Limitaciones del IRCA como estimador de calidad del agua para consumo humano / Limitations of the Water Quality Risk Index as an estimator of quality for human consumption

RESUMEN Objetivo Analizar los resultados del Índice de Riesgo de la Calidad del Agua para Consumo Humano (IRCA) para los 116 municipios del Departamento de Cundinamarca, del año 2007 a 2013. Materiales y Métodos Información recolectada de los 116 municipios del Departamento de Cundinamarca, seleccionados y clasificados en función de los datos porcentuales del IRCA. Resultados Se observa una disminución del promedio anual del IRCA, lo cual refleja un mejoramiento de la calidad del agua entregada en el departamento; sin embargo, un 26,7% de municipios no reportan información de la zona rural y un 56,9% de los municipios reportan un IRCA superior a 5, que aunque se ubican en Riesgo Bajo, son un agua no apta para consumo humano. Conclusiones Se propone una nueva ponderación de los parámetros evaluados en el IRCA, con el fin de permitir que este índice sea más representativo del riesgo a la salud y, como estudios futuros un análisis estadístico concienzudo sobre el tamaño de la muestra que permita que los resultados obtenidos sean confiables para los tomadores de decisiones sobre el mejoramiento de la calidad del agua potable.(AU)

ABSTRACT Objective To analyze the results of the Water Quality Risk Index (IRCA) in the 116 municipalities of the department of Cundinamarca, between 2007 and 2013. Materials and Methods Information collected from the 116 municipalities of the department of Cundinamarca, selected and classified according to the percentage data retrieved by IRCA. Results A decrease of the annual IRCA average is observed, which reflects an improvement of the water quality delivered in the department. However, 26.7% of the municipalities do not report information from their rural areas, and 56.9% of the municipalities report IRCA figures over 5, which means that even though they are at low risk, they receive water unfit for human consumption. Conclusions A new weighting method for the parameters evaluated with the IRCA is proposed to make this index more representative of the risk to health. In addition, future studies should carry out a thorough statistical analysis on the size of the sample that allows the obtained results to be reliable for decision makers to improve the quality of drinking water.(AU)

Descripción de la microbiota bacteriana residente en el biosólido generado en la planta de tratamiento de aguas residuales San Fernando. Itagüí, Colombia / Description of bacterial microbiota in biosolids generated in the San Fernando wastewater treatment plant. Itagüí, Colombia

RESUMEN Objetivo Caracterizar la microbiota bacteriana presente en los biosólidos generados en una de las plantas de tratamiento de aguas residuales más grande de Colombia. Materiales y Métodos Se utilizó la plataforma de secuenciamiento 454 de la compañía Roche para secuenciar las regiones variables V1-V3 y V6-V9 del marcador molecular 16S rRNA y caracterizar la microbiota. Adicionalmente, se aplicaron estrategias filogenéticas para la identificación de especies bacterianas de importancia. Resultados Nuestros análisis muestran que los Phyla más abundantes son Chloro-flexi, Proteobacteria, Bacteroidetes, Actinobacteria y Firmicutes. Los géneros clasificados más abundantes fueron Pseudomonas, Dysgonomonas y Proteiniphilum. Sin embargo, el grupo dominante según la región variable V1-V3 es una Anaerolineaceae que no se ajusta a las especies descritas para esta familia. Conclusiones En las muestras de biosólido analizadas predominan bacterias ambientales que participan en los procesos de estabilización de la materia orgánica durante los tratamientos biológicos de tipo secundario y la digestión anaerobia. Se detectaron secuencias de especies dentro de la familia Anaerolineaceae, los análisis filogenéticos muestran que probablemente se trata de especies no descritas. En el momento del estudio, se encontró que en el sistema de digestión anaerobia se genera biosolido con una baja carga de bacterias potencialmente patógenas.(AU)

