On-site Sanitation Research Articles

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.

Evidence-Based User Interface Sanitation Technology Selection for Urban Slums: A Multi-Criteria Analysis; The Case of Jimma Town, Ethiopia.

Slums are urban areas with insufficient public services and access to sanitation. Evidence-based selection of sustainable sanitation options is critical for addressing the sanitation crisis in slums. This mixed methods study was conducted in Jimma Town, southwest Ethiopia, to assess sanitation status and prioritize sustainable sanitation options for slums. The study was done in 2 phases: quantitative and qualitative. The quantitative cross-sectional household survey aimed to assess sanitation status and the qualitative exploratory method to explore alternative sanitation options and prioritize sustainable alternatives. A total of 310 households were chosen using systematic random sampling methods, of which 302 participated. Data was gathered through interviews, which were supplemented with questionnaires and observation checklists, and 2 focus group discussions (FGD) were held. First, FGD was with expertise in the sanitation sector, and the second was with community members. The state of sanitation was summarized, and multi-criteria analysis (MCA) was used to prioritize sustainable sanitation options. According to our findings, 68% of households had access to improved facilities, and 22.5% didn’t have any form of toilet facility. About 7 off-site and on-site user interface sanitation technology options were considered in the selection of alternative sanitation technologies, and each option was evaluated against 17 health, economic, social, technical, and environmental criteria. In the final analysis, the options with the highest scores for the setting were flush to septic tanks, compost toilets, and biogas toilets. Mobilizing such a promising sanitation option is recommended for future interventions.

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.

Effect of Ageing on the Physicochemical Properties of Human Faeces in the Context of Onsite Sanitation

Effect of Ageing on the Physicochemical Properties of Human Faeces in the Context of Onsite Sanitation

Addendum of data related to drying of faecal sludge from on-site sanitation facilities and fresh faeces

The present document consists of an addendum of data to the Handbook of Methods for Faecal Sludge Analysis. It is part of a project funded by the Bill & Melinda Gates (BMGF) through the OPP1164143, untitled “Characterization of faecal material during drying”. This project was granted for funding after the 5-years Transformative Technologies convening at the BMGF headquarters in 2016, where drying was recognized as a gap in the transformative technologies for the implementation of innovative sanitation technologies. The addendum of data compiles the results from experiments directly related to drying or having indirect implications in the process. The data was obtained from experimental work conducted from 2013 to date, and involving several research institutions. As the addendum of data is an initiative led by the Pollution Research Group at the University of KwaZulu-Natal, most of the data come from this research group. Partner institutions adhered to this initiative and shared their data, including: (i) Swansea University through the SPECIFIC research group; (ii) Cranfield University through their Bioenergy laboratory; (iii) Duke University through their WASH-AID centre; (iv) Laval University through their Civil and Water Engineering department; (v) Victoria University through their Public & Environmental Engineering laboratory; (vi) Swiss Federal Institute of Aquatic Science and Technology (EAWAG) through their Sanitation, Water and Solid Waste for Development (SANDEC) department. In the addendum, the data is organized in datasheets that are categorized in different thematics according to the content. In each datasheet, the data is displayed as graphs and includes an interpretation. In addition to this, the datasheets contain the basic information that is required to understand how the data was obtained, including the information about the feedstock, laboratory equipment, experimental conditions and performed analysis. The datasheets also offer the bibliographic references about where the results can be found in literature and the hyperlink to access to the raw files with the data. Moreover, this document includes a background with a landscape about faecal sludge drying, description of the fundamentals aspects from faecal sludge drying to understand better the significance and applicability of the data, and a summary of the analysis from results from the datasheets with their practical implications in the field. The datasheets were categorized into eight groups: thermodynamics, kinetics, physiochemical properties, morphology, mechanical properties, dewaterability, disinfection, gas emission. Different types of faecal samples were involved on the generation of the data: fresh faeces and faecal sludge from various types of onsite sanitation facilities, among which ventilated improved pit (VIP) latrines, urine diversion dry toilets (UDDT), anaerobic baffled reactor (ABR) from a decentralized wastewater treatment plant (DEWAT).

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.

