Browsing by Author "Omwene, Philip Isaac"
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Item Anodic oxidation of effluents from stages of MBR-UF Municipal landfill leachate treatment plant(Mary Ann Liebert, 2020-05-18) Ukundimana, Zubeda; Kobya, Mehmet; Omwene, Philip Isaac; Gengec, Erhan; Can, Orhan TanerThis study used boron-doped diamond electrode on niobium substrate (Nb/boron-doped diamond [BDD]) for the anodic oxidation of landfill leachate in a batch reactor. Raw leachate and biologically pretreated effluent samples were collected from each step of the existing unit operation of a municipal landfill leachate treatment plant (Kocaeli-Turkey). The influence of parameters, such as treatment time, initial pH (3.50–10.0), and applied current density (j = 76–1,060 A/m2), on the removal of total organic carbon (TOC), chemical oxygen demand (COD), and ammonium nitrogen (NH4+-N) was assessed. The highest pollutant removal efficiencies were obtained at leachate inherent pH (6.50–8.75), moreover, pollutant removal rates increased with the increase in current density. The NH4+-N removal mainly occurred by indirect oxidation and well fitted second-order kinetics, whereas COD removal followed pseudo first-order kinetics. The optimum current density ensuring simultaneous removal of COD and NH4+-N was 756 and 455 A/m2 for raw leachate and for pretreated effluents, respectively. Under these optimums, nearly complete NH4+-N removal was attained, while ≥97% removal of TOC and COD was recorded. Herein, we present anodic oxidation as a suitable alternative for treatment of both stabilized raw leachate and effluents from stages of the membrane bioreactor/ultrafiltration treatment plant for the abatement of COD, TOC, and NH4+-N.Item 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, BülentBio-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.Item 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, AhmetThe 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.Item 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, BülentIn 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.Item Investigating the removal efficiency of different textile dye classes from wastewater by electrocoagulation using aluminum electrodes(Springer Nature, 2023-02-23) Omwene, Philip Isaac; Can, Orhan Taner; Oz, Ufuk Muhammed; Keyikoglu, RamazanTextile production is one of the largest sectors in the manufacturing industry; however, the textile dyeing process produces a voluminous amount of highly colored wastewater. The dyes used are organic compounds of different dye classes that are stable in an aquatic environment with low decomposition rates. This study investigated the removal efficiency of five textile dyes of different dye classes (Disperse Orange 30, Acid Blue 324, Basic Yellow 28, Reactive Black 5, Vat Brown 1) from wastewater by electrocoagulation (EC) process that was equipped with aluminum electrodes. EC process achieved 91.98, 98.13, 47.46, 92.55, and 82.60% removal efficiencies for AB324, BY28, VBI, and RB5, respectively, at a current density of 0.83 mA/cm2. The energy consumption for dyestuff removal was in the following order: DO30 < VB1 < RB5 < AB324 < BY28. The total operating cost per kilogram of dyestuff removed in 15 min at 0.0502 mA/cm2 was determined as 0.250, 0.274, 0.550, 0.647, and 0.764 $/kg for DO30, VB1, RB5, AB324, and BY28, respectively. The removal mechanism was well fitted to the pseudo-first-order kinetic model with R2 above 0.94 for AB324, BY28, and RB5 dyes. However, the removals for DO30 and VBI dyes were exponential and neither fitted the first-order kinetic nor second-order kinetic model. The overall removal trend was as follows: DO30 > VB1 > AB324 > RB5 > BY28. Therefore, the use of dyes that can easily be removed from wastewater should be encouraged to preserve the quality of water in the receiving environments and to reduce the cost of wastewater treatment.Item Novel chromatographic purification of succinic acid from whey fermentation broth by anionic exchange resins(Springer Nature, 2022-11-09) Omwene, Philip Isaac; Öcal, Zehra Betül; Yağcıoğlu, Meltem; Karagündüz, Ahmet; Keskinler, BülentReplacement of the petroleum-based refineries with the biorefinery is regarded as an essential step towards a “zero” waste (circular) economy. Biobased succinic acid (SA) is listed by the United States Department of Energy among the top ten chemicals with the potential to replace chemicals from petroleum synthesis with renewable sources. Purification of biobased succinic acid from fermentation by-products such as alcohols, formic acid, acetic acid and lactic is a major drawback of fermentative SA production. This study addresses this issue through a novel chromatographic separation using three distinct anionic resins: Amberlite IRA958 Cl (strong base anion exchange resin), Amberlite HPR 900 OH (strong base anion exchange resin) and Amberlyst A21 (week base anion exchange resin). The influence of process variables such as flow rate (0.18 BV/h, 0.42 BV/h and 0.84 BV/h), eluent concentration (1%, 5% and 10% HCl) and temperature (20, 30 and 40 °C) were investigated. The results indicated SA separation efficiency of 76.1%, 69.3% and 81.2% for Amberlyst A21, Amberlite HPR 900 OH and Amberlite IRA958 Cl, respectively. As the regenerant HCl concentration increased from 1 to 10%, calculated succinic acid separation efficiencies decreased from 80.3 to 70.7%. Notably, as the regenerant strength increased from 1 to 10%, the total amount of organic acids desorbed from the resin sharply increased. At operation temperatures of 20, 30 and 40 °C, SA separation efficacies were 81.2%, 73.9% and 76.4%, respectively. The insights from this study will be of great value in design of chromatographic separation systems for organic acids.Item 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, NadirThe 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.