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Öğe Biological denitrification for water detoxification: A review(Elsevier Science Sa, 2025) Ucar, Deniz; Sahinkaya, Erkan; Sabba, Fabrizio; Di Capua, FrancescoBiological denitrification is an established process for nitrate (NO3-) removal that is typically applied in wastewater treatment plants (WWTPs) and sometimes for drinking water treatment. In WWPTs, conventional denitrification is driven by the oxidation of the organic matter existing in the influents of municipal and/or industrial origin. Alternatively, some inorganic compounds, including sulfur, hydrogen, and iron, can act as electron acceptors for denitrification purposes. In industrial wastewater and in water from contaminated water bodies, toxic compounds including heavy metals such as chromium, arsenic, uranium, and manganese as well as other pollutants such as sulfide, thiocyanate, perchlorate, and aromatic compounds can be present. Interestingly, these compounds can also act as energy sources for denitrifying bacteria and/or be co-reduced with NO3 - and other denitrification intermediates. In this way, their toxicity can be partially or totally removed, which demonstrates the potential of biological denitrification for the detoxification of both water and wastewater. This work reviews the toxicity, degradation pathways, and impacts on denitrification steps, microorganisms, and bioreactor operation of eight types of toxic compounds that can be detoxified via biological denitrification. The role of the different compounds on nitrous oxide (N2O) emissions during denitrification is also discussed to provide useful information for the minimization of greenhouse gas emissions.Öğe Co-removal of P-nitrophenol and nitrate in sulfur-based autotrophic and methanol-fed heterotrophic denitrification bioreactors(Elsevier Sci Ltd, 2023) Yenilmez, Aylin Ebru; Ertul, Selin; Yilmaz, Tulay; Ucar, Deniz; Di Capua, Francesco; Sahinkaya, ErkanP-nitrophenol (PNP) can co-occur with nitrate (NO3-) in industrial and municipal wastewater due to effluent discharges from industry and agricultural activities. In this study, the simultaneous removal of PNP and NO3- was investigated under autotrophic and heterotrophic denitrifying conditions in two bioreactor columns at laboratory scale. Autotrophic denitrification with elemental sulfur showed efficient elimination of both PNP (85 % on average for 5-50 mg/L) and NO3- (99 % on average) even at feed PNP concentration of 50 mg/L. In contrast, the heterotrophic column showed significantly lower PNP removal (53 % on average for 5-50 mg/L) despite denitrification efficiency being >= 95 %. ORP was identified as a possible control parameter to modulate PNP removal efficiency. The autotrophic column showed better resiliency than the heterotrophic one under intermittent feeding of 50 mg/L of PNP. Absorbance spectra and HPLC results revealed no accumulation of PNP by-products, i.e., aminophenol, in the autotrophic column during transient feeding conditions.Öğe Effects of trace elements (Fe, Cu, Ni, Co and Mg) on biomethane production from paper mill wastewater(Walter De Gruyter Gmbh, 2023) Toprak, Dilan; Yilmaz, Tulay; Gulpinar, Kerem; Yucel, Amine; Cakmak, Yakup; Ucar, DenizTrace elements have a significant effect on biochemical reactions and therefore the presence of optimum levels of trace elements is essential for bioreactor performances. In this study, the effects of five trace elements on biomethane production have been investigated. Experimental studies have been carried out with multiple batch reactors at 15 day HRT and mesophilic temperatures. The optimum concentrations for each of the trace elements Fe, Cu, Ni, Co and Mg were found as 5, 0.5, 0.5, 0.5 and 100 mg/L, respectively. Among tested trace elements, Cu was the one which provided the highest biomethane production. Cu addition was resulted in a 46 % increase in biomethane production followed by Co with 24 %. The biomethane production rate for these two trace elements was 191.70 and 110.77 ml CH4/g COD, respectively. Optimum levels for Ni, Fe and Mg increased biomethane production rate by approximately 14.3, 10 and 17 % compared to control groups, respectively. Because the exact amount of trace element requirement for each industry/reactor is different, specific case studies should be performed for each application. These results could be used as initial trace element concentrations for further continuous studies.