scholarly journals Sign-constrained linear regression for prediction of microbe concentration based on water quality datasets

2019 ◽  
Vol 17 (3) ◽  
pp. 404-415 ◽  
Author(s):  
Tsuyoshi Kato ◽  
Ayano Kobayashi ◽  
Wakana Oishi ◽  
Syun-suke Kadoya ◽  
Satoshi Okabe ◽  
...  
Keyword(s):  
Domain Knowledge ◽  
Environmental Pollutants ◽  
Model Fitting ◽  
Environmental Parameters ◽  
Prediction Performance ◽  
Global Network ◽  
Contamination Level ◽  
Explanatory Variables ◽  
Tobit Analysis ◽  
Generous Support

Abstract This study presents a novel methodology for estimating the concentration of environmental pollutants in water, such as pathogens, based on environmental parameters. The scientific uniqueness of this study is the prevention of excess conformity in the model fitting by applying domain knowledge, which is the accumulated scientific knowledge regarding the correlations between response and explanatory variables. Sign constraints were used to express domain knowledge, and the effect of the sign constraints on the prediction performance using censored datasets was investigated. As a result, we confirmed that sign constraints made prediction more accurate compared to conventional sign-free approaches. The most remarkable technical contribution of this study is the finding that the sign constraints can be incorporated in the estimation of the correlation coefficient in Tobit analysis. We developed effective and numerically stable algorithms for fitting a model to datasets under the sign constraints. This novel algorithm is applicable to a wide variety of the prediction of pollutant contamination level, including the pathogen concentrations in water. This article has been made Open Access thanks to the generous support of a global network of libraries as part of the Knowledge Unlatched Select initiative.

scholarly journals Turbidity reduction in drinking water by coagulation-flocculation with chitosan polymers

2019 ◽  
Vol 17 (2) ◽  
pp. 204-218 ◽  
Author(s):  
Ampai Soros ◽  
James E. Amburgey ◽  
Christine E. Stauber ◽  
Mark D. Sobsey ◽  
Lisa M. Casanova
Keyword(s):  
Drinking Water ◽  
Functional Groups ◽  
Dose Range ◽  
Optimal Dose ◽  
Global Network ◽  
Point Of Zero Charge ◽  
Household Water ◽  
Generous Support ◽  
Higher Doses ◽  
Model Household

Abstract Turbidity reduction by coagulation-flocculation in drinking water reduces microbes and organic matter, increasing effectiveness of downstream treatment. Chitosan is a promising household water coagulant, but needs parameters for use. This study tested the effects of chitosan dose, molecular weight (MW), degree of deacetylation (DD), and functional groups on bentonite and kaolinite turbidity reduction in model household drinking water. Higher MW or DD produced greater reductions. Highest reductions were at doses 1 and 3 mg/L by MW >50,000 or >70% DD (residual turbidity <5 NTU). Higher doses did not necessarily continually increase reduction. For functional groups, 3 mg/L produced the highest reductions by lactate, acetate, and HCl, and lower reductions of kaolinite than bentonite. Doses where the point of zero charge was observed clustered around 3 mg/L. Chitosan reduced clay turbidity in water; effectiveness was influenced by dose, clay type, MW, DD, and functional groups. Reduction did not necessarily increase with MW. Bentonite had a broader effective dose range and higher reduction at the optimal dose than kaolinite. Chitosans with and without functional groups performed similarly. The best of the studied doses was 3 mg/L. Chitosans are promising for turbidity reduction in low-resource settings if combined with sedimentation and/or filtration. This article has been made Open Access thanks to the generous support of a global network of libraries as part of the Knowledge Unlatched Select initiative.

scholarly journals The pursuit of good microbiological conditions in domestic softeners: a new improvement

2020 ◽  
Vol 18 (2) ◽  
pp. 200-206
Author(s):  
L. Bolelli ◽  
Elida Nora Ferri ◽  
Stefano Sangiorgi ◽  
Giuseppe Novelli ◽  
Stefano Girotti
Keyword(s):  
Pathogenic Bacteria ◽  
Microbiological Quality ◽  
Global Network ◽  
Plate Count ◽  
Bacteria Growth ◽  
Warm Environment ◽  
Quality Of Water ◽  
Softened Water ◽  
Generous Support

