Wastewater-based epidemiology: the crucial role of viral shedding dynamics in small communities.

Background: Wastewater surveillance (WWS) of pathogens is a rapidly evolving field owing to the 2019 coronavirus disease pandemic, which brought about a paradigm shift in public health authorities for the management of pathogen outbreaks. However, the interpretation of WWS in terms of clinical cases remains a challenge, particularly in small communities where large variations in pathogen concentrations are routinely observed without a clear relation to clinical incident cases. Methods: Results are presented for WWS from six municipalities in the eastern part of Canada during the spring of 2021. We developed a numerical model based on viral kinetics reduction functions to consider both prevalent and incident cases to interpret the WWS data in light of the reported clinical cases in the six surveyed communities. Results: The use of the proposed numerical model with a viral kinetics reduction function drastically increased the interpretability of the WWS data in terms of the clinical cases reported for the surveyed community. In line with our working hypothesis, the effects of viral kinetics reduction modeling were more important in small communities than in larger communities. In all but one of the community cases (where it had no effect), the use of the proposed numerical model led to a change from a +1.5% (for the larger urban center, Quebec City) to a +48.8% increase in the case of a smaller community (Drummondville). Conclusion: Consideration of prevalent and incident cases through the proposed numerical model increases the correlation between clinical cases and WWS data. This is particularly the case in small communities. Because the proposed model is based on a biological mechanism, we believe it is an inherent part of any wastewater system and, hence, that it should be used in any WWS analysis where the aim is to relate WWS measurement to clinical cases.

Environmental life cycle impacts of small wastewater treatment plants: Design recommendations for impact mitigation.

The objective of this study was to quantify potential mitigation of environmental impacts from the operation and construction of wastewater treatment plants (WWTP) from implementing specific design recommendations. The study investigated small WWTPs, many of which are serving slow growing or declining populations. Life Cycle Assessment methodology was used to evaluate and compare the inventory and environmental impacts of nine small WWTP case studies. Detailed inventory data was collected from the facilities' engineering design plans and utility bills. One recommended practice was to avoid significant overdesign by planning for no lower than a 75% capacity utilization by the facilities' end-of-life. A theoretical correction to a 75% capacity utilization was estimated to mitigate 0.4% of lifetime electricity usage and 1% of secondary process concrete for every 1% reduction in design average flow rate. Relatedly, a 0.4% mitigation in the Carcinogenic and Global Warming impacts could be achieved for every 1% reduction in design average flow toward a 75% capacity utilization. Other suggested practices were focused on conveyance, namely, to minimize non-process facility area and to use polyvinyl chloride pipe instead of ductile iron pipe where possible. The latter practice was estimated to mitigate between 1.1 and 4.8% of the Carcinogenic impact in the nine case studies.

Managing qualitative research as insider-research in small rural communities.

Rural clinicians in small communities face the pressure of always being 'on duty', and the ethical challenges of overlapping relationships with members of the community and duality of roles. The lead author of this commentary has experience as an insider researcher living within a small rural community, and has navigated the ethical challenges and community pressures of conducting qualitative research within an interconnected network. With appropriate measures and planning, insider research can be conducted rigorously, while maintaining ongoing relationships, confidentiality and anonymity.

Will a small randomly assembled community be feasible and stable?

How likely is it that few species can randomly assemble into a feasible and stable community? Some studies have answered that as long as the community is feasible, it will nearly always be stable. In contrast, other studies have answered that the likelihood is almost null. Here, we show that the origin of this debate has been the underestimation of the association of the parameter space of intrinsic growth rates with the feasibility and stability properties of small randomly-assembled communities. In particular, we demonstrate that not all parameterizations and sampling distributions of intrinsic growth rates lead to the same probabilities of stability and feasibility, which could mistakenly lead to under- or overestimate the stability properties of feasible communities. Additionally, we find that stability imposes a filtering of species abundances "towards" more even distributions in small feasible randomly-assembled communities. This indicates that the stability of feasible communities is inherently linked to the starting distribution of species abundances, a characteristic that many times has been ignored, but should be incorporated in manageable lab and field experiments. Overall, the return to this debate is a central reminder that a more systematic exploration of the feasible parameter space is necessary to derive general conclusions about the stability properties of ecological communities.

Field-scale electrolysis/ceramic membrane system for the treatment of sewage from decentralized small communities.

The electrolysis process adopting copper electrodes and ceramic membrane with pore sizes of 0.1-0.2 µm were consisted to a system for the treatment of sewage from decentralized small communities. The system was operated under an HRT of 0.1 hour, voltage of 24 V, and TMP of 0.05 MPa. The system showed average removals of organics, nitrogen, phosphorus, and solids of up to 80%, 52%, 92%, and 100%, respectively. Removal of organics and nitrogen dramatically increased in proportion to increment of influent loading. Phosphorus and solids were remarkably eliminated by both electro-coagulation and membrane filtration. The residual particulate constituents could also be removed successfully through membrane process. A system composed of electrolysis process with ceramic membrane would be a compact, reliable, and flexible option for the treatment of sewage from decentralized small communities.

