Modelling the impact of weather parameters on the microbial quality of water in distribution systems.

In this study, a framework for integrating weather variables and seasons into the modelling and prediction of the microbial quality in drinking water distribution networks is presented. Statistical analysis and Bayesian network (BN) modelling were used to evaluate relationships among water quality parameters in distribution pipes and their dependencies on weather parameters. Two robust predictive models for Total Bacteria in the network were built based on a deep learning approach (Long Short-Term Memory (LSTM)).

Self-optimizing attainable regions of the anaerobic treatment process: Modeling performance targets under kinetic uncertainty.

Despite the advantage of model-based design, anaerobic digesters are seldom designed using biokinetic models due to lack of reliable kinetic coefficients and/or systematic approaches for incorporating kinetic models into digester design. This study presents a systematic framework, which couples practical identifiability, uncertainty quantification and attainable region (AR) concepts for defining process performance targets, especially when reliable kinetic coefficients are unavailable. Within the framework, we introduce the concept of self-optimizing ARs, which define performance targets that results in near optimal operation in spite of variations in kinetic coefficients.

Attainable regions and fuzzy multi-criteria decisions: Modeling a novel configuration of methane bioreactor using experimental limits of operation.

This study sets out to develop an approach that couples attainable regions and fuzzy multicriteria decision methods for modeling optimal configurations of multistage digesters without using a kinetic model of the process. The approach is based on geometric analysis of methane curves as their shapes contain valuable insight into substrate biodegradability characteristics during anaerobic digestion. With the case study of abattoir waste, the results indicate that the optimal batch operation policy involves four anaerobic sequencing batch reactors operated in series with fresh feed being added at the second and the four stages (fed-batch systems).

Simulation of two-dimensional attainable regions and its application to model digester structures for maximum stability of anaerobic treatment process.

Unlike high-rate anaerobic digesters that employ some mechanism to retain microbial sludge mass, low-rate systems use sufficiently long hydraulic retention times to ensure process stability, which becomes economically unattractive for treating large quantities of waste. This study presents the use of attainable region to develop a new strategy to enhance the stability of low-rate digesters. By considering three digestion cases, diary manure only (batch 1) or diary manure with granular (batch 2) or lagoon (batch) sludge as innoculum, the following findings were obtained.

Dengue-like illness surveillance: a two-year longitudinal survey in suburban and rural communities in the Lao People's Democratic Republic and in Thailand.

Objective: This study aimed to determine the incidences of dengue-like illness (DLI), dengue virus (DENV) infection, and serotypes and to identify socio-demographical and entomological risk factors of DLI in selected suburban and rural communities in the Lao People's Democratic Republic and in Thailand.

Methods: A two-year longitudinal study was conducted in four villages during the inter-epidemic period between 2011 and 2013. Entomological surveys, semi-structured interviews of household heads and observations were conducted.

Climate-driven QMRA model for selected water supply systems in Norway accounting for raw water sources and treatment processes.

Formulating effective management intervention measures for water supply systems requires investigation of potential long-term impacts. This study applies an integrated multiple regression, random forest regression, and quantitative microbial risk assessment (QMRA) modelling approach to assess the effect of climate-driven precipitation on pathogen infection risks in three drinking water treatment plants (WTPs) in Norway. Pathogen removal efficacies of treatment steps were calculated using process models.

Comparative predictive modelling of the occurrence of faecal indicator bacteria in a drinking water source in Norway.

Presently, concentrations of fecal indicator bacteria (FIB) in raw water sources are not known before water undergoes treatment, since analysis takes approximately 24h to produce results. Using data on water quality and environmental variables, models can be used to predict real time concentrations of FIB in raw water. This study evaluates the potentials of zero-inflated regression models (ZI), Random Forest regression model (RF) and adaptive neuro-fuzzy inference system (ANFIS) to predict the concentration of FIB in the raw water source of a water treatment plant in Norway.

Concentration of soil-transmitted helminth eggs in sludge from South Africa and Senegal: A probabilistic estimation of infection risks associated with agricultural application.

The use of sludge in agriculture has been encouraged as a means of increasing soil nutrient content and improving the water holding capacity. On the negative side, major public health concerns with sludge application prevail, mainly due to the high concentration of pathogenic microorganisms. Soil-transmitted helminths (STHs) are of major health concern in this regard, especially in endemic regions, mainly due to the high environmental resistant of the eggs combined with a low infectious dose.

Removal of helminth eggs by centralized and decentralized wastewater treatment plants in South Africa and Lesotho: health implications for direct and indirect exposure to the effluents.

