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Öğe A Review of Dehydration of Various Industrial Sludges(Taylor & Francis Inc, 2014) Tunçal, Tolga; Uslu, OrhanWastewater characteristics and sludge generation potential of point source categories are reviewed critically. Novel industry-specific sludge dewatering/drying solutions necessary to establish a sustainable model are examined through a detailed literature survey. Knowledge of sludge properties is one of the most critical issues needed to design dewatering/drying equipment. This study focuses on industrial wastewater/sludge characterization. In addition, a comprehensive review of current drying models and technologies is also presented. A summary of the results derived from a novel thin-film-based photonic sludge dewatering/drying study is outlined as an alternative approach for industrial sludge control. Sludge was dried in a tubular quartz reactor (TQR), the inner surface of which was coated with a TiO2 thin film. The TQR was irradiated with UV A, UV B, and UV C lamps. The consumed and generated energy fluxes through endergonic and exergonic reactions driven by photolysis and photocatalysis were investigated. In addition, the variations in sludge dewatering/drying characteristics were also examined and compared with conventional methods to evaluate the energy requirements.Öğe Determination of optimum extinction wavelength for paracetamol removal through energy efficient thin film reactor(Elsevier Science Sa, 2016) Çifçi, Deniz İzlen; Tuncal, Tolga; Pala, Ayşegül; Uslu, OrhanParacetamol (PAM) mineralization through nano-composite thin film (TF) based photocatalytic system was investigated under variable operational conditions. The experiments were conducted using a non stirred flow through coated tubular quartz reactor (TQR). Elimination of energy demand arising from stirring and aeration through the developed TF reactor configuration was also among the main research interests. Ag-doped Si-TiO2 TFs were grown on Si-decorated inner surface of the TQR using sol-gel dip coating technique. The fabricated TF was characterized by SEM-EDS, TEM, AFM, XPS and UVvis spectroscopy methods. TF-based PAM mineralization kinetics were observed for both UVvis and UV wavelengths using pure, Si-Ti and Ag-doped Si-TiO2 TF(s). The direct and indirect optical ban gap energies (BGE) for the Ag doped Si-TiO2 TF were estimated to be 2.56 eV and 2.86 eV respectively. While no visible light activity was observed for pure TiO2 TF, Ag-doped Si-TiO2 TF exhibited significant PAM degradation activity for lambda > 400 nm with a k(obs) value of 2.1 +/- 0.1 10(-3) min(-1). In addition to known phenolic and carboxylated intermediates, UVvis spectroscopy, HPLC-MS and UPLC-MS/MS measurements indicated alpha-cyano-4-hydroxicinnamic acid (alpha PHC) formation as a result of photo-addition reactions under UV C irradiation. Experimental results also indicated that alpha PHC blocks h(+)/e(-) formation completely. Paracetamol could be degraded economically under UV B irradiation through the fabricated TF reactor without stirring, aeration or adding external electron acceptors. (C) 2016 Elsevier B.V. All rights reserved.Öğe Industrial sludge remediation with photonic treatment using Ti-Ag nano-composite thin films: Persistent organic pollutant removal from sludge matrix(Academic Press Ltd- Elsevier Science Ltd, 2015) Tunçal, Tolga; Uslu, OrhanMechanically dewatered industrial sludge (MDIS) was treated using pure and silver-doped thin films (TFs) grown on quartz substrates. TFs were prepared using a sol-gel dip coating technique. The resulting films were annealed at 450 degrees C for 3 h and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Mixtures that were homogeneous in the UV A (380 nm) and UVvis (450 nm) regions of the electromagnetic spectrum were used as the irradiation source. The results revealed that illumination with different wavelengths helps to generate well-separated e(-)/h(+) pairs, resulting in a decrease in the recombination rate. An electron transfer chain model was also developed using the experimental results. The performance of the applied method was evaluated by observing variations in the sludge bound water content (SBWC), volatile solids removal rate (VSR), and the consumed and generated energy fluxes through endergonic and exergonic reactions. After treatment, SBWC was reduced from 65% +/- 1% to 39% +/- 1 and the highest VSR was measured to be 27 +/- 0.1 mg VSS cm(-2) h(-1). The consumed and recovered energy fluxes were 960 +/- 151 and 412 +/- 26 J g(-1) VSremoved, respectively. Raw sludge and polychlorinated biphenyls (Sigma 15PCB) and polyaromatic hydrocarbon (Sigma(16)PAH) concentrations were 4356.82 +/- 22 mu g kg(-1) and 446.25 +/- 4.8 mu g kg(-1), respectively. The Sigma(15) PCB and E-16 PAH concentrations in the treated sludge samples were 129.86 +/- 22 mu g kg(-1) and 34.85 +/- 13 mu g kg(-1), respectively. (C) 2014 Elsevier Ltd. All rights reserved.