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Microbially induced carbonate precipitation (MICP) has been proposed as a sustainable approach to solve various environmental, structural, geotechnical and architectural issues. In the last decade, a ubiquitous microbial metabolism, nitrate reduction (also known as denitrification) got attention in MICP research due to its unique added benefits such as simultaneous corrosion inhibition in concrete and desaturation of porous media. The latter even upgraded MICP into a more advanced concept called microbially induced desaturation and precipitation (MIDP) which is being investigated for liquefaction mitigation. In this paper, we present the findings on MICP through denitrification by covering applications under two main titles: (i) applications solely based on MICP, such as soil reinforcement, development of microbial self-healing concrete, restoration of artwork and historical monuments, and industrial wastewater treatment, (ii) an application based on MIDP: liquefaction mitigation. After explaining the denitrification process in detail and describing the MICP and MIDP reaction system occurring through denitrification metabolism, the most recent advances in each potential field of application are collected, addressing the novel findings and limitations, to provide insights toward the practical applications in situ. Finally, the research needs required to deal with the defined challenges in application-oriented upscaling and optimization of MICP through denitrification are suggested. Overall, collected research findings revealed that MICP through denitrification possesses a great potential to replace conventionally used petrochemical-based, labour intensive, destructive and economically unfeasible techniques used in construction industry with a bio-based, labourless, low-carbon technology. This worldwide applicable bio-based technology will facilitate the sustainable development and contribute to the carbon-emission-reduction.
Wenbin Lin; Wei Lin; Xiaohui Cheng; Guozhou Chen; Yusuf Cagatay Ersan. Microbially Induced Desaturation and Carbonate Precipitation through Denitrification: A Review. Applied Sciences 2021, 11, 7842 .
AMA StyleWenbin Lin, Wei Lin, Xiaohui Cheng, Guozhou Chen, Yusuf Cagatay Ersan. Microbially Induced Desaturation and Carbonate Precipitation through Denitrification: A Review. Applied Sciences. 2021; 11 (17):7842.
Chicago/Turabian StyleWenbin Lin; Wei Lin; Xiaohui Cheng; Guozhou Chen; Yusuf Cagatay Ersan. 2021. "Microbially Induced Desaturation and Carbonate Precipitation through Denitrification: A Review." Applied Sciences 11, no. 17: 7842.
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.
Beyza Kardogan; Kadir Sekercioglu; Yusuf Çagatay Erşan. Compatibility and Biomineralization Oriented Optimization of Nutrient Content in Nitrate-Reducing-Biogranules-Based Microbial Self-Healing Concrete. Sustainability 2021, 13, 8990 .
AMA StyleBeyza Kardogan, Kadir Sekercioglu, Yusuf Çagatay Erşan. Compatibility and Biomineralization Oriented Optimization of Nutrient Content in Nitrate-Reducing-Biogranules-Based Microbial Self-Healing Concrete. Sustainability. 2021; 13 (16):8990.
Chicago/Turabian StyleBeyza Kardogan; Kadir Sekercioglu; Yusuf Çagatay Erşan. 2021. "Compatibility and Biomineralization Oriented Optimization of Nutrient Content in Nitrate-Reducing-Biogranules-Based Microbial Self-Healing Concrete." Sustainability 13, no. 16: 8990.
The exploration of biodeposition treatment for the surface consolidation of natural stones is limited by thus-far used study-specific treatment conditions. This study explores the surface consolidation performance of Bacillus sphaericus in varying treatment conditions and compares the results with the application of a tetraethyl orthosilicate (TEOS)-based chemical consolidant to suggest a more standardized treatment procedure. Initially, the biodeposition medium was optimized for maximal ureolytic activity. Then, consolidation procedures with different times and numbers of applications were conducted on sound (no aging) Maastricht limestone. Consolidation performances were evaluated by comparing the changes in the ultrasonic pulse velocity (P-wave) through the specimens and the drilling resistance of the specimens. Upon two or more subsequent biotreatments, the transmitting velocity of the P-wave increased by up to 25% in the first 20 mm of the specimen. The drilling resistance of the specimen increased by 100% up to a depth of 35 mm from the surface. A minimum of two subsequent biotreatments are suggested for a decent consolidation of Maastricht limestone, and a minimum of four subsequent treatments are suggested to replace TEOS.