Abstract Effective resin disinfection is mandatory to ensure the microbiological quality of water treated by domestic softeners. The wet and sometimes warm environment inside the softener is ideal for bacteria growth. Our research was focused on the evaluation of the microbial quality of water from softeners sanitized by chlorine solutions or by electrolytic systems. We employed the heterotrophic plate count and specific tests to monitor the presence of opportunistic and pathogenic bacteria (Pseudomonas aeruginosa, Escherichia coli, enterococci, and coliforms). Completely new devices were equipped with a commercially available electrolytic system or with a newly patented one or sanitized by automatic or manual addition of chlorine solutions. In all cases, the contamination was reduced, not completely avoided. In particular, the patented electrolytic system significantly reduced bacterial proliferation in strongly contaminated devices. Our data confirm the difficulties encountered to solve the problem of microbiological quality of softened water and offer encouraging information on new possible solutions. This article has been made Open Access thanks to the generous support of a global network of libraries as part of the Knowledge Unlatched Select initiative.

scholarly journals Does the source of water for piped supplies affect child health? Evidence from rural Vanuatu

2019 ◽  
Vol 9 (3) ◽  
pp. 591-595
Author(s):  
Tim Foster ◽  
Emily Rand ◽  
Erie Sami ◽  
Brieana Dance ◽  
Jeremy Kohlitz ◽  
...  
Keyword(s):  
Water Supply ◽  
Water Source ◽  
Service Level ◽  
Water Systems ◽  
Global Network ◽  
Water Supply Systems ◽  
Piped Water ◽  
Generous Support ◽  
Year 2000 ◽  
Supply Systems

Abstract Piped water systems are considered to provide the highest service level for drinking water supplies; however, global monitoring of safe water access pays little attention to the type of water source that piped systems draw upon, even if the water is not treated prior to distribution. This study sought to understand whether the source of water for untreated piped supplies influences the prevalence of diarrhoea among children in rural Vanuatu. The analysis was based on a dataset integrating a Demographic and Health Survey and a nationwide water supply inventory. After adjusting for a range of potential confounders, the results revealed a significant association between diarrhoea and the type of water source supplying a piped system. Compared with borehole-supplied piped systems, spring-fed piped systems were significantly associated with increased odds of diarrhoea (adjusted odds ratio [AOR] 5.8, 95% confidence interval [CI] 1.1–31, p = 0.040). No significant association between diarrhoea and piped systems drawing on surface water was observed. Increased odds of diarrhoea were significantly associated with water supply systems constructed prior to the year 2000 (AOR 4.9, 95% CI 1.9–13, p = 0.001). The results highlight the need for improvements in spring protection as well as ongoing maintenance and periodic renewal of water supply infrastructure. This article has been made Open Access thanks to the generous support of a global network of libraries as part of the Knowledge Unlatched Select initiative.

scholarly journals Does self-reported water collection time differ from observed water collection time? Evidence from the Upper West Region of Ghana

2020 ◽  
Vol 10 (2) ◽  
pp. 357-365
Author(s):  
Alfred Dongzagla ◽  
Abraham Marshall Nunbogu ◽  
Nicholas Fielmua
Keyword(s):  
Developing Countries ◽  
Drinking Water ◽  
Open Access ◽  
Global Network ◽  
Round Trip ◽  
Key Indicator ◽  
West Region ◽  
Water Collection ◽  
Generous Support ◽  
Collection Time

Abstract Water collection time is a key indicator in tracking access to drinking water. Over the years, water surveillance agencies have relied on water collectors for information on water collection time to measure progress of water supply. However, emerging evidence shows that water collection times reported by water collectors in developing countries are often imprecise. To contribute to knowledge about the validity or otherwise of self-reported water collection times, this study explored the association between self-reported water collection times and observed water collection times in the Upper West Region of Ghana. Data on water collection times were gathered from 412 water collectors in Daffiama-Issa-Bussie District and Lawra Municipality, first through interviews, and second by observation. From the results, self-reported water collection times were significantly (P < 0.01) lower than observed water collection times. The average round-trip water collection time reported by water collectors (32 minutes) was 8 minutes lower than observed water collection times (40 minutes). This implies that existing statistics on basic water coverage that are largely based on self-reported water collection times are overestimated. Going forward, we call on water surveillance agencies to collect data on water collection times through observation. This article has been made Open Access thanks to the generous support of a global network of libraries as part of the Knowledge Unlatched Select initiative.

scholarly journals Context and intentions: practical associations for fecal sludge management in rural low-income Cambodia

2020 ◽  
Vol 10 (2) ◽  
pp. 191-201
Author(s):  
James Harper ◽  
Angela Bielefeldt ◽  
Amy Javernick-Will ◽  
Toeur Veasna ◽  
Chris Nicoletti
Keyword(s):  
Low Income ◽  
Behavioral Science ◽  
Contextual Factors ◽  
Global Network ◽  
Poverty Level ◽  
Sludge Management ◽  
Fecal Sludge ◽  
Decision Making Processes ◽  
Generous Support ◽  
Future Work

