Contribution à l'étude de la détermination des conditions de formation des haloformes

In recent years the presence of haloforms has been observed by some researchers in waters of various origins.The aim of this study is to determine the conditions in which chloroform is formed by chlorination of aqueous solutions of some organic compounds.The first part of this work was carried out by chlorination of synthetic basic solutions of acetone and thus enabled us to determine the reagent concentrations needed to obtain the maximum quantity of chloroform.We studied next the effect of chlorination on organic material solutions (humic acids and phenols), in the course of an oxidation treatment; the results obtained by chlorination of aqueous solutions of humic substances show that the quantity of chloroform produced passes through a maximum value which depends on the time of ozonisation. Similar results were obtained for the chlorination of phenol solutions during oxidation by the u.v. + H₂O₂ system. These results may be explained by the partial degradation of the molecules which leads in the formation of reactional intermediate precursors of the haloform reaction. We undertook at the same time the study of a rapid test allowing us to detect the presence of haloform reaction precursors in a certain sample of water.     

Decomposing regional productivity growth using an aggregate production frontier

The main contribution of this paper is the implementation of a new model which combines the two parametric approaches most commonly used in the productivity literature: fixed effects and stochastic frontiers. This allows us to discuss whether it is better to use average or frontier functions to estimate regional productivity. The empirical section uses panel data of Spanish regions over the period 1980–1995. Additionally, we calculate and decompose total factor productivity growth for the Spanish regions.     

Dynamic analysis and optimal feedback control synthesis applied to biological waste treatment

The dynamics and optimal feedback control of biological waste treatment processes are examined. Modern feedback control theory is applied and results are obtained for both proportional and proportional plus integral control. A dynamic mathematical model of the system is developed by employing a Monod kinetic model, which is modified to account for endogenous metabolism, and a complete mixing flow model in the growth chamber. The feedback control is implemented via the flow rate so as to maintain desired effluent concentrations. External disturbances which cause changes in substrate concentration and/or cell concentration are considered and optimal control effort is applied. Results are also presented for impulse and step changes in the influent substrate concentration. It is found that by changing the values of the weighting factors in the objective function, it is possible to obtain good control of either the effluent substrate concentration or cell concentration.     

A large-scalein situ permeability test at Presenzano (Italy)

Bulletin of Engineering Geology and the Environment - Soil permeability had to be carefully determined in order to decide whether or not the whole lower reservior (750.000 m2) of the Presenzano...     

Levels of copper in the urine of women from nonpolluted farming regions of Japan.

Nearly 1500 spot urine samples were collected in the winter of 1987-1988 from women of seven farming prefectures located throughout Japan. Samples were analyzed for copper by flameless atomic absorption spectrometry. The copper content of the urine samples (Cu-U) distributed log-normally with a geometric mean (geometric standard deviation) of 36.9 (1.47) micrograms/l after adjustment for the specific gravity of urine of 1.016. The 95% confidence range was 17.1-79.7 micrograms/l. Neither alcohol consumption nor smoking habit affected the Cu-U. A literature survey showed that the observed level appears to be somewhat higher than previously reported values.     

Fire Safety Engineering Research and Technology Centre (FireSERT) University of Ulster: Recent Developments

The Institute of Fire Safety Engineering Research and Technology Centre (FireSERT) at the University of Ulster in Northern Ireland has been a major provider of higher technical fire safety education, fire related research and services to industry for over 20 years. Its internationally recognised research spans the fields of fire dynamics, structural fire engineering, human behaviour in fire and more recently fire (CFD) modelling. Since 1991, it has offered the only PG Dip/MSc Fire Safety Engineering programme in the United Kingdom. In September 2000 FireSERT was the recipient of a £5.7 m Joint Infrastructure Fund (JIF) Award to build new fire safety engineering laboratories on the University's Jordanstown campus. These new facilities unparallel in the University sector in the UK offer greater scope and depth to the FireSERT's research portfolios. The new facilities will be extensively used in support of FireSERT's suite of MSc Fire Safety Engineering and DPhil programmes. This paper presents a brief history of FireSERT and its achievements, together with an update on the new facility, current research themes, taught programmes, research opportunities and visions for the future.     