Wastewater may contain contaminants harmful to human health; hence, there is the need for treatment before discharge. Centralized wastewater treatment systems are the favored treatment options globally, but these are not necessarily superior in reduction of pathogens as compared to decentralized wastewater treatment systems (collectively called DEWATS). This study was therefore undertaken to assess the soil-transmitted helminth (STH) and Taenia sp.

Effects of socio-demographic characteristics and household water management on Aedes aegypti production in suburban and rural villages in Laos and Thailand.

Background: Dengue fever is a mosquito-borne disease accounting for 50-100 million annual cases globally. Laos and Thailand are countries in south-east Asia where the disease is endemic in both urban and rural areas. Household water storage containers, which are favourable breeding sites for dengue mosquitoes, are common in these areas, due to intermittent or limited access to water supply.

Contribution of Wastewater Irrigation to Soil Transmitted Helminths Infection among Vegetable Farmers in Kumasi, Ghana.

Wastewater irrigation is associated with several benefits but can also lead to significant health risks. The health risk for contracting infections from Soil Transmitted Helminths (STHs) among farmers has mainly been assessed indirectly through measured quantities in the wastewater or on the crops alone and only on a limited scale through epidemiological assessments. In this study we broadened the concept of infection risks in the exposure assessments by measurements of the concentration of STHs both in wastewater used for irrigation and the soil, as well as the actual load of STHs ova in the stool of farmers and their family members (165 and 127 in the wet and dry seasons respectively) and a control group of non-farmers (100 and 52 in the wet and dry seasons, respectively).

A probabilistic assessment of the contribution of wastewater-irrigated lettuce to Escherichia coli O157:H7 infection risk and disease burden in Kumasi, Ghana.

Wastewater use for vegetable production is widespread across the cities of many developing countries. Studies on the microbial health risks associated with the practice have largely depended on faecal indicator organisms with potential underestimation or overestimation of the microbial health risks and disease burdens. This study assessed the Escherichia coli O157:H7 infection risk and diarrhoeal disease burden measured in disability-adjusted life years (DALYs) associated with the consumption of wastewater-irrigated lettuce in Kumasi, Ghana using data on E.

Comparative assessment of the bacterial communities associated with Aedes aegypti larvae and water from domestic water storage containers.

Background: Domestic water storage containers constitute major Aedes aegypti breeding sites. We present for the first time a comparative analysis of the bacterial communities associated with Ae. aegypti larvae and water from domestic water containers.

Modeling the die-off of E. coli and Ascaris in wastewater-irrigated vegetables: implications for microbial health risk reduction associated with irrigation cessation.

This study assessed the die-off of Escherichia coli (E. coli) and Ascaris suum on lettuce (Great Lakes 118) and cabbage (Brassica oleracea var capitata) in wastewater-irrigated fields using comparative mathematical die-off models. The study revealed that none of the survival curves of E.

Relationship between Aedes aegypti production and occurrence of Escherichia coli in domestic water storage containers in rural and sub-urban villages in Thailand and Laos.

In a cross-sectional survey in one rural and one suburban village each in Thailand and Laos the relationship between Aedes aegypti production and Escherichia coli contamination in household water storage containers was investigated. Entomological and microbiological surveys were conducted in 250 and 239 houses in Thailand and Laos, respectively. Entomological indices across all four villages were high, indicating a high risk for dengue transmission.

Diarrhea and dengue control in rural primary schools in Colombia: study protocol for a randomized controlled trial.

Background: Diarrheal diseases and dengue fever are major global health problems. Where provision of clean water is inadequate, water storage is crucial. Fecal contamination of stored water is a common source of diarrheal illness, but stored water also provides breeding sites for dengue vector mosquitoes.

Long-term hygienic barrier efficiency of a compact on-site wastewater treatment system.

The long-term use of a filter-based, on-site wastewater treatment system increases nutrient discharge to receiving waters and may reduce its hygienic barrier efficiency. The main purpose of this research was to assess the hygienic barrier efficiency and the associated health risks of an on-site system that had exceeded its 5-yr design capacity with respect to phosphorus (P) removal. The system was investigated for bacteria and virus removal and assessed with respect to potential health risks in relation to reuse of effluent for irrigation.

Quantification of the health risk associated with wastewater reuse in Accra, Ghana: a contribution toward local guidelines.

Quantitative Microbial Risk Assessment (QMRA) models with 10,000 Monte Carlo simulations were applied to ascertain the risks of rotavirus and Ascaris infections for farmers using different irrigation water qualities and consumers of lettuce irrigated with the different water qualities after allowing post-harvest handling. A tolerable risk (TR) of infection of 7.7 x 10(-4) and 1 x 10(-2) per person per year were used for rotavirus and Ascaris respectively.