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Prof. Cigdem ESKICIOGLU
The University of British Columbia, UBC Bioreactor Technology Group, School of Engineering, Kelowna, Canada

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Research Keywords & Expertise

0 Sludge pretreatment
0 Advanced anaerobic digestion
0 Nutrient removal/recovery from wastewater
0 Odor minimization
0 Fate of micropollutants

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Advanced anaerobic digestion
Sludge pretreatment

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Journal article
Published: 02 June 2021 in Science of The Total Environment
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Many trace contaminants of emerging concern (CECs) including a number of pharmaceutically active compounds are not effectively removed during conventional wastewater treatment processes and instead accumulate in wastewater sludge. Unfortunately, many existing sludge stabilization treatments such as anaerobic digestion (AD) also have limited effectiveness against many of these CECs including the four pharmaceuticals ibuprofen, diclofenac, carbamazepine, and azithromycin which can then enter the environment through the disposal or land application of biosolids. Single-stage AD, single-stage cycling aerobic-anoxic (AERO/ANOX) and sequential digesters (AD followed by an AERO/ANOX digester) at sludge retention times (SRT) of 5 to 20-days were evaluated side-by-side to assess their effectiveness in removing pharmaceuticals and conventional organic matter. Single-stage ADs (35°C) and AERO/ANOX (22°C) digesters effectively removed total solids while sequential AD + AERO/ANOX digesters offered further improvements. Ibuprofen was not effectively removed during AD and resulted in up to a 23 ± 8% accumulation. However, ibuprofen was completely removed during AERO/ANOX digestion and in several sequential digestion scenarios. Each type of digestion was less effective against carbamazepine with slight (3 ± 2%) accumulations to low levels (14 ± 1%) of removals in each type of digestion studied. Diclofenac was more effectively removed with up 30 ± 3% to 39 ± 4% reductions in the single-stage digesters (AD and AERO/ANOX, respectively). While sequential digestion scenarios with the longest aerobic SRTs significantly increased diclofenac removals from their first-stage digesters, scenarios with the longest anaerobic SRTs actually decreased removals from first-stage digesters, possibly due to reversable biotransformation of diclofenac conjugates/metabolites. Up to 43 ± 6% of azithromycin was removed in AERO/ANOX digesters, while the best performing sequential-digester scenario removed up to 63 ± 7% of azithromycin. This study shows that different digester configurations can reduce the CEC burden in biosolids while also greatly reducing their volumes for disposal, although none can remove CECs completely.

ACS Style

Timothy Abbott; Gokce Kor-Bicakci; Cigdem Eskicioglu. Examination of single-stage anaerobic and anoxic/aerobic and dual-stage anaerobic-anoxic/aerobic digestion to remove pharmaceuticals from municipal biosolids. Science of The Total Environment 2021, 791, 148237 .

AMA Style

Timothy Abbott, Gokce Kor-Bicakci, Cigdem Eskicioglu. Examination of single-stage anaerobic and anoxic/aerobic and dual-stage anaerobic-anoxic/aerobic digestion to remove pharmaceuticals from municipal biosolids. Science of The Total Environment. 2021; 791 ():148237.

Chicago/Turabian Style

Timothy Abbott; Gokce Kor-Bicakci; Cigdem Eskicioglu. 2021. "Examination of single-stage anaerobic and anoxic/aerobic and dual-stage anaerobic-anoxic/aerobic digestion to remove pharmaceuticals from municipal biosolids." Science of The Total Environment 791, no. : 148237.

Review
Published: 24 April 2021 in Water Research
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Additional options for the sustainable treatment of municipal sludge are required due to the significant amounts of sludge, high levels of nutrients (e.g., C, N, and P), and trace constituents it contains. Hydrothermal processing of municipal sludge has recently been recognized as a promising technology to efficiently reduce waste volume, recover bioenergy, destroy organic contaminants, and eliminate pathogens. However, a considerable amount of solid residue, called hydrochar, could remain after hydrothermal treatment. This hydrochar can contain abundant amounts of energy (with a higher heating value up to 24 MJ/kg, dry basis), nutrients, and trace elements, as well as surface functional groups. The valorization of sludge-derived hydrochar can facilitate the development and application of hydrothermal technologies. This review summarizes the formation pathways from municipal sludge to hydrochar, specifically, the impact of hydrothermal conditions on reaction mechanisms and product distribution. Moreover, this study comprehensively encapsulates the described characteristics of hydrochar produced under a wide range of conditions: Yield, energy density, physicochemical properties, elemental distribution, contaminants of concern, surface functionality, and morphology. More importantly, this review compares and evaluates the current state of applications of hydrochar: Energy production, agricultural application, adsorption, heterogeneous catalysis, and nutrient recovery. Ultimately, along with the identified challenges and prospects of valorization approaches for sludge-derived hydrochar, conceptual designs of sustainable municipal sludge management are proposed.

ACS Style

Huan Liu; Ibrahim Alper Basar; Ange Nzihou; Cigdem Eskicioglu. Hydrochar derived from municipal sludge through hydrothermal processing: A critical review on its formation, characterization, and valorization. Water Research 2021, 199, 117186 .

AMA Style

Huan Liu, Ibrahim Alper Basar, Ange Nzihou, Cigdem Eskicioglu. Hydrochar derived from municipal sludge through hydrothermal processing: A critical review on its formation, characterization, and valorization. Water Research. 2021; 199 ():117186.

Chicago/Turabian Style

Huan Liu; Ibrahim Alper Basar; Ange Nzihou; Cigdem Eskicioglu. 2021. "Hydrochar derived from municipal sludge through hydrothermal processing: A critical review on its formation, characterization, and valorization." Water Research 199, no. : 117186.

