Browsing by Author "Ersan, Yusuf Cagatay"

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Citation - WoS: 6
Citation - Scopus: 8
Compatibility and Biomineralization Oriented Optimization of Nutrient Content in Nitrate-Reducing Microbial Self-Healing Concrete
(MDPI, 2021) Kardogan, Beyza; Sekercioglu, Kadir; Ersan, Yusuf Cagatay; 01. Abdullah Gül University
Microbially induced calcium carbonate precipitation (MICP) can be mentioned among the popular approaches to develop a self-healing concrete. The production of dissolved inorganic carbon through microbial activity is the main precursor for MICP in concrete and it is limited by the bioavailability of the nutrients. When nutrients are added to the mortar as admixtures, their bioavailability becomes more significant for crack repair because nutrients disperse in the mortar and considerable fraction stays far from a single crack. Therefore, the determination of bioavailability of nutrients and its variation with the initial nutrient content and crack age is essential to optimize a recipe for bacteria-based self-healing concrete. This study presents the optimum nutrient content defined for nitrate-reduction-based self-healing bioconcrete. In the tests, calcium nitrate (CN) and calcium formate (CF) were combined with a CF:CN w/w ratio of 2.50. Mortar properties and bioavailability of nutrients were analysed at different nutrient doses. Moreover, the bioavailability of nutrients at different crack ages changing between 3 and 56 days was monitored. Finally, resuscitation, microbial activity and the MICP performance of nitrate reducing biogranules were tested at defined nutrient bioavailabilties. The optimum nutrient content was determined as 7.00% (CF 5.00% and CN 2.00%). The leaching rates of formate ions were twice the leaching rate of the nitrate ions at similar initial concentrations, which led to a bioavailable HCOO-/NO3-N ratio of 23 g/g in cracked mortar. Under optimum nutrient conditions, the CaCO3 precipitation yield of nitrate reducing biogranules was recorded as 1.5 g CaCO3/g HCOO- which corresponded to 68% C precipitation efficiency.
Citation - WoS: 10
Citation - Scopus: 12
The Effect of Seed Sludge Type on Aerobic Granulation via Anoxic-Aerobic Operation
(Taylor & Francis Ltd, 2014) Ersan, Yusuf Cagatay; Erguder, Tuba Hande; 01. Abdullah Gül University
The effects of two seed sludge types, namely conventional activated sludge (CAS) and membrane bioreactor sludge (MBS), on aerobic granulation were investigated. The treatment performances of the reactors were monitored during and after the granulation. Operational period of 37 days was described in three phases; Phase 1 corresponds to Days 1-10, Phase 2 (overloading conditions) to Days 11-27 and Phase 3 (recovery) to Days 28-37. Aerobic granules of 0.56 +/- 0.23 to 2.48 +/- 1.28mm were successfully developed from both MBS and CAS. First granules appeared on Day 9 in both reactors, indicating that there was no difference between two seed sludge types in terms of the time period for granulation initiation. The results revealed that the granules developed from MBS performed better than CAS in terms of settleability, stability, biomass retention, adaptation, protection of granular structure at high loading rates (0.86 gN/L d and 3.92 gCOD/Ld) and low COD/TAN ratio (5). Granules of MBS were also found to be capable of providing better protection for nitrifiers at toxic free-ammonia concentrations (38-46 mg/L NH3-N), thus showing better treatment recovery than those of CAS.
Citation - WoS: 18
Citation - Scopus: 22
The Effects of Aerobic/Anoxic Period Sequence on Aerobic Granulation and COD/N Treatment Efficiency
(Elsevier Sci Ltd, 2013) Ersan, Yusuf Cagatay; Erguder, Tuba Hande; 01. Abdullah Gül University
The effects of period sequence (anoxic-aerobic and aerobic-anoxic) on aerobic granulation from suspended seed sludge, and COD, N removal efficiencies were investigated in two sequencing batch reactors. More stable granules with greater sizes (1.8-3.5 mm) were developed in R1 (anoxic-aerobic sequence). Yet, no significant difference was observed between the reactors in terms of removal efficiencies. Under optimum operational conditions, 92-95% COD, 89-90% TAN and 38-46% total nitrogen removal efficiencies were achieved. The anoxic-aerobic period sequence (R1) resulted in almost complete denitrification during anoxic periods while aerobic-anoxic sequence (R2) led to nitrate accumulation due to limited-carbon source and further granule disintegration. NH3-N concentration of 15-28 mg/L was found to inhibit COD removal up to 30%. This study also revealed the inhibitory sulfide production during anoxic periods. Sulfate concentration of 52.6-70.2 mg/L was found to promote sulfate reduction and sulfide generation (0.24-0.62 mg/L) which, together with free-ammonia, inhibited TAN oxidation by 10-50%. (C) 2013 Elsevier Ltd. All rights reserved.
