COMPARING CHLORINA TION AND CHLORAMINATION FOR CONTROLLING BACTERIAL REGROWM

Douglas G. Neden, Robert J ]ones, ]udy R. Smith, Gregory J Kirmeyer, and Glenn w: Foust

The Greater Vancouver (B.C.) Water District compared chlorine and chloramine as secondaIY disinfectants and their effects on bacterial regrowth in a distribution system supplied with disinfected, unfiltered surface water .The selected section of the distribution system was divided into three areas: a control area that received no secondary disinfectant, an area that received free chlorine as the secondary disinfectant, and an Brea that received chloramine. Water samples were analyzed for chlorine residual, coliform bacteria, heterotrophic plate count (HPC) bacteria, and turbidity'. A1though both chlorine and chloramine were effective in reducing bacterial growth in the distribution system. chloraminated water had a lower HPC. less taste and odor, fewer positive coliforms and a more stable residual. 

      INNOVACIONES  EN LATECNOLOGIA DEL TRATAMIENTO DEL AGUA

 Por: L. di Bernardo. Escuela de Ingeniería de Sao Carlos Universidad de Sao Paulo. Brasil  

Introducción 

Durante los últimos años, en todo el mundo, la tecnología de tratamiento del agua ha sido objeto de numerosas innovaciones. El presente informe es un intento de resumir las más recientes e importantes de estas innovaciones, desarrolladas en algunos países y adoptadas para el suministro de agua público e industrial.

Puesto que se ha conseguido un progreso sustancial en las operaciones y los procesos unitarios, este artículo está relacionado inicialmente con las operaciones de coagulación, f1uculación. sedimentación y filtración rápida.

EFFECT OF PREOZONA TION ON COAGULANT -NOM INTERACIONS

Marc Edwards andMark M. Benjamin

 Preozonation of water sources containing natural organic matter (NOM) may alter coagulant requirements. the total organic carbon (T'OC) removed by coagulation. and the concentration of aluminium and iron in the finished drinking water. In this work, these phenomena were investigated and interpreted as resulting from (1) changes in the zeta potential of precipitates (flocs) that fonn in the presence of ozonated NOM; (2) slight losses of TOC by .oxidation and volatilization of NOM molecules; and (3) changes in the quantity of TOC removed by precipitation and sórption

INVESTIGATING THE MACHANISM OF INACTIVATION OF ESCHERlCHIA COLI B BY MONOCHLORAMINE

Joseph G. Jacangelo, Vincent P. Olivieri, and Kazuyoshi Kawata .

To better understand the mode of adion of monochloramine. its effect on the structural and physiological integrity of Echerichia coli B was studied. The disinfectant did not severey damage the cell envelope of the baderium or affect nucleic acid function. Inhibition of typical protein-associated biological adivities, e.g.. bacterial transport, respiration. and substrate dehydrogenation, were observed at concentrations nornally used for disinfection. Differences in rates of kiil and inhibition of various biological activities suggest tbat the shoulder formation on inactivation curves was due to reactions at many sensitive sites in the bacerium, the extent of which ddermined whether the organism remained recoverable.  

ELIMINA TION OF  ZOOPLANKTON BY FLOCCULATION AND FILTRATION                          H.Bernhardt and B.Lusse

ABSTRACT: In flocculation and filtration processes. the removal of zooplankton. which should not be present in drinking water. is dependent on the shape. size. and mobility of the individuals. Large and bulky organisms with large caudal appendages are better retained in the filter than small compact forms. Rotifers can discharge from attaching flocs by the help of their rotatory organ. In order to optimize elimination ( > 90% ) an inactivation of these planktonic organisms is necessary. In addition to chlorine. which is undesirable because of the formation of organochlorides ozone (1.5-2 mg/1 for 1 min) potassium permanganate (0.5-1 mg/1 for 15-20 min) and the physical process of ultrasonic waves with a reaction time of a few seconds are aII appropriate. The elimination of rotifers by flocculation and filtration after an inactivation was investigated at a pilot plant and successfulIy employed at a technical scale.

 .

Coagulation ofNatural Organic Matter frorn Surface Water Using Cationic Polyrner

A.D.Levine, L.M.Mercurio , and J.R Carman

Coagulation of hydrophilic and hydrophobic fractions of natural organic matter (NOM) from two surface water sources was evaluated in a case study. The goal of the study was to evaluate the role of cationic polymer in enhanced coagulation applications for removal of disinfection by-product (DBP) precursors. Compre- hensive laboratory studies were conducted using cationic polymer alone and in combination with alum to treat surface water sources low in turbidity. The formation potential of trihalomethanes (THMFP) was used as an indicator of the concentration of DBP precursors before and after each treatrnent. Evidence that NOM reactions with cationic polymer differ from reactions with inorganic coagulants is presented. The importance of conducting an integrated assessment of chemical interactions that occur within a water treatrnent facility prior to implementation of enhanced coagulation is emphasized.