Review
Published: 20 April 2021 in Journal of Environmental Chemical Engineering
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Although two-staged anaerobic digestion (AD) is not a new process, information about process stability and optimum operating conditions for improving its overall performance and resource recovery is limited and often inconsistent. The review examined the critical operating conditions and the various AD treatment options for municipal wastewater treatment plants to identify the best possible two-staged AD systems. Contour plots, multi-criteria evaluation, principal component analysis (PCA), energy balances, and economic analysis were the basis of identifying the best two-staged AD systems in this study from published literature. Contour plots generated using 29 data points from the literature showed higher volatile fatty acids (VFAs) yield prediction at lower temperatures (30–34°C), relatively higher sludge retention time (SRT) (4–9 days), and at either acidic (5−6) or alkaline pH (7.7–8) for the acid-stage AD. Also, the PCA showed that SRT and pH have a more significant influence on VFA yield than the temperature in the acid phase of two-staged ADs. A multi-criteria analysis performed on 51 data points obtained from the literature showed the thermophilic-mesophilic (T-M) two-staged AD as the best option for overall % improvement in volatile solids removal and methane yield over the control among the six two-staged configurations. Additionally, T-M also achieves higher pathogen reduction and better dewaterability. Lastly, energy and economical analysis of the different two-staged AD configurations revealed a higher positive energy balance for single-stage thermophilic, thermophilic-thermophilic, and T-M than the others. This article provides a guide for the implementation and practical applicability of the two-staged AD process for wastewater treatment plants.

ACS Style

Resty Nabaterega; Vikas Kumar; Shiva Khoei; Cigdem Eskicioglu. A review on two-stage anaerobic digestion options for optimizing municipal wastewater sludge treatment process. Journal of Environmental Chemical Engineering 2021, 9, 105502 .

AMA Style

Resty Nabaterega, Vikas Kumar, Shiva Khoei, Cigdem Eskicioglu. A review on two-stage anaerobic digestion options for optimizing municipal wastewater sludge treatment process. Journal of Environmental Chemical Engineering. 2021; 9 (4):105502.

Chicago/Turabian Style

Resty Nabaterega; Vikas Kumar; Shiva Khoei; Cigdem Eskicioglu. 2021. "A review on two-stage anaerobic digestion options for optimizing municipal wastewater sludge treatment process." Journal of Environmental Chemical Engineering 9, no. 4: 105502.

Review article
Published: 29 March 2021 in Renewable and Sustainable Energy Reviews
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Microbial communities play an important role in various biochemical and metabolic reactions that occur in natural and engineered anaerobic systems. Methanogenic syntrophy is an integral part of global carbon recycling, waste decomposition, and biofuel production. The electron transfer in microorganisms is an essential process in numerous reactions, particularly those controlled by symbiotic associations. Electron transfer between species occurs through the production of metabolites (such as hydrogen, carbon dioxide, and formate) by bacterial fermentation, which is then consumed by methanogens. The discovery of direct interspecies electron transfer (DIET), where intercellular interactions permit the exchange of extracellular electrons between microorganisms, is vital for many biochemical processes. Therefore, understanding the interactions between microbial communities is essential for designing effective biological treatment processes. This article provides a comprehensive overview of electron transfer mechanisms for methane generation from organic matter. It also describes the effectiveness of various conductive materials to improve interspecies interactions for enhanced bioenergy production and provides suggestions for nanoparticles (NPs) application for DIET and methane enhancement.

ACS Style

Vikas Kumar; Resty Nabaterega; Shiva Khoei; Cigdem Eskicioglu. Insight into interactions between syntrophic bacteria and archaea in anaerobic digestion amended with conductive materials. Renewable and Sustainable Energy Reviews 2021, 144, 110965 .

AMA Style

Vikas Kumar, Resty Nabaterega, Shiva Khoei, Cigdem Eskicioglu. Insight into interactions between syntrophic bacteria and archaea in anaerobic digestion amended with conductive materials. Renewable and Sustainable Energy Reviews. 2021; 144 ():110965.

Chicago/Turabian Style

Vikas Kumar; Resty Nabaterega; Shiva Khoei; Cigdem Eskicioglu. 2021. "Insight into interactions between syntrophic bacteria and archaea in anaerobic digestion amended with conductive materials." Renewable and Sustainable Energy Reviews 144, no. : 110965.

Review
Published: 17 March 2021 in Chemical Engineering Journal
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Phosphorus (P) is a non-renewable resource, and its recovery and recycling are necessary for meeting future P demands and environmental conservation. Ash and hydrochar from incineration and hydrothermal liquefaction (HTL) of municipal sludge, respectively, represent promising sources for efficient P recovery. The full-scale application of wet-chemical techniques has proven their technical feasibility for P recovery from sludge-derived ash. HTL for sludge treatment has received significant attention for producing biocrude with net-positive energy recovery. P recovery from the solid by-product of sludge HTL, hydrochar, is a critical step in holistic sustainable sludge management. This review aims to guide P recovery from sludge-derived ash and hydrochar by presenting recent advances in wet-chemical extraction and precipitation. By comparing their characteristics, ash and hydrochar derived from municipal sludge exhibit similar feasibilities and challenges for P recovery. Extraction is recognized as the critical step for P recovery. The advantages and disadvantages of various P extraction approaches are provided. Acidic extraction achieves high efficiency (up to 100%) but requires removal of co-extracted heavy metals. Alkaline extraction prevents metals contamination but shows low efficiency (<70%). Sequential extraction is first identified as an important advance in this review, with promising P extraction efficiencies (70–91%) and low metal interferences. Three possible fertilizers (struvite, calcium phosphates, and vivianite) are recommended through the final precipitation, given their pros and cons of recovery. Ultimately, this review highlights the need for a wastewater biorefinery integrating wastewater treatment, HTL (energy recovery), and nutrient recovery for sustainable sludge management.

