Aerobic biodegradation and inhibition kinetics of poly‐aromatic hydrocarbons (PAHs) in a petrochemical industry wastewater in the presence of biosurfactants

BACKROUND: In Izmir, Turkey, wastewaters from the petrochemical industry are treated using conventional activated sludge systems. A significant proportion of poly‐aromatic hydrocarbons (PAHs) with high‐molecular weights remains in this treatment system and inhibits the biological activity. Biosurfactants increase PAHs degradation by enhancing the solubility of the petroleum components. The aerobic inhibition kinetics of PAHs has not previously been investigated in the presence of biosurfactants for a real petrochemical industry wastewater. RESULTS: Among the kinetic models used (Monod‐type, zero, first‐order and second‐order) it was found that the Monod kinetic was effective for describing the biodegradation of PAHs in petrochemcal industry wastewater in the presence of three biosurfactants, namely Rhamnolipid (RD), Surfactine (SR) and Emulsan (EM) in an aerobic activated sludge reactor (AASR). The maximum PAH removal rate (R_max) and specific growth rate of PAH degrading bacteria (µ_max) increased, while the half saturation concentration of PAH (K_s) decreased at 15 mg L^?1 RD concentration compared with the control without biosurfactant at a sludge retention time (SRT) of 25 days. CONCLUSION: PAH oxidation is typified by competitive inhibition at RD concentrations > 15 mg L^?1 resulting in increases in K_s values with PAH accumulation. Low inhibition constant (K_ID) values reflect difficulties in the metabolizability of PAHs. Metabolite production decreased at RD = 25 mg L^?1 in the PAHs indeno (1,2,3‐cd) pyrene (IcdP), flourene (FLN), phenanthrene (PHE) and benzo(a)pyrene (BaP). Copyright © 2011 Society of Chemical Industry     

A device for the fabrication of multifunctional particles from microbubble suspensions

A novel V-junction microfluidic (VJM) device has been used to generate several types of particles from the break-up of bubbles. The flow rates of selected solutions and the gas pressure were adjusted in order to successfully generate monodisperse polymer coated microbubbles, which serve as a platform for particle generation. Uniform particles in both the nano and micro size ranges with different shapes were spontaneously generated from bubbles and have the potential to be used in several advanced technological applications.     

A repair and overhaul methodology for aeroengine components

Repair and maintenance of aeroengine components have been one of the main tasks to be overwhelmed by aerospace industries due to continual increase in raw material and manufacturing costs. In this paper, an advanced methodology for the repair of complex geometry and expensive components via reverse engineering, free-form surface modeling and machining is presented. The methodology has been successfully implemented on a critical aeroengine component, i.e. thin-curved compressor blade. The approach involves the integration of 3D non-contact digitization, adaptive free-form surface reconstruction and multi-axis milling operation. Each operation is individually automated and inter-connected each other in order to reduce the total repair time. The workshop results have shown that the proposed repair methodology can be considered a reliable and time-cost effective as compared with the current repair approaches.     

CCII-Based Grounded to Floating Immittance Converter and a Floating Inductance Simulator