ABSTRACT Objective To describe bacterial microbiota in the biosolids generated in one of the largest wastewater treatment plants of Colombia. Materials and Methods Using NGS technology, 16S rRNA Gene Amplicon libraries were amplified and sequenced. The Roche 454 FLX Titanium platform was used, while the V1-V3 and V6-V9 hypervariable regions were amplified and analyzed independently. Amplicon processing and bacterial classification were performed using the AmpliconNoise pipeline and the RDP Classifier tool. Results The analysis showed that the most dominant Phyla in the biosolids were Chlo-roflexi, Proteobacteria, Bacteroidetes, Actinobacteria and Firmicutes. The most dominant genera were Pseudomonas, Dysgonomonas and Proteiniphilum; however, the dominant group according in the V1-V3 variable region was Anaerolineaceae, which does not conform to the species described for this family. Pathogenic bacteria such as Salmonella and E. coli/Shigella were not detected in the studied biosolid sample. Conclusions In the biosolids samples analyzed, environmental bacteria involved in organic matter stabilization processes during secondary biological treatments and anaerobic digestion were predominant. One of the dominant species in this sludge is a novel species of the Anaerolineaceae group. At the time of the study, it was found that the anaerobic digester system was able to maintain pathogenic bacteria at very low concentrations.(AU)

Evaluación del tratamiento de agua para consumo humano mediante filtros Lifestraw® y Olla Cerámica / Evaluation of drinking-water treatment by Lifestraw® and Ceramic-pot filters

Objetivo Evaluar la eficiencia de dos sistemas de filtración casera: LifeStraw® family (FM) y Filtro de Olla Cerámica (FOC) en el tratamiento del agua para consumo humano bajo condiciones controladas de laboratorio y en términos de remoción de Turbiedad y E.coli. Métodos Ambos sistemas se operaron durante 6 meses tratando diariamente 7,5 litros de sustrato sintético. La turbiedad del sustrato se ajustó con Caolín y la concentración de E.coli con la réplica de la cepa ATCC 95922. Los resultados obtenidos en términos de remoción de turbiedad y E. coli fueron evaluados con un análisis de varianza (ANOVA) y considerando aspectos operativos y de mantenimiento. Resultados La turbiedad del sustrato sintético presentó un promedio 32,3 ± 2,8 UNT y la concentración de E. coli 3,9 x105 UFC/100mL. Ambos sistemas de filtración disminuyeron la turbiedad a niveles menores de 2 UNT y lograron la inactivación del 100 % de E.coli. Se encontraron diferencias significativas en la remoción de turbiedad siendo más eficiente el FM (99,2 % ± 0,4) que el FOC (97,6 % ± 1.14). Conclusiones Los dos sistemas de filtración son adecuados para el tratamiento del agua a nivel casero, cumpliendo con la reglamentación Colombiana. El FM resultó más eficiente en remoción de turbiedad y tasa de filtración; Sin embargo, cuando se tienen en cuenta aspectos como aceptabilidad social operación, mantenimiento y vida útil, el filtro de olla cerámica parece más apropiado especialmente en áreas rurales.(AU)

Objective To evaluate under laboratory conditions, the removal efficiency of turbidity and E. coli of two household water filters: LifeStraw® family (MF) and ceramic pot filter (CPF). Methods The two systems were operated over 6 months using two identical control units per system, treating 7.5 L/d of a synthetic substrate used as raw water. The turbidity of the substrate was adjusted with Kaolinite and the E. coli concentration, with a replica of the ATCC 95922 strain. The differences of effluent quality of the systems, in terms of turbidity and E. coli, were evaluated with Analysis of Variance (ANOVA). Operative and maintenance aspects, that could limit or enhance the use of the systems, were also considered in the evaluation. Results The water synthetic substrate quality had an average of 32.2 ± 2.8 NTU for turbidity and 3,9x105 UFC/100 mL for E. coli. Both systems reduce the turbidity to values below 2 NTU with an inactivation of 100 % of E. coli. Statistical differences were found between the systems in terms of turbidity removal, MF being more efficient than the CPF (99,2 ± 0.4 % and 97.6 % ± 1.14, respectively). Conclusions Both systems are suitable for household water supply treatment, acheiving the water quality standards established by Colombian regulations. The MF was more efficient for suspended solids removal and filtration rate, but when economic, operative, and maintenance aspects along with social acceptability and lifespan are considered, the CPF seems more suitable, especially in rural areas.(AU)

Surveillance of water quality in a medical college campus in a rural area in North West India.