LAS AGUAS DULCES Y EL EQUILIBRIO CARBONICO

J.Le Brun  . Compagnie Génerale des Eaux

L'élimination de I'agressivité constitue le traitement de base généralement nécessaire pour les eaux douces. M. LE BRUN en décrit les diverses techniques. Les cas d'application sont complétés par les exemples de filiéres de traitement présentés par M. VILLESSOT .

MANGANESO CONTROL DURING OZONATION OF WATER CONTAINING ORGANIC COMPOUND

Andrzej Wilczak , William R.Knocke, Richard .Hubel and E.Marco Aieta

Bench-scale tests were conducted to investigate the removal of dissolved manganese from Delaware River water. Prior pilot-plant results had indicated that manganese was not effectively removed by ozonation, sludge blanket clarification, and filtration, because ofthe breakthrough or resolubilization of colloidal manganese dioxide [MnO2!(s)] specie". Increasing the alkalinity was not an effective means of controlling manganese. But applicatjon of potassium permanganate after ozonation and at the beginning of coaulation considerably improved the removal of soluble manganese.

ORIGEN, FORMACION Y ELIMINACION DE LOS TRIHALOMETANOS EN LAS AGUAS DE SUMINISTRO PUBLICO

Por: José Mosquera Arias, Ing. Químico I.Q.S.

Manuel A. Soler Manuel, Dr. Ing. Industrial, Dtor. del Centro de Estudios e InveStigación del Agua*.

RESUMEN

La actualidad e interés de los T .H .M. presentes en el agua de abastecimiento, no ha cesado desde su puesta en cuestión por medios sanitarios. Este trabajo de tipo bibliográfico, en esta su primera parte, va dirigido básicamente a obtener información sobre los com- puestos precursores de los T .H.M., los mecanismos de formación, factores de mayor importancia a tener en cuenta, en el proceso de cloración en las plantas potabilizadoras, así como las técnicas de eliminación o no generación de T .H.M. También se indican diversas técnicas analíticas. -

SUMMARY

The present situation and interest in the T.H.M. present in the water supply has not ceased since this was questioned in health circles. This work, of a bibliographic nature, in this jirst part, is basjca//y directed to the obtention of information concerning the precursor compounds of those T.H.M., the mechanism of their formation, factors of greatest importance to be taken into account in the process of chlorhynation in the drinking water factories, as we// as the techniques of elimitation or non-generation of the T.H.M. Also given are various analytical techniques.

CUCUMBER FLAVOR IN PHILADELPHIA'S DRINKING WATER

GaryA. Burlingame,JohnJ; Muldowney, and Roy E. Maddrey

Since 1981, when the use of free chlorine was curtailed to control trihalomethanes at the Baxter Treatment PIant in Philadelphia, Pa., a seasonal cucumber f1avor problem occurred. Flavor profile analysis was the only tool available to guide treabnent. During 1990, the cucumber odor was tracked more than 250 mi (402 km) up the Delaware River to the Cannonsville Reservoir, and the odor-causing compound was identified as trans ,2-cis,6.non- adienal. A1gae growth beneath the winter ice produced the compound. Other treatment pIants on the river that used free chlorine for disinfection and a final residual never had a problem with trans,2-cis,6.nonadienal. Therefore, use of chlorine was increased at the Baxter pIant to control the cucumber flavor . Studies were conducted on trans,2-cis,6-nonadienal to describe its sensory characteristics and analytical detection limit.

INTERACCIONES ENTRE LOS MA TERIALES y EL AGUA POTABLE

Por: D. van de, Kooij, F. L Schulting

y J. T. van der Zwan

..Introducción

La distribución del aguapotable con una red compleja de tuberías, depósitos y sistemas de cañerías domésticas se traduce, inevitablemente, en cambios de la calidad que tenía el agua en la planta de tratamiento. La naturaleza y extensión de estos cambios de calidad dependen fundamentalmente de la composición y temperatura del agua producida, de la estructura y dimensiones de la red de distribución y de los materiales de construcción que se utilicen.

La degradación de la calidad del agua durante la distribución puede tener consecuencias estéticas, higiénicas y técnicas.

