The development and improvement of natural water and wastewater purification technologies utilizing low-cost raw materials like bricks are necessary to make possible easy application in poor countries. The present work concerns the detailed studies on a soil which is commonly used to make bricks by craftsmen in Bangui region (Central African Republic). The chemical and mineralogical composition of this soil before and after thermal transformation, and its crystalline, morphological and surface properties were determined by combining several techniques: X-ray Diffraction (XRD), ThermoGravimetric Analyses (TGA), Differential Thermal (DTA) Analyses, TGA/Mass Spectrometry (MS), 27Al and 29Si NMR spectroscopy, and Environmental Scanning Electron Microscopy (ESEM; an apparatus equipped with an Energy Dispersive X-ray Spectrometer, EDS). The basic brick making led to an interesting mesoporous material that was found to be a good adsorbent for Fe(II) removal from contaminated natural waters. Column experiments further revealed significant improvement of the sorption capacity of this brick when its surface was coated with iron oxy-hydroxide. ESEM/EDS micro-analyses revealed that FeOOH was preferentially deposited onto brick clays (mainly disordered metakaolinite), thus showing the key role played by these minerals in the study water treatment when compared to the sorption performances obtained with raw sand and FeOOH-coated sand.

Experiments were conducted to evaluate copper and nickel sorption on artificially manganese oxide‐coated burned brick (MCBb), a waste by‐product of brick industry. The effect of metal concentration, contact time, solution pH, and temperature on the amount of Ni(II) and Cu(II) sorbed was studied and discussed. Langmuir and Freundlich isotherm constants and correlation coefficients for the present systems at different temperatures were calculated and compared. The equilibrium process was well described by the Langmuir isotherm model: the maximum sorption capacities (at 293 K) were 2.4 mg Ni/g and 3.7 mg Cu/g for MCBb. Isotherms were also used to evaluate the thermodynamic parameters (ΔG°, ΔH°, and ΔS°) of adsorption. The sorption kinetics was tested for the pseudo‐first order, pseudo‐second order, and intraparticle diffusion models. Good correlation coefficients were obtained for the pseudo‐second‐order kinetic model, showing that nickel and copper uptake process followed the pseudo‐second‐order rate expression. © 2011 American Institute of Chemical Engineers Environ Prog, 2011

Dans un contexte de politiques dites de « developpement durable », les pratiques visant les economies d'eaux et d'energie sont de plus en plus frequentes et notamment l'installation de turbines hydroelectriques sur des systemes d'adduction d'eau potable existants. Il est primordial dans ce cas que la qualite de l'eau ne soit pas alteree et que l'approvisionnement en eau pour la consommation et la defense incendie soit toujours prioritaire sur la production d'energie. Ainsi, une analyse des risques sanitaires doit etre realisee et les mesures de maitrise des points critiques identifies doivent etre mises en oeuvre. En outre, l'installation d'une turbine ajoutant un danger alors qu'elle n'est en aucun cas necessaire a la production et a la distribution d'eau destinee a la consommation humaine, un systeme de management de la qualite incluant le turbinage et un programme de surveillance renforce de la qualite des eaux produites doivent etre mis en œuvre.

The removal characteristics of cadmium (Cd(II)) and nickel (Ni(II)) ions from aqueous solution by exhausted olive cake ash (EOCA) were investigated under various conditions of contact time, pH, initial metal concentration and temperature. Batch kinetic studies showed that an equilibrium time of 2h was required for the adsorption of Ni(II) and Cd(II) onto EOCA. Equilibrium adsorption is affected by the initial pH (pH0) of the solution. The pH0 6.0 is found to be the optimum for the individual removal of Cd(II) and Ni(II) ions by EOCA. The adsorption test of applying EOCA into synthetic wastewater revealed that the adsorption data of this material for nickel and cadmium ions were better fitted to the Langmuir isotherm since the correlation coefficients for the Langmuir isotherm were higher than that for the Freundlich isotherm. The estimated maximum capacities of nickel and cadmium ions adsorbed by EOCA were 8.38 and 7.32mgg−1, respectively. The thermodynamic parameters for the adsorption process data were evaluated using Langmuir isotherm. The free energy change (ΔG°) and the enthalpy change (ΔH°) showed that the process was feasible and endothermic respectively. As the exhausted olive cake is discarded as waste from olive processing, the adsorbent derived from this material is expected to be an economical product for metal ion remediation from water and wastewater.