Heavy metals in maternal and cord blood

Heavy metal concentrations have been determined in maternal and cord blood samples collected from mothers in the age group 20-25 years with full-term neonates (37-40 weeks). The concentrations of Pb, Cd, Cu and Zn were found to be low in cord blood as compared to mother's blood and the ratio between cord blood and maternal blood for the respective elements was found to be approximately 0.80, 0.86, 0.47 and 0.40. On the other hand, the concentrations of Fe and Mg in the mother's blood were found to be lower than those in the cord blood. Prenatal exposure to lead in Mumbai, though low (5.1 microg/dl), is approximately 2-3 times higher than that observed in Canada or Italy. A strong correlation (r = 0.79) between the maternal and cord blood lead levels has been observed during the present study.     

Organochlorines in egg samples from Norwegian birds of prey: congener-, isomer- and enantiomer specific considerations

The content of chlorinated persistent organic pollutants was determined in a total of 44 egg samples from 8 different raptor species collected throughout Norway in the period 1991-1997. The content of 8 chlorinated bornanes, 9 chlorinated pesticides, and 15 polychlorinated biphenyl congeners (PCB) were determined. The highest average concentrations for PCB were found for eggs from White-tailed Sea Eagle and Peregrine Falcon (average sum PCB concentration: 8.9 and 9.1 microg/g wet weight (w.w.), respectively). Merlin and Sparrowhawk eggs were the highest contaminated with chlorinated pesticides (average sum pesticide concentration: 3.0 and 4.3 microg/g w.w.). For the first time, the content of chlorobornanes was determined in Norwegian birds of prey eggs. However, only minor contamination compared to PCBs and conventional chlorinated pesticides was found. The highest sum concentration was determined for White-tailed Sea Eagle eggs (0.09 microg/g w.w.). No chlorobornane contamination was found in Osprey and Merlin eggs. No spatial and regional specific trends or pattern distribution were found for organochlorine contamination in the egg samples analysed. In order to gain information about enantiomer specific bioaccumulation and biotransformation capacity of the organism, enantioselective analyses was performed for the chiral contaminants trans-chlordane, oxy-chlordane and the chlorobornane B9-1679 (Parlar #50). Indications for species-dependent deviation from the racemic distribution (enantiomeric ratio = 1) were found. Peregrine Falcon and Merlin eggs were characterised with an extremely high enantiomeric excess of the (-)-trans-chlordane (enantiomeric ratio (ER) <0.01). For Golden Eagle, Goshawk and Sparrowhawk eggs, the ERs were between 0.1 and 0.22 demonstrating also here that the (-)-trans-chlordane was the most abundant enantiomer. For the distribution of oxy-chlordane and B9-1679 enantiomers no species-dependent differences were found. For all species the ER values between 0.3 and 0.8 were determined. Thus, also for oxy-chlordane and B9-1679, the (-)-enantiomers are the most dominating stereoisomers in the birds of prey eggs analysed.     

Application of GaN-based ultraviolet-C light emitting diodes--UV LEDs--for water disinfection

GaN-based ultraviolet-C (UV-C) light emitting diodes (LEDs) are of great interest for water disinfection. They offer significant advantages compared to conventional mercury lamps due to their compact form factor, low power requirements, high efficiency, non-toxicity, and overall robustness. However, despite the significant progress in the performance of semiconductor based UV LEDs that has been achieved in recent years, these devices still suffer from low emission power and relatively short lifetimes. Even the best UV LEDs exhibit external quantum efficiencies of only 1-2%.The objective of this study was to investigate the suitability of GaN-based UV LEDs for water disinfection. The investigation included the evaluation of the performance characteristics of UV LEDs at different operating conditions as well as the design of a UV LED module in view of the requirements for water treatment applications. Bioanalytical testing was conducted using Bacillus subtilis spores as test organism and UV LED modules with emission wavelengths of 269 nm and 282 nm.The results demonstrate the functionality of the developed UV LED disinfection modules. GaN-based UV LEDs effectively inactivated B. subtilis spores during static and flow-through tests applying varying water qualities. The 269 nm LEDs reached a higher level of inactivation than the 282 nm LEDs for the same applied fluence. The lower inactivation achieved by the 282 nm LEDs was compensated by their higher photon flux. First flow-through tests indicate a linear correlation between inactivation and fluence, demonstrating a well designed flow-through reactor. With improved light output and reduced costs, GaN-based UV LEDs can provide a promising alternative for decentralised and mobile water disinfection systems.