NFLUENCIA Y ELIMINACION DE LA MATERIA ORGANICA EN LOS PROCESOS DE TRATAMENTO

por:-J.C.Kruithof, THE Netherlands Waterworks Testing and Research Institute, KIWA

El KIWA, Instituto Holandés de Pruebas de Investigaciones de Instalaciones de Abastecimiento de Aguas, en cooperación con las plantas de agua potable, viene haciendo muchas invcs- tigaciones sobre la eliminación de materia orgánica en el agua por coagu- laci6n y filtraci6n con GAC, así como sobre la conversión de materia orgánica por procesos de oxidación, como la ozonización y la cloracion.

En el campo de la coagulación, se han desarrollado procedimientos aplicables a los equipos normalizados de prueba de vibración. En estos equipos, se ha estudiado profundamente el efecto de la coagulación, en combinación con sedimentación o flotación, sobre la concentración de materia orgánica natural.

Se han hecho muchos estudios con plantas piloto para determinar la po.sibilidad de la filtración con GAC en relacion con tales objetivos. También ha sido objeto de estudio detenido la eliminación de los TTHM y precursores de ellos.

La aplicación de la ozonizacion se orientó en principio, junto al propósito de desinfeccion, a la rcduccion del sabor y del olor y a la oxidación de la

GENERACION ECONOMICA DEL OZONO : .

Por: w. Reichelt, K. sChw~ E. Feuerstacke

Introducción

En los últimos años, el ozono ha adquirido rápidamente gran importancia en el dominio de la ingeniería hidráulica. Ha encontrado crecientes aplicaciones no solo para la depura- ción y trataminto del agua potable sino, también. para el tratamiento de las aguas industriales y rcsiduales. Recientemente han mostrado interés por el ozono las industrias químicas yderivadas.

Este interés despertado porel ozono, ha llevado a los institutos de investiga- ci6n científica y a los fabricantes de ozonizadorcs, a intensificar sus inves- tigaciones en la producci6n economica y operacionalmente fiable del ozono en plantas compactas y con pequeñas necesidades de mantenimiento.

El proposito del informe que sigue es el de determinar las condiciones que conducen a la producción econ6mica del ozono en plantas operacionalmente seguras. Este informe se basa, esencialmente, en las investigaciones llevadas a cabo con ozonizadores comer- ciales y en condiciones parciales de trabajo. Se ha dado especial importancia a que los experimentos se ejecutasen en lascircunstancias más parecidas posibles a las de servicio.

COMPARATIVE STUDY DIFFERENT PRE-TRATMENT ALTERNATIVES

G. Gal vis, J. Femández and J. T. Visscher* , CINARA. Centro lnter-regional de Abastecimiento y Remoción de Agua. 

Universidad del Valle. Cali. Colombia and *IRC. lntemational Water and Sanitation Centre. The Hague. the Netherlands

ABSTRACT: The results of an ongoing comparative study of different pre-treatment alternatives based on two stages of roughing filtration are presented. The first stage is orientated mainly to cope with coarser suspended solids and the second with finer particles and microorganisms. They are part of experimental lines which include slow sand filters in the treatment stage. These lines are processing raw water from a polluted tropical lowland river. The findings support the need to take into account not only suspended solids or turbidity levels but more importantly. the sanitary risk involved in a particular water source when planning and designing roughing filters. The two stages of roughing filtration represent around 3 log units ofthe overall5.5log units reduction offaecal colifonn bacteria that the experimental lines are now consistently reaching.

Etude comparative de différentes alternatives de prétraitement

RESUME: On présente les résultats d'une étude comparative continue de différentes altematives basées sur deux étapes de filtration de dégrossissage. La premiere étape est plus spécialement orientée pour éliminer les matieres en suspensions grossieres et la seconde pour les panicules plus fines et les microorganismes. Elles font partie de filieres expérimentales qui incluent, dans une des étapes de traitement, une filtration a sable lente. Ces filieres traitent de l' eau brote provenant d'une riviere polluée de basse plaine tropicale. Les résultats corroborent la nécéssité de tenir compte non seulement des niveaux des matieres en suspension ou de la turbidité mais plus encore du risque sanitaire afférent a des sources d' eau particulieres lors du projet et des études des filtres de dégrossisssage. Les deux étapes de filtration de dégrossissage représentent environ 3 unités, sur un total de 5.51ogs d'abattement des bactéries coliformes fécales que les filieres expérimentales atteignent actuellement.

