Ergun Yildiz
Atatürk University
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Publication
Featured researches published by Ergun Yildiz.
Journal of Hazardous Materials | 2009
Handan Ucun; Ozkan Aksakal; Ergun Yildiz
The biosorption properties of copper(II) and zinc(II) onto a cone biomass of Pinus sylvestris L. was investigated by using batch techniques. The biosorption studies carried out with single metal solutions. The removal of copper(II) and zinc(II) from aqueous solution increased with pH and sharply decreased when pH of the solution was decreased. The maximum biosorption efficiency of P. sylvestris was 67% and 30% for Cu(II) and Zn(II), respectively. Batch kinetic and isotherm of biosorption metal ions were investigated. The second-order kinetic model was used to correlate the experimental data. The Freundlich and Langmuir model can describe the adsorption equilibrium of metal(II) on cone biomass. The biosorption constants were found from the Freundlich and Langmuir isotherms at 25 degrees C. It is found that the biosorption data of metals on cone biomass fitted both the Freundlich and Langmuir adsorption models.
Separation and Purification Technology | 2004
Ergun Yildiz
Removal of phosphate ions (PO4-P) from aqueous solution by means of fly ash was investigated in a crossflow microfiltration system. Batch experiments prior to membrane filtration were conducted to determine PO4-P removal capacity of the fly ash. The effect of PO4-P concentration, initial pH of solution and the fly ash dosage on the PO4-P removal was studied. It was found that if the initial pH of solution is about 6, maximum PO4-P removal is obtained and as the fly ash dosage increase the percentage of PO4-P removal rises due to an increase in solubility of calcium ions and final pH in water. In membrane filtration, PO4-P treated with the fly ash was separated from water with crossflow microfiltration technique. The effect of the fly ash dosage, PO4-P concentration, transmembrane pressure drop (ΔP) and membrane type on the membrane fluxes (J*) and PO4-P rejections (Rp*) were investigated. Under certain conditions, 100% Rp* could be achieved depending on the fly ash dosage. It was seen that J* and Rp* increase with increasing of the dosage. When the concentration of PO4-P in the feed solution is increased, Rp* reduces because of the low final pH and inadequate calcium ion concentration. Furthermore, it was also found that results obtained for J* and Rp* were better for cellulose nitrate (CN) membranes compared with cellulose acetate (CA) membranes. The effect of transmembrane pressure drop (ΔP), the fly ash dosage and PO4-P concentration on steady state permeate fluxes and rejections have been explained by specific cake resistances (α). It has been seen that separation of insoluble PO4-P compounds by crossflow membrane filtration seems to be advantageous to classical batch separation in respect of efficiency.
Water Research | 2002
Alper Nuhoglu; Turgay Pekdemir; Ergun Yildiz; Bulent Keskinler; Galip Akay
Drinking water denitrification performance of a bench scale membrane bio-reactor (MBR) was investigated as function of hydraulic and biological parameters. The reactor was a stirred tank and operated both in batch and continuous mode. The mixed denitrifying culture used in the batch mode tests was derived from the mixed liquor of a wastewater treatment plant in Erzincan province in Turkey. But the culture used in the continuous mode tests was that obtained from the batch mode tests at the end of the denitrification process. The nitrate contaminated water treated was separated from the mixed liquor suspended solids (MLSS) containing active mixed denitrifying culture and other organic substances by a membrane of 0.2 microm average pore diameter. The results indicated that the use of a membrane module eliminated the need for additional post treatment processes for the removal of MLSS from the product water. Concentration of nitrite and that of MLSS in the membrane effluent was below the detectable limits. Optimum carbon to nitrogen (C/N) ratio was found to be 2.2 in batch mode tests. Depending on the process conditions, it was possible to obtain denitrification capacities based on the reactor effluent and membrane effluent up to 0.18kgm(-3)day(-1) and 2.44 kg m(-2) day2(-1) NO(3-)-N, respectively. The variation of the removal capacity with reactor dilution rate and membrane permeate flux was the same for two different degrees of [MLSS]0/[NO3-N]0 (mass) ratios of 25.15 and 49.33. The present MBR was able to produce a drinking water with NO(3-)-N concentration of less than 4 ppm from a water with NO3-N contamination level of 367 ppm equivalent to a NO(3-)-N load of 0.310 kgm(-3) day(-1). The results showed that MBR system used was able to offer NO(3-)-N removals of up to 98.5%. It was found that the membrane limiting permeate flux increased with increasing MLSS concentration.