Citation - WoS: 41
Citation - Scopus: 47
Life Cycle Assessment of Lightweight Concrete Containing Recycled Plastics and Fly Ash
(Taylor & Francis Ltd, 2022) Ersan, Yusuf Cagatay; Gulcimen, Sedat; Imis, Tuba Nur; Saygin, Osman; Uzal, Nigmet; 01. Abdullah Gül University; 02.03. İnşaat Mühendisliği; 02. Mühendislik Fakültesi
Researchers put significant effort to decrease the environmental impact of concrete by using industrial by-products as an alternative binder. However, the considerable environmental impact still exists due to the consumption of natural resources as aggregates. Natural aggregates are the most used resources by volume in the construction sector. Therefore, it is necessary to investigate by-products as an alternative to natural aggregates as well. This study presents the environmental impact of lightweight concrete (LWC) produced by replacing natural aggregates with recycled waste plastic (polyethylene) (RWP) and partially replacing Portland cement with Class F fly ash (FA). Life Cycle Assessment (LCA) was performed to compare a conventional LWC, containing pumice as natural aggregate and Portland cement as a binder, with green LWC, containing 30% RWP as pumice replacement and 20% FA as cement replacement. These scenarios were evaluated in terms of global warming potential, abiotic depletion, ozone layer depletion, terrestrial ecotoxicity, photochemical oxidation, acidification and eutrophication. LCA was coupled with mechanical tests at 7 days and 28 days. RWPs were found to be an environment-friendly replacement material for natural lightweight aggregates with an overall decrease in all CML-IA impacts except eutrophication. Tested green mix design also provided sufficient strength for nonstructural applications.
Overlooked Strategies in Exploitation of Microorganisms in the Field of Building Materials
(SPRINGER-VERLAG SINGAPORE PTE LTD, 152 BEACH ROAD, #21-01/04 GATEWAY EAST, SINGAPORE, 189721, SINGAPORE, 01.09.2019) Ersan, Yusuf Cagatay; 0000-0003-4128-0195; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; 01. Abdullah Gül University
Resource efficiency reports released in the last decade point out construction industry as one of the key sectors that needs improvement in terms of ecological sensitivity. Being aware of this unfavorable reputation of construction industry, researchers embarked on replacing the ongoing conventional methods with more sustainable and environmentally friendly ones. One of the approaches for the latter is incorporating microorganisms into construction industry. Popularly investigated strategies can be listed as biocementation, biomasonry, biorepair, and bioconsolidation. Most of these processes are the outcome of a single approach, namely microbial-induced calcium carbonate precipitation (MICP) which was mostly investigated by means of axenic cultures and through one single microbial process, ureolysis. The state of the art about the latter is close to saturation. Moreover, approaching from the ecological wisdom perspective it can be said that some promising microbial strategies to achieve green building materials were overlooked and drawing attention to these strategies became necessary. This review study reveals the overlooked promising microbial strategies in the field of construction biotechnology. The context mainly discusses the potential of five overlooked microbial strategies: (i) heterotrophic and autotrophic MICP pathways, (ii) microbial strategies for surface treatment, (iii) microbial-induced corrosion inhibition, (iv) microbial sequestration of greenhouse gases, and (v) microbial- produced polymers, for their application in the field of construction materials. Further suggestions aim to integrate the microbial resource management approach and non-axenic cultures into the relevant fields of research for the development of environmentally friendly building materials.
Citation - WoS: 12
Overlooked Strategies in Exploitation of Microorganisms in the Field of Building Materials
(Springer-Verlag Singapore Pte Ltd, 2019) Ersan, Yusuf Cagatay; 01. Abdullah Gül University
Resource efficiency reports released in the last decade point out construction industry as one of the key sectors that needs improvement in terms of ecological sensitivity. Being aware of this unfavorable reputation of construction industry, researchers embarked on replacing the ongoing conventional methods with more sustainable and environmentally friendly ones. One of the approaches for the latter is incorporating microorganisms into construction industry. Popularly investigated strategies can be listed as biocementation, biomasonry, biorepair, and bioconsolidation. Most of these processes are the outcome of a single approach, namely microbial-induced calcium carbonate precipitation (MICP) which was mostly investigated by means of axenic cultures and through one single microbial process, ureolysis. The state of the art about the latter is close to saturation. Moreover, approaching from the ecological wisdom perspective it can be said that some promising microbial strategies to achieve green building materials were overlooked and drawing attention to these strategies became necessary. This review study reveals the overlooked promising microbial strategies in the field of construction biotechnology. The context mainly discusses the potential of five overlooked microbial strategies: (i) heterotrophic and autotrophic MICP pathways, (ii) microbial strategies for surface treatment, (iii) microbial-induced corrosion inhibition, (iv) microbial sequestration of greenhouse gases, and (v) microbial- produced polymers, for their application in the field of construction materials. Further suggestions aim to integrate the microbial resource management approach and non-axenic cultures into the relevant fields of research for the development of environmentally friendly building materials.