Water bacteriology is an important component of providing safe and potable water supply. Surveillance of drinking water helps in identifying possible sources of water contamination. The present study was done in DRPGMC Tanda campus to monitor the quality of water samples. A total of 79 water samples were collected and tested over a period of two and a half years. About 33 % of these were found to be not fit for drinking. The findings of the study underscore the importance of following the steps of water purification.

Análise da concentração de flúor na água em Curitiba, Brasil: comparação entre técnicas / Analysis of water fluoride concentration in Curitiba, Brazil: comparison of techniques

OBJETIVO: Avaliar a adequação dos níveis de fluoreto nas águas de abastecimento público em Curitiba, Estado do Paraná, Brasil, de acordo com duas técnicas (SPADNS e eletrométrica). MÉTODOS: Foram levantados os dados do heterocontrole na Cidade de Curitiba de janeiro de 2000 a julho de 2008 no banco de dados da Secretaria Municipal da Saúde para cálculo das médias anuais. Na sequência, foram comparadas as concentrações de fluoreto fornecidas pela companhia de saneamento SANEPAR (técnica eletrométrica) com as concentrações obtidas pelo heterocontrole (SPADNS) em 1 470 amostras de água coletadas e analisadas entre 2006 e 2007. Foi calculada a proporção de amostras dentro do padrão ideal de fluoretação para a Cidade (0,8 ppmF), abaixo do ideal e acima do ideal para ambas as metodologias. Foram exploradas diferenças na fluoretação entre distritos sanitários, meses do período dezembro de 2007 a julho de 2008 e estações de tratamento de água (ETA). RESULTADOS: A média geral de flúor entre 2000 a 2008 foi de 0,7 ppmF conforme os dados do heterocontrole. A comparação das técnicas eletrométrica e SPADNS revelou que o valor médio de fluoreto na água é maior quando avaliado pela técnica eletrométrica (0,743 ppmF ± 0,133) quando comparado com a técnica SPADNS (0,637 ppmF ± 0,164). A proporção de amostras dentro do padrão ideal de fluoretação foi de 15,05 por cento para SPADNS e 63,97 por cento para eletrométrica; de 62,03 e 22,85 por cento para amostras abaixo do ideal; e de 21,10 e 13,18 por cento para amostras acima do ideal, respectivamente. Houve diferença estatisticamente significativa na fluoretação entre os distritos sanitários (P < 0,001) e os meses pesquisados. CONCLUSÕES: A escolha da técnica analítica interfere significativamente no processo do heterocontrole. O heterocontrole deve utilizar a mesma técnica de determinação de flúor utilizada pela empresa de tratamento de água. Novos estudos devem definir qual técnica é a mais adequada para medir o teor de flúor.

OBJECTIVE: To evaluate the adequacy of fluoride levels in the public water system in Curitiba, state of Paraná, Brazil, as determined by two techniques (colorimetric and electrometric). METHODS: Data from independent measurements of fluoride in the public water system in Curitiba routinely performed by the city government were obtained for the period between January 2000 and July 2008. Mean levels of fluoride concentration were calculated for each of these years. After that, fluoride concentrations measured in 1 470 samples by the state water utility (SANEPAR) using the electrometric technique in 2006 and 2007 were compared with the corresponding levels measured by the city using the colorimetric method. The rate of samples meeting the standard for the city (0.8 ppmF), and below and above the standard, was calculated for both methods. Fluoride levels were compared between sanitary districts, months for the period between December 2007 and July 2008, and water treatment facilities. RESULTS: The overall mean fluoride level between 2000 and 2008 was 0.7 ppmF based on the independent measurements. The comparison between techniques showed a higher mean fluoride level with the electrometric technique (0.743 ppmF ± 0.133) vs. the colorimetric technique (0.637 ppmF ± 0.164). The rate of samples meeting the ideal standard of 0.8 ppmF was 15.05 percent for the colorimetric and 63.97 percent for the electrometric technique; 62.03 percent and 22.85 percent of the samples were below that standard and 21.10 percent and 13.18 percent were above that standard, respectively. Fluoride levels were statistically significant (P < 0.001) for the comparison between sanitary districts and months. CONCLUSIONS: The choice of technique significantly influences the resulting levels of fluoride. Independent monitoring of fluoride levels should employ the same technique used by the water utility. Further studies should aim at defining which technique is the most adequate to determine fluoride concentration in public water systems.