Yusuf Çağatay Erşan; Jianyun Wang; Domien Fraeye; Nico Boon; Nele De Belie. Surface Consolidation of Maastricht Limestone by Means of Bacillus Sphaericus under Varying Treatment Conditions. Journal of Materials in Civil Engineering 2020, 32, 04020342 .
AMA StyleYusuf Çağatay Erşan, Jianyun Wang, Domien Fraeye, Nico Boon, Nele De Belie. Surface Consolidation of Maastricht Limestone by Means of Bacillus Sphaericus under Varying Treatment Conditions. Journal of Materials in Civil Engineering. 2020; 32 (11):04020342.
Chicago/Turabian StyleYusuf Çağatay Erşan; Jianyun Wang; Domien Fraeye; Nico Boon; Nele De Belie. 2020. "Surface Consolidation of Maastricht Limestone by Means of Bacillus Sphaericus under Varying Treatment Conditions." Journal of Materials in Civil Engineering 32, no. 11: 04020342.
Recently, cost-efficient nitrate reducing biogranules were suggested as an alternative to axenic microbial cultures for development of microbial self-healing concrete. In a marine environment, biogranule containing microbial self-healing concrete showed simultaneous self-healing of cracks and immunisation against rebar corrosion. Yet, information about the production strategy of these biogranules and their compatibility with a mortar matrix is limited. This study presents the production of biogranules and their compatibility with mortar specimens when incorporated at dosages between 0.36% to 4.30% w/w cement (0.25% to 3% of bacteria w/w cement). In-house produced biogranules composed of 70% bacteria and 30% of minerals w/w of biogranule were used for the compatibility tests. In test mortars, calcium formate (CF) and calcium nitrate (CN) were used as regular nutrient admixtures, and nutrient content was set identical in every batch. Up to 2.9% incorporation, biogranules had no significant influence on the fresh properties of mortar. More than 2.9% incorporation caused poor workability and a 26% decrease in 3-Day compressive strength of biomortar specimens. Overall, the biogranules produced are compatible with a cementitious matrix up to 2.9% w/w cement, and even up to 3.6% if early age strength is not essential, which makes biogranules one of the most compatible microbial healing agents among the suggested agents in the literature.
Merve Sonmez; Yusuf Cagatay Ersan. Production of concrete compatible biogranules for self-healing concrete applications. MATEC Web of Conferences 2019, 289, 01002 .
AMA StyleMerve Sonmez, Yusuf Cagatay Ersan. Production of concrete compatible biogranules for self-healing concrete applications. MATEC Web of Conferences. 2019; 289 ():01002.
Chicago/Turabian StyleMerve Sonmez; Yusuf Cagatay Ersan. 2019. "Production of concrete compatible biogranules for self-healing concrete applications." MATEC Web of Conferences 289, no. : 01002.
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 μm 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.
Yusuf Cagatay Ersan; Damian Palin; Sena Busra Yengec Tasdemir; Kasim Tasdemir; Henk M. Jonkers; Nico Boon; Nele De Belie. Volume Fraction, Thickness, and Permeability of the Sealing Layer in Microbial Self-Healing Concrete Containing Biogranules. Frontiers in Built Environment 2018, 4, 1 .
AMA StyleYusuf Cagatay Ersan, Damian Palin, Sena Busra Yengec Tasdemir, Kasim Tasdemir, Henk M. Jonkers, Nico Boon, Nele De Belie. Volume Fraction, Thickness, and Permeability of the Sealing Layer in Microbial Self-Healing Concrete Containing Biogranules. Frontiers in Built Environment. 2018; 4 ():1.
Chicago/Turabian StyleYusuf Cagatay Ersan; Damian Palin; Sena Busra Yengec Tasdemir; Kasim Tasdemir; Henk M. Jonkers; Nico Boon; Nele De Belie. 2018. "Volume Fraction, Thickness, and Permeability of the Sealing Layer in Microbial Self-Healing Concrete Containing Biogranules." Frontiers in Built Environment 4, no. : 1.
Chemicals and synthetic coatings are widely used to protect steel against corrosion. Bio-based corrosion inhibition strategies can be an alternative in the arising bioeconomy era. To maintain the good state of steel reinforcement in cracked concrete, microbe-based self-healing cementitious composites (MSCC) have been developed. Yet, proposed strategies involve reasonably slow crack filling by biomineralization and thus risk the possible rebar corrosion during crack healing. Here we upgrade the rebar protection to a higher level by combining MSCC with microbial induced corrosion inhibition. Presented NO3− reducing bacterial granules inhibit rebar corrosion by producing the anodic corrosion inhibitor NO2− and meanwhile heal a 300-µm-wide crack in 28 days. During 120 days exposure to 0.5 M Cl− solution, the rebars in cracked MSCC keep showing open circuit potentials above the critical value of −250 mV and they lose less than 2% of the total rebar material which corresponds to half the material loss in cracked plain mortar. Overall, the obtained rebar protection performance is comparable with that of uncracked mortar and mortar containing chemical inhibitor, hence the microbe-based system becomes an alternative to the traditional methods.
