Impact of treatment plant management on human health and ecological risks from wastewater irrigation in developing countries - case studies from Cochabamba, Bolivia.

Wastewater irrigation is a common practice in developing countries due to water scarcity and increasing demand for food production. However, there are health risks and ecological risks associated with this practice. Small-scale wastewater treatment plants (WWTPs) intend to decrease these risks but still face management challenges. This study assessed how the management status of five small-scale WWTPs in Cochabamba, Bolivia affects health risks associated with consumption of lettuce and ecological risks due to the accumulation of nutrients in the soil for lettuce and maize crops. Risk simulations for three wastewater irrigation scenarios were: raw wastewater, actual effluent and expected effluent. Results showed that weak O&M practices can increase risk outcomes to higher levels than irrigating with raw wastewater. Improving O&M to achieve optimal functioning of small-scale WWTPs can reduce human health risks and ecological risks up to 2 log10 DALY person-1 year-1 and to 2 log10 kg nitrogen ha-1 accumulated in soil, respectively.

GIS-based spatial analysis: basic sanitation services in Parana State, Southern Brazil.

The objective of this study is to provide a view of the geographic distribution of basic sanitation services offered in Parana, Brazil. Temporal distributions, spatial patterns, and clusters were determined using 2000, 2010, and 2016 data. Tabular data of the percentages of households receiving water supply, waste collection, and sanitary sewage treatments were used as the basic inputs of the study. Time series maps were created using geographic information systems (GIS) for the visualization of the temporal changes in basic sanitation rates. The spatial variation in sanitation services was measured using Moran's Global Index (Moran's I), while the Local Indicators of Spatial Association (LISA) and Getis-Ord Gi*(d) were used to identify the presence of possible clusters and hot spots in the percentage of households with sanitation services. The study showed strong evidence that the service rates for sanitary sewage were significantly lower than those for water supply and waste collection. Waste collection proved to have the highest service rate in the study area. Waste collection was also the service that increased the most in the study period, followed by the water supply service. Identification of the most vulnerable municipalities was performed using LISA and the local Getis-Ord Gi*(d) statistic. Most of the low value clusters and cold spots were detected in the southern and west-central regions, while the high value hot spots and clusters were detected in the northern and northeastern regions of the state of Parana.

Relationship of sanitation, water boiling, and mosquito nets to health biomarkers in a rural subsistence population.

OBJECTIVES: Throughout human evolutionary history, parasites and pathogens were a major cause of mortality-modern urban life with public health infrastructure has changed disease exposure. We examine associations between boiling water, using latrines, mosquito net usage, and biomarkers among the Tsimane, a nonindustrial subsistence population with little public health infrastructure. METHODS: We conducted cross sectional surveys on water, latrines, and bed nets among 507 heads of households (aged 18-92 years, median age 41 years). Regression models estimated associations between behaviors and health biomarkers (ie, white blood cell count [WBC], hemoglobin, eosinophil count, and erythrocyte sedimentation rate) adjusting for age, sex, body mass index, wealth, schooling, and distance to the nearby market town. RESULTS: Latrine use is associated with 6.5% lower WBC count (ß = -679.6, P = .031, SE = 314.1), 17.4% lower eosinophil counts (ß = -244.7, P = .023, SE = 107.2), and reduced odds of eosinophilia (adjusted OR = 0.40, P < .019, 95% CI = 0.18-0.86). Boiling water and mosquito net use are not significantly associated with any biomarkers measured. CONCLUSIONS: In a subsistence population currently undergoing epidemiological transition, we find that latrine use was associated with several objective measures of health. This suggests that relatively low cost and low maintenance public health interventions may wish to focus on latrine use, as there is unmet need and potential health benefits for those who use latrines. Additionally, while the cost is higher, public health organizations aimed at improving sanitation may be able to use minimally invasive field-collected biomarkers as a diagnostic to objectively test the efficacy of interventions with greater specificity than anthropometric measurements.

Exploring the influence of meteorological conditions on the performance of a waste stabilization pond at high altitude with structural equation modeling.

Algal photosynthesis plays a key role in the removal mechanisms of waste stabilization ponds (WSPs), which is indicated in the variations of three parameters, dissolved oxygen, pH, and chlorophyll a. These variations can be considerably affected by extreme climatic conditions at high altitude. To investigate these effects, three sampling campaigns were conducted in a high-altitude WSP in Cuenca (Ecuador). From the collected data, the first application of structure equation modeling (SEM) on a pond system was fitted to analyze the influence of high-altitude characteristics on pond performance, especially on the three indicators. Noticeably, air temperature appeared as the highest influencing factors as low temperature at high altitude can greatly decrease the growth rate of microorganisms. Strong wind and large diurnal variations of temperature, 7-20 °C, enhanced flow efficiency by improving mixing inside the ponds. Intense solar radiation brought both advantages and disadvantages as it boosted oxygen level during the day but promoted algal overgrowth causing oxygen depletion during the night. From these findings, the authors proposed insightful recommendations for future design, monitoring, and operation of high-altitude WSPs. Moreover, we also recommended SEM to pond engineers as an effective tool for better simulation of such complex systems like WSPs.