Study of water supply & sanitation practices in India using geographic information systems: Some design & other considerations in a village setting.

Background & objectives: Availability of clean water and adequate sanitation facilities are of prime importance for limiting diarrhoeal diseases. We examined the water and sanitation facilities of a village in southern India using geographic information system (GIS) tools. Methods: Places of residence, water storage and distribution, sewage and places where people in the village defaecated were mapped and drinking water sources were tested for microbial contamination in Nelvoy village, Vellore district, Tamil Nadu. Results: Water in the village was found to be microbiologically unfit for consumption. Analysis using direct observations supplemented by GIS maps revealed poor planning, poor engineering design and lack of policing of the water distribution system causing possible contamination of drinking water from sewage at multiple sites. Interpretation & conclusions: Until appropriate engineering designs for water supply and sewage disposal to suit individual village needs are made available, point-of-use water disinfection methods could serve as an interim solution.

Modeling of ozone as a disinfectant of indicators bacteria in the drinking water

Ozone is considered one of the most effective disinfectants that can inactivate resistant pathogenic microorganisms in which conventional disinfectant such as chlorine and chlorine dioxide fail due to its strong biocidal oxidizing properly. The study aimed at modeling of ozone as a disinfectant of indicators bacteria in the drinking water. This work involved a series of batch experiments with raw water, taken from the intake of El-Nozha Water Purification Plant, Alexandria governorate. The ozone doses applied in this study were 1.2, 2.2, 3.4, and 4.3 mg/l. The disinfected effluent was collected at 5, 10, 20 and 30 min. The indicator microorganisms HPC bacteria, total coliforms, faecal coliforms and Streptococcus faecalis were examined before and after the ozonation. The optimum ozone dosage applied in raw water to achieve 90% reduction of the indicator microorganisms was 2.5 mg/l. The optimum contact time to achieve 90% reduction of the indicator microorganisms in raw water was 8 min. By applying of ozone as post disinfection on filtered water the reduction percent of the indicator microorganisms were 100%. This study estimated that the ozones cost was 1.76 piasters/m[3]. Ozone as a primary disinfection must be applied on raw water to reduce the formation of THMs due to pre-chlorination of raw water at present, in addition to effective killing power of ozone onto microorganisms that will improve water quality

Dez anos de heterocontrole da fluoretação de águas em Chapecó, Estado de Santa Catarina, Brasil / Ten years of external control over water fluoridation in Chapecó, Santa Catarina State, Brazil

O objetivo deste estudo foi analisar a concentração de flúor na água de abastecimento público em Chapecó, Santa Catarina, Brasil, no período de 1995 a 2005 e, adicionalmente, avaliar a efetividade de uma intervenção ocorrida em 2003 na qualidade da fluoretação. Foram analisadas 989 amostras de água. Para adequação da concentração de flúor as amostras foram classificadas obedecendo a três critérios utilizados no Brasil. Uma intervenção político-jurídica foi realizada pela municipalidade no ano de 2003. A fim de avaliar a tendência da fluoretação ao longo de todo período e antes e depois da intervenção, utilizou-se o procedimento de Prais-Winsten. Nos dez anos analisados, o sistema de fluoretação de águas apresentou 46 por cento, 32 por cento e 43 por cento de amostras adequadas, dependendo do critério adotado. Previamente à intervenção municipal, a proporção de amostras adequadas foi de 40 por cento, 26 por cento e 36 por cento, aumentando para 63 por cento, 49 por cento e 61 por cento após intervenção, segundo os diferentes critérios de análise. Verificou-se uma melhora na adequação da concentração de flúor após a intervenção municipal. Recomenda-se a continuidade da vigilância da fluoretação de águas, considerando-a processual e de caráter permanente.

