Taner Yonar

Pre-treatment studies on olive oil mill effluent using physicochemical, Fenton and Fenton-like oxidations processes.

In this paper, the results of olive oil mill wastewater (OOMW) using physicochemical pre-treatment and Fenton and Fenton-like processes are presented. On the other hand, acute toxicities of raw, physicochemical pre-treated, and Fenton and Fenton-like oxidations applied samples of OOMW on activated sludge microorganisms using respiration inhibition test (ISO 8192) are presented. Chemical pre-treatment (acid cracking and coagulation-flocculation) positively affected the biodegradability and inhibition on activated sludge was considerably removed (>67% COD and >72% total-phenol removal). Fenton and Fenton-like processes showed high COD (>80%) and total-phenol (>85%) removal performance on evaluated effluents. Inhibitory effect of Fenton-like reagents applied samples on activated sludge mixture was considerably removed. In addition to the toxicity, total-phenol and COD removal efficiencies of applied processes, their associated operating costs were also determined in this paper.

Comparative evaluation of a laboratory and full-scale treatment alternatives for the vegetable oil refining industry wastewater (VORW)

Abstract The efficiency of alternative treatment processes in producing a final effluent conforming to regulatory standards with regards to chemical oxygen demand (COD) and oil and grease (O&G) loads was assessed. The study was conducted in three principal stages: waste characterization, lab-scale treatability studies and full-scale applications. The effluent were characterized in terms of pH (6.3–7.2), total COD (13,750–15,000 mg l −1 ), soluble COD (COD s ) (6500–7000 mg l −1 ), biochemical oxygen demand (BOD 5 ) (4300–4700 mg l −1 ), O&G (3600–3900 mg l −1 ), total suspended solids (TSS) (3800–4130 mg l −1 ), total Kjeldahl nitrogen (TKN) (636–738 mg l −1 ) and total phosphorus (TP) (61–63 mg l −1 ). After analyzing various raw effluent parameters, lab-scale chemical treatability studies were conducted using Al 2 (SO 4 ) 3 ·18H 2 O and FeCl 3 ·6H 2 O. The results showed 88 and 84% influent COD reduction, while O&G removal was 81 and 93%, respectively. The removal of total suspended solids (TSS) varied from 78 to 86%. Lab-scale aerobic biological treatment reactors with a HRT of 24 h and food to microorganism ratio of 0.3–0.5 were also run to assess the process efficiency and determine the residual soluble COD in the effluent. Residual soluble COD was 59–70 mg l −1 . Based on the results from waste characterization and treatability studies, a continuous full-scale treatment system was constructed and operated in two vegetable oil refining plants with a different pretreatment flow scheme. The overall percentage removal of COD, TSS, and O&G was 92–96, 83–98 and 93–95%, respectively.

The Electrochemical Generation of Ozone: A Review

This article reviews work on the electrochemical generation of ozone from the original studies by Schönbein in the early 1800s to the present day, and is intended for specialists and nonspecialists in the field of electrochemistry. The experimental techniques employed to study the mechanism of electrochemical ozone generation are described, as is the most commonly quoted mechanism and the experimental evidence for the mechanism is summarized and discussed. The types of electrochemical cells employed are described, and the effects of temperature, anode type and composition, current density and electrolyte composition and pH are discussed.

Pilot-scale treatment of olive oil mill wastewater by physicochemical and advanced oxidation processes

