On-site Sanitation Systems Research Articles

Public health performance of sanitation technologies in Tamil Nadu, India: Initial perspectives based on E. coli release

Sanitation is intended to reduce the spread and burden of diseases transmitted from excreta. Pathogen reduction from excreta before sludge or effluent discharge to the environment would seem a logical and useful performance indicator for sanitation systems. However, the relative magnitudes of pathogen release from common sanitation technologies are not well understood. We, therefore, investigated the feasibility of performance measurement of different sanitation technologies in Tamil Nadu, India in reducing the release of the pathogen indicator Escherichia coli (E. coli). After conducting users’ surveys and technical assessments of the locally prevalent sanitation systems, we classified them into 7 distinct categories (based on both observed physical characteristic and usage) within a widely-accepted physical typology. Faecal sludge and wastewater samples were collected and analysed for E. coli and total solids from 136 household systems, 24 community systems, and 23 sanitary sewer oveflows. We estimated the average volumetric release rates of wastewater and faecal sludge from the different sanitation technologies. Average daily per capita E. coli release was computed, and used as one indicator of the public health performance of technologies. We found that on-site installations described by owners as “septic systems” included diverse forms of tanks and pits of uncertain performance. We observed a statistically significant difference in the average daily per capita E. coli release from different sanitation technologies (p = 0.00001). Pathogen release from the studied on-site sanitation technologies varied by as much as 5 orders of magnitude from “lined pits” (5.4 Log10 E. coli per person per day) to “overflowing sanitary sewers” and “direct discharge pipes” (10.3–10.5 Log10 E. coli per person per day). Other technologies lay between these extremes, and their performances in E. coli removal also varied significantly, in both statistical and practical terms. Our results suggest that although faecal sludge management along the sanitation service chain is important, sanitation planners of the observed systems (and probably elsewhere) should direct higher priority to proper management of the liquid effluents from these systems to minimize public health hazards. We conclude that (i) the work demonstrates a new and promising approach for estimating the public health performance of differing sanitation technologies, (ii) if E.coli is accepted as an indicator of the public health hazard of releases from sanitation systems, our results strongly suggest that safe containment of excreta for an extended period substantially reduces pathogen numbers and the risk of pathogen release into the environment; and (iii) there are some simple but little-used technical improvements to design and construction of on-site sanitation systems which could significantly reduce the release of pathogens to the environment.

Generation and Management of Faecal Sludge Quantities and Potential for Resource Recovery in Phnom Penh, Cambodia

At the current rate of progress, there will probably still be 2.8 billion people world-wide without safely managed sanitation by 2030. To incentivise and increase implementation of sustainable faecal sludge management (FSM), especially in low and middle-income countries like Cambodia, human waste must be regarded as a resource. However, planning data, e.g. on the quantities, composition and fate of faecal sludge after leaving households, are inadequate and lack accuracy. The aim of this study was to provide baseline data for effective FSM planning by sanitation stakeholders in Phnom Penh. This was done by quantifying sludge volumes generated, transport logistics and resource recovery potential to incentivise sustainable management. Interviews were conducted with users and emptying and transportation contractors, together with collection of technical data about on-site sanitation systems. Geographical coordinates of household sampling locations and disposal sites were also mapped. The results revealed that Cheung Ek and Kob Srov wetlands are the main recipients of faecal sludge collected in Phnom Penh with the amount of 18,800 m3 and 13,700 m3 annually, respectively. The analysis showed that faecal sludge in Phnom Penh contains valuable resources such as nitrogen (6 tons), phosphorus (13 tons) and energy (148-165 GWh) annually, but in-depth investigations of appropriate treatment options for resource recovery are required. Detailed documentation of the location of potential recoverable resources from faecal sludge would assist decision-makers in developing action plans for sustainable FSM in Phnom Penh and similar cities.