New filtration materials covered with metallic oxides are good adsorbents for both cation and anion forms of pollutants. Sfax is one of the most important industrial towns in Tunisia. Its phosphate manufacture in particular is causing considerable amounts of water pollution. Therefore, there is a need to find out a new way of getting rid of this excessive phosphate from water. This work is aimed to examining the potential of three sorbent materials (synthetic iron oxide coated sand (SCS), naturally iron oxide coated sand (NCS) and iron oxide coated crushed brick (CB)) for removing phosphate ions from aqueous solutions. According to our literature survey CB was not used as adsorbent previously. Phosphate ions are used here as species model for the elimination of other similar pollutants (arsenates, antimonates). Optical microscope and scanning electron microscope (SEM) analyses were used to investigate the surface properties and morphology of the coated sorbents. Infra-red spectroscopy and X-ray diffraction techniques were also used to characterize the sorbent structures. Results showed that iron coated crushed brick possess more micro pores and a higher surface area owing to its clay nature. The comparative sorption of PO43− from aqueous solutions by SCS, CB and NCS was investigated by batch experiments. The estimated optimum pH of phosphate ion retention for the considered sorbents was 5. The equilibrium data were analysed using the Langmuir and Freundlich isotherms. The sorption capacities of PO43− at pH 5 were 1.5 mg/g for SCS, 1.8 mg/g for CB and 0.88 mg/g for NCS. The effect of temperature on sorption phenomenon was also investigated. The results indicated that adsorption is an endothermic process for phosphate ions removal. This study demonstrates that all the considered sorbents can be used as an alternative emerging technology for water treatment without any side effect or treatment process alteration.

In the present work, the abilities of sewage sludge and pomace ashes to remove copper (Cu2+) ions from aqueous solutions are compared. Batch adsorption experiments were performed in order to evaluate the removal efficiency of these materials. Effect of contact time, solution pH, ash concentration and temperature on the removal of Cu2+ was investigated. The results of batch equilibrium studies showed that the solution pH was the key factor affecting the adsorption characteristics. In general, the amount of Cu removed increased as the solid concentration and pH increased, and then it remained constant over a wide pH region. The adsorption test of applying sewage sludge and pomace ashes into synthetic wastewater revealed that the adsorption data of these materials for copper ions were better fitted to the Langmuir isotherm since the correlation coefficients for the Langmuir isotherm were higher than that for the Freundlich isotherm. The estimated maximum capacities of copper adsorbed by sewage sludge and pomace ashes were 5.71 and 6.98 mg g−1, respectively. Experimental results indicated that the adsorption was favorable at higher pH and higher temperature. Values of ΔG° ranging from −4.64 to −5.13 kcal mol−1 for sewage sludge ash and from −4.97 to −5.53 kcal mol−1 for pomace ash suggest that the adsorption reaction is a physical process enhanced by the electrostatic effect. The values of ΔH° and ΔS° are, respectively, 4.27 kcal mol−1 and 30.6 cal K−1 mol−1 for sewage sludge ash and 4.33 kcal mol−1 and 31.3 cal K−1 mol−1 for pomace ash. The mechanisms of copper removal by these materials included adsorption and precipitation. The sewage sludge and pomace ashes are shown to be effective adsorbents for this metal.

The present work explored the use of Tunisian olive-waste cakes, a by-product of the manufacture process of olive oil in mills, as a potential feedstock for the preparation of activated carbon. Chemical activation of this precursor, using phosphoric acid as dehydrating agent, was adopted. To optimize the preparation method, the effect of the main process parameters (such as acid concentration, impregnation ratio, temperature of pyrolysis step) on the performances of the obtained activated carbons (expressed in terms of iodine and methylene blue numbers and specific surface area) was studied. The optimal activated carbon was fully characterized considering its adsorption properties as well as its chemical structure and morphology. To enhance the adsorption capacity of this carbon for heavy metals, a modification of the chemical characteristics of the sorbent surface was performed, using KMnO(4) as oxidant. The efficiency of this treatment was evaluated considering the adsorption of Cu(2+) ions as a model for metallic species. Column adsorption tests showed the high capacity of the activated carbon to reduce KMnO(4) into insoluble manganese (IV) oxide (MnO(2)) which impregnated the sorbent surface. The results indicated also that copper uptake capacity was enhanced by a factor of up to 3 for the permanganate-treated activated carbon.