ACS Style

Huan Liu; Guangji Hu; Ibrahim Alper Basar; Jianbing Li; Nathalie Lyczko; Ange Nzihou; Cigdem Eskicioglu. Phosphorus recovery from municipal sludge-derived ash and hydrochar through wet-chemical technology: A review towards sustainable waste management. Chemical Engineering Journal 2021, 417, 129300 .

AMA Style

Huan Liu, Guangji Hu, Ibrahim Alper Basar, Jianbing Li, Nathalie Lyczko, Ange Nzihou, Cigdem Eskicioglu. Phosphorus recovery from municipal sludge-derived ash and hydrochar through wet-chemical technology: A review towards sustainable waste management. Chemical Engineering Journal. 2021; 417 ():129300.

Chicago/Turabian Style

Huan Liu; Guangji Hu; Ibrahim Alper Basar; Jianbing Li; Nathalie Lyczko; Ange Nzihou; Cigdem Eskicioglu. 2021. "Phosphorus recovery from municipal sludge-derived ash and hydrochar through wet-chemical technology: A review towards sustainable waste management." Chemical Engineering Journal 417, no. : 129300.

Review
Published: 12 February 2021 in Green Chemistry
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This paper summarizes the existing hydrothermal liquefaction process literature and reveals the effect of process parameters on the bio-crude yield.

ACS Style

Ibrahim Alper Basar; Huan Liu; Helene Carrere; Eric Trably; Cigdem Eskicioglu. A review on key design and operational parameters to optimize and develop hydrothermal liquefaction of biomass for biorefinery applications. Green Chemistry 2021, 23, 1404 -1446.

AMA Style

Ibrahim Alper Basar, Huan Liu, Helene Carrere, Eric Trably, Cigdem Eskicioglu. A review on key design and operational parameters to optimize and develop hydrothermal liquefaction of biomass for biorefinery applications. Green Chemistry. 2021; 23 (4):1404-1446.

Chicago/Turabian Style

Ibrahim Alper Basar; Huan Liu; Helene Carrere; Eric Trably; Cigdem Eskicioglu. 2021. "A review on key design and operational parameters to optimize and develop hydrothermal liquefaction of biomass for biorefinery applications." Green Chemistry 23, no. 4: 1404-1446.

Review
Published: 03 December 2020 in International Journal of Molecular Sciences
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Antimicrobial compounds are used in a broad range of personal care, consumer and healthcare products and are frequently encountered in modern life. The use of these compounds is being reexamined as their safety, effectiveness and necessity are increasingly being questioned by regulators and consumers alike. Wastewater often contains significant amounts of these chemicals, much of which ends up being released into the environment as existing wastewater and sludge treatment processes are simply not designed to treat many of these contaminants. Furthermore, many biotic and abiotic processes during wastewater treatment can generate significant quantities of potentially toxic and persistent antimicrobial metabolites and byproducts, many of which may be even more concerning than their parent antimicrobials. This review article explores the occurrence and fate of two of the most common legacy antimicrobials, triclosan and triclocarban, their metabolites/byproducts during wastewater and sludge treatment and their potential impacts on the environment. This article also explores the fate and transformation of emerging alternative antimicrobials and addresses some of the growing concerns regarding these compounds. This is becoming increasingly important as consumers and regulators alike shift away from legacy antimicrobials to alternative chemicals which may have similar environmental and human health concerns.

ACS Style

Timothy Abbott; Gokce Kor-Bicakci; Mohammad S. Islam; Cigdem Eskicioglu. A Review on the Fate of Legacy and Alternative Antimicrobials and Their Metabolites during Wastewater and Sludge Treatment. International Journal of Molecular Sciences 2020, 21, 9241 .

AMA Style

Timothy Abbott, Gokce Kor-Bicakci, Mohammad S. Islam, Cigdem Eskicioglu. A Review on the Fate of Legacy and Alternative Antimicrobials and Their Metabolites during Wastewater and Sludge Treatment. International Journal of Molecular Sciences. 2020; 21 (23):9241.

Chicago/Turabian Style

Timothy Abbott; Gokce Kor-Bicakci; Mohammad S. Islam; Cigdem Eskicioglu. 2020. "A Review on the Fate of Legacy and Alternative Antimicrobials and Their Metabolites during Wastewater and Sludge Treatment." International Journal of Molecular Sciences 21, no. 23: 9241.

