Climate Change Impacts on Urban Sanitation: A Systematic Review and Failure Mode Analysis

High temperatures promote antibiotic resistance genes conjugative transfer under residual chlorine: Mechanisms and risks

The impact of residual chlorine on the dissemination of antibiotic resistance during the distribution and storage of water has become a critical concern. However, the influence of rising temperatures attributed to global warming on this process remains ambiguous, warranting further investigation. This study investigated the effects of different temperatures (17, 27, 37, and 42°C) on the conjugative transfer of antibiotic resistance genes (ARGs) under residual chlorine (0, 0.1, 0.3, and 0.5 mg/L). The results indicated that high temperatures significantly increased the conjugative transfer frequency of ARGs in intra-species under residual chlorine. Compared to 17°C, the transfer frequencies at 27°C, 37°C, and 42°C increased by 1.07-2.43, 1.20-4.80, and 1.24-2.82 times, respectively. The promoting effect of high temperatures was mainly due to the generation of reactive oxygen species, the triggered SOS response, and the formation of pilus channels. Transcriptomic analysis demonstrated that higher temperature stimulates the electron transport chain, thereby enhancing ATP production and facilitating the processes of conjugative, as confirmed by inhibitor validation. Additionally, rising temperatures similarly promoted the frequency of conjugative transfer in inter-species and communities under residual chlorine. These further highlighted the risk of antibiotic resistance spread in extreme and prolonged high-temperature events. The increased risk of antibiotic resistance in the process of drinking water transmission under the background of climate warming is emphasized.

Temporal trends and spatial heterogeneity of sanitation facilities in Ethiopia: evidence from the 2005-2019 Demographic and Health Surveys

BACKGROUND

The main aim of sanitation is to prevent human contact with faecal pathogens to decrease occurrences of diseases. However, no region in the world is on the right track to accomplish Sustainable Development Goal (SDG) 6.2 for universal access to sanitation. Sub-Saharan Africa, including Ethiopia, is significantly behind in meeting the 2030 SDG 6.2 targets. Hence, this study focused on the spatial and temporal analysis of sanitation in Ethiopia based on four demographic health surveys.

DESIGN

This research was undertaken among households in Ethiopia based on a weighted sample size. Variables with a p<0.2 in bivariable analysis were incorporated into the multivariable analysis. Subsequently, a 95% CI and a p<0.05 were used to assess the statistical significance of the final model. Global and local indicators of spatial correlation were done. Statistical analyses were performed by using STATA V.17 and ArcGIS V.10.7 software.

RESULTS

This study includes data from 13 721 households in the 2005 Ethiopian Demographic and Health Survey (EDHS), 16 702 households in the 2011 EDHS, 16 650 households in the 2016 EDHS and 8663 households in the 2019 EDHS. The prevalence of improved sanitation facilities in Ethiopia was 20.46%, 25.61%, 25.86% and 27.45% based on EDHS 2005, 2011, 2016 and 2019, respectively. Global Moran's I spatial autocorrelations, hotspots and spatial interpolation analysis indicated the inequality of improved sanitation facilities. Educational status of primary (adjusted OR, AOR 2.43, 95% CI 2.00, 2.95), secondary (AOR 2.02, 95% CI 1.61, 2.54) and higher (AOR 4.12, 95% CI 3.35, 7.54), watching television (AOR 5.49, 95% CI 4.37, 6.89), urban areas (AOR 9.08, 95% CI 6.69, 12.33) and region were factors statistically associated with sanitation facilities.

CONCLUSION

The overall finding of this study concludes a very slow increment in sanitation facilities over time and the presence of geographical heterogeneity in Ethiopia. Educational status, watching television, wealth index, community-level education, type of residence and region were factors statistically associated with sanitation facilities.

Designing for climate change: twenty-five design features to improve sanitation technology resilience in low- and middle- income countries

Climate change is exacerbating events such as floods and droughts, and trends including sea-level rise, leading to failures in sanitation technologies, increased public health risks and environmental pollution. To reduce these risks, it is crucial to incorporate climate resilience into sanitation technology designs. In this study, we reviewed academic and selected grey literature and identified 25 design features that can contribute to the technology's resilience to an increasingly volatile and extreme climate. Design features that were conceptually similar were collated into seven categories. These categories included: (i) avoid exposure to hazards, (ii) withstand exposure to hazards, (iii) enable flexibility, (iv) contain failures, (v) limit consequences of complete failure, (vi) facilitate fast recovery and (vii) features that provide resilience benefits beyond technological resilience. In this paper we define the categories and design features, and provide examples of each feature in practice. We also outline how the resilience design features can support sanitation designers and implementers to critique the climate resilience of sanitation technology, and prompt more resilient designs of sanitation technology.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11027-024-10177-7.