                           RESIDUAL ALUMINIUM IN DRINKING WATER TREATMENT

   M. R. Jekel and B. Heinzmann .

ABSTRACT: The residual concentrations of aluminium in drinking-water treatment are determined by the solubility of the hydroxide precipitate which is strongly pH-dependent. Stability and solubility diagrams based on known chemical cquilibrium reactions cannot be used directly due to various reasons. Therefore. a practical diagram. showing the ranges of residual aluminium as a function of pH in membrane-filtered samples was derived from various jar-test data. While sulphate and calcium ions do not influence the residual concentrations significantly, dissolved humic and fulvic acids, especially after pre-ozonation and at low alum dosages. can induce excessively high aluminium residuals by surface complexation.  

Aluminium résiduel dans le traitement d'eaux potables

RESUME: Les concentrations résiduelles d.aluminium dans le traitement des eaux potables. sont déterminées par la solubilité du précipité hydroxide. qui dépend fortement du pH. On ne peut pas utiliser directement. pour une variété de raisons, les courbes de stabilité et de solubilité basé es sur les réactions connues des équilibres chimiques. Donc, un diagramme pratique. montrant des plages de concentrations en aluminium résiduel en Conction du pH dans des échantillons filtrés sur mem- brane. a été obtenu au moyen d.essais de floculation en laboratoire. Alors que les ions sulfate et calcium n.influent pas de fac,on significative sur les concentrations résiduelles. les acides humiques et fulviques dissouts. surtout apres ozonation et en présence de faibles dose d'alun, peuvent induire de tres fortes concentrations résiduelles dues a la complexification des surfaces.

Nine oxidizing agents were evaluated for removing six taste and odor compounds spiked into Colorado River water (CRW). one ofthe supplies ofthe Metropolitan Water District (MWD) of Southem Califomia. Of the oxidation processes investigated. ozone alone and ozone with hydrogen peroxide appear to have the most potential for control of taste and odor compounds at existing MWD plants. In State Project water ( SPW). another MWD source water. the rate of oxidation of geosmin and methylisobomeol (MIB) with ozone-with or without hydrogen peroxide-is higher than in CRW. The oxidation of geosmin and MIB is postulated to occur through the formation ofhighly reactive hydroxyl radicals. The higher oxidation rates in SPW are indicative of higher levels of natural initiators of ozone decomposition and lower levels of hydroxyl radical scavengers.

EL PERMANGANATO POTASICO EN EL TRATAMIENTO DEL AGUA

Industrial Química del Nalon, S. A.

El desarrollo económico y la consiguiente mejora de la calidad de vida demandan, de una manera creciente, una mayor cantidad y mejor calidad de agua potable. El ciudadano, que paga y consume el agua, tiene derecho a exigir un suministro abundante de agua potable de buena calidad, limpia y sin turbidez, sin problemas bacteriológicos, sin problemas de uso y libre de color, olor y sabor . Se exige un agua no ya potable, sino paladeable.

LEAD IN DRINKING WATER -ORIGINS , SOLUBILITY , TREA TMENT

 P.Leroy ,  Centre de recherche et de Controle des Eaux de Paris (CRECEP)  

ABSTRACT: Lead in drinking water appears after contact with lead pipes but it can come from other materials like brass. copper pipes. or galvanized steel. Plumbosolvency depends on physico-chemical parameters like temperature. pH and alkalinity. Treatmedt by adding orthophosphates can reduce the lead level if the alkalinity is low. But adding polyphosphates leads to increase significantly the plumbosolvency. The emission of particles of lead compounds in the water results. as shown by our laboratory experiments. on the presence of fittings like valves. or copper pipes welded to the lead pipe. But protection of lead pipes by calcium carbonate is not possible and cannot reduce lead level in the water. Finally it appears impossible to respect the WHO standard of 10 μg/l without removing and materials made of lead  

Le plomb dans I'eau potable -origines; solubilité; traitements

RESUME: La présence de plomb dans l'eau peut résulterdu contact avec des conduites en plomb mais aussi avec d'autres matériaux métalliques ou non tels que tubes de cuivre, laiton, acier galvaoisé. Apres contact avec une conduite en plomb la teneur de l'eau en ce métal est fonction de parametres physico- chimiques tels que température, pH ou T AC. L 'addition a l'eau d'orthophosphates peut amener une diminution de la teneur en plomb pourvue que le TAC de l'eau soit faible. Par contre, l'addition de polyphosphates peut entrainer un accroissement de cette teneur; L 'émission de plomb particulaire apparait a la lumiere d'expériences de laboratoire liée a la présence de discontinuités dans la conduite telles que vannes ou raccords en un autre métal. Enfin la protection par un dépót calcique n'apparait pas possible et la présence de calcium ne semble pas diminuer la teneur en plomb de l'eau. En tout état de cause le respect de la norme OMS de 10 μg/l implique l'élimination des éléments de conduite en plomb.