Journal article
Published: 19 July 2020 in Science of The Total Environment
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The antimicrobial triclosan (TCS) is a pervasive and persistent environmental micropollutant which can contaminate land, biota, and water through the land application of biosolids. Many existing sludge management techniques have limited effectiveness against TCS and TCS metabolites including triclosan-sulfate (TCS-SO4). The objective of this study was to evaluate the impacts of different digestion types (anaerobic, aerobic/anoxic, and sequential anaerobic + aerobic/anoxic), temperatures, and digester sludge retention times (SRTs) on the destruction of organic matter, and on TCS/TCS metabolites. Conventional mesophilic anaerobic digesters (AD), room temperature cycling aerobic/anoxic digesters (AERO/ANOX), and sequential AD + AERO/ANOX digesters were all effective in removing organic matter. The optimum single-stage AD, and AERO/ANOX scenarios were both 20-day SRTs which had 52.3 ± 1.4 and 47.1 ± 3.7% chemical oxygen demand (COD) removals, respectively. Sequential AD + AERO/ANOX digesters improved organic matter destruction, removing up to 68.2 ± 2.1% of COD at an 8-day AD + 12-day AERO/ANOX second-stage (mesophilic) SRTs. While AD showed modest levels of TCS removals (all <40%), TCS was substantially more degradable aerobically with AERO/ANOX removing up to 80.3 ± 2.5% of TCS and nearly all TCS-SO4 entering the digester at a 20-day SRT. Sequential AD + AERO/ANOX removed virtually all TCS-SO4 entering the system and improved TCS removals from first stage ADs. However, they were less effective than a single-stage AERO/ANOX digester operating at the same overall SRT. These results demonstrate that AERO/ANOX and sequential AD + AERO/ANOX processes could be used to reduce the amount of TCS, TCS-SO4 and TCS-related compounds in digested sludge, minimizing the environmental burden of the land application of biosolids.

ACS Style

Timothy Abbott; Cigdem Eskicioglu. Comparison of anaerobic, cycling aerobic/anoxic, and sequential anaerobic/aerobic/anoxic digestion to remove triclosan and triclosan metabolites from municipal biosolids. Science of The Total Environment 2020, 745, 140953 .

AMA Style

Timothy Abbott, Cigdem Eskicioglu. Comparison of anaerobic, cycling aerobic/anoxic, and sequential anaerobic/aerobic/anoxic digestion to remove triclosan and triclosan metabolites from municipal biosolids. Science of The Total Environment. 2020; 745 ():140953.

Chicago/Turabian Style

Timothy Abbott; Cigdem Eskicioglu. 2020. "Comparison of anaerobic, cycling aerobic/anoxic, and sequential anaerobic/aerobic/anoxic digestion to remove triclosan and triclosan metabolites from municipal biosolids." Science of The Total Environment 745, no. : 140953.

Waste and biomass management and valorization
Published: 12 May 2020 in Environmental Science and Pollution Research
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The inevitable discharge of zinc oxide nanoparticles (ZnO NPs), from consumer and industrial products, into wastewater treatment plants (WWTPs) has created a need to determine their effect on sludge digestion. In this study, the effect of particle size (30 nm and 100 nm), type (coated and non-coated), and dose (6, 75, and 150 mg/g feed total solids (TS)) of ZnO NPs on anaerobic sludge digestion was studied under mesophilic (35 °C) and thermophilic (55 °C) conditions. The effect was investigated in two stages with different digester feeding regime: (1) batch biochemical methane potential (BMP) assays, and (2) semi-continuously fed reactors. Results showed that ZnO NPs were inhibitory at medium and high levels (75 and 100 mg ZnO/g TS, respectively). Coated NPs created less inhibition than non-coated NPs. Thermophilic bacteria were more sensitive to ZnO NPs compared with mesophilic bacteria. For the non-coated ZnO NPs, only the mesophilic batch assays were able to recover at the medium concentration and the thermophilic reactors presented chronic inhibition and could not recover. As a beneficial outcome, coated ZnO NPs significantly reduced odor-causing volatile sulfur compounds in digester headspace in comparison with the non-coated NPs. In summary, the condition in which ZnO NPs would have little to no effect would be 6 mg/g TS-coated ZnO NPs under mesophilic conditions.

ACS Style

Wesley Olaya; Hina Dilawar; Cigdem Eskicioglu. Comparative response of thermophilic and mesophilic sludge digesters to zinc oxide nanoparticles. Environmental Science and Pollution Research 2020, 28, 24521 -24534.

AMA Style

Wesley Olaya, Hina Dilawar, Cigdem Eskicioglu. Comparative response of thermophilic and mesophilic sludge digesters to zinc oxide nanoparticles. Environmental Science and Pollution Research. 2020; 28 (19):24521-24534.

Chicago/Turabian Style

Wesley Olaya; Hina Dilawar; Cigdem Eskicioglu. 2020. "Comparative response of thermophilic and mesophilic sludge digesters to zinc oxide nanoparticles." Environmental Science and Pollution Research 28, no. 19: 24521-24534.

Journal article
Published: 23 March 2020 in Waste Management
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Digestion of biological nutrient removal (BNR) plant sludge can be challenging, particularly for small- to medium-sized wastewater treatment facilities (WWTF) which often lack the economies of scale, and/or expertise to make digestion feasible. This study compared various types of sludge digestion, sludge retention times (SRTs), and temperatures on the release of recalcitrant nutrients, digestion economics, and digester performance utilizing mixed primary and secondary sludge from a small- to medium-sized BNR facility. Mesophilic anaerobic digestion (AD), cycling aerobic/anoxic (AERO/ANOX) digestion, and sequential anaerobic/aerobic/anoxic (AD/AERO/ANOX) digestion at room and mesophilic temperatures were compared at SRTs between 5 and 20 days. AERO/ANOX digestion was very effective in treating recalcitrant forms of nitrogen and phosphorous by removing up to 87% of dissolved organic nitrogen (DON), up to 88 ± 2% of non-reactive dissolved phosphorous (NRDP). AERO/ANOX digestion also offered the lowest increase in sludge management costs versus the existing no-digestion baseline scenario. ADs removed up to 53 ± 1% of volatile solids (VS), whereas unheated AERO/ANOX digesters were less effective, removing up to 39 ± 1% of VS. Sequential AD/AERO/ANOX digesters with a mesophilic second-stage removed up to 61 ± 3% of VS but had the highest operational and capital costs. Experiments also indicated that significant amounts of orthophosphate (PO43−) may be released from digested AERO/ANOX sludge during on-site storage, with longer SRTs releasing PO43− more rapidly than shorter ones. These results are important as more WWTFs deploy BNR to meet increasingly stringent nutrient limits.