Características individuais associadas à autopercepção da extensão territorial da vizinhança / Individual characteristics associated with perception of the local neighborhood’s territory / Las características individuales asociadas con la percepción de la extensión territorial del vecindario

É crescente o interesse em investigar os impactos da vizinhança na saúde. Para definir vizinhança, duas estratégias principais são encontradas: uma utiliza fronteiras artificiais criadas para finalidades administrativas, a outra considera a definição do indivíduo, vizinhança autopercebida. O objetivo deste estudo foi identificar os fatores associados à heterogeneidade da autopercepção da dimensão territorial da vizinhança entre os participantes de um inquérito de saúde em Belo Horizonte, Minas Gerais, Brasil. Para verificar tal a associação, foi utilizada regressão logística ordinal. Maiores percepções de vizinhança estiveram associadas a: melhor posição socioeconômica, trabalhar, avaliação positiva dos aspectos estéticos da vizinhança e da mobilidade no interior da vizinhança, maior identificação de problemas na vizinhança, menor envolvimento em atividades de esporte/lazer e conhecer maior número de pessoas na vizinhança. Os resultados deste estudo podem ajudar a delimitar vizinhanças mais próximas da percepção dos indivíduos, fornecendo estimativas mais precisas dos impactos da vizinhança na saúde.

There is a growing interest in evaluating the impact of neighborhood characteristics on health. The definition of neighborhood involves two main strategies, one using artificial boundaries, usually created for administrative purposes, and the other based on the individual’s definition, namely the perceived neighborhood. The aim of this study was to identify factors associated with heterogeneity in the perceived neighborhood among participants in a health survey in Belo Horizonte, Minas Gerais State, Brazil. Ordinal logistic regression was used to determine and quantify this association. Larger size of the perceived neighborhood was associated with better socioeconomic status, positive employment status, positive assessment of aesthetic aspects and mobility within the neighborhood, active identification of problems in the neighborhood, less involvement in sports/leisure activities, and knowing more neighbors. The study’s results can help produce more significant neighborhood definitions that are more consistent with residents’ own perceptions, thereby favoring more accurate estimates of neighborhood impact on health.

El estudio trata sobre el creciente interés en investigación por los impactos en salud del vecindario. Para definir vecindario hay dos estrategias principales: una utilizar fronteras administrativas, la otra tiene en cuenta la percepción subjetiva del individuo. El objetivo de este estudio fue identificar los factores asociados a la heterogeneidad de la percepción subjetiva de la dimensión territorial del vecindario entre los participantes en una encuesta de salud en Belo Horizonte, Minas Gerais, Brasil. Para verificar esta asociación se utilizó la regresión logística ordinal. Percepciones del vecindario más grandes se asocian con: mejor situación socioeconómica, el trabajo, la evaluación positiva de los aspectos estéticos de la vecindad y la movilidad en el barrio, una mayor identificación de los problemas del barrio, una menor participación en actividades/pasatiempos deportivos y conocer a tantas personas en el barrio. Los resultados de este estudio pueden ayudar a definir los vecindarios más cercanos a la percepción de las personas, proporcionando estimaciones más precisas de los efectos del vecindario en la salud.

Assessing the sustainability of small wastewater treatment systems: a composite indicator approach.

The assessment of the sustainability of wastewater treatment (WWT) systems has gained interest in recent years. However, most previous studies have focused on environmental and/or economic dimensions ignoring social aspects. Moreover, they tend to be based on sets of indicators rather than providing a holistic assessment. To overcome this limitation, this paper proposes an innovative methodology to assess the sustainability of WWT systems based on the development of a composite indicator embracing economic, environmental and social issues. Subsequently, the global sustainability of seven WWT technologies for secondary treatment in small communities is compared. The joint application of the analytical hierarchical process (AHP) to assign weights to each indicator allows the incorporation of the preferences of experts. Initially, the global sustainability of the WWT technologies evaluated is quite similar. However, a scenario analysis illustrates that constructed wetlands technology is the most sustainable in five out of the seven scenarios evaluated. Moreover, extended aeration and rotating biological contactors are identified as the technologies with the lowest variability in their sustainability. Hence, in an uncertain context, they might be considered the preferred options. The proposed approach contributes to ease of interpretation of a complex problem such as the selection of the most sustainable WWT alternative.

Design flow factors for sewerage systems in small arid communities.

Reliable estimation of sewage flow rates is essential for the proper design of sewers, pumping stations, and treatment plants. The design of the various components of the sewerage system should be based on the most critical flow rates with a focus on extremely low and peak flow rates that would be sustained for a duration related to the acceptable limits of behavior of the components under consideration. The extreme flow conditions and to what extent they differ from the average values are closely related to the size of the community or network, and the socioeconomic conditions. A single pumping station is usually sufficient to pump flow from small community in either flat or non-undulating topography. Therefore, the hydraulic loading on the wastewater treatment plant (WWTP) results from the pumped flow from the pumping station rather than the trunk sewer flow. The intermittent operation of the pumping units further accentuates the sewage hydrograph in the final trunk sewer. Accordingly, the design flow for the various components of the WWTP should be determined based on their relevant flow factors. In this study, analysis of one representative small community out of five monitored small communities in Egypt and the Kingdom of Saudi Arabia is presented. Pumped sewage flow rates were measured and the sewer incoming flows were hydraulically derived. The hourly and daily sewer and pumped flow records were analyzed to derive the relationship between the flow factors that would be sustained for various durations (instantaneously, 1 h, 2 h, etc.) and their probability of non-exceedance. The resulting peaking factors with a consideration for their sustained flow duration and specified probability would permit the design of the various components of the treatment plant using more accurate critical flows.