The use of natural adsorbent such as phosphate rock to replace expensive imported synthetic adsorbent is particularly appropriate for developing countries such as Tunisia. In this study, the removal characteristics of lead, cadmium, copper and zinc ions from aqueous solution by activated phosphate rock were investigated under various operating variables like contact time, solution pH, initial metal concentration and temperature. The kinetic and the sorption process of these metal ions were compared for phosphate rock (PR) and activated phosphate rock (APR). To accomplish this objective we have: (a) characterized both (PR) and (APR) using different techniques (XRD, IR) and analyses (EDAX, BET-N(2)); and, (b) qualified and quantified the interaction of Pb(2+), Cd(2+), Cu(2+) and Zn(2+) with these sorbents through batch experiments. Initial uptake of these metal ions increases with time up to 1h for (PR) and 2h for (APR), after then, it reaches equilibrium. The maximum sorption obtained for (PR) and (APR) is between pH 2 and 3 for Pb(2+) and 4 and 6 for Cd(2+), Cu(2+) and Zn(2+). The effect of temperature has been carried out at 10, 20 and 40 degrees C. The data obtained from sorption isotherms of metal ions at different temperatures fit to linear form of Langmuir sorption equation. The heat of sorption (DeltaH degrees), free energy (DeltaG degrees) and change in entropy (DeltaS degrees) were calculated. They show that sorption of Pb(2+), Cd(2+), Cu(2+) and Zn(2+) on (PR) and (APR) an endothermic process. These findings are significant for future using of (APR) for the removal of heavy metal ions from wastewater under realistic competitive conditions in terms of initial heavy metals, concentrations and pH.

SAGEP-EAU DE PARIS produces drinking water for the city of Paris (France). In order to supply a high quality water, one of the main SAGEP's concerns is to monitor the Biofilm Formation Potentials of the produced drinking waters. Biofilm incubators were installed at the outlet of three Water Treatment Plants (WTP). These incubators allowed biofilm formation and quantification in terms of Fixed Total Organic Carbon (FTOC), fixed culturable bacteria (HPC-R2A) and fixed total bacteria. During this study, quantitative differences appeared between the biofilms formed at the outlet of the three WTPs, leading to different classifications of the Biofilm Formation Potentials of the three produced waters, depending on the used parameter for biofilms quantification. This observation underlined the necessity of a multi-parametric approach for the study of biofilms. More generally, our results validated the use of these sturdy stainless steel incubators, highly adapted to industrial field conditions, for the monitoring of Biofilm Formation Potentials in drinking water networks.

During the last ten years, interest concerning the occurrence of bromate in drinking water has grown due to its potential carcinogenicity and the new regulations. One source of bromate in finished water is due to its presence in the sodium hypochlorite solutions used for the disinfection of water. In fact, the brine solutions used for the production of sodium hypochlorite contain bromide ions in varying degrees that subsequently generate a certain quantity of bromate ions. Bromate concentrations ranging from 82 to 857 mg l(-1) (0.5-7.4 mg BrO3-/ g Cl2) have been found in commercial solutions of sodium hypochlorite used by Société Anonyme Gestion des Eaux de Paris (SAGEP), a company that produces drinking water for Paris, France. In addition, the chlorine concentration of the hypochlorite solution can decrease during storage, consequently the added amount of bromate increases for a given applied dose of chlorine.

Cette étude a eu pour but de déterminer l'effet d'un traitement par le sulfite de sodium sur la concentration en composés organohalogénés totaux (TOX) et sur l'activité mutagène de solutions chlorées de substances humiques d'origine aquatique (SHA), après avoir cherché à préciser l'influence du pH et du temps sur la concentration en TOX. Les résultats obtenus à partir d'échantillons chlorés de SHA en absence de chlore résiduel ont permis de mettre en évidence une diminution de la concentration en composés organohalogénés totaux, soit par stockage en milieu neutre ou basique, soit par addition de sulfite de sodium. L'intensité de cette réduction de la concentration en TOX augmente avec le pH, le temps de réaction et la dose de sulfite de sodium introduite. Les résultats obtenus à partir d'échantillons contenant du chlore libre indiquent que seule une déchloration totale avec un excès de sulfite de sodium peut conduire, en milieu neutre, à une diminution de l'activité mutagène et de la concentration en TOX des solutions diluées de SHA. La comparaison des pourcentages d'abattement obtenus sur le paramètre TOX et sur l'activité mutagène indique que la diminution de la génotoxicité par déchloration totale est due à l'action du sulfite sur des composés mutagènes non chlorés ou sur des composés chlorés fortement mutagènes et ne représentant qu'une très faible fraction du TOX.