ACS Style

Timothy Abbott; Cigdem Eskicioglu. Mitigation of recalcitrant nutrients and organic pollutants from small- to medium-scale biological nutrient removal plant sludge by digester optimization. Waste Management 2020, 106, 132 -144.

AMA Style

Timothy Abbott, Cigdem Eskicioglu. Mitigation of recalcitrant nutrients and organic pollutants from small- to medium-scale biological nutrient removal plant sludge by digester optimization. Waste Management. 2020; 106 ():132-144.

Chicago/Turabian Style

Timothy Abbott; Cigdem Eskicioglu. 2020. "Mitigation of recalcitrant nutrients and organic pollutants from small- to medium-scale biological nutrient removal plant sludge by digester optimization." Waste Management 106, no. : 132-144.

Journal article
Published: 21 March 2020 in Water
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The effects of microwave (MW) pretreatment were investigated by six anaerobic digesters operated under thermophilic and mesophilic conditions at high organic loading rates (4.9–5.7 g volatile solids/L/d). The experiments and analyses were mainly designed to reveal the impact of MW pretreatment and digester temperatures on the process stability and microbial community structure by correlating the composition of microbial populations with volatile fatty acid (VFA) concentrations. A slight shift from biogas production (with a reasonable methane content) to VFA accumulation was observed in the thermophilic digesters, especially in the MW-irradiated reactors. Microbial population structure was assessed using a high-throughput sequencing of 16S rRNA gene on the MiSeq platform. Microbial community structure was slightly affected by different MW pretreatment conditions, while substantially affected by the digester temperature. The phylum Bacteroidetes proliferated in the MW-irradiated mesophilic digesters by resisting high-temperature MW (at 160 °C). Hydrogenotrophic methanogenesis (mostly the genus of Methanothermobacter) was found to be a key route of methane production in the thermophilic digesters, whereas aceticlastic methanogenesis (mostly the genus of Methanosaeta) was the main pathway in the mesophilic digesters.

ACS Style

Gokce Kor-Bicakci; Emine Ubay-Cokgor; Cigdem Eskicioglu. Comparative Analysis of Bacterial and Archaeal Community Structure in Microwave Pretreated Thermophilic and Mesophilic Anaerobic Digesters Utilizing Mixed Sludge under Organic Overloading. Water 2020, 12, 887 .

AMA Style

Gokce Kor-Bicakci, Emine Ubay-Cokgor, Cigdem Eskicioglu. Comparative Analysis of Bacterial and Archaeal Community Structure in Microwave Pretreated Thermophilic and Mesophilic Anaerobic Digesters Utilizing Mixed Sludge under Organic Overloading. Water. 2020; 12 (3):887.

Chicago/Turabian Style

Gokce Kor-Bicakci; Emine Ubay-Cokgor; Cigdem Eskicioglu. 2020. "Comparative Analysis of Bacterial and Archaeal Community Structure in Microwave Pretreated Thermophilic and Mesophilic Anaerobic Digesters Utilizing Mixed Sludge under Organic Overloading." Water 12, no. 3: 887.

Journal article
Published: 05 March 2020 in Renewable Energy
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Using high-strength wastes, such as grease trap waste mixture (GTWM) from multiple commercial facilities, as a co-substrate in anaerobic digestion can contribute to a significant increase in methane production. However, challenges such as long chain fatty acids (LCFAs) accumulation, sludge flotation, washout and scum formation can lead to digester failure. In this study, the optimal operating condition to achieve the highest methane production from an anaerobic, semi-continuous flow, mesophilic co-digester at a solids retention time of 20 days was determined. The ratio of GTWM/sludge was increased based on volatile solids (VS) concentration from 10% to 50% in 10% increments. A 40% GTWM/sludge ratio was determined to be optimum in which up to 22%, 200% and 68% improvements in VS removal, daily biogas production and specific methane production, respectively, were observed with respect to control utilizing sludge only. Beyond a 40% GTWM/sludge, the anaerobic co-digester experienced failure and addition of biochar to mitigate LCFA inhibition to failing co-digester could not recover the process. Digester LCFA concentrations were also measured during stable and unstable digester operations.

ACS Style

Niloofar Shakourifar; David Krisa; Cigdem Eskicioglu. Anaerobic co-digestion of municipal waste sludge with grease trap waste mixture: Point of process failure determination. Renewable Energy 2020, 154, 117 -127.

AMA Style

Niloofar Shakourifar, David Krisa, Cigdem Eskicioglu. Anaerobic co-digestion of municipal waste sludge with grease trap waste mixture: Point of process failure determination. Renewable Energy. 2020; 154 ():117-127.

Chicago/Turabian Style

Niloofar Shakourifar; David Krisa; Cigdem Eskicioglu. 2020. "Anaerobic co-digestion of municipal waste sludge with grease trap waste mixture: Point of process failure determination." Renewable Energy 154, no. : 117-127.