Potential Applications of Land Treatment Systems for Disinfectant-Rich Wastewater in Response to the COVID-19 Health Protocol: A Narrative Review

Introduction: The use of antiseptics and disinfectants in daily health protocols has a consequence of changing the quality of wastewater to be toxic to microbes. As a result, microbiological wastewater treatment has the potential to not be processed properly. To solve the problem of disinfectant-rich wastewater, a plant-based treatment method can be useful, the implementation of which is a land treatment system for wastewater.
 Materials and Methods: The data collection method was carried out through the Mendeley Reference Manager, searching for articles online, and placing the terms “land treatment system”, and “disinfectant-rich wastewater”. The selected articles were up-to-date and had a significant relationship between the two terms.
 Results: This sanitation system can be a stretch of land and/or a pond of water, on which plants can grow and process. Normal concentrations of disinfectants for microbial elimination had no negative effects on the growth of various types of plants. Plants continue to live in the stress of water rich in disinfectants, as a condition of their ability to treat wastewater. The involvement of various wastewater treatment media makes evapotranspiration dry bed and evapotranspiration wet bed or wetland ponds capable of processing various pollutants. This approach can be implemented for on-site and off-site sanitation system.
 Conclusion: In this context, under conditions of enrichment of disinfectants in wastewater during the COVID-19 era, the land treatment system becomes feasible to solve the problem of changing the quality of wastewater.

Dichotomy to Continuum: Importance of Faecal Sludge Management in Shaping Future Urban–Rural Linkages in Urbanizing India

Meeting the sanitation needs of a growing and urbanizing population in India led the incumbent national government to launch a large-scale sanitation programme, the Swachh Bharat Mission in 2014. Having reduced the deficit in basic rural sanitation in its first phase, the programme is targeting to achieve universal safely managed sanitation in its second phase launched in February 2020. Since the trajectory to achieving safely managed sanitation is inherently path-dependent, the present article utilizes novel survey data from rural India to understand the nature of sanitation systems in transitioning spaces and identify the investments they require to provide safely managed sanitation. It finds that the de facto preference in sanitation systems that households manifest is in direct contrast to the governmental choice of the low-cost twin pit system. The choice of the on-site sanitation system is informed by the household’s economic status and how ‘characteristically’ urban the settlements they reside in are. The article further discusses the implications of these findings for the short-term responsiveness and long-term effectiveness of the massive sanitation investments (USD 19 billion) planned for the next five years in India.

Characterisation of selected human excreta-derived fertilisers for agricultural use: A scoping review

Most countries in Sub-Saharan Africa rely on on-site sanitation systems. Integrating on-site sanitation systems with local food systems by recovering nutrients and materials from human excreta, and reuse in agriculture can promote a sustainable circular bioeconomy, which could improve livelihoods and minimize environmental pollution in low-income communities. Although there are several technologies that can valorise human excreta into valuable waste-based agricultural products the scaling up and adoption of these innovations by societies is limited by several institutional challenges. These include an unclear policy and regulatory environment due to inadequate evidence-based information that can inform policy change, stimulate social acceptance, establish economically viable environment and include active participation of women and youth. Based on previous untreated human excreta characterisation studies, meant to inform treatment technological requirements, a scoping review with metanalyses was done to assess the extent to which selected technologies are meeting the requirements of a sustainable sanitation value chain. The selected technologies were shown to comply with the South African and international regulations for the recovery of nutrients from human excreta and reuse in agriculture. The review shows that there is potential to establish circular bio economies, characterised by safe recovery of nutrients and materials from human excreta and subsequent agricultural use, in South Africa and beyond. However minor modifications to the technologies are required to ensure that the products are safe for unrestricted agricultural use, economically viable, socially acceptable and environmentally sustainable.

Effects of aqwise carrier media and brick media as filter materials on performance of biofilm reactor

The present study identifies the effects of two different filter materials, aqwise carrier media (ACM) and brick media (BM), on the performance of an integrated settler-based biofilm reactor (ISBR). The ISBR was designed to work as an onsite sanitation system to treat the domestic wastewater generated through household activities. The reactor consisted of three chambers connected in a series and accommodated within a single unit. The first chamber was a settler, which was followed by two other chambers working as biofilm reactors containing two different filter media. In the second and third chambers, ACM and BM were used as a filter material that helped in formation of biofilm on the surface of the media. A biofilm is a complex structure of a microbiome formed by a group of distinct bacterial colonies or single cell types. The biofilms play an important role in the natural attenuation of biodegradation and biotransformation of organic and inorganic pollutants present in wastewater. It was observed that the performance of the ISBR was significantly improved due to formation of biofilm on the surface of the filter materials, which was seen during the morphological analysis of the filter materials using scanning electron microscopy. The results indicated that the ISBR showed more than 91% pollutant removal efficiency in terms of total suspended solids (TSS), total suspended solids (BOD) and chemical oxygen demand (COD). The removal of faecal coliform was also observed to be more than 97%. Such a remarkable performance of the ISBR make it a suitable system for wastewater treatment at onsite level using filter materials with high specific surface area. The present biofilm reactor has a simple design and does not require much maintenance and operation cost as it does not require electricity.

