Person: TUĞTAŞ KARNABAT, ADİLE EVREN
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TUĞTAŞ KARNABAT
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ADİLE EVREN
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Publication Metadata only Bio-electrochemical post-treatment of anaerobically treated landfill leachate(ELSEVIER SCI LTD, 2013) TUĞTAŞ KARNABAT, ADİLE EVREN; Tugtas, A. Evren; Cavdar, Pelin; Calli, BarisBio-electrochemical treatment of anaerobically pre-treated landfill leachate was investigated in batch and continuous-flow two-chambered microbial fuel cells (MFCs). A high strength young landfill leachate was pre-treated using an upflow anaerobic sludge blanket reactor and the effluent resembling medium-aged landfill leachate was fed to the anode chamber of MFCs. The highest maximum current and power densities achieved in continuous-flow MFC with hydraulic retention time (HRT) of five days were 525 mA/m(2) (8227 mA/m(3)) and 158 mW/m(2) (2482 mW/m(3)), respectively. Increase of HRT from one day to five days resulted in the occurrence of partial nitrification, where influent ammonia was converted into nitrite presumably due to the inhibitory effects of free ammonia. The maximum power and current densities obtained in this study were higher compared to other studies with similar leachate characteristics. The results of this study suggest that MFCs can be exploited as a polishing step for anaerobically pre-treated landfill leachate. (C) 2012 Elsevier Ltd. All rights reserved.Publication Metadata only Extent of bioleaching and bioavailability reduction of potentially toxic heavy metals from sewage sludge through pH-controlled fermentation(PERGAMON-ELSEVIER SCIENCE LTD, 2021) TUĞTAŞ KARNABAT, ADİLE EVREN; Yesil, Hatice; Molaey, Rahim; Calli, Baris; Tugtas, Adile EvrenUtilization of anaerobically stabilized sewage sludge on arable lands serve as a renewable alternative to chemical fertilizers as it enables recycling of valuable nutrients to food chain. However, probable pres-ence of heavy metals in sewage sludge restricts the use of stabilized sludge on lands. In this study, a novel approach based on pH-controlled fermentation and anaerobic metal bioleaching was developed to reduce ecotoxicity potential of fermented sludge prior to its land application. Sewage sludge was sub-jected to pH-controlled fermentation process at acidic, neutral, and alkaline pH levels with the aim of increasing metal solubilization and decreasing bioavailable metal fractions through anaerobic bioleaching. Alkaline reactor performed the best among all reactors and resulted in 3-fold higher hydrolysis (34%) and 6-fold higher acidification (19%) efficiencies along with 43-fold (in average) higher metal solubiliza-tion than that of neutral pH reactor. As a result of alkaline fermentation, 32-57% of the metals remained as bioavailable and 34-59% of the metals were encapsulated as non-bioavailable within solid fraction of fermented sludge (biosolid), whereas 8-12% of total metal was solubilized into fermentation liquor. Our results reveal that anaerobic bioleaching through alkaline fermentation enables biosolid production with less metal content and low bioavailability, facilitating its utilization for agricultural purposes. (c) 2021 Elsevier Ltd. All rights reserved.Publication Open Access Conceptual system for sustainable and next-generation wastewater resource recovery facilities(2023-08-10) YEŞİL, HATİCE; TUĞTAŞ KARNABAT, ADİLE EVREN; ÇALLI, BARIŞ; Owusu-Agyeman I., Plaza E., Elginöz N., Atasoy M., Khatami K., Perez-Zabaleta M., Cabrera-Rodríguez C., YEŞİL H., TUĞTAŞ KARNABAT A. E., ÇALLI B., et al.Shifting the concept of municipal wastewater treatment to recover resources is one of the key factors contributing to a sustainable society. A novel concept based on research is proposed to recover four main bio-based products from municipal wastewater while reaching the necessary regulatory standards. The main resource recovery units of the proposed system include upflow anaerobic sludge blanket reactor for the recovery of biogas (as product 1) from mainstream municipal wastewater after primary sedimentation. Sewage sludge is co-fermented with external organic waste such as food waste for volatile fatty acids (VFAs) production as precursors for other bio-based production. A portion of the VFA mixture (product 2) is used as carbon sources in the denitrification step of the nitrification/denitrification process as an alternative for nitrogen removal. The other alternative for nitrogen removal is the partial nitrification/anammx process. The VFA mixture is separated with nanofiltration/reverse osmosis membrane technology into low-carbon VFAs and high-carbon