Yusuf Çağatay Erşan; Kim Van Tittelboom; Nico Boon; Nele De Belie. Nitrite producing bacteria inhibit reinforcement bar corrosion in cementitious materials. Scientific Reports 2018, 8, 1 -10.
AMA StyleYusuf Çağatay Erşan, Kim Van Tittelboom, Nico Boon, Nele De Belie. Nitrite producing bacteria inhibit reinforcement bar corrosion in cementitious materials. Scientific Reports. 2018; 8 (1):1-10.
Chicago/Turabian StyleYusuf Çağatay Erşan; Kim Van Tittelboom; Nico Boon; Nele De Belie. 2018. "Nitrite producing bacteria inhibit reinforcement bar corrosion in cementitious materials." Scientific Reports 8, no. 1: 1-10.
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.
Yusuf Cagatay Ersan. Overlooked Strategies in Exploitation of Microorganisms in the Field of Building Materials. Ecological Wisdom Inspired Restoration Engineering 2018, 19 -45.
AMA StyleYusuf Cagatay Ersan. Overlooked Strategies in Exploitation of Microorganisms in the Field of Building Materials. Ecological Wisdom Inspired Restoration Engineering. 2018; ():19-45.
Chicago/Turabian StyleYusuf Cagatay Ersan. 2018. "Overlooked Strategies in Exploitation of Microorganisms in the Field of Building Materials." Ecological Wisdom Inspired Restoration Engineering , no. : 19-45.
The applications of self-healing in cement-based materials via biomineralization processes are developing quickly. The main challenge is to find a microorganism that can tolerate the restricted environment of cement paste matrix (i.e. very high pH, lack of oxygen and nutrients, small pore size etc.). The focus of this work was to determine the possible use of an ammonium salt-based air-entraining admixture (AEA) as a protection method to improve the survival of incorporated Sporosarcina pasteurii cells in cement-based mortar. Bacterial cells were directly added to the mortar mix with and without nutrients. Nutrients should be provided to keep the microorganisms viable even at early ages (i.e. 7 days). Surface charge of the bacterial cells and in vitro biogenic calcium carbonate (CaCO3) precipitation were not affected by the incorporation of AEA. However, introducing AEA did not influence the viability in mortar samples, which might be attributed to the type and chemistry of AEA used
Zeynep Başaran Bundur; Ali Amiri; Yusuf Çağatay Erşan; Nico Boon; Nele De Belie. Impact of air entraining admixtures on biogenic calcium carbonate precipitation and bacterial viability. Cement and Concrete Research 2017, 98, 44 -49.
AMA StyleZeynep Başaran Bundur, Ali Amiri, Yusuf Çağatay Erşan, Nico Boon, Nele De Belie. Impact of air entraining admixtures on biogenic calcium carbonate precipitation and bacterial viability. Cement and Concrete Research. 2017; 98 ():44-49.
Chicago/Turabian StyleZeynep Başaran Bundur; Ali Amiri; Yusuf Çağatay Erşan; Nico Boon; Nele De Belie. 2017. "Impact of air entraining admixtures on biogenic calcium carbonate precipitation and bacterial viability." Cement and Concrete Research 98, no. : 44-49.
Microbial self-healing of concrete has been widely investigated, yet the suggested microbial pathways are limited to ureolysis and the aerobic oxidation of carbon sources. Each of these pathways has certain environment and process related drawbacks which arise a need for an alternative pathway to proceed further. This study presents the NO3− reduction as an alternative microbial self-healing strategy. In the tests, we used previously described NO3− reducing bacteria, and two different porous protective carriers. The highest crack width healed by the bacteria was 370 ± 20 μm in 28 days and 480 ± 16 μm in 56 days. Water tightness regain up to 85% was achieved at the end of 56 days for 465 ± 21 μm crack width. Precipitates were identified as forms of CaCO3 and were abundant in microbial specimens particularly on the inner crack surface. The findings evidence the potential of the NO3− reduction pathway for development of microbial self-healing concrete.