This study aimed to analyze fluoride concentration in the public water supply in Chapecó, Santa Catarina State, Brazil, from 1995 to 2005 and to assess the effectiveness of a fluoridation quality intervention in 2003. A total of 989 water samples were analyzed. Fluoride concentrations were classified according to three different criteria used in Brazil. The city conducted a political and legal intervention in 2003. The Prais-Winsten procedure was used to evaluate the fluoride concentrations over time. In the ten years, the water fluoridation system showed 46 percent, 32 percent, and 43 percent of adequate samples, depending on the criterion. Prior to the municipal intervention, the proportion of adequate samples was 40 percent, 26 percent, and 36 percent, increasing to 63 percent, 49 percent, and 61 percent after the intervention, according to the three criteria. Fluoride concentration improved after the municipal intervention. On-going surveillance is recommended, including water fluoridation, dental caries, and dental fluorosis.

Cloración y contaminación bacteriana. Aguas turbulentas en los hospitales / Chlorination and bacterial contamination. Hospitals with troubled waters

Objective. To know the quality of the water from hospitals and the risks that poor chlorination implies. Methods. We analyzed 90 water specimens from 15 hospitals (9 from the private and 6 from the public sector). Specimens were obtained from three areas (hospitalization ward, operating room, and kitchen) in two visits. Results. By microbiologic analysis, we found 30 (33.3 %) contaminated specimens. By chemical analysis, we found only 49 (54.5 %) specimens with adequate chlorination (> 1 mg/L). Of the 30 contaminated specimens, only 7 (23.3%) had adequate chlorination. On the other hand, of the 60 specimens without contamination, 42 (79%) had adequate chlorination (x2 - 17.561, p < 0.001). The significant difference was sustained when the criterion for appropriate chlorination was established at > 0.5 mg/L. Conclusions. Hospitals require guidelines for water chlorination and testing to maintain it at > 0.5 mg/L in every point of use.

Objetivo. Conocer la calidad del agua en hospitales y los riesgos de contaminación bacteriana por cloración insuficiente. Material y métodos. Analizamos 90 especímenes de agua de 15 hospitales (nueve del sector privado y seis del público). Los especímenes se obtuvieron de tres áreas (hospitalización, quirófano y cocina) en dos visitas diferentes. Resultados. Por análisis microbiológico, encontramos 30 de los 90 especímenes contaminados (33.3%). Por análisis químico, encontramos que sólo 49 (54.4%) especímenes tuvieron cloración suficiente (> 1 mg/L). De los 30 especímenes contaminados sólo siete (23.3%) tenían cloración suficiente. Por otro lado, de los 60 especímenes sin contaminación, 42 (79%) tenían cloración suficiente (x2 = 17.561, p < 0.001). La significancia se sostuvo al considerar como criterio de cloración suficiente un nivel > 0.5 mg/L. Conclusiones. Todo hospital requiere un manual de cloración del agua y verificar que mantenga niveles mínimos de 0.5 mg/L en todas las áreas.