Turbidity control on dissolved air flotation process using fuzzy logic.

This study intends to explore fuzzy logic control on clean water turbidity process with dissolved air flotation (DAF). Three different strategies were tested to regulate clean water turbidity by manipulating the saturator vessel flow output aiming for low actuators control effort. Saturator pressure was the manipulated variable (MV) in the first control loop named SISO I. The second control loop, SISO II, used recycle stream valve opening as MV. The third control loop (MISO) was developed applying fuzzy logic instead PID control. Several performance criteria were used to analyze the process control performance such as integral absolute error (IAE), recycle stream valve and saturator vessel pressure regulating valve control efforts, ECV01 and ECV02 respectively. Results from SISO I and SISO II strategies showed that recycle stream is a better MV than saturator vessel pressure for clean water turbidity control in the DAF process. Only SISO II and MISO strategies proved to be capable of regulating the process variable. However, MISO control showed better performance based on IAE value against SISO II, with a reduction of 11.24% on its value, even the recycle stream valve control effort for MISO control being fairly higher than that for SISO II. Nevertheless, fuzzy logic control application gave rise to better turbidity control, and consequently prevented the excessive use of clean water in the recycling stream.

pH del agua potable que consumen estudiantes del segundo año de la Carrera de Medicina, Universidad Mayor de San Andrés Gestión 2017 / pH of drinking water that second year students of medicine of the Universidad Mayor de San Andres consume term 2017

INTRODUCCIÓN: El pH es una propiedad básica del agua potable y cuyos valores extremos pueden originar reacciones secundarias dañinas, entendiéndose por agua potable aquel que puede ser consumido sin restricción para el consumo humano, OBJETIVO: Determinar el valor del pH de agua potable que consumen los estudiantes de segundo año de la carrera de medicina de la Universidad Mayor de San Andrés (UMSA). MATERIAL Y MÉTODOS: Se analizaron 388 muestras de agua potable del domicilio de estudiantes regulares de segundo año cátedra de bioquímica entre los meses de julio y agosto del 2017, realizándose un estudio de tipo descriptivo con un enfoque transeccional. RESULTADOS: Se obtuvieron los siguientes resultados, 1) la media del pH total fue de 7,24; con x=7,22 en la ciudad de la Paz y x=7,28 en la ciudad de el Alto. 2) en cuanto al sistema de potabilización se obtuvo: x=7,34 en la planta el Alto, x=7,21 en la planta de Tilata, x=7,15 en la planta de Achachicala y de x=7,20 en la planta de Pampahasi. CONCLUSIONES: El pH del agua potable consumida se encontró dentro de parámetros establecidos con un valor medio de 7,24.

INTRODUCTION: The pH is a basic property of potable water and whose extreme values may cause harmful secondary reactions. It is understood that potable water can be consumed without any restriction by human beings. OBJECTIVE: To determine the pH value of potable water consumed by medicine students of second year at UMSA university. MATERIAL AND METHODS: 388 samples of potable water were analyzed which were taken from the homes of the second year students of the biochemistry department between July and August 2017, developing a descriptive study with a cross-sectional approach. RESULTS: The following results were obtained: 1) the average of the pH was 7.24; with x = 7.22 in La Paz city and x = 7.29 in El Alto city. 2) in relation to the drinking water was obtained: x=7.34 in El Alto plant, x=7.21 in Tilata plant, x=7.16 in Achachicala plant and x=7.21 in Pampahasi plant. CONCLUSION: The pH of the drinking water drunk is established within parameters with an average value of 7.24.

"Improved" But Not Necessarily Safe: An Assessment of Fecal Contamination of Household Drinking Water in Rural Peru.

The indicator used to measure progress toward the Millennium Development Goal (MDG) for water is access to an improved water supply. However, improved supplies are frequently fecally contaminated in developing countries. We examined factors associated with Escherichia coli contamination of improved water supplies in rural Pisco province, Peru. A random sample of 207 households with at least one child less than 5 years old was surveyed, and water samples from the source and storage container were tested for E. coli contamination. Although over 90% of households used an improved water source, 47% of source and 43% of stored water samples were contaminated with E. coli. Pouring or using a spigot to obtain water from the storage container instead of dipping a hand or object was associated with decreased risk of contamination of stored water (adjusted prevalence ratio [aPR] = 0.58, 95% confidence interval [CI] = 0.42, 0.80). Container cleanliness (aPR = 0.67, 95% CI = 0.45, 1.00) and correct handwashing technique (aPR = 0.62, 95% CI = 0.42, 0.90) were also associated with decreased contamination risk. These findings highlighted the limitations of improved water supplies as an indicator of safe water access. To ensure water safety in the home, household water treatment and improved hygiene, water handling, and storage practices should be promoted.

Determinants of Caregivers' Use and Adoption of Household Water Chlorination: A Qualitative Study with Peri-Urban Communities in the Peruvian Amazon.