Citation - WoS: 9
Citation - Scopus: 11
Production and Compatibility Assessment of Denitrifying Biogranules Tailored for Self-Healing Concrete Applications
(Elsevier Sci Ltd, 2022) Sonmez, Merve; Ersan, Yusuf Cagatay; 01. Abdullah Gül University
Microbial granules have been mostly used for wastewater treatment. Recently, biogranules consisting nitrate-reducing microorganisms have appeared as a unique healing agent providing simultaneous self-healing of cracks and corrosion inhibition of rebar in concrete. Yet, information about the production process and microbial activity of these biogranules as well as their compatibility with cementitious materials remains unknown. This study presents the biogranule production procedure in detail and evaluates the compatibility of the produced biogranules with the cementitious composites. In the form of biogranules, bacteria doses varying between 0.25% and 3.00% w/w cement were incorporated into mortar and the variations in fresh and hardened properties of mortars were evaluated with respect to abiotic mortars. Biogranules were also tested for their compatibility with concrete at minimum and the defined maximum tolerable doses. Biogranules with a NOx-N reduction activity of 0.10 g NOx-N.g(-1) bacteria.d(-1) and organic carbon oxidation activity of 1.50 g HCOO-.g(- 1) bacteria.d(-1) were produced successfully by using minimal medium. It was found out that biogranules enable bacteria incorporation into mortar up to a dose of 2.50% w/w cement without compromising fresh and hardened properties of cementitious composites. It was revealed that the compatibility of the biogranules was due to the mineral layer surrounding the biogranules which prevented interaction between the cement matrix and the microbial content. The thickness of the protective mineral layer around the granules was varying between 50 and 300 mu m depending on the granule size. Net yield for concrete compatible biogranule production was determined as 0.05 g bio-granule.g(-1)HCOO-.
Citation - WoS: 10
Self-Healing Performance of Biogranule Containing Microbial Self-Healing Concrete Under Intermittent Wet/Dry Cycles
(Gazi Univ, 2021) Ersan, Yusuf Cagatay; 0000-0003-4128-0195; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Ersan, Yusuf Cagatay; 01. Abdullah Gül University
Development of self-sensing and self-healing concrete is essential to minimize the labour-intensive monitoring and repair activities conducted for the maintenance of concrete structures. A type of self-healing concrete can be achieved by using microbial agents that induce calcium carbonate precipitation inside a concrete crack. Recently, biogranules consist of nitrate reducing microorganisms were presented as a new generation microbial healing agent and biogranule containing specimens revealed decent healing performance under completely submerged conditions. However, their performance under intermittent wetting conditions, a common case for various concrete structures, remains unknown. This study presents the self-healing performance of biogranule containing biomortar specimens under intermittent wet/dry conditions. In-house produced biogranules were incorporated into mortar specimens at a dose of 1.45% w/w cement (1.00% of bacteria w/w cement) and self-healing performance of cracked specimens were investigated under alternating wet/dry conditions for a crack width range of 50 to 600 um. Upon alternating wet/dry treatment for 4 weeks, cracks up to a 400 um crack width were effectively healed in biomortar specimens. Their water tightness regain was 44% better than control specimens due to their enhanced healing performance. Overall, non-axenic biogranules appear to be useful in development of self-healing bioconcrete for applications under spraying or intermittent wetting conditions.
Citation - WoS: 23
Citation - Scopus: 30
Volume Fraction, Thickness, and Permeability of the Sealing Layer in Microbial Self-Healing Concrete Containing Biogranules
(Frontiers Media S.A., 2018) Ersan, Yusuf Cagatay; Palin, Damian; Tasdemir, Sena Busra Yengec; Tasdemir, Kasim; Jonkers, Henk M.; Boon, Nico; De Belie, Nele; 01. Abdullah Gül University
Autonomous repair systems in construction materials have become a promising alternative to current unsustainable and labor-intensive maintenance methods. Biomineralization is a popular route that has been applied to enhance the self-healing capacity of concrete. Various axenic microbial cultures were coupled with protective carriers, and their combination appears to be useful for the development of healing agents for realizing self-healing concrete. The advantageous traits of non-axenic cultures, such as economic feasibility, self-protection, and high specific activity have been neglected so far, and thus the number of studies investigating their performance as healing agents is scarce. Here we present the self-healing performance of a mortar containing a healing agent consisting of non-axenic biogranules with a denitrifying core. Mortar specimens with a defined crack width of 400 mu m were used in the experiments and treated with tap water for 28 days. Self-healing was quantified in terms of the crack volume reduction, the thickness of the sealing layer along the crack depth and water permeability under 0.1 bar pressure. Complete visual crack closure was achieved in the bio-based specimens in 28 days, the thickness of the calcite layer was recorded as 10 mm and the healed crack volume was detected as 6%. Upon self-sealing of the specimens, the water permeability decreased by 83%. Overall, non-axenic biogranules with a denitrifying core shows great potential for development of self-healing bioconcrete.