Nitrification parameter measurement for plant design: experience and experimental issues with new methods.

Nitrification kinetics are important for process design, optimization, and capacity rating of activated sludge wastewater treatment plants. A Water Environment Research Foundation (WERF) project on Methods for Wastewater Characterization in Activated Sludge Modeling (WERF, 2003) focused significantly on the development of procedures for measuring the nitrifier maximum specific growth rate, micro(AUT). In addition, the importance of (and lack of data for) the nitrifier decay rate, b(AUT), was identified. This paper describes three bench-scale methods for measuring micro(AUT): the Low F/M SBR, Washout and High F/M methods. During the WERF project, the importance of pH and temperature control was investigated briefly; this paper summarizes further experimental work performed to address these issues. A summary of micro(AUT) measurements in a number of locations and using the different measurement techniques is provided.     

Degradation of wine industry wastewaters by photocatalytic advanced oxidation.

Wine industry wastewaters contain a high concentration of organic biodegradable compounds as well as a great amount of suspended solids. These waters are difficult to treat by conventional biological processes because they are seasonal and a great flow variation exists. Photocatalytic advanced oxidation is a promising technology for waters containing high amounts of organic matter. In this study we firstly investigated the application of H2O2 as oxidant combined with light (artificial or natural) in order to reduce the organic matter in samples from wine industry effluents. Secondly, we studied its combination with heterogeneous catalysts: titanium dioxide and clays containing iron minerals. The addition of photocatalysts to the system reduces the required H2O2 concentration. Although the H2O2/TiO2 system produces higher efficiencies, the H2O2/clays system requires a H2O2 dosage between three and six times lower.     

Final Drying of Whole Milk Powder in Vibrated-Fluidized Beds

Vibro-fluidized beds are widely used in drying sticky powders and agglomerated materials as milk powder. Using a vibro-fluidized laboratory scale dryer, this work is aiming at analyzing preliminarily the effect of its operational variables on the drying kinetics and characteristics of whole milk powder. The full-factorial design technique with three replications at the central point has been employed to generate data and correlations to quantify the effect of inlet air temperature, air flow rate, and vibration bed amplitude on the drying curves and the milk powder properties related to its faster reconstitution in water (as tapped density, Hausner cohesion ratio, agglomerate size distribution, and internal pore concentration). Results obtained are analyzed and discussed to identify the adequate operation condition for final drying whole milk powder in vibro-fluidized beds, assuring a high product quality.     

Intraoperative neurological monitoring

Intraoperative neurological monitoring (INM) is the evaluation of the nervous system within the operating room (OR) environment. In this paper, the INM system is tested in a clinical setting in comparison with conventional somatosensory evoked potential (SEP) monitoring. The study results demonstrate the capability of the INM system in extracting clearer and more stable SEP signals. The high SNR of SEP signals collected in various clinical environments, including the OR, makes the INM system a robust platform for continuous monitoring. While the current use of EP monitoring is limited to intermittent analysis by a highly trained clinical neurophysiologist, the authors believe in changing this paradigm by developing continuous monitoring systems, such as the INM system, capable of automated quantitative EP analysis. This noninvasive monitoring modality will allow for a wider range of use in clinical practice. Based on volunteer and clinical patient studies, the INM monitoring system demonstrates much greater reliability and accuracy via the artifact rejection and denoising strategies. It provides more strategic filtering options for different situations under which the clinical SEP response signal could be greatly contaminated and distorted. Furthermore, the INM system offers a promising approach to signal extraction in real-time monitoring during SEP research.     

The first experiments on electrical safety.

This paper discusses the experiments conducted by physicist and physician Arsenne d'Arsonval on the effect of sinusoidal ac on the body, well before the era of electronics. d'Arsonval's first experiments were on the effect of ac on muscle contraction using frog muscle. He contrived a most ingenious device, which displayed the voltage curve and the force of muscle contraction on a smoked-drum kymograph. By using this instrument, along with various alternators such as the Gramme machine, d'Arsonval was able to show that the muscular contraction force decreased with increasing frequency of the electric current. d'Arsonval then turned his attention to the effect of high-frequency ac on the human body. To this end, he created a spark-gap generator of the type described by Hertz in 1888. d'Arsonval demonstrated two important facts: 1) muscle contraction force decreased with increasing frequency of the current and 2) substantial current could be passed through the body and it produced a sensation of warmth. This he proved with conductive and capacitive coupling. By his experiments, d'Arsonval laid the foundation for two new medical techniques: 1) electrosurgery and 2) diathermy. Today both fields are well established in medicine     

A rate adaptive bit-loading algorithm for in-building power-line communications based on DMT-modulated systems

This paper deals with a variable rate discrete multitone modulation system for broadband power-line communications, based on the bit-loading algorithm proposed by Leke and Cioffi. In the proposed system a suitable least mean square channel estimator is considered, which is based on the insertion of a training sequence (TS). The proposed approach will be compared with the ideal channel estimates, showing its effectiveness. Moreover, different TS lengths will be compared. The system performance, expressed in terms of bit rate and bit-error rate, is derived by simulation with and without estimation errors. The propagation environment has been assumed as a frequency-selective multipath fading channel with additive colored Gaussian noise, according to the in-building networks model.     

RZ-DPSK signal regeneration based on dual-pump phase-sensitive amplification in fibers

All-optical regeneration of differential phase-shift keying signals by means of a phase-sensitive amplification scheme solely based on highly efficient four-wave mixing in fibers is theoretically and numerically studied. The analytical and numerical investigation demonstrates almost ideal phase regeneration accompanied with enhanced amplitude noise suppression in the regime of pump depletion.     

Effects of solid retention time on the performance of submerged anoxic/oxic membrane bioreactor.

In this study, four similar bench-scale submerged Anoxic/Oxic Membrane Bioreactors (MBR) were used simultaneously to investigate the effects of solids retention time (SRT) on organic and nitrogen removal in MBR for treating domestic wastewater. COD removal efficiencies in all reactors were consistently above 94% under steady state conditions. Complete conversion of NH(4+)-N to NO(3-)-N was readily achieved over a feed NH(4+)-N concentration range of 30 to 50 mg/L. It was also observed that SRT did not significantly affect the nitrification in the MBR systems investigated. The average denitrification efficiencies for the 3, 5, 10 and 20 days SRT operations were 43.9, 32.6, 47.5 and 66.5%, respectively. In general, the average effluent nitrogen concentrations, which were mainly nitrate, were about 22.2, 27.6, 21.7 and 13.9 mg/L for the 3, 5, 10 and 20 days SRT systems, respectively. The rate of membrane fouling at 3 days SRT operation was more rapid than that observed at 5 days SRT. No fouling was noted in the 10 days and 20 days SRT systems during the entire period of study.     

The Grey-Rankin bound for nonbinary codes

The Grey-Rankin bound for nonbinary codes is obtained. Examples of codes meeting this bound are given. Original Russian Text Ş L.A. Bassalygo, S.M. Dodunekov, V.A. Zinoviev, T. Helleseth, 2006, published in Problemy Peredachi Informatsii, 2006, Vol. 42, No. 3, pp. 37–44. Supported in part by the Russian Foundation for Basic Research, project no. 06-01-00226.