Öğe Tetrachlorobiphenyl removal from sludge matrix using mixed crystal Ti0.97Fe0.02Ni0.01O2 thin film(Elsevier Science Bv, 2015) Tunçal, Tolga; Çifçi, Deniz İzlen; Uslu, OrhanIn this study, 2,2',5,5'-tetrachlorobiphenyl removal from activated sludge matrix using thin film (TF)-based photocatalytic (PCT-TF+UVC+H2O2) and UVC+H2O2 (photolytic) treatment systems were investigated for three different initial sludge pH(i) values of 3.0 +/- 0.1; 7.3 +/- 0.1 and 10.0 +/- 0.1. A novel, visible light active Ti:Fe:Ni nano composite TF was successfully synthesized and used as catalyst. The fabricated TF was characterized by SEM, TEM, XRD, XPS and UV-vis spectroscopy methods. Experimental results indicated that while raw industrial sludge contains only 2,2',5,5''-tetrachlorobiphenyl, treated sludge samples contained more chlorinated PCB congeners in descending chlorination order from 2,2',3,3',4,4',5,5',6,6' decachlorobiphenyl to 2,3',4,4',5 pentachlorobiphenyl. Experimental results also indicated that 2,2',5,5'-tetrachlorobiphenyl was removed from the sludge matrix by only TF-based PCT that was carried out at neutral pH(i). In addition, UVC+H2O2 system caused significant PCB formation at all studied pH levels. PCB generation/degradation reactions followed pseudo-first order reaction kinetics. Obtained results also proposed that UV irradiation can induce C-Cl bond cleavage in chlorinated compounds yielding Cl-center dot radicals, responsible for further chlorination. The k(obs) value observed in 2,2',5,5'-tetrachlorobiphenyl degradation by TF-based PCT at pH(i) = 7.3 +/- 0.1 was 0.0169 +/- 10(-3) min(-1) and 1.5 times higher than at pH(i)=3.0 +/- 0.1. The observed k(obs) values in TF based PCT for PCB generation at pH(i)=3.0 +/- 0.1 and pH(i)=10.0 +/- 0.1 were 0.0037 +/- 10(-3) and 0.0015 +/- 10(-3) min(-1), respectively. (C) 2015 Elsevier B.V. All rights reserved.Öğe Variations in sludge organic composition and dewatering behaviors through visible light driven photocatalysis: In-situ O-2 generation(Elsevier Sci Ltd, 2018) Tunçal, Tolga; Pala, Ayşegül; Uslu, OrhanIn this research, carbon and nitrogen doped TiO2 nano-particles were successfully synthesized and immobilized onto inner surface of a tubular thin film reactor (TTFR). CO3-NxOy-TiO2 nano-composite thin films (NCTF(s)) were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM-EDX), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Characterization results indicated that the CO3-NxOy-TiO2 NCTF has a broad adsorption edge in the visible light region. Decorated TTFR was used to observe the impacts of visible light irradiation on sludge dewatering characteristics and organic structure. In the experiments, H2O2, NaOCl and their various gravimetric combinations were added to the sludge as electron acceptor combination (EAC). Obtained experimental results revealed a photocatalytic synergy between hydrogen peroxide and chlorite molecules. The optimum H2O2 and OCl mixing dosage for photocatalytic and photolytic experiments was determined to be 0.02 g H2O2 g(-1) DS and 4 x 10(-3) g(-1) NaOCl g(-1) DS, respectively. The pseudo-first order kinetic constants (k(obs)) for volatile solids (VS) removal observed in EAC(3) (with NCTF), EAC(2) (with NCTF) and photolysis were 0.140 min(-1), 0.045 min(-1) and 0.025 min(-1), respectively. The average VS removal rate depending on the applied unit photonic power to unit TTFR area was 218 +/- 14 mgVS(removed) W-1 h(-1) cm(-2). Experimental results obtained using different EAC(s) dosage schemes revealed that O-2 was the main active specie and HO radicals also contributed to sludge treatment. Naphthalene, pyrene, anthracene and phenanthrene were detected in raw sludge and removed 87 +/- 1% by the method.
