhaust. Various combinations of coal and biomass mixtures were tested. During the combustion tests, it was observed that the volatile matter from the biomass quickly volatilizes and mostly burns in the freeboard. The temperature profiles along the bed and the freeboard also confirmed this phenomenon. It was found that as the volatile matter of the biomass increases, combustion takes place more in the freeboard region. Better combustion conditions occur at higher excess air ratios. The results showed that co-combustion with these three proposed biomasses lowers the SO2 and NO x emissions considerably. CO and hydrocarbon emissions are lower at the higher excess air ratios.

ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 72 (2009) 781-786

Title: The Growth Behavior of Chlorella Vulgaris in the Presence Of 4-Chlorophenol and 2,4-Dichlorophenol
Authors: Erkan Sahinkaya and Filiz B. Dilek
Abstract:Toxicity of 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) on the growth of Chlorella vulgaris was investigated in batch reactors. Results revealed that 4-CP did not adversely affect the growth of algae up to 20 mg/L, however higher concentrations inhibited growth appreciably and no growth was detected at 100 mg/L. 4-CP also caused some physiological changes in the algal cells as increasing initial 4-CP concentration caused a linear decrease in chlorophyll a (chl-a) content of the cell. 2,4-DCP up to 20 mg/L did not exert toxic effect on the growth of C. vulgaris, rather an induction effect was evident. Unlike a linear decrease with 4-CP, no exact correlation between 2,4-DCP concentration and chl-a content of the cell was observed, but it was certain that thc presence of 2,4-DCP caused some physiological changes in thc cell of C. vulgaris. No biodegradation of 4-CP and 2,4-DCP was observed over a 30-day incubation.

ENVIRONMENTAL ENGINEERING SCIENCE 26 (2009) 385-395

Title: A Laboratory Column Investigation for the Treatment of Cr(VI) with Zero-Valent Iron
Authors: Burcu Uyuşur and Kahraman Ünlü
Abstract:Permeable reactive barrier (PRB) technology is commonly placed in the list of options for groundwater remediation at hazardous waste sites, where Cr(VI) treatment in groundwater has been a concern more than any other inorganic contaminants. The objective of this study was to investigate the effectiveness and longevity of Cr(VI) removal with zero-valent iron based PRBs. The main focus was on two parameters affecting the performance of Cr(VI) removal with PRBs: (1) amount of reactive media and (2) groundwater flux. Laboratory scale columns packed with different amounts of iron powder and quartz sand mixture were fed with an aqueous solution containing 20 mg/L chromium under different groundwater fluxes. When chromium treatment efficiencies of the columns were compared with respect to iron powder/quartz sand ratio, the amount of iron powder was found to be an important parameter for treatment efficiency of PRBs. When the same experiments were conducted at higher fluxes, an increase was observed in the treatment efficiency in the column containing 50% iron. This suggested that the precipitates may not be accumulating at higher fluxes, which in turn, create available surface area for reduction. Extraction experiments were also performed to determine the fraction of chromium that sorbed onto iron hydroxides or iron oxyhydroxides. Analyses showed that chromium was not removed by sorption and that reduction is the only removal mechanism in the laboratory experiments. Cr(VI) removal rate constant and complete removal efficiency values were determined for each reactive mixture. These values are considered to be important design parameters for the field scale permeable reactive barrier applications.

ENVIRONMENTAL ENGINEERING SCIENCE 26 (2009) 1443-1450

Title: Volatile Fatty Acid Production from Organic Fraction of Municipal Solid Waste through Anaerobic Acidogenic Digestion
Authors: Eylem Doğan, Göksel N. Demirer
Abstract:There are numerous studies on two-phase anaerobic digestion of municipal solid waste (MSW) in the literature. Yet, in the majority of these studies, applied organic loading rates (OLR) were relatively low. This study differs from those in the literature in terms of high OLR application and focuses on the optimization of the acidification phase. Effect of high OLRs and pH values were investigated and optimum operational conditions for acidification were determined. Although conversion of particulate organics to soluble chemical oxygen demand (COD) was achieved in the reactors, total COD values remained the same. Various types of organic acids were produced in the reactors and the selective production of organic acids in the anaerobic acidogenesis process was possible by controlling the organic loading rate and pH. Optimum OLR and pH values were determined as 15 g volatile solid (VS)/L•day and 5.5 ± 0.1, respectively, for the MSW composition investigated.

