Identification and phylogeny of eukaryotic 18S rDNA phylotypes detected in chlorinated finished drinking water samples from three Parisian surface water treatment plants.

AIMS: We performed a preliminary assessment of the eukaryotic 18S rDNA diversity present in finished drinking water samples from three different surface water treatment plants supplying water to the city of Paris (France). METHODS AND RESULTS: A molecular analysis was performed on a sample from each site based on sequencing of PCR amplified and cloned 18S ribosomal RNA genes. Overall, the 18S rDNA sequences combined from all samples could be affiliated to the Amoebozoa (20.8% of the phylotypes), Ciliophora (25%), Metazoa (33.3%), Fungi (8.3%), Cercozoa (4.2%) and unclassified eukaryotes (8.3%) groups. CONCLUSIONS: The 18S rDNA sequences affiliated to the Amoebozoa, Ciliophora and Metazoa lineages were found to be the most abundant phylotypes observed in the drinking water samples. Phylotypes found to be present in two, or all three, samples (41.7% of the total) may represent groups with members adapted to drinking water treatment plant (DWTP) ecosystem conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: This study shows that finished drinking water can contain 18S rDNA sequences representing a variety of eukaryotic taxa. Further research is needed to better characterize the eukaryotic biodiversity of DWTPs and the effects of the finished drinking water diversity on the downstream water distribution network.

Evaluation of bromate ions level introduced by sodium hypochlorite during post-disinfection of drinking water.

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.

Role of oxidants and disinfectants on the removal, masking and generation of tastes and odours.

This paper summarises the positive and negative effects of the most commonly used oxidants and disinfectants: chlorine, chloramines, chlorine dioxide, potassium permanganate ozone, and advanced oxidation with ozone/hydrogen peroxide on tastes and odours present in natural and drinking waters. The case studies reported illustrate the generation of odorous by-products such as chlorophenols, iodoforms, aldehydes, the masking effect between earthy-musty and chlorinous odours, and the removal of odorous algal metabolites or anthropogenic pollutants by ozone alone or by ozone coupled with hydrogen peroxide.

Son realmente un problema las toxinas de algas después dun tratamiento de desinfección?

Analiza la cloración de agua durante su desinfección y las toxinas que pueden llegar a afectar la salud humana.También diferencia los tipos de toxinas provenientes de las algas, y su concentración en el agua a ser clorada

Lutilisation du fer comme catalyseur doxydation dans le tratement des eaux

Es conocido que durante tres años los átomos metálicos (Fe,Mn,Co,Ni,Cu,Ag) tengan propiedades catalíticas en relación a las reacciones de la oxidación. Este artículo tiene el fin de demostrar las posibilidades de los átomos de hierro y de manganeso con respecto a la oxidación. Se detallan los tipos de oxidantes, el sistema Fe/H2O2, y el sistema H2O2/con hierro y las conclusiones logradas

Elimination du fer et du manganese contenus dans les eaux par des oxydants forts tels que lozone ou le chlore

El trabajo presenta las características del hierro y del manganeso y sus efectos en el agua y los problemas que pueden causar. Se da un gráfico de los límites sugeridos por la OMS, CMA y otros. Luego se da detalles de los métodos de eliminación por el cloro y por la ozonización, por bióxido de cloro, el permanganato con gráficos ilustrativos

Alternative methods for chlorination.

Existing disinfectants are oxidative agents which all present negative effects on subsequent treatment processes. None of them has decisive advantages over chlorine, although chlorine-dioxide and chloramines might at times be preferable. Optimum treatment practices will improve the removal of organic precursors before final disinfection which could then consist in a light chlorine addition. A philosophy of radical change in water treatment technology encompassing physical treatment without chemicals such as membrane filtration, solid disinfectants is presented.