Journal article
Published: 12 January 2020 in Molecules
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Treatment of emerging contaminants, such as antimicrobials, has become a priority topic for environmental protection. As a persistent, toxic, and bioaccumulative antimicrobial, the accumulation of triclosan (TCS) in wastewater sludge is creating a potential risk to human and ecosystem health via the agricultural use of biosolids. The impact of microwave (MW) pretreatment on TCS levels in municipal sludge is unknown. This study, for the first time, evaluated how MW pretreatment (80 and 160 °C) itself and together with anaerobic digestion (AD) under various sludge retention times (SRTs: 20, 12, and 6 days) and temperatures (35 and 55 °C) can affect the levels of TCS in municipal sludge. TCS and its potential transformation products were analyzed with ultra-high-performance liquid chromatography and tandem mass spectrometry. Significantly higher TCS concentrations were detected in sludge sampled from the plant in colder compared to those in warmer temperatures. MW temperature did not have a discernible impact on TCS reduction from undigested sludge. However, AD studies indicated that compared to controls (no pretreatment), MW irradiation could make TCS more amenable to biodegradation (up to 46%), especially at the elevated pretreatment and digester temperatures. At different SRTs studied, TCS levels in the thermophilic digesters were considerably lower than that of in the mesophilic digesters.

ACS Style

Gokce Kor-Bicakci; Timothy Abbott; Emine Ubay-Cokgor; Cigdem Eskicioglu. Occurrence of the Persistent Antimicrobial Triclosan in Microwave Pretreated and Anaerobically Digested Municipal Sludges under Various Process Conditions. Molecules 2020, 25, 310 .

AMA Style

Gokce Kor-Bicakci, Timothy Abbott, Emine Ubay-Cokgor, Cigdem Eskicioglu. Occurrence of the Persistent Antimicrobial Triclosan in Microwave Pretreated and Anaerobically Digested Municipal Sludges under Various Process Conditions. Molecules. 2020; 25 (2):310.

Chicago/Turabian Style

Gokce Kor-Bicakci; Timothy Abbott; Emine Ubay-Cokgor; Cigdem Eskicioglu. 2020. "Occurrence of the Persistent Antimicrobial Triclosan in Microwave Pretreated and Anaerobically Digested Municipal Sludges under Various Process Conditions." Molecules 25, no. 2: 310.

Journal article
Published: 30 November 2019 in Science of The Total Environment
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This study, for the first time, investigated the impact of microwave pretreatment on the fate of the pervasive antimicrobial triclocarban (TCC) that was already present in municipal sludge, before and during advanced anaerobic digestion (AD) under thermophilic and mesophilic conditions. A range of microwave temperature (80 and 160 °C) and exposure duration (1 and 30 min) configurations were studied by employing ten bench-scale anaerobic digesters fed with mixed sludge at three different solids retention times (SRTs) including 20, 12, and 6 days. Seasonal changes influenced the levels of TCC in municipal sludge sampled from a plant employing the biological nutrient removal. Initial batch pretreatment studies showed that microwave irradiation itself can achieve TCC removal efficiencies up to 30 ± 4 and 64 ± 5% at 80 and 160 °C, respectively. The control digesters utilizing un-pretreated mixed sludge showed limited TCC removals, between 18 and 32% and 11–26% respectively, under thermophilic and mesophilic temperatures. On the other hand, the highest TCC elimination (78 ± 2%) was obtained from the thermophilic digester utilizing microwaved sludge at 160 °C for 30 min at SRT of 12 days. The non-chlorinated carbanilide (a transformation product of TCC) was detected and quantified for the first time during conventional and microwave-pretreated anaerobic sludge digestion. The formation of carbanilide in biosolids through reductive dechlorination could be an indicator of efficient and complete TCC transformation. This research demonstrated that AD coupled with microwave pretreatment can be used to reduce environmental concentrations of TCC in municipal sludge and biosolids.

ACS Style

Gokce Kor-Bicakci; Timothy Abbott; Emine Ubay-Cokgor; Cigdem Eskicioglu. Occurrence and fate of antimicrobial triclocarban and its transformation products in municipal sludge during advanced anaerobic digestion using microwave pretreatment. Science of The Total Environment 2019, 705, 135862 .

AMA Style

Gokce Kor-Bicakci, Timothy Abbott, Emine Ubay-Cokgor, Cigdem Eskicioglu. Occurrence and fate of antimicrobial triclocarban and its transformation products in municipal sludge during advanced anaerobic digestion using microwave pretreatment. Science of The Total Environment. 2019; 705 ():135862.

Chicago/Turabian Style

Gokce Kor-Bicakci; Timothy Abbott; Emine Ubay-Cokgor; Cigdem Eskicioglu. 2019. "Occurrence and fate of antimicrobial triclocarban and its transformation products in municipal sludge during advanced anaerobic digestion using microwave pretreatment." Science of The Total Environment 705, no. : 135862.

Journal article
Published: 18 November 2019 in Bioresource Technology
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Biochemical methane production (BMP) assays of acidified municipal sludge were conducted with local char (biochar and wood ash) in granular (0.85–4.75 mm) and powdered (<0.075 mm) form. The effects of char addition on BMP were investigated under high acid stress conditions at substrate to inoculum ratios of 2.2, 3.2 and 4.4 g volatile solids (VS)/g-VS and char dosages of 0.2–3.7 g/g-VSsubstrate. Powdered biochar at dosage of 0.8–3.7 g/g-VSsubstrate achieved the highest improvement in rate of methane production with 192–461% increase from controls, in the first 16 days. This increase was followed by an early stationary methane production phase and a reduction of total methane yield by up to 25%. Results indicated that the early plateau could be caused by adsorption of volatile fatty acids by the biochar.