FUEL 88 (2009) 1000-1008

Title: Investigation of Co-Combustion of Coal and Olive Cake in a Bubbling Fluidized Bed with Secondary Air Injection
Authors: Aysel T. Atimtay and Murat Varol
Abstract:In this study, a bubbling fluidized bed of 102 mm inside diameter and 900 mm height was used to burn olive cake and coal mixtures. Tunçbilek lignite coal was used together with olive cake for the co-combustion tests. Combustion performances and emission characteristics of olive cake and coal mixtures were investigated. Various co-combustion tests of coal with olive cake were conducted with mixing ratios of 25%, 50%, and 75% of olive cake by weight in the mixture. Operational parameters (excess air ratio, secondary air injection) were changed and variation of pollutant concentrations and combustion efficiency with these operational parameters were studied. The results were compared with that of the combustion of olive cake and coal. Flue gas concentrations of O2, CO, SO2, NOx, and total hydrocarbons (CmHn) were measured during combustion tests. For the setup used in this study, the optimum operating conditions with respect to NOx and SO2 emissions were found to be 1.35 for excess air ratio, and 30 L/min for secondary air flowrate for the combustion of 75 wt% olive cake and 25 wt% coal mixture. The highest combustion efficiency of 99.8% was obtained with an excess air ratio of 1.7, secondary air flow rate of 40 L/min for the combustion of 25 wt% olive cake and 75 wt% coal mixture.

FUEL PROCESSING TECHNOLOGY 90 (2009) 939-946

Title: Investigation of Combustion Kinetics of Treated and Untreated Waste Wood Samples with Thermogravimetric Analysis
Authors: Sema Yurdakul Yorulmaz and Aysel T. Atimtay
Abstract:In the present study, combustion mechanisms, thermal kinetics, and phases of combustion were investigated for waste wood samples (untreated pine and treated MDF, plywood and particleboard). Waste wood samples were combusted in air at 10, 20 and 30 °C/min heating rates in TGA. The results of TG analysis have shown that thermal decomposition of treated samples takes place at lower temperatures as compared to the untreated pine sample because of the catalyzing effects of the chemicals in the samples. Therefore, there were less flammable products, lower weight losses in the main oxidation region, and decrease in the maximum weight loss temperatures and formation of more char for treated samples as compared to untreated pine sample. Thermal kinetic constants for the samples were calculated by using Coats Redfern Method. In order to find out the mechanisms responsible for the oxidation of the waste wood samples, six solid-state mechanisms of Coats Redfern Method were tested. The results of the Coats Redfern Method have shown that diffusion mechanism is the effective mechanism for all regions of the pine samples. For the main oxidation region, D4 mechanism (Ginstling–Brounshtein equation) was found to be the main diffusion mechanism for pine samples. For the treated samples such as MDF, plywood and particleboard, first-order reaction (F1) was found as an effective mechanism. Treatment of wood with different additives and glues seemed to alter the thermal oxidation process and change the effective oxidation mechanisms.