China should focus beyond access to toilets to tap into the full potential of its Rural Toilet Revolution

In China, over 47 million toilets in rural areas have been upgraded since the nationwide sanitation program, popularly referred to as the “toilet revolution”, was launched in 2015. However, little is known about the perceptions of rural households regarding these new toilets or the fate of human excreta collected using them. To investigate the other side of the toilet revolution, we surveyed 980 rural households from 22 provinces across China in 2020. We found that most households used an on-site sanitation system (i.e. septic tanks and pit latrines), where urine and feces were mixed and collected (88%), stored in pits or tanks (79%), emptied by the households themselves (60%), applied on farmland as fertilizer (45%), or used for biogas production (5%). Despite the toilet revolution-driven infrastructure upgrade, only 25% of the households were satisfied with their sanitation system and pointed to health risks from issues in the toilet interface and the treatment and reuse of excreta as areas of concern. The majority preferred an “out of sight, out of mind” approach, in which the local government handles excreta without involving the households and without asking them to pay for such management. Meanwhile, 80% supported the idea of local nutrient recycling and believed that human excreta should return to farmland as fertilizer or used for biogas production. Our findings suggest that decision makers in local governments across China must urgently explore ways to upgrade all parts of the sanitation service chain so that rural sanitation can be truly improved to positively influence the progress on other national sustainability goals.

Non-Sewered Sanitation Systems’ Global Greenhouse Gas Emissions: Balancing Sustainable Development Goal Tradeoffs to End Open Defecation

Discharge of excreta into the environment and the use of decentralized sanitation technologies, such as septic tanks, pit latrines and ecological sanitation variants (i.e., container-based sanitation), contribute to greenhouse gas (GHG) emissions but have remained poorly quantified. The purpose of this analysis was to investigate the impacts that meeting Sustainable Development Goal (SDG) 6.2 (i.e., ending open defecation by 2030) would have on SDG 13 (i.e., combatting climate impacts). The current Intergovernmental Panel on Climate Change GHG estimation methodology was used as the basis for calculations in this analysis, augmented with improved emission factors from collected data sets for all types of on-site sanitation infrastructure. Specifically, this assessment focused on the three different service levels of sanitation (i.e., improved, unimproved and no service) as defined by UNICEF and WHO as they pertain to three Shared Socioeconomic Pathways. This analysis considered the 100-year global warming potential values in carbon dioxide equivalents of methane and nitrous oxide that can be emitted for each scenario and decentralized sanitation technology. Ultimately, six scenarios were developed for various combinations of pathways and sanitation technologies. There was significant variability between the scenarios, with results ranging from 68 Tg CO2eq/year to 7 TgCO2eq/year. The main contributors of GHG emissions in each scenario were demonstrated to be septic tank systems and pit latrines, although in scenarios that utilized improved emission factors (EFs) these emissions were significantly reduced compared with those using only standard IPCC EFs. This analysis demonstrated that using improved EFs reduced estimated GHG emissions within each SSP scenario by 53% on average. The results indicate that achieving SDG sanitation targets will ultimately increase GHG emissions from the current state but with a relatively small impact on total anthropogenic emissions. There is a need for the continued improvement and collection of field-based emission estimations to refine coarse scale emissions models as well as a better characterization of relevant biodegradation mechanisms in popular forms of on-site sanitation systems. An increase in the understanding of sanitation and climate change linkages among stakeholders will ultimately lead to a better inclusion of sanitation, and other basic human rights, in climate action goals.