Effluents from septic systems and impact on groundwater contamination: a systematic review

Globally, 2.2 billion people rely on groundwater for their water supply, and 2.8 billion use onsite sanitation systems for their sanitation needs. Groundwater contamination from septic systems is a critical public health concern, linked with diseases related to water sanitation and hygiene. Despite the severe impacts of septic systems on groundwater quality, comprehensive global studies remain limited. This study conducted a systematic review of articles published between 2012 and 2023 on topics related to septic systems and groundwater contamination, and 82 peer-reviewed articles met the inclusion criteria. The review identified key contaminants, including E.coli, nitrate, Enterococcus spp., total coliform, ammonium, phosphate, chlorides, and pharmaceuticals. Research on microbial indicators is more prevalent in Africa, while research on nutrients is common in North America. Research on organic contaminants including polyfluoroalkyl substances (PFAS), pharmaceuticals, and personal care products (PCPPs) is limited, particularly in low-and middle-income countries. Critical factors contributing to groundwater contamination include soil, hydrogeological conditions, climate, septic system maintenance and functioning, and septic density. The goal of this study was to comprehensively assess the extent of groundwater contamination resulting from septic system effluents by identifying the major contaminants typically found in affected groundwater sources and exploring the factors contributing to contamination. Identifying the major contaminants and factors related to groundwater contamination from septic systems is crucial for developing effective management strategies to protect groundwater sources.

Assessment of sanitation infrastructure resilience to extreme rainfall and flooding: Evidence from an informal settlement in Kenya

Sanitation infrastructure can fail during heavy rainfall and flooding, allowing the release of fecal waste - and the pathogens it carries - into spaces where people live, work, and play. However, there is a scarcity of reliable frameworks that can effectively assess the resilience of such infrastructure to extreme rainfall and flooding events. The purpose of this study was to develop and apply a novel framework for assessing and ranking the resilience of sanitation infrastructure in informal settlements. A framework for assessing sanitation infrastructure resilience was developed consisting of 19 indicators that were categorized into three domains: physical infrastructure design (8 indicators), operations and management (5 indicators), and environmental factors (6 indicators). The framework was applied to data from 200 shared sanitation facilities in Kibera, Kenya, collected through transect walks, field observations, surveys, and sanitary risk inspections. Results indicate that sanitation infrastructure type impacts resilience. Toilet facilities connected to a piped sewer (r = 1.345, 95% CI: 1.19-1.50) and toilets connected to a septic system (r = 1.014, 95% CI: 0.78-1.25) demonstrated higher levels of resilience compared to latrines (r = 0.663, 95% CI: 0.36-0.97) and hanging toilets (r = 0.014, 95% CI: 0.30-0.33) on a scale ranging from 0 to 4. The key determinants of sanitation infrastructure resilience were physical design, functionality, operational and maintenance routines, and environmental factors. This evidence provides valuable insights for developing standards and guidelines for the design and safe siting of new sanitation infrastructure and encourages investment in sewer and septic systems as superior options for resilient sanitation infrastructure. Additionally, our findings underscore the importance for implementers and communities to prioritize repairing damaged infrastructure, sealing potential discharge points into open drains, and emptying filled containment systems before the onset of the rainy season.

Urban Sanitation: New Terminology for Globally Relevant Solutions?

Progress toward Sustainable Development Goals for global access to safe sanitation is lagging significantly. In this Feature, we propose that misleading terminology leads to errors of categorization and hinders progress toward sanitation service provision in urban areas. Binary classifications such as "offsite/onsite" and "sewered/nonsewered" do not capture the need for "transport to treatment" or the complexity of urban sanitation and should be discarded. "Fecal sludge management" is used only in the development context of low- or middle-income countries, implying separate solutions for "poor" or "southern" contexts, which is unhelpful. Terminology alone does not solve problems, but rather than using outdated or "special" terminology, we argue that a robust terminology that is globally relevant across low-, middle-, and upper-income contexts is required to overcome increasingly unhelpful assumptions and stereotypes. The use of accurate, technically robust vocabulary and definitions can improve decisions about management and selection of treatment, promote a circular economy, provide a basis for evidence-based science and technology research, and lead to critical shifts and transformations to set policy goals around truly safely managed sanitation. In this Feature, the three current modes of sanitation are defined, examples of misconceptions based on existing terminology are presented, and a new terminology for collection and conveyance is proposed: (I) fully road transported, (II) source-separated mixed transport, (III) mixed transport, and (IV) fully pipe transported.