Monitoramento sanitário de um sistema integrado de tratamento de águas residuárias da suinocultura / Sanitary monitoring of an integrated system for the treatment of wastewaters from pig farming

OBJETIVO: Avaliar o potencial de contaminaçäo de águas residuárias da suinocultura. MÉTODOS: As águas residuárias da suinocultura foram estocadas em um tanque. Depois de 0, 30, 60, 90 e 120 dias de retençäo hidráulica, foram incorporadas em lisímetros preenchidos com solos argilosos, arenosos e médios. Esses lisímetros foram entäo submetidos à simulaçäo de duas condiçöes climáticas: estaçäo de chuvas e estiagem. O número de unidades formadoras de colônias de coliformes totais, coliformes fecais e estreptococos fecais foi medido nos efluentes do tanque de estocagem (para os diversos períodos de retençäo hidráulica), nos percolados dos lisímetros e nos três tipos de solo. As análises microbiológicas foram realizadas através da técnica de membrana filtrante. As análises de pH foram realizadas potenciometricamente. RESULTADOS: Para os três microrganismos, as reduçöes bacterianas máximas no tanque de estocagem foram obtidas a partir de 90 dias de retençäo. A quantificaçäo bacteriana nos percolados dos três solos foi caracterizada por reduçöes elevadas. Em relaçäo aos três tipos de solo, os maiores valores de reduçäo bacteriana foram verificados nos solos médios, devido à sua acidez (pH < 7,0). Para os coliformes fecais a retençäo hidráulica näo foi suficiente para permitir a adequaçäo sanitária das águas residuárias e sua utilizaçäo na irrigaçäo (valores acima de 1 000 UFC.100 mL-1). Nesse caso, a incorporaçäo desses resíduos nos solos foi caracterizada como uma segunda etapa de tratamento. CONCLUSÖES: A retençäo da água residuária, seguida da aplicaçäo no solo, mostrou-se eficiente na minimizaçäo do efeito contaminante dos resíduos da suinocultura. Recomenda-se uma diminuiçäo no tempo de estocagem das águas residuárias da suinocultura, de 120 para 90 dias.

Effect of chlorination of drinking-water on water quality and childhood diarrhoea in a village in Pakistan.

To evaluate the importance of public-domain transmission of pathogens in drinking-water, an intervention study was carried out by chlorinating the public water-supply system in a village in Pakistan. The water quality improved and reached a geometric mean of 3 Escherichia coli per 100 mL at the last standpipe of the water-supply system. Drinking-water source used and the occurrence of diarrhoea were monitored on a weekly basis over a six-month period among 144 children aged less than five years in the village. In this group, the children using chlorinated water from the water-supply scheme had a higher risk of diarrhoea than children using groundwater sources, controlled for confounding by season and availability of a toilet and a water-storage facility. The incidence of diarrhoea in the village (7.3 episodes per 10(3) person-days) was not statistically different from that in a neighbouring village where most children used water from a non-chlorinated water-supply system with very poor water quality. In this study area, under non-epidemic conditions, the reduction of faecal bacteria in the public drinking-water supply by chlorination does not seem to be a priority intervention to reduce childhood diarrhoea. However, the study was of limited size and cannot provide conclusive evidence.

Parasitic and bacterial contamination in collards using effluent from treated domestic wastewater in Chiang Mai, Thailand.

Thailand often has inadequate water supply for agriculture during the dry season. The reuse of treated wastewater treatment plants could solve this problem. Treatment of domestic wastewater of Chiang Mai municipality by the aerated lagoon system (AL) releases more than 25,000 m3 of treated water everyday. The reuse of wastewater in agriculture is an efficient use of water, especially in tropical countries or in drought zones. The objective of this study is to demonstrate the possibility of using treated wastewater in growing edible vegetables, ie collards (kale), without pathogenic parasite and bacterial contamination. Collards (Brassica oleracea var acephala) were grown using either the treated wastewater from the aerated lagoon system (AL) or ground water (GW). Three cropping times were scheduled in February, May and July, 2000. Samples of water from AL system and GW were taken two times per month (the consecutive weeks) from February to July and examined for bacteria and parasites. Irrigation water (IW) that was normally used in agriculture was also collected, at the same time of the AL and GW collection, for bacteria and parasite investigation. A soil sample was taken before and after each crop for parasite examination. Collards were also collected at the end of the crop for parasite investigation. The results showed that GW seems to be a clean water since no pathogenic bacteria were found although small amount of Escherichia coli was noted in May. For AL and IW, similar number and types of bacteria were found. They were Aeromonas sobria, A. hydrophila, E. coli, Citrobacter freundii, Pseudomonas aeruginosa, non-pathogenic type of Vibrio cholerae. The small number of Salmonella enteritidis gr E was found in AL in April. After investigating 12 samples in 6 months of each kind of water, ie GW, Al, and IW, no parasite was found. Only unidentified free living nematodes were found in IW but those parasites are non pathogenic. A small number of unidentified free living nematodes (UFLN), a natural parasite, were found in soil after cropping. After each cropping time, similar number of hookworm was found in the plots which used either GW or AL. Collards grown by using either GW or AL showed no harmful parasite contamination. We conclude that the effluent from wastewater treatment, using aerated lagoon system, of Chiang Mai municipality could be safely used for growing collards.