The pilot-scale treatability of olive oil mill wastewater (OOMW) by physicochemical methods, ultrafiltration and advanced oxidation processes (AOPs) was investigated. Physicochemical methods (acid cracking, oil separation and coagulation–flocculation) showed high efficiency of chemical oxygen demand (COD) (85%), oil and grease (O&G) (>97%), suspended solids (SS) (>99%) and phenol (92%) removal from the OOMW. Ultrafiltration followed by physicochemical methods is effective in reducing the SS, O&G. The final permeate quality is found to be excellent with over 90% improvements in the COD and phenol parameters. AOPs (ozonation at a high pH, O3/UV, H2O2/UV, and O3/H2O2/UV) increased the removal efficiency and the O3/H2O2/UV combination among other AOPs studied in this paper was found to give the best results (>99% removal for COD,>99% removal for phenol and>99% removal for total organic carbon). Pilot-scale treatment plant has been continuously operated on site for three years (3 months olive oil production campaign period of each year). The capital and operating costs of the applied treatment alternatives were also determined at the end of these seasons. The results obtained in this study have been patented for 7 years by the Turkish Patent Institute.

Treatability studies on wastewater from textile dyeing factories in Bursa, Turkey

The textile industry is one of the most rapidly developing industries in Turkey. It generates a large amount of wastewater, with corresponding concerns about pollution. The main sources of pollution in wastewater are the dyeing and finishing processes. The dyestuffs and polyvinyl alcohol (PVA) are the main refractory organics of concern in terms of meeting more stringent effluent standards of chemical oxygen demand (COD) and colour. In this study, wastewaters from textile dyeing factories in Bursa were characterized, and physical, chemical and biological treatability studies were carried out. In the physical and chemical studies, 60-80% COD, 80% suspended solids (SS) and 10-92% turbidity removal efficiencies were obtained. In the biological studies, 90% COD and 40% SS removal were obtained. The initial soluble inert COD of wastewater was determined by using comparison methods. The initial inert COD of wastewater and the microbial product concentration were determined as 37 mg/l and 13 mg/l, respectively.

Determination of the acute toxicities of physicochemical pretreatment and advanced oxidation processes applied to dairy effluents on activated sludge.

In this study, the acute toxicities of raw, physicochemical pre-treated, ozonated, and Fenton reagent applied samples of dairy wastewater toward activated sludge microorganisms, evaluated using the International Organization for Standardizations respiration inhibition test (ISO 8192), are presented. Five-day biological oxygen demand (BOD5) was measured to determine the biodegradability of physicochemical treatment, ozonation, Fenton oxidation or no treatment (raw samples) of dairy wastewater. Chemical pretreatment positively affected biodegradability, and the inhibition exhibited by activated sludge was removed to a considerable degree. Ozonation and the Fenton process exhibited good chemical oxygen demand removal (61%) and removal of toxins. Low sludge production was observed for the Fenton process applied to dairy effluents. We did not determine the inhibitory effect of the Fenton-process on the activated sludge mixture. The pollutant-removal efficiencies of the applied processes and their associated operating costs were determined.

Treatment of Jewelry Manufacturing Effluent Containing Cyanide Using Ozone-Based Photochemical Advanced Oxidation Processes

This article considers Advanced Oxidation Processes involving O3, O3/UV, O3/H2O2/UV, and H2O2/UV to destroy cyanide in jewelry manufacturing wastewaters. All experiments were performed in a semibatch reactor. The results showed that total cyanide can be reduced with different reaction rates, and the decrease of total cyanide can be described by pseudo–first-order kinetics. The reaction was performed under different pH values and H2O2 dosages to find the optimal conditions for the oxidation processes. The ozonation process destroyed total cyanide faster at a pH = 12, whereas ozonation combined with H2O2 and/or UV destroyed cyanide faster at a pH =10. The total cyanide destruction rate in the UV/H2O2 (700 mg/L) treatment was the highest among all studied processes, with removal efficiencies of 99% for CN−, 99% for COD and 99% for TOC.