VFAs. Polyhydroxyalkanoate (as product 3) is produced from the low-carbon VFAs. Using membrane contactor-based processes and ion-exchange techniques, high-carbon VFAs are recovered as one-type VFA (pure VFA) and in ester forms (product 4). The nutrient-rich fermented and dewatered biosolid is applied as a fertilizer. The proposed units are seen as individual resource recovery systems as well as a concept of an integrated system. A qualitative environmental assessment of the proposed resource recovery units confirms the positive environmental impacts of the proposed system.Publication Metadata only Removal and recovery of heavy metals from sewage sludge via three-stage integrated process(PERGAMON-ELSEVIER SCIENCE LTD, 2021) TUĞTAŞ KARNABAT, ADİLE EVREN; Yesil, Hatice; Molaey, Rahim; Calli, Baris; Tugtas, Adile EvrenHeavy metal contamination of sewage sludge is one of the concerns preventing its land application. Traditional processes applied for stabilization of sewage sludge are still inadequate to serve sustainable solutions to heavy metal problem. In this study, fermentation and bioleaching potentials of sewage sludge were investigated in anaerobic reactors for either non-pretreated or ultrasonicated sludge at three different pH regimes (free of pH regulation, acidic, and alkaline). The results of the study revealed that combination of ultrasonication pretreatment and alkaline fermentation performed the best among the other cases, resulting in 33.7% hydrolysis, 10.5% acidification, 11-33% metal leaching, and up to 25% reduction in bioavailability of potentially toxic heavy metals. Bioleaching effluent obtained from the best performing reactor was subjected to membrane-based metal recovery. A supported liquid membrane impregnated with a basic carrier successfully recovered soluble metals from the bioleaching effluent with an efficiency of 39-68%. This study reveals that the proposed three-stage process, ultrasonication pretreatment-alkaline fermentation-supported liquid membrane, effectively produces stable sludge with reduced heavy metal toxicity and recovers metals from organic waste streams. (C) 2021 Elsevier Ltd. All rights reserved.Publication Metadata only Enhanced heavy metal leaching from sewage sludge through anaerobic fermentation and air-assisted ultrasonication(PERGAMON-ELSEVIER SCIENCE LTD, 2021) TUĞTAŞ KARNABAT, ADİLE EVREN; Molaey, Rahim; Yesil, Hatice; Calli, Baris; Tugtas, Adile EvrenInterest in using stabilized sewage sludge in agriculture is mainly to benefit from its nutrient content, soil conditioning properties, and water holding capacity. Therefore, sludge management practice needs to be directed from treatment liability towards the recovery of chemical assets embedded in sludge. In this study, anaerobic fermentation process integrated with a new treatment method; i.e., air-assisted ultra-sonication, was used to assess the leaching of heavy metals (HM) from waste activated sludge (WAS). Fermentation processes resulted in 9390 mg COD/L of volatile fatty acids (VFAs) production, 26% Ni solubilization and up to 3.4% solubilization of other target metals (Cu and Zn). Application of the air-assisted ultrasonication as a post-treatment to fermentation process stimulated the migration and transformation of HMs to the liquid fraction of the digestate. Applying specific energy input greater than 9 kJ/g total solids (TS) through ultrasonication and supplying air with constant flow rate of 0.875 L of air/(L of digestate.min) resulted in leaching of more than 83% of Ni, 82% of Cu and 80% of Zn. (C) 2021 Elsevier Ltd. All rights reserved.Publication Metadata only Recovery of volatile fatty acids via membrane contactor using flat membranes: Experimental and theoretical analysis(PERGAMON-ELSEVIER SCIENCE LTD, 2014) TUĞTAŞ KARNABAT, ADİLE EVREN; Tugtas, Adile EvrenVolatile fatty acid (VFA) separation from synthetic VFA solutions and leachate was investigated via the use of a membrane contactor. NaOH was used as a stripping solution to provide constant concentration gradient of VFAs in both sides of a membrane. Mass flux (12.23 g/m(2) h) and selectivity (1.599) observed for acetic acid were significantly higher than those reported in the literature and were observed at feed pH of 3.0, flow rate of 31.5 +/- 0.9 mL/min, and stripping solution concentration of 1.0 N. This study revealed that the flow rate, stripping solution strength, and feed pH affect the mass transfer of VFAs through the PTFE membrane. Acetic and propionic acid separation performances observed in the present study provided a cost effective and environmental alternative due to elimination of the use of extractants. (C) 2014 Elsevier Ltd. All rights reserved.