Examination for intestinal parasites and enteric bacteria in the wastewater and treated wastewater from the city of Chiang Mai, Thailand.

An attempt to use treated wastewater for agriculture in the Chiang Mai area was made, but the re-use process had to be performed under a condition that limited the risks liable to leave pathogens present in the water. The objective of our study was to examine the intestinal parasites and enteric bacteria in the wastewater and treated wastewater from the Chiang Mai University campus as well as the treated wastewater from the Chiang Mai municipality. The raw wastewater (RW), primary treatment effluent water (PE), treated wastewater using the activated sludge system (AS) from the Chiang Mai University campus and treated wastewater using the aerated lagoon (AL) system from the Chiang Mai municipality were examined for intestinal parasites and enteric bacteria by using the centrifugal sedimentation and conventional methods respectively. The ground water (GW) and the irrigation water (IW) were used for comparison. All kinds of water were collected and examined twice a month for 6 months (February to July 2000). None of human intestinal parasites were found from any wastewater, whereas the RW and PE water contained hookworm larva, Ascaris egg and Taenia egg on some occasions. A small amounts of pathogenic bacteria that can cause severe diarrhea were detected. Salmonella enteritidis gr E was isolated from the AL water in April, while Vibrio cholerae type O139 was detected from the PE water in June. Some pathogenic bacteria that might cause gastroenteritis, such as Aerobacter spp, Citrobacter spp, Pseudomonas spp and Escherichia coli were also found in all kinds of water. Between the two types of treated wastewater, the bacteria found in AS water was less than that in AL water in terms of both amount and type of bacteria. The treated wastewater from the city of Chiang Mai, compared to natural water such as irrigation water, appears to be safe to use for agriculture.

Evaluation of the updated Omani regulations for waste water re-use and discharge

Guidelines for wastewater re-use quality are based on scientific and epidemiological findings. As such, it provides guidance towards making risk management decision that are related to the protection of public health and environmental preservation [Hespanol, 1992]. Over the last thirty years, or so, considerable work has been, done to assess risks emerging from wastewater re-use and develop methods that would aid removal or 'minimization of the risks. For example reports by WHO [WHO, 1973 and 1989] have contributed greatly in reviewing and summarizing research and experience all over the world with the purpose of establishing sensible guidelines for wastewater re-use. Wastewater regulations are established by countries while adopting their national priorities and strategies. Attention is usually paid to technical, economical, social, cultural, hygienic practices, and political characteristics and constraints. The regulations for wastewater re-use and discharge in the Sultanate of Oman were first introduced in 1986. This paper gives a critical review of the updated regulations and makes procedural recommendations

Flúor: benefícios e controvérsias dos programas de fluoretaçäo / Fluoride: the benefits and controversies of the fluoridation program

Os autores revisam benefícios e controvérsias sobre o Flúor Tópico e Sistêmico nos programas de abastecimento público de água e bochecho semanal com soluçäo de fluoreto de sódio a 0,2 por cento em escolares de 6 a 12 anos da rede pública de ensino. Apresentam levantamentos epidemiológicos, analisando o percentual da reduçäo de cárie em diversos municípios do Estado do Paraná bem como analisam a implantaçäo e evoluçäo dos programas de prevençäo da cárie dentária no Estado