Filtration & Separation | 2003
Burhanettin Farizoglu; Alper Nuhoglu; Ergun Yildiz; Bulent Keskinler
Abstract Deep bed sand filters are used extensively in drinking water and wastewater treatment. In this study, sand and pumice were used as a filtration media under rapid filtration conditions and performance results for both were compared. Turbidity removal performance and head losses were investigated as functions of filtration rate, bed depth and particle size. Under the same experimental conditions such as 750 mm bed depth, 7.64m 3 /m 2 .h flow rate and, 0.5−1.0 mm grain size, turbidity removal rates for sand and pumice were found to be 85–90% and 98–99%, respectively. Furthermore, the head loss for sand and pumice were found to be 460 mm and 215 mm, respectively. The results obtained have shown that pumice has a high potential for use as a filter bed material.
Bioresource Technology | 2010
Handan Ucun; Ergun Yildiz; Alper Nuhoglu
Phenol biodegradation in a batch jet loop bioreactor (JLB) using activated sludge was investigated. The biodegradation experiments were conducted at different phenol concentrations (S(0)) from 50 to 1000 mg/l. The results of the biodegradation of phenol by JLB show that a good phenol removal of 100%. The biodegradation capacity of the JLB was higher than that of the stirred tank reactor reported in literatures. The Haldane equation was adopted in order to describe the relation between the specific growth rates (micro) and S(0). Kinetic constants of Haldane equation were micro(m) = 0.119 1/h, K(s) = 11.13 mg/l and K(i) = 250.88 mg/l. Model equations were simulated using the MATHCAD 7.0 softwares ordinary differential equation solver. Simulations were performed at each experiment with different initial phenol concentrations.
Desalination | 2003
Ergun Yildiz; Alper Nuhoglu; Bulent Keskinler; Galip Akay; Burhanettin Farizoglu
Abstract This paper presents an investigation on the removal of hardness by using a crossflow membrane reactor. Lime soda (LS) and caustic soda (CS) were added to hard water as softening chemical agents. The effect of the LS-CS dosage, specific cake resistances (α) and transmembrane pressure drop ( ΔP ) on steady-state rejection and flux was investigated. Also, flux declines were evaluated with respect to various flux decline models. It was found that hardness rejections decrease for LS and increase for CS with increasing LS and CS dosage, respectively. As ΔP increases, it was observed that while steady-state fluxes rise for both additives, hardness rejections were decreased for CS and remained constant for LS. A maximum of 97.5% hardness removal was achieved for 100% stochiometric dosages of CS. Obtained steady-state flux values varied between 224 to 881 L/m 2 h, depending on added chemical dosages and applied ΔP . It was determined that the reason for the flux decline at the beginning of the filtration (i.e., in the rapid flux decline period, RPD) was due to an intermediate pore blocking mechanism. As filtration progressed to the slow flux decline period (SDP), it was concluded that cake filtration occurred for all experiments. If solid matter concentration in the feed solution and applied ΔP are relatively low, the experiments showed that flux decline is due to the intermediate pore blocking mechanism. However, it was determined that if solid matter concentration in the feed solution and applied ΔP are relatively high, the flux decline model fits well with the cake filtration model.
International Journal of Environment and Pollution | 2004
Alper Nuhoglu; Ergun Yildiz; Bulent Keskinler; Mehmet Karpuzcu
A detailed characterisation of the incoming wastewater and a performance evaluation were carried out for the domestic wastewater treatment plant of Erzincan City. Conventional characterisation results showed that Erzincan has a medium strength wastewater quality. Structural characterisation of the chemical oxygen demand (COD) indicated that the biodegradable fraction of the total COD was 64.7%. The soluble inert fraction was computed as 10.9% of the total COD. In Erzincan, an activated sludge plant provides secondary treatment using Carrousel treatment units. Because some operational problems, such as sludge bulking and foaming, have been experienced, and performance failures related to carbonaceous matter removal have been recorded many times, a new operational strategy suitable for this type of treatment plant was developed. In the new strategy, the sludge age was kept at 22 days, intermittent aeration was abandoned and replaced by continuous aeration, and the sludge recycle ratio was increased to 1.35 from 0.85. The developed operational strategy showed its merit in that previous operational problems largely disappeared and COD concentrations remained below the Turkish discharge limits of 100 mg/l and the NH4 removal rate was in the range 87–95%.
Process Biochemistry | 2004
Burhanettin Farizoglu; Bulent Keskinler; Ergun Yildiz; Alper Nuhoglu
Journal of Hazardous Materials | 2006
Mevra Yalvac Can; Ergun Yildiz
Journal of Membrane Science | 2005
Coskun Aydiner; Ibrahim Demir; Ergun Yildiz