JOURNAL OF CLEANER PRODUCTION 17 (2009) 239-247

Title: A Chemical Substitution Study for a Wet Processing Textile Mill in Turkey
Authors: Ertan Ozturk, Ulku Yetis, Filiz B. Dilek and Goksel N. Demirer
Abstract:Wet processing textile industry has many different processing stages (dyeing, sizing, de-sizing, scouring, softening, etc). Many chemicals currently used in the vvet processing textile industry affect the amount and the type of waste produced and their influence on the aquatic life of the receiving stream. One of the critical steps in pollution prevention studies is auditing the use of chemicals and making the necessary chemical substitutions. This chemical substitution study was conducted on one of the major textile factories in Turkey with a capacity of 20,000 tons of denim fabric per year. During this study, chemical consumption level, receipts applied, environmentally problematic and alternative chemicals were ex¬amined. Integrated Pollution Prevention and Control (IPPC) Reference Document on Best Available Techniques (BAT) for the Textiles Industry was accepted as main reference document and also related case studies were examined. According to the study, over 70% reduction in sulphide, which is very toxic to aquatic life, was achieved by replacing sulphur dyestuff with low sulphide content. By replacing an alternative complexing agent, the mill not only prevented the 3100 kg/month COD load to the waste¬water treatment plant (VVWTP), but also obtained more biodegradable wastewater generated during production. On the other hand, some of the chemical substitution options were on progress or dropped.

JOURNAL OF ENVIRONMENTAL MANAGEMENT 91 (2009) 102-113

Title: Adoption of European Union's IPPC Directive to a Textile Mill: Analysis of Water and Energy Consumption
Authors: A. Merve Kocabas, Hande Yukseler, Filiz B. Dilek and Ulku Yetis
Abstract:The present study was undertaken as part of the first application and evaluation of the BREF (Best Available Techniques; BAT Reference Document) Textile Document within the context of the European Union's Integrated Pollution Prevention and Control (IPPC) Directive to a large scale textile mill in Turkey. The BAT requirements for the denim manufacturing textile mill were selected in cooperation with the factory management. Detailed mass balance calculations were conducted to evaluate the overall effect of the selected BAT options. The initial findings indicated that the adoption of the selected BAT options resulted inconsiderable savings in water and energy consumption in the mill. Besides the installation of flow meters and use of semi-counter current rinsing in the most water-intensive processes, minimization of wash waters in the water softening plant, reuse of the concentrate stream from the reverse osmosis plant and compressor cooling waters provided a 29.5% reduction in the total specific water consumption of the mill, reaching the lower limits suggested by the BREF Textile Document In terms of energy consumption, use of waste heat from finishing wastewater streams in heating up the wash waters, heat insulation and maintenance applications in addition to BAT measures taken for water minimization reduced specific energy consumption by 9% achieving the limits set by the BREF Textile Document.

WATER ENVIRONMENT RESEARCH 81 (2009)

Title: Modification of a Conventional Anaerobic Digester for Improving the Effluent and Sludge Characteristics
Authors: S. Uludag-Demirer, G. N. Demirer, M. Othman
Abstract:The aim of this study was to enrich the composition of anaerobic digester sludge in terms of nitrogen and phosphorus by struvite (MgNH4PO4) formation. Waste activated sludge was anaerobically digested in batch reactors under the conditions that the minimum stoichiometric requirement for struvite formation was satisfied in all reactors. For this purpose, different amounts of magnesium (Mg2+) and phosphate (PO4) 3- ions were added initially to the batch reactors. The results showed the effects of adding Mg2+ and PO43- ions on the performance of anaerobic digestion and on the amounts of ammonium (NH4)+ and PO43- ions released during digestion. The results indicated that the performance of the anaerobic digestion in chemical oxygen demand removal changed between 24.0% and 15.4% for a Mg2+ concentration range of 277.2 to 529.3 mg/L and a PO43- concentration range of 377.4 to 2372.4 mg/L. There was an increase in the concentration of NH4+ in all reactors during digestion, but the extent of concentration increase could be controlled by increasing the initial concentrations of Mg2+ and PO43-. The maximum removal of NH4+ ions (33.7%) was observed in the reactor dosed initially by Mg2+ and PO43- concentrations of 467.2 and 2123.3 mg/L, respectively. The concentration of PO43- ion was lower than its initial concentration in all reactors, indicating considerable fixation of PO43- as it was released, by struvite and other solid species formation. The decrease in the concentration of Mg2+ ions similar to PO43- was accepted as evidence for the formation of solid species composed of Mg2+ and PO43-, in addition to struvite. Water Environ. Res., 81 (2009).