A new circuit employing second-generation current conveyors (CCIIs), and unmatched resistors for converting a grounded immittance to the corresponding floating immittance with either positive or negative adjustable multiplier, is presented. Moreover, the proposed circuit can also realize a synthetic floating inductance employing a grounded capacitor depending on the passive element selection. Simulation results using 0.35 μ m TSMC CMOS technology parameters are given. Erkan Yuce was born in 1969 in Nigde, Turkey. He received the B.Sc. from Middle East Technical University and M.Sc. degrees from Pamukkale University in 1994 and 1998 respectively. He is a Ph.D. student at Bogazici University all in Electrical and Electronics Engineering. He is currently Research Assistant at the Electrical and Electronics Engineering Department of Bogazici University. His current research interests include analog circuits, active filters, synthetic inductors, and current-mode circuits. He is the author or co-author of about 10 papers published in scientific journals or conference proceedings. Oguzhan Cicekoglu was born in 1963 in Istanbul, Turkey. He received the B.Sc. and M.Sc. degrees from Bogazici University and the Ph.D. degree from Istanbul Technical University all in Electrical and Electronics Engineering in 1985, 1988 and 1996 respectively. He served as lecturer at the School of Advanced Vocational Studies Electronics Prog. of Bogazici University where he held various administrative positions between 1993 and 1999, and as part time lecturer at various institutions. He was with Biomedical Engineering Institute between 1999 and 2001. He is currently Associate Professor at the Electrical and Electronics Engineering Department of Bogazici University. His current research interests include analog circuits, active filters, analog signal processing applications and current-mode circuits. He is the author or co-author of about 150 papers published in scientific journals or conference proceedings. Oguzhan Cicekoglu is a member of the IEEE. Shahram Minaei received his B.Sc. degree in Electrical and Electronics Engineering from Iran University of Science and Technology in 1993. He received his M.Sc. and Ph.D. degrees in Electronics and Communication Engineering from Istanbul Technical University in 1997 and 2001, respectively. He is currently an Associate Professor at the Electronics and Communication Engineering Department of Dogus University in Istanbul, Turkey. He has more than 50 journal or conference papers in scientific review. He served as reviewer for a number of international journals and conferences. His current field of research concerns current-mode circuits and analog signal processing. Shahram Minaei is a member of the IEEE.     

A novel dual output universal filter topology using a single current conveyor

In this paper, a new voltage mode universal filter topology is presented. The proposed topology can provide three circuits with all-pass, notch, band-pass, low-pass and high-pass filtering functions employing minimum number of active and passive components, namely a single first generation current conveyor, two resistors and two capacitors. Furthermore, these circuits obtained from general topology have dual outputs that can be used simultaneously. Sensitivities of the pole frequency and quality factor of the filter to the passive components can be made lower than unity in magnitude. Finally, natural frequencies of the presented circuits are independent from non-ideal voltage gain of the active element. Simulations are performed to verify the theoretical results.     

A new differential configuration suitable for realization of high CMRR, all-pass/notch filters

In this paper, a new configuration suitable for realization of differential input-differential output first order, second order all-pass and notch filters with high CMRR is given. The proposed configuration uses two negative type second-generation current conveyors (CCII-), and three admittances. Two first order and one second order all-pass filters and a notch filter (tunable if current controlled conveyor CCCII is used) are extracted from the proposed configuration. Tracking error, element mismatch, sensitivity analysis, simulation and experimental results are included.     

ICCII-Based Voltage-Mode Filter with Single Input and Six Outputs Employing Grounded Capacitors

In this paper, a novel second-order voltage-mode filter with single input and six outputs employing inverting second-generation current conveyors (ICCIIs) is presented. This filter simultaneously realizes negative and positive gain lowpass, bandpass, and highpass filter responses, and does not require active and passive element matching. The new filter has low active and passive element sensitivities, and offers orthogonal control of the angular resonance frequency (ω_o) and quality factor (Q).     

A Versatile Active Circuit for Realising Floating Inductance, Capacitance, FDNR and Admittance Converter

An active circuit suitable for realizing floating inductance, capacitance, FDNR and admittance converter depending on the selection of passive elements of the circuit is presented. The proposed circuit employs only two dual output second-generation current conveyors (DO-CCIIs) and does not require passive element matching. The proposed network has a grounded capacitor for the floating inductance and capacitance simulation. Frequency performance of the circuit is tested using SPICE.     

First-order allpass sections-based current-mode universal filterusing ICCIIs

An inverting type current conveyor (ICCII) is presented and its usefulness in active filter synthesis illustrated by presenting a new current-mode universal filter using this element. The universal filter configuration based on the implementation of first-order allpass sections employs the absolute minimum number of passive and active components and hence leads to a filter circuit with very simple implementation