Sewage Markers as Determinants to Differentiate Origins of Emerging Organic Pollutants in an Urban Sri Lankan Water Drainage Network

Urban sanitation is a major challenge during the rapid urbanization being experienced by developing countries, as a low sewerage infrastructure capacity and irregular onsite wastewater treatment raise the risk of surface water contamination. The application of specific sewage markers to characterize contaminant sources is therefore essential for managing urban sanitation issues. In this study, we investigated the concentrations of eight sewage markers (acetaminophen, caffeine, carbamazepine, cotinine, sulfamethoxazole, sulfapyridine, atenolol, and acesulfame) in various water sources within urban area of the Galle City, Sri Lanka. The total concentration of the eight markers was in the order of hospital discharge > sewage treatment plant (STP) influent > surface drainage system. Among the eight selected markers, acetaminophen was dominant in hospital discharge (70.2–123.6 µg/L) while caffeine was the largest contributor to STP influent (16.2–68.7 µg/L) and surface drainage (0.95–21.73 µg/L). We then proposed and tested a set of criteria for evaluating the applicability of markers, including removal efficiency, concentration magnitude, excretion rate, and wastewater burden. The labile markers caffeine and acetaminophen were suitable for characterizing domestic gray and black wastewater, respectively. These results imply that the city’s drainage system receives both domestic graywater and human excretion, likely due to insufficient on-site sanitation systems. The conservative marker carbamazepine was useful for tracking hospital residues over long distances; these results imply that hospital wastewater treatment was not working properly, accounting for pharmaceutical residues reaching surface water via a hidden discharges connected to the drainage system.

Inconvenient truth: unsafely managed fecal sludge after achieving MDG for decades in Thailand

Abstract In most low- and middle-income countries, due to financial constraints and improper management practices, the expansion of conventional centralized systems to enhance wastewater management services is not practical. Despite the fact that the majority of the world population has met the Millennium Development Goals 7c (MDG7c) targets, more than 2.5 billion are still using unimproved sanitation facilities and affecting the safety of drinking water and public health. Because of this problem, a novel approach on ‘Non-Sewered Sanitation’ with decentralized treatment systems is being recognized as a promising alternative to accomplish the Sustainable Development Goal No. 6 (SDG6) targets on ‘Safe Water and Sanitation’ and bringing health benefits to the people. This study aimed to investigate the current status of access to improved sanitation facilities in relation to the MDG7c and SDG6 in Thailand and comparing with other countries, including the effects of unsafely managed fecal sludge (FS) on the prevalence of diarrhea and liver fluke infections. The prevailing constraints and weaknesses were identified, and effective sanitation management measures to accomplish SDG6 targets were recommended. Based on data collected from 20 cities located in the north and northeastern regions of Thailand during the period of 2015–2020, the sanitation facilities data on conventional centralized systems and FS management facilities that affect the prevalence of diarrhea and liver infections were analyzed and interpreted using statistical and response surface methodology techniques. The findings showed that most of the surveyed cities have achieved the MDG7c targets, but 70% of the FS generated from on-site sanitation systems are still unsafely managed, caused by limited expansion of sewage systems for wastewater collection and conveyance (with inadequate operation and maintenance) as well as the financial constraints, especially in areas outside of urban neighborhoods. The effective sanitation management practices to accomplish the SDG6 targets were proposed such as increasing the capacity of sanitation facilities to be 55,000 m3/day/30,000 households, designing appropriate FS collection program and treatment technology, and providing more awareness programs for safe sanitation management and health risk protection.

Human excreta as a resource in agriculture – Evaluating the fertilizer potential of different composting and fermentation-derived products

Acknowledging the resources in human excreta provides new options to address future challenges for fertilizer availability and nutrient management in a sustainable way. In dry on-site sanitation systems, the high nutrient concentration and low volume of the waste provides an opportunity for low-tech recycling, while the product can be a valuable input to the local agro-ecological system. However, successful recycling requires balanced fertilization with a low environmental impact. The aim of this study was therefore, to evaluate and compare the nutritional content and fertilizer potential of different organic amendments derived from human excreta. Nine amendments were obtained previously by treating human excreta from a dry toilet through composting or fermentation at 7°C, 20°C or 38°C, followed by a secondary vermicomposting. We evaluated the fertilizer potential of the amendments by conducting a soil incubation study to determine nitrogen and phosphorus mineralization, and by a pot experiment with barley. For all amendments, the nitrogen mineralization was slow and the available nitrogen determined the yield. The treatment method had a significant effect on the availability of nitrogen and the amendments obtained by active composting at 38°C had significantly higher levels of total and mineral nitrogen than those composted/fermented at 7°C and 20°C. These amendments also led to the highest barley yields, which were equivalent to a mineral nitrogen fertilization of 30 to 60 kg N ha−1. These findings contribute towards better agronomic value quantification of products from on-site dry sanitation systems and the effect of treatment method on the availability of nitrogen.

