Browsing by Author "Karagunduz, Ahmet"

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    Batch fermentation of succinic acid from cheese whey by Actinobacillus succinogenes under variant medium composition
    (Springer, 2021-07-29) Omwene, Philip Isaac; Yağcıoğlu, Meltem; Öcal-Sarihan, Zehra Betül; Ertan, Fatma; Keris-Sen, Ülker Diler; Karagunduz, Ahmet; Keskinler, Bülent
    Bio-based succinic acid production has attracted global attention since its consideration as a potential replacement to petroleum-based platform chemicals. This study used three different CO2 sources, namely NaHCO3, K2CO3 and MgCO3 for fermentation of succinic acid (SA) by Actinobacillus succinogenes under three distinct substrate conditions i.e. lactose, whey and whey devoid of any supplements. Batch experiments were performed in both anaerobic flasks and 5L benchtop fermenter. SA fermentation in anaerobic flasks was unfettered by supplementary nutrients. However, fermentation in the benchtop fermenter devoid of supplementary nutrients resulted into 42% reduction in SA yield as well as lower SA productivities. Furthermore, a significant reduction of cell growth occurred in anerobic flasks at pH < 6.0, and complete termination of bacterial activity was noted at pH < 5.3. The highest SA titer, yield and productivity of 15.67 g/L, 0.54 g/g and 0.33 g/L/h, respectively, was recorded from whey fermentation with MgCO3. The present study further highlights significant inhibitory effect of K2CO3 buffered medium on Actinobacillus succinogenes. Thus, we can claim that environmental pollution as well as costs of SA production from whey can be reduced by leveraging on whey residual nutrients to support the activity of Actinobacillus succinogenes.
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    Bio-based succinic acid recovery by ion exchange resins integrated with nanofiltration/reverse osmosis preceded crystallization
    (Elsevier, 2021-07-03) Omwenea, Philip Isaac; Sarihan, Zehra Betul Ocal; Karagunduz, Ahmet; Keskinlera, Bulen
    Succinic acid is a key platform chemical for production of various products such as biodegradable polymers, pharmaceuticals, fine chemicals and foods. In the present study, bio-based succinic acid was recovered through two processes. Process I consisted of chromatographic separation with anionic exchange resin followed by direct crystallization, whereas process II sequentially consisted of cationic exchanger, activated carbon, NF/RO membrane, vacuum distillation, and crystallization. The highest chromatographic separation efficiency for succinic acid by Amberlite IRA900 Cl column was calculated as 69.3% at flow rate of 0.42 BV/h. Rejection of succinic aid (SA), lactic acid (LA), formic acid (FA) and acetic acid (AC) by NF90 membrane was 53.1, 51.8, 46.6 and 39.8%, respectively at pH less than 2. However, at pH 6.8 the respective rejections increased to 96.8, 90.6, 71.3 and 70.5%. Double pass with BW30 or HP reverse osmosis membranes achieved retention of SA, LA, FA and AC of 95.9%, 95.8%, 65.4% and 46.9%, respectively. Analysis of generated SA crystals by X-ray diffraction technique (XRD) and Fourier transform infrared (FTIR) showed the crystallinity of recovered SA as conformable to standard grade crytsals. The purity of generated succinic acid crystals was recorded as 98.5% and 96.7% for process I and process II, respectively. The calculated succinic acid yield was 78% for process I and 65% for process II. Herein, we demonstrated two alternative systems for bio-based succinic acid recovery, which will set a stage for research in efficient downstream purification of SA.
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    Boric acid recovery from wastewater by chromatographic separation and mathematical modeling
    (Elsevier, 2024-03-04) Kole, Zehra; Ocal, Zehra Betul; Omwene, Philip Isaac; Soydemir, Gulfem; Keskinler, Bulent; Karagunduz, Ahmet
    The new approaches in industrial wastewater management underscores the importance of reclaiming valuable materials. Within the boron industry, the generation of substantial wastewater containing preliminary boron species is a significant concern. This study focuses on recovering boric acid from boron production wastewater, addressing the challenge of separating impurities like sulfate, calcium, and magnesium. The methodology adopts chromatographic separation using a cation exchange resin in two forms: (1) Finex CS10GC cation exchanger in Na+ form and (2) Finex CS10GC cation exchanger in Ca2+/Mg2+ form. Notably, the Finex CS10GC ion exchanger in Na+ form achieves a separation efficiency of 95.5 % at a flow rate of 5 mL/min with a 0.20 bed volume (BV) loading. In contrast, the Ca2+/Mg2+ loaded resin achieves a separation efficiency of 23.3 % at the same flow rate. As the boron loading rate decreases to 10 %, the separation efficiency increases to 42.6 %. The flow rate also plays a crucial role, as an increase corresponds to a decrease in separation efficiency. Notably, the Finex CS10GC ion exchanger in Na+ form consistently exhibits superior separation efficiency and band resolution. A mathematical model is introduced to simulate the effective separation of boric acid from other impurities. The quality of the recovered boric acid conforms to the standard grade (Merck KGaA), exhibiting a purity level within the range of 99.5–100 %, suggesting substantial economic value. The proposed recovery process contributes significantly to environmental preservation by mitigating waste discharge, exemplifying a noteworthy commitment to resource conservation.