Abstract Finite storage capacities of household pit latrines make safely managing fecal sludge a recurring challenge for 2.7 billion people globally. Frequently without guidance from standards or regulation, rural latrine owners choose how to manage their own fecal sludge. However, their intentions – what behavioral science says are the best predictors of future behaviors – when pits fill are poorly understood, inhibiting the development of safe fecal sludge management (FSM) solutions and deteriorating public and environmental health. Using survey data commonly measured by development practitioners, we analyze response frequencies and their associations with contextual factors, such as location, month that the survey was administered, and poverty level. We also use binomial logistic regression to determine if contextual factors can be used to predict the intentions of rural Cambodian latrine owners when pits fill. We found that four in ten rural latrine owners intend to manage their fecal sludge unsafely (41%), and one in six did not have a plan (16%). Desirable FSM intentions increased markedly after rice harvest and varied markedly across provinces. Many predictors of desirable FSM intentions, such as location and satisfaction with the household's latrine, were also identified. Associations between FSM intentions and contextual factors can be used to help predict FSM behaviors and improve FSM service delivery, behavior change campaigns, and product design. However, future work should seek to characterize the complete decision-making processes of rural latrine owners when pits fill. This article has been made Open Access thanks to the generous support of a global network of libraries as part of the Knowledge Unlatched Select initiative.

scholarly journals Solar energy-based water treatment system applicable to the remote areas: Case of Indonesia

2020 ◽  
Vol 10 (2) ◽  
pp. 347-356 ◽  
Author(s):  
Arsanto Ishadi Wibowo ◽  
Keh-Chin Chang
Keyword(s):  
Water Treatment ◽  
Treatment System ◽  
Global Network ◽  
Clean Water ◽  
Water Services ◽  
Water Treatment System ◽  
Remote Areas ◽  
Photovoltaic Applications ◽  
Generous Support ◽  
Geographical Accessibility

Abstract Remote areas usually lack basic clean water services. Considering low population, poor geographical accessibility and lack of electricity, a small-scaled water treatment system capable of producing clean fresh water associated with solar thermal/photovoltaic applications, which is characterized with low capital cost, easy operation and less need of maintenance, is employed in the techno-economic study. Indonesia is one of the countries which owns considerable water resources in their territories but has moderate coverage in basic water services, and is chosen as a case for demonstration. The price of clean water from this system is profitable as compared to that of bottled water, which is an accessible safe water in these areas, but still much higher than that of municipal water. This article has been made Open Access thanks to the generous support of a global network of libraries as part of the Knowledge Unlatched Select initiative.

On the determinants of the 2008 financial crisis: a Bayesian approach to the selection of groups and variables

2017 ◽  
Vol 21 (5) ◽  
Author(s):  
Ray-Bing Chen ◽  
Yi-Chi Chen ◽  
Chi-Hsiang Chu ◽  
Kuo-Jung Lee
Keyword(s):  
Variable Selection ◽  
Robustness Analysis ◽  
Prediction Performance ◽  
Financial Policies ◽  
Bayesian Hierarchical ◽  
Explanatory Variables ◽  
Alternative Measures ◽  
The 2008 Financial Crisis ◽  
Group Variable ◽  
Selection Of

AbstractWe consider the determinants of the 2008 crisis and address two main forms of model uncertainty: the uncertainty in selecting theoretical groups and the uncertainty in selecting explanatory variables. We introduce Bayesian hierarchical formulation that allows for the joint treatment of group and variable selection using the Group-wise Gibbs sampler. Our group variable selection shows that pre-crisis financial policies and trade linkages play a particularly important role in explaining the severity of the crisis, alongside institutions, and within the selected groups we identify a broader set of variables correlated with the crisis, which in turn leads to an improvement in prediction performance. In the robustness analysis we also find that our results are not qualitatively changed on alternative measures of crisis intensity, different groupings of variables, or prior assumptions. We further argue that the established results in the literature may well be attributed to different prior choices used in the analysis.

scholarly journals Mineralization of organic matter and productivity of tifton 85 grass (Cynodon spp.) in soil incorporated with stabilized sludge from a vertical flow constructed wetland

2019 ◽  
Vol 9 (2) ◽  
pp. 309-318
Author(s):  
Diogo André P. Silva ◽  
Antonio T. Matos ◽  
Mateus P. Matos
Keyword(s):  
Organic Matter ◽  
Kinetic Equations ◽  
Global Network ◽  
Septic Tank ◽  
Vertical Flow ◽  
Two Phase ◽  
Mineralization Of Organic Matter ◽  
Total Ammonia ◽  
Generous Support ◽  
Different Depths