Hydrogeochemistry and groundwater quality assessment using the water quality index and heavy-metal pollution index in the alluvial plain of Atibaia river- Campinas/SP, Brazil

Alluvial aquifers are highly vulnerable to contamination, especially in areas with peri-urban occupation and on-site sanitation systems. Due to the importance of the quality of groundwater in those areas, this article aims to understand hydrochemical characteristics and to evaluate groundwater quality using the Water Quality Index (WQI) and Heavy-Metal Pollution Index (HPI). Seasonal sampling campaigns of 20 samples of groundwater in hand dug wells were done during wet and dry seasons. The main hydrochemical facies determined in the Piper Diagram allowed to classify the waters as Ca–HCO3, Ca–Na–HCO3 and Na–Ca–HCO3 during the wet season, and Ca–HCO3, Na–Ca–HCO3 and Na–Ca–Cl during dry season, suggesting shallow waters and short residence time. The groundwater in the study area is mostly controlled by the incongruous weathering of silicates and the process of ionic exchange, as well as the anthropogenic sources that act as secondary contributions. The saturation index results show a state of supersaturation (SI > 0) for the following minerals: goethite, kaolinite and illite, and subsaturation (SI < 0) for the minerals: calcite and dolomite. The groundwaters were subsaturated in most of the samples, and supersaturated in other samples related to the mineral phase Fe(OH)3. The significant correlations between NO3− and Cl− allowed to conclude that the study area is contaminated by domestic septic tanks, and that in the majority of the samplings natural iron rests above the limit for human consumption. WQI and HPI indicate that the majority of the samples showed excellent indexes and are adequate for consumption. However, in this study those indexes presented limitations, because they minimize some parameters that presents concentrations above the maximum value or evidences of contamination, as seen with Nitrate and Iron, respectively.

Hydraulic characteristics of integrated settler based biofilm reactor as onsite sanitation system

Abstract The present study identifies the hydraulic efficiency of a novel onsite sanitation system at variable hydraulic shock loading conditions. The system consisted of three chambers, each working as an up-flow anaerobic bioreactor, accommodated within a single unit. The hydraulic characteristics were identified with the help of residence time distribution (RTD) analysis by step feeding of lithium chloride (LiCl) solution into the system. The experiments were run at variable hydraulic loading conditions at different peak flow factors (PFF) of 1, 2, 4 and 6 while maintaining 24-h hydraulic retention time. As revealed in the RTD analysis, the biofilm reactor achieved a very good hydraulic efficiency that varied from 0.76 to 0.81 at PFF 1, 2 and 4. Although in the case of PFF6, it was comparatively low. It was noted that the dispersion number was always below 0.2 at variable hydraulic shock loading conditions under different PFFs, which indicated that the reactor behaved perfectly between mixed-flow and plug-flow reactor. The system was also able to achieve good pollutant removal efficiency for chemical oxygen demand (COD) and total suspended solids (TSS) under all PFFs, which was more than 68 and 75%, respectively.

Quantification and characterisation of faecal sludge from on-site sanitation systems prior the design of a treatment plant in Bangangte, West Region of Cameroon

Poor access to basic sanitation is a global concern, but alarmingly prevalent in low-and middle- income countries. In peri-urban areas, access to sanitation is provided mainly through the use of on-site sanitation systems. Unfortunately, the lack of emptying services as well as treatment plants for faecal sludge hamper the access to sustainable sanitation. The design of such treatment plants requires the mastering of the faecal sludge production and quality from sanitation systems. The present work therefore aims at evaluating the quantity and quality of faecal sludge in the city of Bangangte, West Cameroon, with a view to design and build a treatment plant for this waste. Through a survey of 1350 households as well as public services, on-site existing systems for faecal sludge management were identified, the production of sludge estimated using current estimation methodologies and the sludge quality determined. Five types of on-site systems for faecal sludge containment and treatment were identified: pit latrines (78%), septic tanks (18%), hand-flush toilets (3%), VIP latrines (1%). Faecal sludge production was estimated at 13,659 m3using specific production methodology, 8081 m3 based on the characteristics of the sanitation facilities and 9697 m3 based on the demand for mechanical emptying. An average of 10,479 ± 2870 m3 from the three estimates was proposed in order to minimise the limitations of individual estimation methodologies and avoid the over or under sizing of treatment plants using these estimates. The characterization of the sludge produced exhibited high variability of the sludge quality. The sludge COD/BOD5 and TS/COD ratios confirm the suitability of the sludge produced in the municipality of Bangangte for biological treatments.