Treatment of 3-indole butyric acid with solar photo-catalytic reactor

Abstract Solar photo-catalytic process is an emerging and promising technology both as an alternative treatment to conventional wastewater treatment methods and enhancement of biodegradability of highly toxic and recalcitrant pollutants. In this study, results for the treatment of 3-indole butyric acid solutions using pilot scale solar photo-catalytic treatment process are presented. The effecting parameters, such as adsorption of 3-indole butyric acid on TiO2, pH, the initial concentration of 3-indole butyric acid and catalyst concentration, on the treatment of 3-indole butyric acid using solar photo-catalytic system were investigated. Solar photo-catalytic processes demonstrated high COD (>80%), TOC (>80%) and 3-indole butyric acid (>90%) removal efficiencies for the samples in this study. The increase of the 3-indole butyric acid concentration from 10 to 150 mg/L decreases the removal rate constant from 0.0757 to 0.0088 1/min in 240 min of oxidation using 100–1500 mg/L TiO2 at 3–9 pH.

Electrochemical degradation of dairy effluent using novel Sn/Sb/Ni-Ti anodes

Global warming caused by CO2 gas can no longer be ignored. Therefore, we are trying to contribute to reducing the problem with our electrolytic technology accumulated so far in our company. Our target is to develop a large of alkaline water electrolysis (AWE) plant with high performance and contribute to problem solving. The performance of AWE is largely classified and influenced by four factors of anode, cathode, separator and cell structure of electrolyzer. Here, the results of electrodes and separators are mainly explained in our evaluation. Considering the use of renewable energy as standard, electricity always fluctuates in the operation of AWE. Therefore, the components of the cell must be sufficient resistant to such fluctuations. Electrode: there are two types of activated coating to reduce the overvoltage of electrode. Our investigation revealed that the anode coating of thermal decomposition is not enough tough, but the dispersion electroplating such as Raney Ni showed good durability against 100 times shutdown. During the shutdown of operation, revers current pass through in the cell. The revers current deteriorates the electrode performance and the phenomena causes difficult for anode coating life. Each saving of anode oxygen overvoltage of thermal and electroplating is around 50 mV and 100 mV compared with bare Ni. Separator: In the AWE, electrolyte is the same in both anode chamber and cathode chamber, so that diaphragm instead of ion exchange membrane can be used as separator. The point of its performance is that low cell voltage and high purity gas can be obtained. Currently, AGFA and KHI diaphragm are considered to be applicable to large-scale AWE plants. The performance of our AWE plant was around1.8 V at 5 kA/m2 and 80oC. Its performance is affected by the electrode to be used. The differences in cell voltage occur from 100 mV to 200 mV. Alkaline water electrolysis is the easiest methods for hydrogen production because of their simplicity. Although the simplicity is an advantage; reducing the energy consumption and maintaining the durability and the safety of these systems are the main challenges. In this paper, alkaline water electrolysis system, that uses cost effective electrode materials and magnetic field effects are presented. Cost effective electrodes such as high carbon steel, 304 stainless steel, 316L low carbon steel and graphite material are used for the hydrogen production. After the selection of the best electrode pair, effects of magnetic field to hydrogen production and change of current density are investigated for KOH electrolytes in different concentrations (5 wt%, 10 wt% and 15 wt%). According to the experimental observations the direction of the Lorentz Force affects the hydrogen production and current density. When the Lorentz Force is directed upward, it enhances the hydrogen production for 5 wt% and 15 wt% KOH solution by almost 17%. The increase in current density for 5 wt%, 10 wt% and 15 wt% concentration is 19%, 5%, 13%, respectively. Forced convection in