Human rotavirus Wa and porcine rotavirus OSU solutions were irradiated with simulated solar UV and visible light in the presence of different photosensitizers dissolved in buffered solutions. For human rotavirus, the exogenous effects were greater than the endogenous effects under irradiation with full spectrum and UVA and visible light at 25 °C. For porcine rotavirus, the exogenous effects with UVA and visible light irradiation were only observed at high temperatures, >40 °C. The results from dark experiments conducted at different temperatures suggest that porcine rotavirus has higher thermostability than human rotavirus. Concentrations of 3'-MAP excited triplet states of 1.8 fM and above resulted in significant human rotavirus inactivation. The measured excited triplet state concentrations of ≤0.45 fM produced by UVA and visible light irradiation of natural dissolved organic matter solutions were likely not directly responsible for rotavirus inactivation. Instead, the linear correlation for human rotavirus inactivation rate constant (kobs) with the phenol degradation rate constant (kexp) found in both 1 mM NaHCO3 and 1 mM phosphate-buffered solutions suggested that OH radical was a major reactive species for the exogenous inactivation of rotaviruses. Linear correlations between rotavirus kobs and specific UV254 nm absorbance of two river-dissolved organic matter and two effluent organic matter isolates indicated that organic matter aromaticity may help predict formation of radicals responsible for rotavirus inactivation. The results from this study also suggested that the differences in rotavirus strains should be considered when predicting solar inactivation of rotavirus in sunlit surface waters.

Longitudinal water quality monitoring is important for understanding seasonal variations in water quality, waterborne disease transmission, and future implications for climate change and public health. In this study, microfluidic quantitative polymerase chain reaction (MFQPCR) was used to quantify genes from pathogens commonly associated with human intestinal infections in water collected from protected springs, a public tap, drainage channels, and surface water in Kampala, Uganda, from November 2014 to May 2015. The differences in relative abundance of genes during the wet and dry seasons were also assessed. All water sources tested contained multiple genes from pathogenic microorganisms, with drainage channels and surface waters containing a higher abundance of genes as compared to protected spring and the public tap water. Genes detected represented the presence of enterohemorrhagic Escherichia coli, Shigella spp., Salmonella spp., Vibrio cholerae, and enterovirus. There was an increased presence of pathogenic genes in drainage channels during the wet season when compared to the dry season. In contrast, surface water and drinking water sources contained little seasonal variation in the quantity of microbes assayed. These results suggest that individual water source types respond uniquely to seasonal variability and that human interaction with contaminated drainage waters, rather than direct ingestion of contaminated water, may be a more important contributor to waterborne disease transmission. Furthermore, future work in monitoring seasonal variations in water quality should focus on understanding the baseline influences of any one particular water source given their unique complexities.

We conducted a study to examine the effect of seasonal variations and the disruptive effects of the 2015 Nepal earthquake on microbial communities associated with drinking water sources. We first characterized the microbial communities of water samples in two Nepali regions (Kathmandu and Jhapa) to understand the stability of microbial communities in water samples collected in 2014. We analyzed additional water samples from the same sources collected from May to August 2015, allowing the comparison of samples from dry-to-dry season and from dry-to-monsoon seasons. Emphasis was placed on microbes responsible for maintaining the geobiochemical characteristics of water (e.g., ammonia-oxidizing and nitrite-oxidizing bacteria and archaea and sulfate-reducing bacteria) and opportunistic pathogens often found in water (Acinetobacter). When examining samples from Jhapa, we identified that most geobiochemical microbe populations remained similar. When examining samples from Kathmandu, the abundance of microbial genera responsible for maintaining the geobiochemical characteristics of water increased immediately after the earthquake and decreased 8 months later (December 2015). In addition, microbial source tracking was used to monitor human fecal contamination and revealed deteriorated water quality in some specific sampling sites in Kathmandu post-earthquake. This study highlights a disruption of the environmental microbiome after an earthquake and the restoration of these microbial communities as a function of time and sanitation practices.

The 2015 Nepal earthquake destroyed over half a million buildings including the drinking water and sanitation infrastructures, causing the displacement of around 2.8 million people. However, knowledge of how individuals coped with water, sanitation, and hygiene (WASH) inadequacies following the earthquake remains incomplete. We conducted focus group discussions and detailed interviews with 30 participants in the affected areas of Kavrepalanchowk and a temporary settlement in Bhaktapur to assess their response and access to WASH after the earthquake. The data were analyzed based on the cultural empowerment domain of the PEN-3 cultural model. Results show that responses to WASH include the provision of water from public and private resources (positive response), the provision of chlorine tablets for treating drinking water (unique response), and limited water supply for household chores and limited sanitation and hygiene resources (negative response). These findings underscore the need to understand how individuals and households cope with WASH following an earthquake. It also highlights the need for targeted interventions focused on building community resilience in addition to providing critical relief efforts.

A novel wastewater treatment process, known as an alternating activated sludge reactor (AASR), is proposed to treat wastewater in full-scale operations. The AASR is a technical development based on the sequencing batch reactor (SBR) and cyclic activated sludge technology (CAST). The performance of AASR was evaluated in this study and found to be effective for the removal of pollutants. The average effluent NH-N, TN, TP, and COD concentrations were 0.5, 17, 0.8, and 40 mgL, respectively. The corresponding average removal efficiencies were 97%, 59%, 83%, and 83%, respectively, indicating that the AASR was also a successful operating system for the removal of organic matter. The AASR has many advantages, such as successive filling, high removal efficiency, high stability and reliability, low area requirement, no sludge circulation reflux, and low construction costs. The operation mode of the alternating anoxic, anaerobic, and aerobic conditions displayed a higher efficiency for nitrification than that of conventional SBR. The effective mode for denitrification was a step-feed. The control program of the AASR is highly flexible and can easily be modified by a plant manager to meet various loading requirements.