Ce travail explore les performances de deux types de membranes de nanofiltration (Desal DK et NF200) dans l'élimination dans les eaux de certains pesticides (l'atrazine et son métabolite la déséthylatrazine (DEA), la simazine, la cyanazine, l'isoproturon et le diuron) et évalue l'influence de la présence de matière organique ou inorganique dans la matrice d'eau sur l'efficacité de ce traitement. Des eaux synthétiques, composées à partir d'eau distillée à laquelle a été ajoutée de la matière organique (acides humiques) ou inorganique (CaCl2 ou CaSO4), ont été traitées sur un pilote de nanofiltration durant 96 heures. Les taux rétention en pesticides et ceux de leur adsorption sur les membranes ont été calculés et comparés aux résultats obtenus sur une matrice d'eau distillée pure. Une influence du type de membrane et de la présence de la matière humique sur le taux d'abattement de certains pesticides a été constatée. L'influence de la matière inorganique est pratiquement insignifiante.

Slow sand filtration is a biological means of surface water clarification that involves both biological and physical mechanisms. During this process, as time progresses, microbiological growth occurs, mainly consisting of micro-algae and bacteria which form a fixed microbial ecosystem (biofilm) on the sand of biofilters. The establishment and maintenance of this biofilm are necessary for an effective treatment because some extracellular polymeric molecules, synthesized by fixed bacteria and fixed micro-algae, act as a coagulant. Very often, the presence of macro-algae in too great quantity inevitably leads to a clogging of biofilters and thus to important pressure losses. To prevent these phenomena, washings of variable intensity are made periodically in order to eliminate the macro-algae responsible for clogging but with preserving the biofilm (fixed bacteria and fixed micro-algae). In spite of these precautions, after an in-depth washing, there must frequently be a filter ripening period before a new filter run. At present, the restarting of a biofilter is determinated by analyses carried out on the effluents because there is no direct, simple and quickly measurable parameter which allows the appreciation of the biofilm maturity. This study, carried out during the summer, constitutes a very first approach. Using the number of fixed micro-algae as an indicator of the biofilm density, its goal was twofold: to evaluate the effect of washing operations on the quantity of fixed biomass and to follow the quantitative evolution of this one between two washings of moderate intensity. The results show that washings can involve the elimination of nearly 90% of the fixed biomass. After washing, this latter increases again but finds an equilibrium state only after 20 days. More generally, the simple method suggested here could complement the indirect measurements classically taken before the restarting of the filters. It could also contribute to enhance the ripening period with helping the operators to adapt washings according to the state of the fixed biomass.

The new european régulation spécifies that drinking water quality should now be assessed at the consumer's tap rather than at the outlet of treatment plants. So, it is very important for all drinking water producers and suppliers, whatever their analytical means are, to have efficient tools for the quantification of biofilms, so that they can detect problems and react as quickly as possible. Thus, on the basis of a previous european programme research, we developed and tested a simple and easily reproducible experimental procedure to assess the biofilm formation potential of waters.Sturdy stainless steel incubators, highly adapted to industrial field conditions and containing glass beads were designed to allow the biofilm formation and the measurement of technically basic parameters (HPC) or more complex parameters (Fixed Total Organic Carbon, fixed total bacteria).Such incubators were connected to a surface water after a slow sand filtration stage. The maximal quantities measured were lower than those typically reported in the literature: about 103/cm2 for HPC-R2A, 104/cm2 for total bacteria and 0.5 µg/cm2 for Fixed Total Organic Carbon (FTOC).A significant linear relationship exists between FTOC and total bacteria or HPC but it seems that the most part of FTOC is of extra-cellular origin.More generally, the resutts obtained validate the use of this type of incubators as a monitoring System which is a suitable tool for all potable water producers and suppliers.