Modelling Faecal Sludge Dewatering Processes in Drying Beds Based on the Results from Tete, Mozambique

Currently, in sub-Saharan African countries, 65 to 100% of the urban population is served by on-site sanitation systems, typically pit latrines and septic tanks. Faecal sludge dewatering in drying beds is one of the most commonly adopted low-cost treatment technologies in developing countries due to favourable climate conditions in terms of temperature and radiation and because their operation and maintenance are simple. Nevertheless, research in tropical dry zones regarding these processes is scarce. In this paper, a mathematical model for faecal sludge dewatering in sludge drying beds (SDBs) focusing on gravity drainage and evaporation processes is presented and discussed. Experimental campaigns were carried out at a pilot site in Tete, Mozambique, to determine the model parameters. The results suggest that the model can be used to estimate, in similar situations, the dewatering process of different types of faecal sludge. The present research might be considered as a contribution to the design and operation of SDBs, supporting sludge management and allowing the estimation of drying times and optimal loading cycles, namely, the sludge thickness and final moisture content.

A critical review on sludge management from onsite sanitation systems: A knowledge to be revised in the current situation

Access to safe excreta disposal is a basic human right and an essential element of human development. Developing countries (like India) have constructed millions of toilets with on-site sanitation technologies (OSTs). However, these OSTs lack the required management system for collection, transportation and disposal of Faecal Sludge (FS, sludge getting accumulated in OST), leading to considerable water and soil pollution. The major challenge in FS Management is the collation of scattered data and concentrated experiences (i.e., existing knowledge remains with the practitioners in the field without a written record). Therefore, a critical review of existing knowledge on OST, FS collection, transportation, and its utilisation is essential. This study highlighted shortcomings associated with existing OST, FS collection, transportation, and treatment systems. Furthermore, this study provided a framework for appropriate selection of OST based on available sanitation chains, and a critical analysis of FS characteristics (i.e., total solids, pH, electrical conductivity, biological oxygen demand, chemical oxygen demand, and pathogens of FS ranged from 830 to 72000 mg/L, 6.8 to 7.8, 1.9 to 3.5 mS/cm, 500–5000 mg/L, 100 to 49,000 mg/L, and 106 to 107 E-coli and 103 to 104 parasitic worms per litre of FS, respectively) to design treatment systems for FS utilisation as a resource in agricultural, aqua-culture, and construction application.

Safely Managed On-Site Sanitation: A National Assessment of Sanitation Services and Potential Fecal Exposure in Indonesia.

Sustainable Development Goal target 6.2 calls for universal access to adequate and equitable sanitation, setting a more ambitious standard for ‘safely managed sanitation services’. On-site sanitation systems (e.g., septic tanks) are widely used in low- and middle-income countries (LMICs). However, the lack of indicators for assessing fecal exposure risks presents a barrier to monitoring safely managed services. Furthermore, geographic diversity and frequency of disasters require a more nuanced approach to risk-informed decision-making. Taking Indonesia as an example, the purpose of this paper is to provide insights into current status and practices for on-site sanitation services in the contexts of LMICs. Using a dataset from a national socio-economic survey (n = 295,155) coupled with village census (n = 83,931), we assessed (1) household sanitation practices across Indonesia stratified by city-level population density and meteorological factors, (2) factors associated with septic tank emptying practice, and (3) inequalities in potential fecal exposure as measured by population density and WASH access by wealth quintile. We found a high reliance on on-site sanitation facilities (80.0%), almost half of which are assumed to be ‘uncontained’ septic tanks and one in ten facilities discharging untreated waste directly into the environment. The most densely populated areas had the highest rates of septic tank emptying, though emptying rates were just 17.0%, while in the lowest population density group, emptying was rarely reported. Multivariate regression analysis demonstrated an association between flooding and drought occurrence and septic tank emptying practice. Higher groundwater usage for drinking among poorer households suggests unsafe sanitation may disproportionally affect the poor. Our study underscores the urgent need to strengthen the monitoring of on-site sanitation in LMICs by developing contextualized standards. Furthermore, the inequalities in potential fecal exposure require greater attention and tailored support mechanisms to ensure the poorest gain access to safely managed sanitation services.