Öğe Extracellular azo dye oxidation: Reduction of azo dye in batch reactors with biogenic sulfide(Taylor & Francis Ltd, 2022) Toprak, Dilan; Demir, Ozlem; Ucar, DenizIn this study, the sulfide-based reduction of azo dyes (Acid Blue 264) was investigated. Sulfate was reduced to sulfide with an ethanol-fed sulfate reduction reactor and the sulfide produced was used to reduce azo dyes in separate batch reactors using sulfide as the electron carrier. The Box-Behnken experiment design method was used to identify how operational parameters affect the decolorization efficiency. As independent variables, initial dye concentration, sulfide concentration and reaction time were selected while dye removal was considered as the response function. Based on the Box Behnken design, the higher regression coefficient (R-2=0.9397) shows that the experimental results are in good agreement with model predictions. At the initial dye concentration of 80 mg/L, the highest dye removal efficiency, about 82.39%, was obtained at the sulfide concentration of 50 mg/L and the reaction time of 25 h. This study showed that Box Behnken's model prediction was a suitable approach for identifying the best conditions for dye removal.Öğe Impact of temperature and biomass augmentation on biosulfur-driven autotrophic denitrification in membrane bioreactors treating real nitrate-contaminated groundwater(Elsevier, 2022) Demir, Ozlem; Atasoy, Ayse Dilek; Calis, Bedia; Cakmak, Yakup; Di Capua, Francesco; Sahinkaya, Erkan; Ucar, DenizNitrate (NO3-) contamination of groundwater is a major health concern worldwide as it can lead to serious illnesses such as methemoglobinemia and cancer. Autotrophic denitrification is a smart approach for treating groundwater, being typically organic-deficient. Lately, biogenic sulfur (S-bio(0)) has emerged as a sustainable, free, and high-efficiency substrate to fuel membrane bioreactors (MBRs) treating contaminated groundwater. However, the effects of moderate temperature and biomass concentration on the performance and fouling of the S-bio(0)-fed MBR were not investigated previously. This study shows that biomass levels of similar to 1 g MLVSS/L limit membrane fouling but also denitrification efficiency. Biomass augmentation up to 3 g MLVSS/L enhanced denitrification but worsened fouling due to increase of extracellular polymeric substance (EPS) levels in the bulk liquid. Temperature decrease from 30 degrees C to 20 degrees C halved denitrification efficiency, which could be partially recovered through bioaugmentation. The mechanisms affected by temperature decrease, practical applications, and future research needs were discussed.Öğe Perchlorate reduction in a thiosulfate-based denitrifying membrane bioreactor(Elsevier, 2023) Yilmaz, Tuelay; Yurtsever, Adem; Sahinkaya, Erkan; Ucar, DenizReductive removals of perchlorate and nitrate, which can be present simultaneously in groundwater, were investigated in a novel thiosulfate-based denitrifying lab-scale membrane bioreactor (MBR) equipped with a polyethersulfone membrane module. Complete denitrification at a hydraulic retention time (HRT) as low as 3 h and a rate of 800 mg NO3--N/(L.d) was accomplished. Simultaneous with nitrate, complete perchlorate reduction was also detected at the feed concentration of 3000 mu g/L and at 12 h HRT. Although further rise in perchlorate loading caused its incomplete reduction, the reduction rate reached up to 38 mg/(L.d). Hence, the developed process is promising for simultaneous perchlorate and nitrate reduction from contaminated groundwater. Sus-tainable filtration performance was observed up to a flux of 12.5 L/(m2.h) (LMH) at which the fouling rate was 85.32 +/- 19.65 mbar/d. However, when the flux was raised further to 25 L/(m2.h), the TMP drastically increased to a rate of 393 +/- 40 mbar/d.Öğe Physicochemical and microbiological investigation of ballast waters of the ships operating in the Marmara Sea(Elsevier Sci Ltd, 2024) Dobrucali, Erinc; Uyanik, Sinan; Altuntas, Volkan; Yilmaz, Mete; Balci, Muharrem; Sahan, Aybuke Nur; Ucar, DenizBallast water, an essential component of global shipping operations, plays a pivotal role in maintaining vessel stability and load distribution. However, its inadvertent discharge can introduce a myriad of physicochemical and microbiological hazards to marine ecosystems, necessitating rigorous investigation. This study presents a comprehensive analysis of ballast waters from ships operating in the ecologically significant Marmara Sea. Different than previous studies, physicochemical