Abstract Little is known regarding how to discard the sludge accumulated in vertical flow constructed wetlands (VF-CWs) and what the potential impacts could be. The objective of this paper was to evaluate the mineralization of organic matter (OM) in soil and productivity of tifton 85 grass (Cynodon spp.) after incorporating sludge collected at different depths from a VF-CW (used to treat septic tank sludge), to a tropical soil (Oxisol). Sludge samples were collected at depths of 0–5, 5–10 and 10–15 cm from a VF-CW that was used over a period of three years. The sludge collected at each depth was incorporated into the soil at a dose equivalent to 30 g m–2 year–1 of total nitrogen, and the experimental area was planted. During a period of 215 days, total and easily oxidizable carbon, total, ammonia, nitric and organic nitrogen in the residue-soil mixtures were analyzed. Based on the data obtained, the mineralization fractions (MF) were estimated for the specific monitoring period and annually considering first order and two-phase kinetic equations. The annual MF of the OM were higher than 96% and the sludge-amended soil resulted in an increase in grass yield. This article has been made Open Access thanks to the generous support of a global network of libraries as part of the Knowledge Unlatched Select initiative.

scholarly journals Detection of human fecal pollution in environmental waters using human mitochondrial DNA and correlation with general and human-associated fecal genetic markers

2019 ◽  
Vol 18 (1) ◽  
pp. 8-18 ◽  
Author(s):  
A. B. M. Tanvir Pasha ◽  
Jessica Hinojosa ◽  
Duc Phan ◽  
Adrianne Lopez ◽  
Vikram Kapoor
Keyword(s):  
Mitochondrial Dna ◽  
Genetic Markers ◽  
Fecal Pollution ◽  
Global Network ◽  
Limited Data ◽  
Environmental Application ◽  
Human Mitochondrial Dna ◽  
Sewage Contamination ◽  
Generous Support ◽  
Rain Events

Abstract Human mitochondrial DNA (mtDNA) genetic markers are abundant in sewage and highly human-specific, suggesting a great potential for the environmental application as human fecal pollution indicators. Limited data are available on the occurrence and co-occurrence of human mtDNA with fecal bacterial markers in surface waters, and how the abundance of these markers is influenced by rain events. A 1-year sampling study was conducted in a suburban watershed impacted by human sewage contamination to evaluate the performance of a human mtDNA-based marker along with the bacterial genetic markers for human-associated Bacteroidales (BacHum and HF183) and Escherichia coli. Additionally, the human mtDNA-based assay was correlated with rain events and other markers. The mtDNA marker was detected in 92% of samples (n = 140) with a mean concentration of 2.96 log10 copies/100 ml throughout the study period. Human mtDNA was detected with greater abundance than human-associated Bacteroidales that could be attributed to differences in the decay of these markers in the environment. The abundance of all markers was positively correlated with rain events, and human mtDNA abundance was significantly correlated with various bacterial markers. In general, these results should support future risk assessment for impacted watersheds, particularly those affected by human fecal pollution, by evaluating the performance of these markers during rain events. This article has been made Open Access thanks to the generous support of a global network of libraries as part of the Knowledge Unlatched Select initiative.

scholarly journals Effect of Spathiphyllum blandum on the removal of ibuprofen and conventional pollutants from polluted river water, in fully saturated constructed wetlands at mesocosm level

2020 ◽  
Vol 18 (2) ◽  
pp. 224-228
Author(s):  
Luis Sandoval ◽  
José Luis Marín-Muñíz ◽  
Jacel Adame-García ◽  
Gregorio Fernández-Lambert ◽  
Florentina Zurita
Keyword(s):  
River Water ◽  
Constructed Wetlands ◽  
Large Scale ◽  
Wastewater Treatment Plants ◽  
Oxygen Demand ◽  
Climatic Conditions ◽  
Global Network ◽  
Large Scale Systems ◽  
Polluted River ◽  
Generous Support

Abstract In this study, the effect of Spathiphyllum blandum on the removal of ibuprofen (IB) and conventional pollutants such as chemical oxygen demand (COD), total nitrogen (TN), ammonium (NH4+-N), total phosphorus (TP), and total suspended solids (TSS) is reported; this, through its use as an emergent vegetation in fully saturated (FS) constructed wetlands (CWs) at mesocosm level treating polluted river water. With the exception of TP and COD, it was found that for TN (12%), NH4+-N (11%), TSS (19%), and IB (23%), the removals in systems with vegetation were superior to systems without vegetation (p < 0.05). These findings demonstrate the importance of the species S. blandum, in particular, for the removal of ibuprofen, which is an anti-inflammatory drug commonly found in effluents of wastewater treatment plants. Thus, the results obtained provide information that can be used for the design of future efficient large-scale systems using a new ornamental species, mainly under tropical climatic conditions. This article has been made Open Access thanks to the generous support of a global network of libraries as part of the Knowledge Unlatched Select initiative.

Sign in / Sign up

Export Citation Format

Share Document