the magnetic field enhances the separation of gas bubbles from electrode surface. Downward directed Lorentz Force decreases hydrogen production and current density values significantly. For 5 wt%, 10 wt% and 15 wt% the hydrogen production decreases by 14%, 8%, 7%, respectively. Similarly, current density for downward directed Lorentz Force decreases by 11%, 7%, 4%, respectively. In order to realize future hydrogen society, hydrogen production systems must meet the large demand of hydrogen usage. Alkaline water electrolysis (AWE) would be one of the candidate technologies to produce hydrogen on a large scale from renewable energy. We have conducted basic research into AWE, trying to reveal technical issues under zero gap system in new cell technology. The zero gap system contributes lower cell voltage without causing any major operating problems compared with conventional finite gap cell. However, it was observed that Ni base electrodes showed corrosion phenomena in a number of test trials including steady operating conditions and several shut-downs. Activated Raney Ni alloy coating for anode material had an advantage for oxygen overvoltage. It showed a saving of around 100 mV at 40 A/dm2 (0.4 A/cm2) against Ni bare anodes. In the Chlor–Alkali (C/A) industry, thermal decomposition coating of mixed noble metal on Ni substrate is commonly used for advanced activated cathodes. It showed very low hydrogen over-potential of around 100 mV in AWE. To achieve better cell performance, separator selection is very important. We evaluated several separators including ion exchange membrane (IEM) to understand the basic function in AWE. IEM for C/A electrolysis showed high cell voltage (over 2.2 V) but low O2 impurity in H2 gas. Hydrogen purity was over 99.95%. Porous separators made of polypropylene showed 1.76 V at 40 A/dm2 (0.4 A/cm2), 80 °C. But there was a weakness on the durability for continuous operation. Proper selection of separator is important in an actual plant for effective and safe cell operation. The concept of safety operation is referred to by diffusion coefficient of hydrogen.So-called perovskite solar cells (PSC) are composed of PbI6 4- (MeNH3 +)4 salt, where PbI6 4- plays an essential role as an effective solar light sensitizer with keeping semiconducting property even when aligned each other. Density-functional-theory-based molecular modeling (DFT/MM) using reported X-ray crystallographic structure of PbI6 4-/MeNH3 +/H2 O salt (named FOLLIB in Cambridge Structural Data) validates that the packing unit consisting of {(PbI6 4-)9 [(MeNH3 +)2 -H2 O]2 (MeNH3 +-H2 O)2 (MeNH3 +)2 }28- should show UV/Vis absorption spectrum at λmax=424 nm (pale yellow color) as observed for the PbI64- crystal. DFT/MM of the FOLLIB horizontal aligned component, [(PbI6 4-[(MeNH3 +)2 -H2 O]2 (MeNH3 +-H2 O)2 (MeNH3 +)2 /(PbI6 4-)2 )4- verifies that the component has narrow energy gap of 0.3 eV, predicting excellent semiconducting property of the PbI64- alignment with MeNH3 +. Three H2 O-free PbI6 4-/MeNH3 + aligned components, PbI6 4-(MeNH3 +)4 , [PbI6 4-(CH3 NH3 +)3 ]- and [PbI6 4-(CH3 NH3 +)2 ]2- are molecular modeled and verified to have UV/Vis spectra at λmax=570 nm, λmax=762 nm, and λmax=945 nm, respectively. Mixtures of them will be colored black, which is consistent with observable black coloration of PbI64- alignments with MeNH3+ in amorphous solute state. It is further verified that PbI6 4- undergoes van der Waals and Coulomb interactions both with electron accepting layers, i.e., nc-TiO2 in PSC of nc-TiO2/MeNH3PbI3/spiro-OMeTAD and with electron donating layer, i.e., spiro-OMeTAD in the PSC. The molecular orbital structure and electrostatic potential map verifies formation of tight interaction between them. The electron density-based alignment PbI6 4- validates unidirectional electron transport at both interfaces, resulting in high open-circuited voltage (Voc) of ~1.0 eV in PSC. In addition, the semi-conducting sensitizing layer of PbI6 4-/MeNH3 + components validates excellent short-circuited photocurrent (Jsc), and respectable fill factor of PSC. The PbI6 4--aligned solar cell will be regarded as a kind of quantum dot solar cell. Effective