parameters, including pH, heavy metal concentrations (Cr, Fe, Co, Ni, Cu, Zn, and As), total organic carbon, turbidity, total nitrogen, and total phosphorus, were extensively assessed. Furthermore, microbial communities were examined through the identification of bacterial, archaeal, and algal taxa using 16S and 18S rRNA gene amplicon sequence data. Particular attention was given to potential pathogens and harmful algal species, employing advanced techniques to ensure accuracy and comprehensiveness. The findings reveal notable variations in the physicochemical profiles of ballast waters, attributed to diverse geographical origins and operational factors. Furthermore, the microbial analysis identifies a diverse array of species, including pathogenic strains and potentially toxin-producing algae, raising concerns about potential ecological and public health implications. These results underscore the urgent need for improved ballast water management strategies and the implementation of effective treatment technologies to mitigate the adverse effects of ballast water discharge in the Marmara Sea. By shedding light on the intricacies of ballast water composition, this study contributes valuable insights toward safeguarding marine biodiversity and human wellbeing in this ecologically sensitive region.Öğe Simultaneous reduction of nitrate and perchlorate by sulfide-based denitrification process(Yildiz Technical Univ, 2023) Calis, Bedia; Ucar, DenizIn this study, sulfide-based denitrification was used for the first time for perchlorate reduction. Perchlorates (CIO4-) are the salts obtained from perchloric acid and are widely used in missile and rocket systems as well as in the automotive industry, fireworks production and some pharmaceutical industries (in the treatment of hyperthyroidism). Perchlorate prevents the iodine uptake of the thyroid gland and inhibits the production of thyroid hormones (triiodothyronine-T3 and thyroxine-T4). Autotrophic reduction methods are gaining popularity in the removal of perchlorate, which is often found together with nitrate in water. In this study, sulfide produced in an ethanol-based sulfidogenic reactor was used for simultaneous reduction of nitrate, nitrite and perchlorate. The study was conducted with batch reactors in 196 hours with varying concentrations of nitrate, nitrite and perchlorate in the presence of 30 mg/L total sulfide. The study showed that the perchlorate removal rate was gradually reduced in reactors containing 10 mg/L nitrite, 10 mg/L nitrate and 20 mg/L nitrite and 20 mg/L nitrate, respectively. The control group reactors revealed that sulfide is used as an electron donor and the process is biological. It was observed that sulfide, a dissolved inorganic sulfur compound, can reduce perchlorate in the presence of nitrate and/or nitrite, and the reduction rate is largely dependent on the presence of nitrate and nitrite.Öğe Treatment of textile industry effluents with up-flow anaerobic sulfidogenic reactor(Wiley, 2024) Ozkaymak, Gulayse; Sahan, Aybuke Nur; Yakamercan, Elif; Cakmak, Yakup; Ucar, DenizBACKGROUNDDyes present in textile wastewater can pose various environmental problems, including toxicity, carcinogenicity and mutagenicity, when released into receiving environments. Sulfidogenic bacteria play a crucial role in wastewater treatment by reducing sulfate and producing sulfide through the utilization of organic compounds in water. The resulting sulfide often transfers its electrons to another electron acceptor. This study focused on the treatment of real textile wastewater using an up-flow sulfidogenic column bioreactor.RESULTSThe reactor was acclimated to sulfate-reducing conditions when influent chemical oxygen demand and sulfate concentrations were 1742 and 2000 mg L-1, respectively. Subsequently, a gradual transition was made from sulfate-reducing conditions to dye-reducing conditions. Throughout the study, the hydraulic retention time was maintained at 1 day.CONCLUSIONThe influent dye concentration was 2722 Pt-Co, and an impressive dye removal efficiency of approximately 90 +/- 2% was achieved. This corresponds to a removal rate of 2450 Pt-Co L-1 day-1. Although the sulfide concentration in the reactor decreased in the last period, investigating the extent to which this sulfide participates in the dye removal may expand the use of sulfidogenic reactors in the treatment of real textile industry wastewater. (c) 2024 The Author(s). Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).
