Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395
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Article Citation - WoS: 11Citation - Scopus: 13The Effect of Seed Sludge Type on Aerobic Granulation via Anoxic-Aerobic Operation(Taylor & Francis Ltd, 2014-06-17) Ersan, Yusuf Cagatay; Erguder, Tuba HandeThe 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.Article Citation - WoS: 8Citation - Scopus: 10Compatibility and Biomineralization Oriented Optimization of Nutrient Content in Nitrate-Reducing Microbial Self-Healing Concrete(MDPI, 2021-08-11) Kardogan, Beyza; Sekercioglu, Kadir; Ersan, Yusuf CagatayMicrobially 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.