sensitizing components in so-called perovskite solar cells (PSC) are lead hexaiodide (PbI64−) salts of PbI64− (MeNH3+)n (n = 2∼4). Density-functional-theory-based molecular modeling (DFT/MM) of X-ray crystalline structure of PbI64−/MeNH3+ salt (FOLLIB) verifies that the packing unit of FOLLIB has UV/Vis absorption spectrum at λmax = 424 nm, giving pale yellow color as complementary color. DFT/MM of the horizontal component in the FOLLIB gives narrow energy gap of 0.3 eV, verifying remarkable semiconducting property through tight alignments of PbI64− components coupled with MeNH3+. DFT/MM of the central PbI64−/MeNH3+ components verifies that the central component has UV/Vis absorption spectra with respective λmax = 570 nm, λmax = 762 nm and λmax = 945 nm, and plays an essential role as panchromatic sensitizers. In addition, their equilibrium geometric structures show slightly hypsochromic UV/Vis absorption spectra at respective λmax = 486 nm, λmax = 560 nm, and λmax = 563 nm as results of migration of MeNH3+ close to PbI64−. DFT/MM also verifies that PbI64− components align tightly to nanocrystalline TiO2 (nc-TiO2) and to spiro-OMeTAD in PSC through electron density induced by van der Waals interaction. Electron density-based alignments of PbI64− components well explain unidirectional and leakage-free electron diffusion leading to high open-circuit voltage in PbI64−-aligned solar cells. At the same time, the semiconducting and panchromatic sensitizing layer of PbI64−/MeNH3+ components contribute to excellent short-circuit photocurrent of PbI64−-aligned solar cells. Effective sensitizing components in so-called perovskite solar cells (PSC) are lead hexaiodide (PbI64−) salts of PbI64− (MeNH3+)n (n = 2~4). Density-functional-theory-based molecular modeling (DFT/MM) of X-ray crystalline structure of PbI64−/MeNH3+ salt (FOLLIB) verifies that the packing unit of FOLLIB has UV/Vis absorption spectrum at λmax = 424 nm, giving pale yellow color as complementary color. DFT/MM of the horizontal component in the FOLLIB gives narrow energy gap of 0.3 eV, verifying remarkable semiconducting property through tight alignments of PbI64− components coupled with MeNH3+. DFT/MM of the central PbI64−/MeNH3+ components verifies that the central component has UV/Vis absorption spectra with respective λmax = 570 nm, λmax = 762 nm and λmax = 945 nm, and plays an essential role as panchromatic sensitizers. In addition, their equilibrium geometric structures show slightly hypsochromic UV/Vis absorption spectra at respective λmax = 486 nm, λmax = 560 nm, and λmax = 563 nm as results of migration of MeNH3+ close to PbI64−. DFT/MM also verifies that PbI64− components align tightly to nanocrystalline TiO2 (nc-TiO2) and to spiro-OMeTAD in PSC through electron density induced by van der Waals interaction. Electron density-based alignments of PbI64− components well explain unidirectional and leakage-free electron diffusion leading to high open-circuit voltage in PbI64−-aligned solar cells. At the same time, the semiconducting and panchromatic sensitizing layer of PbI64−/MeNH3+ components contribute to excellent short-circuit photocurrent of PbI64−-aligned solar cells.

Comparing treatment methods that remove color from the effluent of an Organized Industrial District (OID)

AbstractThis study investigates the treatability, in terms of color removal, of an effluent taken from an Organized Industrial District wastewater treatment plant located in Bursa, western Turkey. To remove the color, chemical coagulation, Fenton and Fenton-like oxidation, ozonation, adsorption, and membrane processes were employed, and the results were compared. In coagulation experiments, maximum color removal (87.4%) was obtained at pH 12.2 with a dose of 240 mg/L MgCl2 + Ca(OH)2. Fenton and Fenton-like oxidation processes showed high color removal efficiencies (93.1 and 80%, respectively) from the evaluated effluents. The best color removal (93.6%) in this study was achieved by an ozonation process at a dose of 8 g/L-min ozone with a pH of 12 and a contact time of 3 min. In addition to the color removal efficiencies for the applied processes, their associated operating costs were also calculated.