Yusuf Çağatay Erşan; Emma Hernandez-Sanabria; Nico Boon; Nele de Belie. Enhanced crack closure performance of microbial mortar through nitrate reduction. Cement and Concrete Composites 2016, 70, 159 -170.
AMA StyleYusuf Çağatay Erşan, Emma Hernandez-Sanabria, Nico Boon, Nele de Belie. Enhanced crack closure performance of microbial mortar through nitrate reduction. Cement and Concrete Composites. 2016; 70 ():159-170.
Chicago/Turabian StyleYusuf Çağatay Erşan; Emma Hernandez-Sanabria; Nico Boon; Nele de Belie. 2016. "Enhanced crack closure performance of microbial mortar through nitrate reduction." Cement and Concrete Composites 70, no. : 159-170.
The beneficial effect of microbially induced carbonate precipitation on building materials has been gradually disclosed in the last decade. After the first applications of on historical stones, promising results were obtained with the respect of improved durability. An extensive study then followed on the application of this environmentally friendly and compatible material on a currently widely used construction material, concrete. This review is focused on the discussion of the impact of the two main applications, bacterial surface treatment and bacteria based crack repair, on concrete durability. Special attention was paid to the choice of suitable bacteria and the metabolic pathway aiming at their functionality in concrete environment. Interactions between bacterial cells and cementitious matrix were also elaborated. Furthermore, recommendations to improve the effectiveness of bacterial treatment are provided. Limitations of current studies, updated applications and future application perspectives are shortly outlined.
Jianyun Wang; Yusuf Cagatay Ersan; Nico Boon; Nele De Belie. Application of microorganisms in concrete: a promising sustainable strategy to improve concrete durability. Applied Microbiology and Biotechnology 2016, 100, 2993 -3007.
AMA StyleJianyun Wang, Yusuf Cagatay Ersan, Nico Boon, Nele De Belie. Application of microorganisms in concrete: a promising sustainable strategy to improve concrete durability. Applied Microbiology and Biotechnology. 2016; 100 (7):2993-3007.
Chicago/Turabian StyleJianyun Wang; Yusuf Cagatay Ersan; Nico Boon; Nele De Belie. 2016. "Application of microorganisms in concrete: a promising sustainable strategy to improve concrete durability." Applied Microbiology and Biotechnology 100, no. 7: 2993-3007.
Microbial healing of concrete cracks is a relatively slow process, and meanwhile the steel rebar is exposed to corrosive substances. Nitrate reducing bacteria can inhibit corrosion and provide crack healing, by simultaneously producing NO2− and inducing CaCO3 precipitation. In this study, the functionality of one non-axenic and two axenic NO3− reducing cultures for the development of corrosion resistant self-healing concrete was investigated. Both axenic cultures survived in mortar when incorporated in protective carriers and became active 3 days after the pH dropped below 10. The non-axenic culture named “activated compact denitrifying core” (ACDC) revealed comparable resuscitation performance without any additional protection. Moreover, ACDC induced passivation of the steel in corrosive electrolyte solution (0.05 M NaCl) by producing 57 mM NO2− in 1 week. The axenic cultures produced NO2− up to 26.8 mM, and passivation breakdown and pitting corrosion were observed. Overall, ACDC appears suitable for corrosion resistant microbial self-healing concrete.
Yusuf Çağatay Erşan; Hilke Verbruggen; Iris De Graeve; Willy Verstraete; Nele De Belie; Nico Boon. Nitrate reducing CaCO3 precipitating bacteria survive in mortar and inhibit steel corrosion. Cement and Concrete Research 2016, 83, 19 -30.
AMA StyleYusuf Çağatay Erşan, Hilke Verbruggen, Iris De Graeve, Willy Verstraete, Nele De Belie, Nico Boon. Nitrate reducing CaCO3 precipitating bacteria survive in mortar and inhibit steel corrosion. Cement and Concrete Research. 2016; 83 ():19-30.
Chicago/Turabian StyleYusuf Çağatay Erşan; Hilke Verbruggen; Iris De Graeve; Willy Verstraete; Nele De Belie; Nico Boon. 2016. "Nitrate reducing CaCO3 precipitating bacteria survive in mortar and inhibit steel corrosion." Cement and Concrete Research 83, no. : 19-30.