Structural Response of Multistory RC Buildings to Excavation of a Disposal Well

AbstractSoakaway disposal wells are used heavily in Sudan for on-site sanitation systems. These wells have a diameter of 1.5–2.0 m, a depth ranging from 10 to 35 m, and postinstalled brick walls. T...

The NEWgeneratorTM non-sewered sanitation system: Long-term field testing at an informal settlement community in eThekwini municipality, South Africa

Globally, there is a dire need for a new class of advanced non-sewered sanitation systems (NSSS) to provide onsite wastewater treatment that is capable of meeting stringent discharge or reuse criteria. These systems need to be simple to operate and maintain, reliable, and resilient to unreliable electrical service. The NEWgenerator (NG) is a compact, automated, solar-powered wastewater treatment system comprised of three major treatment processes: anaerobic membrane bioreactor (AnMBR), nutrient capture system (NCS) with ion exchange and carbon sorption, and electrochlorination (EC). The NG system operated at an informal settlement community in South Africa over a 534 d period, treating high-strength blackwater (BW) and yellow water (YW) from a public toilet facility. Over three test stages (BW, BW + YW, BW) that included several periods of dormancy, the NG system was able to provide a high level of removal of total suspended solids (97.6 ± 3.1%), chemical oxygen demand (94.5 ± 5.0%), turbidity (96.3 ± 9.7%), color (92.0 ± 10.5%), total nitrogen (82.1 ± 24.0%), total phosphorus (43.0 ± 22.1%), E. coli (7.4 ± 1.5 LRV, not detected in effluent), and helminth ova (not detected in effluent). The treatment levels met most of the ISO 30500 NSSS standard for liquid effluent and local water reuse criteria. A series of maintenance events were successfully conducted onsite over the 534 d field trial: two membrane cleanings, two NCS regenerations, and granular activated carbon replacement. Desludging, a major pain point for onsite sanitation systems, was unnecessary during the field trial and thereby not performed. The AnMBR performed well, removing 94.5 ± 5.0% of the influent COD across all three stages. The high COD removal rate is attributed to the sub-micron separation provided by the ultrafiltration membrane. The NCS was highly efficient at removing total nitrogen, residual COD and color, but the regeneration process was lengthy and is a topic of ongoing research. The EC provided effective disinfection, but frequent prolonged run cycles due to power supply and water quality issues upstream limited the overall system hydraulic throughput. This extended field trial under actual ambient conditions successfully demonstrated the feasibility of using advanced NSSS to address the global water and sanitation crises.

Pharmaceutical Contaminants in Shallow Groundwater and Their Implication for Poor Sanitation Facilities in Low-Income Countries.

Rudimentary on-site sanitation systems (OSSs) are extensively used in low-income countries despite the risk of groundwater contamination. The present study investigated the potential impact of community soak pits on sandy shallow aquifers in a rural area in Sri Lanka. Thirty-two groundwater samples were collected and measured for the traditional indicators fecal bacteria Escherichia coli, total coliforms, nitrate, and chloride; 7 pharmaceuticals were added as wastewater indicators. Analysis showed that the local groundwater is infected by fecal bacteria, but it was unable to determine whether the source of fecal bacteria is the OSSs. Similarly, nitrate and chloride provided unclear evidence. Conversely, detection of 3 pharmaceuticals at trace levels in groundwater evidenced wastewater impact from OSSs. Caffeine was detected in 89% of the sample at a maximum concentration 7.9 ng/L, indicating fecal pollution. Carbamazepine was detected in 42% of the samples with a concentration of up to 6.9 ng/L, whereas sulfamethoxazole was detected in only 2 samples. The presence of carbamazepine and sulfamethoxazole was also consistent with recorded drug use of the residents. Escherichia coli showed a moderate positive correlation with caffeine concentration (Kendall's τ = 0.38, p = 0.017), indicating concurring short-lifetime fecal bacteria and labile wastewater organic compounds. Nitrate showed a significant correlation with carbamazepine concentration (τ = 0.39, p = 0.016). Fecal bacteria and nitrate can be used in screening for micropollutants in domestic wells impacted by OSSs. The present case study emphasizes the potential impact of poor sanitation on groundwater resources and the necessity of sanitation improvement in achieving Sustainable Development Goals in developing countries. Environ Toxicol Chem 2022;41:266-274. © 2021 SETAC.