Climate change impacts on wastewater infrastructure: A systematic review and typological adaptation strategy

Wastewater infrastructures play an indispensable role in society's functioning, human production activities, and sanitation safety. However, climate change has posed a serious threat to wastewater infrastructures. To date, a comprehensive summary with rigorous evidence evaluation for the impact of climate change on wastewater infrastructure is lacking. We conducted a systematic review for scientific literature, grey literature, and news. In total, 61,649 documents were retrieved, and 96 of them were deemed relevant and subjected to detailed analysis. We developed a typological adaptation strategy for city-level decision-making for cities in all-income contexts to cope with climate change for wastewater structures. 84% and 60% of present studies focused on the higher-income countries and sewer systems, respectively. Overflow, breakage, and corrosion were the primary challenge for sewer systems, while inundation and fluctuation of treatment performance were the major issues for wastewater treatment plants. In order to adapt to the climate change impact, typological adaptation strategy was developed to provide a simple guideline to rapidly select the adaptation measures for vulnerable wastewater facilities for cities with various income levels. Future studies are encouraged to focus more on the model-related improvement/prediction, the impact of climate change on other wastewater facilities besides sewers, and countries with low or lower-middle incomes. This review provided insight to comprehensively understand the climate change impact on wastewater facilities and facilitate the policymaking in coping with climate change.

Burden of disease attributable to unsafe drinking water, sanitation, and hygiene in domestic settings: a global analysis for selected adverse health outcomes

BACKGROUND

Assessments of disease burden are important to inform national, regional, and global strategies and to guide investment. We aimed to estimate the drinking water, sanitation, and hygiene (WASH)-attributable burden of disease for diarrhoea, acute respiratory infections, undernutrition, and soil-transmitted helminthiasis, using the WASH service levels used to monitor the UN Sustainable Development Goals (SDGs) as counterfactual minimum risk-exposure levels.

METHODS

We assessed the WASH-attributable disease burden of the four health outcomes overall and disaggregated by region, age, and sex for the year 2019. We calculated WASH-attributable fractions of diarrhoea and acute respiratory infections by country using modelled WASH exposures and exposure-response relationships from two updated meta-analyses. We used the WHO and UNICEF Joint Monitoring Programme for Water Supply, Sanitation and Hygiene public database to estimate population exposure to different WASH service levels. WASH-attributable undernutrition was estimated by combining the population attributable fractions (PAF) of diarrhoea caused by unsafe WASH and the PAF of undernutrition caused by diarrhoea. Soil-transmitted helminthiasis was fully attributed to unsafe WASH.

FINDINGS

We estimate that 1·4 (95% CI 1·3-1·5) million deaths and 74 (68-80) million disability-adjusted life-years (DALYs) could have been prevented by safe WASH in 2019 across the four designated outcomes, representing 2·5% of global deaths and 2·9% of global DALYs from all causes. The proportion of diarrhoea that is attributable to unsafe WASH is 0·69 (0·65-0·72), 0·14 (0·13-0·17) for acute respiratory infections, and 0·10 (0·09-0·10) for undernutrition, and we assume that the entire disease burden from soil-transmitted helminthiasis was attributable to unsafe WASH.

INTERPRETATION

WASH-attributable burden of disease estimates based on the levels of service established under the SDG framework show that progress towards the internationally agreed goal of safely managed WASH services for all would yield major public-health returns.

FUNDING

WHO and Foreign, Commonwealth & Development Office.

Perceptions of Inclusivity and Sustainability in Urban Sanitation in Global South Cities

Citywide Inclusive Sanitation (CWIS) calls for sustainable urban sanitation services for all, but the definitions of "inclusion" and "sustainability" within the framework leave room for interpretation. This study aims to provide an initial understanding of how these terms are currently interpreted by a range of sanitation actors in six cities of the Global South. Urban sanitation professionals from private (n = 16), public (n = 28), non-governmental (n = 43), and academic (n = 10) institutions were interviewed using a standardized tool, and data was analyzed to identify themes and trends. Terms such as "everyone" or "for all" shed little light on how to ensure inclusion, though disabled people, women, children, and the poor were all highlighted when probed. Greater specificity of beneficiary groups in policy is likely to enhance their visibility within sanitation service provision. All three pillars of sustainability identified within CWIS were referenced, with different stakeholders focusing more closely on environmental, social, or economic sustainability, based on their organizational goals and interests. Greater collaboration may foster a balanced view across the pillars, with different organizations acting as champions for each one. The findings can facilitate discussions on a shared understanding of multi-stakeholder engagement in achieving inclusive and sustainable sanitation service provision.