Cracks are intrinsic concrete characteristics. However, cracking can endanger the durability of a structure, because it eases the ingress of aggressive gasses and liquids. Traditional practices tackle the problem by applying manual repair. Scientists inspired by nature have created self-healing concrete able to self-repair as a result of the metabolic activity of bacteria. Various research groups have studied bio-based self-healing concepts over the last decade. Although the metabolic pathways of different bacteria can vary, the principle is essentially the same: a bio-based healing agent is incorporated into fresh concrete and when a crack appears in hardened concrete the bacteria become active, precipitate limestone and seal the open crack. Bio-based self-healing concrete technology targets the recovery of the original performance of concrete by regaining water tightness lost by cracking. Along these lines, bio-based repair systems have also been developed to protect existing structures by applying materials that are more concrete-compatible and environmentally friendly than existing repair materials. All these innovative concepts have shown promising results in laboratory-scale tests. Steps have been taken towards the first full-scale outdoor applications, which will prove the functionality of this new technology.
Eirini Tziviloglou; Kim Van Tittelboom; Damian Palin; Jianyun Wang; M. Guadalupe Sierra-Beltrán; Yusuf Çağatay Erşan; Renée Mors; Virginie Wiktor; Henk M. Jonkers; Erik Schlangen; Nele De Belie. Bio-Based Self-Healing Concrete: From Research to Field Application. Advances in Polymer Science 2016, 345 -385.
AMA StyleEirini Tziviloglou, Kim Van Tittelboom, Damian Palin, Jianyun Wang, M. Guadalupe Sierra-Beltrán, Yusuf Çağatay Erşan, Renée Mors, Virginie Wiktor, Henk M. Jonkers, Erik Schlangen, Nele De Belie. Bio-Based Self-Healing Concrete: From Research to Field Application. Advances in Polymer Science. 2016; ():345-385.
Chicago/Turabian StyleEirini Tziviloglou; Kim Van Tittelboom; Damian Palin; Jianyun Wang; M. Guadalupe Sierra-Beltrán; Yusuf Çağatay Erşan; Renée Mors; Virginie Wiktor; Henk M. Jonkers; Erik Schlangen; Nele De Belie. 2016. "Bio-Based Self-Healing Concrete: From Research to Field Application." Advances in Polymer Science , no. : 345-385.
Attentive monitoring and regular repair of concrete cracks are necessary to avoid further durability problems. As an alternative to current maintenance methods, intrinsic repair systems which enable self-healing of cracks have been investigated. Exploiting microbial induced CaCO3 precipitation using (protected) axenic cultures is one of the proposed methods. Yet, only a few of the suggested healing agents were economically feasible for in situ application. This study presents a NO3- reducing self-protected enrichment culture as a self-healing additive for concrete. Concrete admixtures Ca(NO3)2 and Ca(HCOO)2 were used as nutrients. The enrichment culture, grown as granules (0.5 – 2 mm) consisting of 70 % biomass and 30 % inorganic salts were added into mortar without any additional protection. Upon 28 days curing, mortar specimens were subjected to direct tensile load and multiple cracks (0.1 – 0.6 mm) were achieved. Cracked specimens were immersed in water for 28 days and effective crack closure up to 0.5 mm crack width was achieved through calcite precipitation. Microbial activity during crack healing was monitored through weekly NOx analysis which revealed that 92±2 % of the available NO3- was consumed. Another set of specimens were cracked after 6 months curing, thus the effect of curing time on healing efficiency was investigated, and mineral formation at the inner crack surfaces was observed, resulting in 70 % less capillary water absorption compared to healed control specimens. In conclusion, enriched mixed denitrifying cultures structured in self-protecting granules are very promising strategies to enhance microbial self-healing.
Yusuf Çağatay Erşan; Elke Gruyaert; Ghislain Louis; Christine Lors; Nele De Belie; Nico Boon. Self-protected nitrate reducing culture for intrinsic repair of concrete cracks. Frontiers in Microbiology 2015, 6, 1228 .
AMA StyleYusuf Çağatay Erşan, Elke Gruyaert, Ghislain Louis, Christine Lors, Nele De Belie, Nico Boon. Self-protected nitrate reducing culture for intrinsic repair of concrete cracks. Frontiers in Microbiology. 2015; 6 ():1228.
Chicago/Turabian StyleYusuf Çağatay Erşan; Elke Gruyaert; Ghislain Louis; Christine Lors; Nele De Belie; Nico Boon. 2015. "Self-protected nitrate reducing culture for intrinsic repair of concrete cracks." Frontiers in Microbiology 6, no. : 1228.