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    Conforming to agricultural water reuse criteria: wastewater recovery by electrooxidation integrated with nanofiltration/reverse osmosis
    (Springer Nature, 2023-02-21) Çiftçioğlu‑Gözüaçık, Bengisu; Omwene, Philip Isaac; Ergenekon, Sinem Merve; Karagunduz, Ahmet; Keskinler, Bülent
    In this study, two membrane configurations were investigated for water recovery in order to determine the potential for quality irrigation water production from alkaloid industry wastewater. In the first configuration, electrooxidation (EO) was used as a pretreatment before the NF90/BW30 units. In the second configuration, a single-pass, two-stage system consisting of NF4 and NF90/BW30 membranes was applied by replacing the EO unit with NF4. The initial and final fluxes in the single-pass two-stage system with NF4 and NF90 were calculated as 10.2 Lm− 2h− 1 and 5.4 Lm− 2h− 1, respectively. Initial fluxes for the NF4 + BW30 and EO + BW30 combinations were 9.4 Lm− 2h− 1 and 3.2 Lm− 2h− 1, respectively. Increasing the current density from 256 to 768 A/m2 caused the specific energy consumption (SEC) to increase from 10.26 to 15.84 kWh/kg COD. Scanning Electron Microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were used for membrane autopsies. Compliance with the criteria for agricultural reuse of recovered water was evaluated based on four key parameters: salinity, pathogens, nutrients, and heavy metals. The combination of electrooxidation and membrane treatments enabled simultaneous disinfection, reduction of salinity and heavy metals to comparable agricultural water reuse criteria.
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    Recovery of succinic acid from whey fermentation broth by reactive extraction coupled with multistage processes
    (Science Direct, 2020-06) Omwenea, Philip Isaac; Yagcioglu, Meltem; Sarihan, Zehra Betül Ocal; Karagunduz, Ahmet; Keskinler, Bülent
    Fermentative production of succinic acid (SA) from renewable resources such as whey is environmentally sustainable compared to petroleum-based synthesis. However, a major drawback of fermentation is the concurrent production of SA with byproducts such as lactic acid (LA), formic acid (FA) and acetic acid (AA). Therefore, appropriate downstream SA recovery and purification steps are significant in ensuring sustainable SA production. In this study, SA was fermented by Actinobacillus succinogenes and recovered in an integrated process consisting of ultrafiltration, vacuum distillation and reactive extraction. The extractant used was tri-n-octylamine (TOA) with 1-octanol as a diluent for both liquid-liquid (LLE) extraction and supported liquid membrane (SLM). The produced SA titer and yield was 11.16 g/L and 0.44 g/g, respectively. The steady state ultrafiltration permeate flux ranged from 31.18 to 33.42 L/m2h, and complete decolorization of the fermentation broth was achieved with 10 % (w/v) of powdered activated carbon. The extraction efficiency for LLE was 51.5 %, whereas SLM achieved 57.3 % recovery. SA exhibited transport and permeability coefficient of 0.00697 h−1 (R2 > 0.92) and 0.08605 cm h−1, respectively. Extraction of SA tremendously decreased as the aqueous pH was increased from 2 to 5. In SLM, initial SA flux was calculated as 9.65 g/m2h and doubled that of lactic acid. Selective extraction of only SA was not achieved; however, residue biological material and macromolecular substances were effectively removed. Herein, we clearly demonstrated that process integration applied in reactive extraction is a promising approach for recovery of SA from fermentation broth.
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    Treatment of organized industrial zone wastewater by microfiltration/reverse osmosis membrane process for water recovery: from lab to pilot scale
    (Science Direct, 2020-09-21) Ozbey-Unal, Bahar; Omwene, Philip Isaac; Yagcioglu, Meltem; Balcik-Canbolat, Çigdem; Karagunduz, Ahmet; Keskinler, Bulent; Dizge, Nadir
    The global increase in industrialization has resulted into water scarcity. Research on water use efficiency and water reclamation is paramount in addressing this scarcity. In this study, laboratory and on-site pilot scale tests were conducted for water recovery from an industrial wastewater treatment plant. Different RO membranes (BW30, HP, and LE) were investigated with chemical treatment and ceramic microfiltration (MF) as pretreatment steps. Laboratory studies were conducted in dead-end filtration mode, whereas pilot scale studies were performed in cross flow mode with two spiral wound membranes. The removal efficiencies ranged from 40.0-86.3% for COD, 97.6- 99% for SO42-, 69.2-94.9% for Cr ion, 89.3-100% for Pb ion, 66.3-98.2 for Fe ion, 97.5- 99.7% for Zn ion, 95.1-99.5% for Si ion, and 79.1-100% for total phosphorus (TP). For the laboratory studies with 80% water recovery, the permeate flux reduced from 27.2 to 7.1 L/m2h, 35.7 to 1.3 L/m2h and 25.6 to 0.8 L/m2h for BW30, LE, and HP, respectively. On the other hand, four different operation modes were investigated to determine the effect of each mode on membrane performance and fouling properties. Average permeate flux of 18.7 and 21.3 L/m2h, 12.7 and 12.8 L/m2h, 13.4 and 14.6 L/m2h, 12.5 and 14.1 L/m2h were recorded for LE and BW30 membranes in the first, second, third, and fourth modes, respectively. Membrane autopsies were performed by atomic force microscopy (AFM), scanning electron microscopy (SEM), and energy dispersive X-rays (EDX). The system was effective in recovering the permeate to required industrial cooling and boiler water quality.