TALANTA 80 (2009) 329-337

Title: An Interlaboratory Study as Useful Tool for Proficiency Testing of Chemical Oxygen Demand Measurements Using Solid Substrates and Liquid Samples with High Suspended Solid Content
Authors: F. Raposo, M.A. de la Rubia, R. Borja, M. Alaiz, J. Beltrán, C. Cavinato, M. Clinckspoor, G. Demirer, E. Diamadopoulos, B. Helmreich, P. Jenicek, N. Martí, R. Méndez, J. Noguerol, F. Pereira, S. Picard and M. Torrijos
Abstract:In 2008, the first Proficiency Testing Scheme of Chemical Oxygen Demand (1st COD- TADG) was conducted to assess the results obtained for different research groups whose fieldwork is mainly anaerobic digestion. This study was performed using four samples, two solid samples as raw materials and two solid samples to prepare high concentration suspended solid solutions. Invitations were sent to a large number of laboratories, mainly to anaerobic digestion research groups. Finally, thirty labs from sixteen countries agreed to participate, but for different reasons four participants could not send any data. In total, twenty six results were reported to the COD-PT coordinator. This study showed the importance of continuous participation in proficiency testing (PT) schemes in order to compare the results obtained. Taking into account the lack of a general standard method and high quality certified reference materials (CRMs), the traceability of COD determination is not currently easy to check. In addition, the spread of participants’ results obtained was high and pointed to the advisability of using consensus values due to their unreliability. Therefore, the theoretical oxygen demand ThOD) values were considered as assigned values for all the samples analysed. On the other hand, in this PT the established standard deviation (ESD) has been determined by the Horwitz modified function. Participants of this 1st COD-PTADG were asked to give a short report on the analytical method used. Although all the participants used potassium dichromate as their oxidant reagent, their experimental procedures were very different. With the purpose of comparing the results obtained, the different experimental conditions used were classified into five methods, corresponding to two main categories, open and closed reflux. The performance of laboratories was expressed by the z-score, whose value is considered satisfactory when z-score ?±2. The overall analytical data evaluation showed that 64% of z-scores obtained were outside the accepted limits.

WASTE MANAGEMENT 29 (2009) 103-109

Title: Effect of Vadose Zone on the Steady-State Leakage Rates From Landfill Barrier Systems
Authors: B. Çelik, R.K. Rowe, and K. Ünlü
Abstract:Leakage rates are evaluated for a landfill barrier system having a compacted clay liner (CCL) underlain by a vadose zone of variable thickness. A numerical unsaturated flow model SEEP/W is used to simulate the moisture flow regime and steady-state leakage rates for the cases of unsaturated zones with different soil types and thicknesses. The results of the simulations demonstrate that harmonic mean hydraulic conductivity of coarse textured vadose zones is 3–4 orders of magnitude less than saturated hydraulic conductivity; whereas, the difference is only one order of magnitude for fine textured vadose zones. For both coarse and fine textured vadose zones, the effective hydraulic conductivity of the barrier system and the leakage rate to an underlying aquifer increases with increasing thickness of the vadose zone and ultimately reaches an asymptotic value for a coarse textured vadose zone thickness of about 10 m and a fine textured vadose zone thickness of about 5 m. Therefore, the fine and coarse textured vadose zones thicker than about 5 m and 10 m, respectively, act as an effective part of the barrier systems examined. Although the thickness of vadose zone affects the effective hydraulic conductivity of the overall barrier system, the results demonstrated that the hydraulic conductivity of the CCL is the dominant factor controlling the steady-state leakage rates through barrier systems having single low permeability clay layers.