ABSTRACT The latest European Directive 98/83/CE (5 December 1998), concerning the quality of water intended for human consumption, has set a two-stage parametric value for bromate. Bromate concentration will comply with 25 μg/L after December 25, 2003, and with 10 μg/L after December 25, 2008. Bromate formation in water is generally due to bromide oxidation during the ozonation stage. Due to higher temperatures, this latter parametric value is often exceeded in summer. Minimizing bromate levels is thus a crucial problem for drinking water producers. A bromate-minimizing strategy consists of shortening the reaction time between ozone and water. This can be done by neutralizing dissolved ozone residual with bisulfite at the exit of the ozone reactor chamber and/or by managing the introduction of ozone in different chambers depending on the water flow rate. This is only possible if, in our case, the disinfection goal for ozone is respected toward bacteria and viruses. The CT value must comply with 1.6 mg/min/L. In our plants, this value could be very large due to high contact time in and after leaving the ozone reactors.

The titration of adenosine triphosphate (ATP) by bioluminescence permits rapid evaluation of the quantity of viable micro-organisms present in a water sample. During two sampling campaigns, Société Anonyme de Gestion des Eaux de Paris (SAGEP) tested a new extraction and titration system of bacterial ATP in the Paris drinking water distribution network. As far as the entire set of results of analyses of water in the network is concerned there is a linear relationship between log [ATP] and log(HPC-R2A/ml). Furthermore, as regards the drinking water originating from treatment of surface waters, some of the results obtained indicate a slight change as regards the Paris network in the microbiological quality. This is certainly linked to the distance travelled from the production location as well as to a reservoir effect observed on a site. Conversely, no change is apparent with regard to waters of underground origin. Lastly, despite changes in temperature and chlorine residual, no significant influence has been observed, essentially because of the very low density of culturable bacteria.

Apatite appears a useful compound for removing lead from water, due to its ability to immobilize the metal by precipitation. In dilute solution, dissolved hydroxyapatite [HA, Ca-10(PO4)(6)(OH)(2)] provided phosphates that were reactive with aqueous lead (molar ratio HA/Pb = 1/10) forming precipitates at around pH 6. These dissolved at a more acidic pH (3). Solid HA in contact with Pb2+ ions, led to the formation of pyromorphite [Pb-10(PO4)(6)(OH)(2)], identified by X-ray diffraction and insoluble at pH tested (3-8). The amount of pyromorphite increased with the weight ratio of HA/Pb. When this one increased from 1 to 1000, lead precipitated as pyromorphite rose from 19 to 99%. In vivo experiments on rats confirmed the in vitro results. In fact, lead bioavailability assessed by intestinal perfusion was unchanged in the presence of dissolved HA, whereas it was significantly lower in the presence of solid HA, evaluated by gastric intubation, at a weight ratio equal to 10 (amount of lead absorbed decreased by 60%). Apatite could be an effective means of immobilizing lead in drinking or sewage, since accidental pyromorphite ingestion does not yield bioavailable lead. (C) 2003 Elsevier Science Ltd. All rights reserved.

Solid-phase microextraction (SPME) followed by gas chromatography (GC) coupled with an electron capture detector has been applied for the analysis of chlorinated pesticides in water. Molecule adsorption on 100 microm polydimethylsiloxane (PDMS) fibers was activated by immersion of the whole fiber-sample system in an ultrasonic bath. The good reproducibility, low detection limits and wide linear ranges obtained encourage the use of this technique in water control.

L'extraction en phase solide (SPE) est devenue une alternative tres interessante a l'extraction liquide - liquide dans l'analyse des pesticides dans l'eau. Le travail realise consiste a mettre au point une methode SPE sur un nouveau type de cartouche (Oasis - HLB) pour certains herbicides de la famille des triazines et phenylurees substituees. Les cartouches sont conditionnees par le passage de petits volumes de methanol et d'eau de qualite HPLC. L'analyse des extraits a ete realisee par chromatographie en phase gazeuse avec un detecteur a azote et phosphore (CPG / NPD).L'automatisation du procede d'extraction en phase solide a permis l'obtention de resultats tres reproductibles et un important gain de temps et de solvants. Les taux d'extraction obtenus ont ete superieurs a 80 % pour la majorite des molecules etudiees.