Browsing by Author "Değermenci, Nejdet"

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Ammonia stripping using a continuous flow jet loop reactor: mass transfer of ammonia and effect on stripping performance of influent ammonia concentration, hydraulic retention time, temperature, and air flow rate.
(2021-06-01T00:00:00Z) Değermenci, Nejdet; Yildiz, Ergun
When wastewater containing ammonia is discharged into the receiving environment without any kind of treatment, it causes both environmental problems and negatively affects human health. In this study, the aim was to strip ammonia using air in a continuous flow jet loop reactor (JLR) and investigate the effects of ammonia concentration, hydraulic retention time (HRT), air flow rate, and temperature on ammonia removal within this scope. By changing the ammonia concentration in the influent, no significant change was observed in ammonia removal efficiency. With air flow rate 45 L min, temperature 50 °C, pH 11, and HRT 7.5 h, mean 88.1% ammonia removal was achieved. Increasing the HRT, air flow rate, and temperature increased the ammonia removal efficiency. Later the ammonia stripping process in the continuous flow JLR was modeled and the volumetric mass transfer coefficient (Ka) for each parameter was calculated from the model equation. While the experimental parameters of air flow rate and temperature had a significant effect on the mass transfer coefficient, influent ammonia concentration and HRT were determined to have no effect.
Comparison of reactive azo dye removal with UV/HO, UV/SO and UV/HSO processes in aqueous solutions.
(2022-03-28T00:00:00Z) Çobanoğlu, Kübra; Değermenci, Nejdet
Advanced oxidation processes (AOPs) are an effective choice for removal of reactive azo dyes used in the textile industry due to high solubility and low degradability. Within the scope of this study, reactive orange 122 (RO122) azo dye was removed using the UV-based AOPs of ultraviolet (UV) radiation, UV/hydrogen peroxide (UV/HO), UV/persulfate (UV/SO), and UV/peroxymonosulfate (UV/HSO). Oxidant concentration, initial solution pH, initial RO122 concentration, different anions (Cl, NO and SO), and solution temperature effects were compared. With only UV radiation (254 nm), 19.5% RO122 removal occurred at the end of 120 min. The RO122 removal reduced with the UV/oxidant processes at pH 9. Experimental results revealed RO122 removal followed pseudo-first-order (PFO) kinetics. There was a linear correlation identified between initial oxidant concentration and the PFO kinetic rate constant (k). Among the three UV-based processes, with oxidant concentration 50 mg/L, temperature 20 °C, and pH 5, RO122 removal efficiency was in the order UV/HO > UV/HSO > UV/SO. RO122 removal rate increased as initial oxidant concentration and temperature increased and reduced as initial RO122 concentration increased. Energy requirements and oxidant costs were assessed. The UV/HO process was concluded to be the most efficient and economic process for RO122 removal.
Performance investigation of a jet loop membrane bioreactor for the treatment of an actual olive mill wastewater.
(2016-12-15T00:00:00Z) Değermenci, Nejdet; Cengiz, İbrahim; Yildiz, Ergun; Nuhoglu, Alper
In this study, following the pre-treatment of olive mill wastewater (OMW), its treatment in a jet loop membrane bioreactor (JLMBR) was investigated. Among the pre-treatment options, the configuration composed of physical settling, cartridge filter and ceramic membrane showed the best performance in terms of investigated parameters. For the JLMBR that was fed by pretreated OMW, up to 93 and 87% removal efficiencies were achieved for the chemical oxygen demand (COD) and total phenol, respectively, at volumetric organic load (VOL) of 17.8 kg COD/m day. The calculated specific oxygen uptake rate (SOUR) values were in the range 7.7-34.7 g O/kg MLVSS h. When even hydraulic retention times (HRT) values decreased by a factor of 1:24, system performance in terms of COD and total phenol removal remained almost stable. Decreasing the sludge retention time (SRT) to three days made considerable perturbations for the system performance, increasing the effluent COD and total phenol values in 900 and 80 mg/L, respectively. The JLMBR showed a high overall performance for the treatment of an actual OMW under the evaluated operational conditions.