The gap between the efficacy and the effectiveness of household water treatment in reducing diarrhea-related morbidity indicates the need for a better understanding of the determinants of long-term behavior change. To explore the barriers to drinking water chlorination in the Peruvian Amazon, where diarrhea is endemic among under-5 children, we conducted qualitative research with 23 caregivers from peri-urban communities of Iquitos, Peru. Our inquiry drew on the Transtheoretical Model of behavior change and the Integrated Behavioral Model for Water, Sanitation, and Hygiene to identify the most relevant contextual, psychosocial, and technological determinants of initial action and long-term adoption of chlorination. Our findings suggest that the decision to try out this practice resulted from the combined effect of knowledge of chlorination benefits and product availability and affordability. Progress from action to adoption was influenced by caretakers' understanding of dosage, the packaging of chlorine products, knowledge and skills for multipurpose laundry bleach, the taste of treated water, and reinforcement. This analysis suggests that a focus on these determinants and the household domain may help to improve the sustainability of future intervention efforts.

Assessing the consistency and microbiological effectiveness of household water treatment practices by urban and rural populations claiming to treat their water at home: a case study in Peru.

BACKGROUND: Household water treatment (HWT) can improve drinking water quality and prevent disease if used correctly and consistently by vulnerable populations. Over 1.1 billion people report treating their water prior to drinking it. These estimates, however, are based on responses to household surveys that may exaggerate the consistency and microbiological performance of the practice-key factors for reducing pathogen exposure and achieving health benefits. The objective of this study was to examine how HWT practices are actually performed by households identified as HWT users, according to international monitoring standards. METHODS AND FINDINGS: We conducted a 6-month case study in urban (n = 117 households) and rural (n = 115 households) Peru, a country in which 82.8% of households report treating their water at home. We used direct observation, in-depth interviews, surveys, spot-checks, and water sampling to assess water treatment practices among households that claimed to treat their drinking water at home. While consistency of reported practices was high in both urban (94.8%) and rural (85.3%) settings, availability of treated water (based on self-report) at time of collection was low, with 67.1% and 23.0% of urban and rural households having treated water at all three sampling visits. Self-reported consumption of untreated water in the home among adults and children <5 was common and this was corroborated during home observations. Drinking water of self-reported users was significantly better than source water in the urban setting and negligible but significantly better in the rural setting. However, only 46.3% and 31.6% of households had drinking water <1 CFU/100 mL at all follow-up visits. CONCLUSIONS: Our results raise questions about the usefulness of current international monitoring of HWT practices and their usefulness as a proxy indicator for drinking water quality. The lack of consistency and sub-optimal microbiological effectiveness also raises questions about the potential of HWT to prevent waterborne diseases.

Microbiological determinations of some vegetables from the Xochimilco zone in Mexico City, Mexico.

Vegetables intake is widely recommended because of its high content of vitamins, minerals and fiber. However, the irrigation of these vegetables, using wastewaters that have received inadequate treatment often carries unseen microbial pollution that becomes a high risk potential for humans. In the present research, two of the most consumed fresh vegetables cultivated in Mexico City were analyzed, lettuce (Lactuca sativa) and Mexican coriander (Eryngium foetidum). These vegetables are commonly consumed raw. The vegetable choice and the disinfection's method were carried out by the application of two tests to two hundred people in an aleatory form. Similarly, vegetable sampling was carried out by means of a random sampling from the cultivated areas in a chosen "chinampa" (from Náhuatl or Aztec, chinamitl, bulrush or cattail stalks lattice for hydroponics cultivation). Vegetable samples were transferred, in dark plastic bags and in cool boxes at 4 +/- 1.5 degrees C, to the laboratory. Microbiological analysis for Salmonella typhi, mesophilic microorganisms, and fecal coliforms were done according to the "NOM-093SSA1-1994" (Mexico). Results obtained demonstrated that samples treated with the most preferred disinfectant, a colloidal silver based one, had a partial elimination of pathogenic microorganisms found in both vegetables lettuce (Lactuca sativa) and coriander (Eryngium foetidum) samples (mesophyllic microorganisms from 200,000 to 96,500 UFC/g and from 175,000 to 125,000 UFC/g and fecal coliforms from 75 to 0.43 NMP/g and from 150 to 2.10 NMP/g, respectively). Salmonella typhi for all samples gave a positive result. Therefore, it was recommended to the cultivators of the Xochimilco (Náhuatl or Aztec name that means "place where flowers bloom") zone, either stop using contaminated water for irrigation or to use more efficient methods in order to eliminate pathogenic microorganisms, such as diluted chlorine solutions made with commercial cotton clothing bleachers.

Field observations of dilution on the Ipanema Beach outfall.

Field observations of the Ipanema Beach, Rio de Janeiro, ocean sewage outfall are presented. Measurements of dilution and other wastefield characteristics were obtained by adding dye tracer to the effluent and measuring in-situ. Simultaneous measurements of oceanographic conditions were made by Acoustic Doppler Current Profilers, thermistor strings, and profiling instruments. Four experiments were performed, two during unstratified conditions when the plume was surfacing, and two during conditions of strong stratification when the plume was submerged. The minimum dilution varied from 30 to 130. The measurements reflect the worst case conditions as the campaigns were all made for weak currents.