ACS Style

Caroline Cimon; Paul Kadota; Cigdem Eskicioglu. Effect of biochar and wood ash amendment on biochemical methane production of wastewater sludge from a temperature phase anaerobic digestion process. Bioresource Technology 2019, 297, 122440 .

AMA Style

Caroline Cimon, Paul Kadota, Cigdem Eskicioglu. Effect of biochar and wood ash amendment on biochemical methane production of wastewater sludge from a temperature phase anaerobic digestion process. Bioresource Technology. 2019; 297 ():122440.

Chicago/Turabian Style

Caroline Cimon; Paul Kadota; Cigdem Eskicioglu. 2019. "Effect of biochar and wood ash amendment on biochemical methane production of wastewater sludge from a temperature phase anaerobic digestion process." Bioresource Technology 297, no. : 122440.

Journal article
Published: 18 October 2019 in Bioresource Technology Reports
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The fate of pharmaceuticals, azithromycin (AZI), carbamazepine (CBZ), diclofenac (DCF), mefenamic acid (MFA), ibuprofen (IBP) and one ibuprofen metabolite (1-hydroxy ibuprofen (1-OH IBP)), were investigated in single-stage anaerobic (AN) and sequential anaerobic/aerobic/anoxic (AN/AERO/ANOX) sludge digestion under thermophilic conditions (55 °C). Intermittent aeration was used for the sequential AERO/ANOX vessel. Digesters showed an increase in CBZ, MFA and DCF at a hydraulic retention time (HRT) of 18 days as organic matter is degraded. However, the rate of increase for MFA was 10 times lower in sequential digestion compared to single-stage AN digestion (control). Sequential AN/AERO/ANOX digestion showed a 50% decrease in IBP levels while increasing IBPs aerobic metabolite 1-OH IBP by 12%. The control AN digester showed a 62% increase in IBP and a 34% decrease in 1-OH IBP. Sequential digestion provided other benefits, including reduced ammonia generation (44.5%), improved solids removal (4.1%) and enhanced digestate dewaterability (20%) compared to the control.

ACS Style

M. Ahmad; T. Abbott; C. Eskicioglu. Effectiveness of single-stage and sequential sludge digestion on removal of recalcitrant pharmaceuticals and conventional pollutants. Bioresource Technology Reports 2019, 8, 100326 .

AMA Style

M. Ahmad, T. Abbott, C. Eskicioglu. Effectiveness of single-stage and sequential sludge digestion on removal of recalcitrant pharmaceuticals and conventional pollutants. Bioresource Technology Reports. 2019; 8 ():100326.

Chicago/Turabian Style

M. Ahmad; T. Abbott; C. Eskicioglu. 2019. "Effectiveness of single-stage and sequential sludge digestion on removal of recalcitrant pharmaceuticals and conventional pollutants." Bioresource Technology Reports 8, no. : 100326.

Journal article
Published: 21 May 2019 in Waste Management
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Emerging contaminants (ECs), such as pharmaceuticals, sterols and polycyclic aromatic hydrocarbons (PAHs) are frequently detected in the environment. ECs are refractory, toxic, tend to bioaccumulate and have a potential to disrupt the endocrine system of living organisms. These compounds are only partially eliminated in wastewater treatment plants (WWTPs). Due to their hydrophobic nature, they tend to accumulate in sludge. However, the fate of the majority of ECs in sludge treatment processes is not fully understood. In this study, the effect of a sequential anaerobic/aerobic/anoxic (AN/AERO/ANOX) digestion and a conventional single-stage AN digestion (as control) was investigated on mixed primary and secondary sludge. Digesters were operated at an overall solid retention time (SRT) of 18 days. The steady-state results have shown that sequential AN/AERO/ANOX digestion configurations improved the removal of three classes of ECs (e.g., sterols, PAHs and pharmaceuticals) by either reducing their accumulation or enhancing their removal. Moreover, sequential AN/AERO/ANOX digestion also achieved 45% less ammonia generation, 20% faster digestate dewaterability and 4% enhanced volatile solids removal compared to single-stage AN digestion.

ACS Style

M. Ahmad; C. Eskicioglu. Fate of sterols, polycyclic aromatic hydrocarbons, pharmaceuticals, ammonia and solids in single-stage anaerobic and sequential anaerobic/aerobic/anoxic sludge digestion. Waste Management 2019, 93, 72 -82.

AMA Style

M. Ahmad, C. Eskicioglu. Fate of sterols, polycyclic aromatic hydrocarbons, pharmaceuticals, ammonia and solids in single-stage anaerobic and sequential anaerobic/aerobic/anoxic sludge digestion. Waste Management. 2019; 93 ():72-82.

Chicago/Turabian Style

M. Ahmad; C. Eskicioglu. 2019. "Fate of sterols, polycyclic aromatic hydrocarbons, pharmaceuticals, ammonia and solids in single-stage anaerobic and sequential anaerobic/aerobic/anoxic sludge digestion." Waste Management 93, no. : 72-82.

Review article
Published: 14 May 2019 in Renewable and Sustainable Energy Reviews
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Sludge management is still one of the most challenging issues in wastewater treatment plants due to a dramatic increase in sludge production, high sludge disposal costs, legal constraints as well as social and environmental concerns. There is a great effort to develop more environmentally friendly and economical technologies for minimization of excess sludge production and converting wastewater treatment sludge from waste into a renewable resource for bioenergy recovery. Recently, among these technologies, pretreatment processes applied before anaerobic sludge digestion have received a growing attention with several advantages over conventional digestion process. The main goal of the present paper is to present a state-of-the-art review of recent developments on advanced anaerobic digestion employed in municipal wastewater treatment plants. Thermal pretreatment technologies documented in the literature are presented extensively. The effectiveness of thermal pretreatment methods, namely conventional, microwave and radio frequency heatings, are discussed and compared in terms of heating principles, sludge disintegration, digester performance, and sludge rheology. The effectiveness and practicality of the aforementioned methods at industrial-scale and some challenges associated with the implementation at full-scale are also reviewed. Particular attention is paid to integration of combined heat and power systems with thermal hydrolysis for achieving energy self-sufficiency in full-scale plants. Furthermore, the municipal sludge production around the world as well as current sludge disposal and reuse options are addressed.