Yusuf Çağatay Erşan; Nele de Belie; Nico Boon. Microbially induced CaCO3 precipitation through denitrification: An optimization study in minimal nutrient environment. Biochemical Engineering Journal 2015, 101, 108 -118.
AMA StyleYusuf Çağatay Erşan, Nele de Belie, Nico Boon. Microbially induced CaCO3 precipitation through denitrification: An optimization study in minimal nutrient environment. Biochemical Engineering Journal. 2015; 101 ():108-118.
Chicago/Turabian StyleYusuf Çağatay Erşan; Nele de Belie; Nico Boon. 2015. "Microbially induced CaCO3 precipitation through denitrification: An optimization study in minimal nutrient environment." Biochemical Engineering Journal 101, no. : 108-118.
Bacteria that can induce calcium carbonate precipitation have been studied for self-healing concrete applications. Due to the harsh environment of concrete, i.e. very high pH, small pore size and dry conditions, protection methods/materials have been used to preserve the bacterial agents. A wide screening of commercially available materials is thus required to evaluate them as alternatives. This study describes the influence of six commercially available possible protection approaches (diatomaceous earth, metakaolin, expanded clay, granular activated carbon, zeolite and air entrainment) on mortar setting and compressive strength when combined with either Bacillus sphaericus spores or Diaphorobacter nitroreducens and their respective nutrients. The influence of two novel, self-protected, bacterial agents was also investigated within the same scope. The most severe effect on setting time was observed as an undesirable delay of 340 min in all samples containing nutrients for ureolytic bacteria. Samples containing B.sphaericus spores showed the most significant decreases in compressive strength up to 68%. Yet, the addition of either D.nitroreducens or its respective nutrients did not cause major impact on both the setting times and the compressive strengths of the mortar specimens. The latter thus appears to be a suitable bacterial agent for further research on self-healing concrete. Likewise, the use of the novel self-protected bacterial agents did not affect the setting and the compressive strength of mortar. These results pave the way to replace protection materials with self-protection techniques. The latter should be further investigated for development of microbial self-healing concrete.
Yusuf Çağatay Erşan; Filipe Bravo Da Silva; Nico Boon; Willy Verstraete; Nele De Belie. Screening of bacteria and concrete compatible protection materials. Construction and Building Materials 2015, 88, 196 -203.
AMA StyleYusuf Çağatay Erşan, Filipe Bravo Da Silva, Nico Boon, Willy Verstraete, Nele De Belie. Screening of bacteria and concrete compatible protection materials. Construction and Building Materials. 2015; 88 ():196-203.
Chicago/Turabian StyleYusuf Çağatay Erşan; Filipe Bravo Da Silva; Nico Boon; Willy Verstraete; Nele De Belie. 2015. "Screening of bacteria and concrete compatible protection materials." Construction and Building Materials 88, no. : 196-203.
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 ± 1.28 mm 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 g N/L d and 3.92 g COD/L d) 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.
Yusuf Çağatay Erşan; Tuba Hande Erguder. The effect of seed sludge type on aerobic granulation via anoxic–aerobic operation. Environmental Technology 2014, 35, 2928 -2939.
AMA StyleYusuf Çağatay Erşan, Tuba Hande Erguder. The effect of seed sludge type on aerobic granulation via anoxic–aerobic operation. Environmental Technology. 2014; 35 (23):2928-2939.
Chicago/Turabian StyleYusuf Çağatay Erşan; Tuba Hande Erguder. 2014. "The effect of seed sludge type on aerobic granulation via anoxic–aerobic operation." Environmental Technology 35, no. 23: 2928-2939.
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 (1.8-3.5mm) 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 52.6-70.2mg/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%.
Yusuf Çağatay Erşan; Tuba Hande Erguder. The effects of aerobic/anoxic period sequence on aerobic granulation and COD/N treatment efficiency. Bioresource Technology 2013, 148, 149 -156.
AMA StyleYusuf Çağatay Erşan, Tuba Hande Erguder. The effects of aerobic/anoxic period sequence on aerobic granulation and COD/N treatment efficiency. Bioresource Technology. 2013; 148 ():149-156.
Chicago/Turabian StyleYusuf Çağatay Erşan; Tuba Hande Erguder. 2013. "The effects of aerobic/anoxic period sequence on aerobic granulation and COD/N treatment efficiency." Bioresource Technology 148, no. : 149-156.