ACS Style

Gokce Kor-Bicakci; Cigdem Eskicioglu. Recent developments on thermal municipal sludge pretreatment technologies for enhanced anaerobic digestion. Renewable and Sustainable Energy Reviews 2019, 110, 423 -443.

AMA Style

Gokce Kor-Bicakci, Cigdem Eskicioglu. Recent developments on thermal municipal sludge pretreatment technologies for enhanced anaerobic digestion. Renewable and Sustainable Energy Reviews. 2019; 110 ():423-443.

Chicago/Turabian Style

Gokce Kor-Bicakci; Cigdem Eskicioglu. 2019. "Recent developments on thermal municipal sludge pretreatment technologies for enhanced anaerobic digestion." Renewable and Sustainable Energy Reviews 110, no. : 423-443.

Journal article
Published: 23 November 2018 in Energy
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The effects of microwave (MW) final temperature (80 and 160 °C) and holding time (1 and 30 min) were evaluated by ten anaerobic digesters (AD). MW was applied to dewatered secondary sludge with total solids of 10.5 ± 0.5% (by weight) to minimize energy input. Mixed sludge was digested under thermophilic and mesophilic conditions at sludge retention times (SRTs) of 20, 12 and 6 days. MW final temperature had significantly higher effect on solubilization than holding time. At MW of 80/160 °C, longer holding times further enhanced solubilization but increased volatile fatty acid accumulation at thermophilic SRT of 6 days. While all mesophilic digesters met the Class B requirement in terms of pathogens removal, all thermophilic digesters produced Class A biosolids. MW-ADs were able to tolerate 15–20% higher loading rates compared to controls. Up to 21% higher organics removals were achieved by MW. MW at 160 °C generated the highest amount of extra heat that could be used within/outside of plant. However energy recovered from the enhanced methane production was not sufficient to cover the electrical energy consumed by MW. Therefore, a custom-designed electromagnetic heating unit based on dielectric properties of sludge is needed to minimize energy input and maximize energy recovery for full-scale applications.

ACS Style

Gokce Kor-Bicakci; Emine Ubay-Cokgor; Cigdem Eskicioglu. Effect of dewatered sludge microwave pretreatment temperature and duration on net energy generation and biosolids quality from anaerobic digestion. Energy 2018, 168, 782 -795.

AMA Style

Gokce Kor-Bicakci, Emine Ubay-Cokgor, Cigdem Eskicioglu. Effect of dewatered sludge microwave pretreatment temperature and duration on net energy generation and biosolids quality from anaerobic digestion. Energy. 2018; 168 ():782-795.

Chicago/Turabian Style

Gokce Kor-Bicakci; Emine Ubay-Cokgor; Cigdem Eskicioglu. 2018. "Effect of dewatered sludge microwave pretreatment temperature and duration on net energy generation and biosolids quality from anaerobic digestion." Energy 168, no. : 782-795.

Journal article
Published: 11 August 2018 in Molecules
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This paper presents results for a comprehensive study that compares the performance of three electricity-based thermal pretreatment methods for improving the effectiveness of anaerobic digestion (AD) to process municipal wastewater sludge. The study compares thermal pretreatment using conventional heating (CH), microwave (MW), and radio frequency (RF) heating techniques. The effectiveness of the pretreatment methods was assessed in terms of chemical oxygen demand (COD) and biopolymers solubilization, AD bioenergy production, input electrical energy, and overall net energy production of the sequential pretreatment/AD process. The heating applicators for the bench-scale testing consisted of a custom-built pressure-sealed heating vessel for CH experiments, an off-the-shelf programmable MW oven operating at a frequency of 2.45 GHz for MW heating experiments, and a newly developed 1 kW RF heating system operating at a frequency of 13.56 MHz for RF heating experiments. Under identical thermal profiles, all three thermal pretreatment methods achieved similar sludge disintegration in terms of COD and biopolymer solubilization as well as AD bioenergy production (p-value > 0.05). According to the energy assessment results, the application of CH and MW pretreatments resulted in overall negative energy production, while positive net energy production was obtained through the sequential pretreatment/AD process utilizing RF pretreatment.

ACS Style

E. Hosseini Koupaie; T. Johnson; C. Eskicioglu. Comparison of Different Electricity-Based Thermal Pretreatment Methods for Enhanced Bioenergy Production from Municipal Sludge. Molecules 2018, 23, 2006 .

AMA Style

E. Hosseini Koupaie, T. Johnson, C. Eskicioglu. Comparison of Different Electricity-Based Thermal Pretreatment Methods for Enhanced Bioenergy Production from Municipal Sludge. Molecules. 2018; 23 (8):2006.

Chicago/Turabian Style

E. Hosseini Koupaie; T. Johnson; C. Eskicioglu. 2018. "Comparison of Different Electricity-Based Thermal Pretreatment Methods for Enhanced Bioenergy Production from Municipal Sludge." Molecules 23, no. 8: 2006.