Potential Use of Biochar in Pit Latrines as a Faecal Sludge Management Strategy to Reduce Water Resource Contaminations: A Review

Faecal sludge management (FSM) in most developing countries is still insufficient. Sanitation challenges within the sub-Saharan region have led to recurring epidemics of water- and sanitation-related diseases. The use of pit latrines has been recognised as an option for on-site sanitation purposes. However, there is also concern that pit latrine leachates may cause harm to human and ecological health. Integrated approaches for improved access to water and sanitation through proper faecal sludge management are needed to address these issues. Biochar a carbon-rich adsorbent produced from any organic biomass when integrated with soil can potentially reduce contamination. The incorporation of biochar in FSM studies has numerous benefits in the control of prospective contaminants (i.e., heavy metals and inorganic and organic pollutants). This review paper evaluated the potential use of biochar in FSM. It was shown from the reviewed articles that biochar is a viable option for faecal sludge management because of its ability to bind contaminants. Challenges and possible sustainable ways to incorporate biochar in pit latrine sludge management were also illustrated. Biochar use as a low-cost adsorbent in wastewater contaminant mitigation can improve the quality of water resources. Biochar-amended sludge can also be repurposed as a useful economical by-product.

Time and motion assessment of pit-emptying operations in Kigali, Rwanda

Abstract To ensure sanitation for all by 2030, fecal sludge collection services in low-income urban areas with no sewer connections need improvement. One of the major issues is the gap between low-income households' willingness to pay and the cost of emptying services in low-income areas. One way of lowering the cost of these services is through process optimization. In this regard, we conducted a time and motion study to better understand the bottlenecks associated with the collection of fecal waste from different types of on-site sanitation facilities. Our results show that emptying pit latrines, which make up 53% of the market for emptying services in Kigali, takes twice as long as emptying septic tanks. 33% of households that requested the service were located in an informal settlement with no access to road and could only be served by a semi-mechanized method which required use of barrels, and a portable pump. In general, interventions related to minimizing trash disposal in pits and septic tanks can go a long way in making the emptying process more time- and cost-efficient. Additionally, developing effective and efficient pumping technologies that are suitable for use in inaccessible areas should be prioritized.

Regulating sanitation services in sub-saharan africa: An overview of the regulation of emptying and transport of faecal sludge in 20 cities and its implementation

Onsite sanitation is widely used in Sub-Saharan African (SSA) cities. Safe transportation and emptying of the resulting faecal sludge are essential for healthy cities. Typically provided by an informal and unmonitored private sector, these services are being increasingly regulated. This research provides an overview of the regulatory mechanisms in place in 20 cities across SSA, their implementation and emerging common trends. Findings highlight the diversity of tools, mechanisms, and capabilities. We conclude that incremental and pragmatic change is needed to achieve fully regulated services, with adequate implementation particularly facilitated by support and incentive mechanisms, and participation of all stakeholders.

Faecal contamination pathways of shallow groundwater in low-income urban areas: implications for water resource planning and management

Abstract Shallow groundwater is vulnerable to faecal contamination, especially in low-income urban areas where use of on-site sanitation facilities is high. This paper explores statistical relationships between potential factors influencing contaminant pathways (i.e., variables) and observed faecal contamination of shallow groundwater, represented by nitrate concentrations and counts of Escherichia coli (i.e., response function) in a small, growing town in Uganda over dry and wet seasons in 2018 and 2019. A statistically significant (p = 0.004) multiple linear regression model from dry-season E. coli counts in 2018 identifies medium sanitary risk levels and modes of construction as significant pathways (p = 0.01). Water source depth (<20 m) and proximity (>10 m) to a pit latrine were also significant (p<0.05) in both hydrogeological formations. No significant linear regression models were established for NO3 during both seasons due to low pH and rapid infiltration velocities; inconsistent sample timing during the wet season impaired the significance of the statistical models of E. coli counts. We show that modes of construction of water sources and pit latrines play key roles in determining the quality of the shallow groundwater in urban environments. Greater emphasis is therefore required to improve the functionality and sustainability of on-site water sources and pit latrines.

Nitrate in groundwater of the west side Magelang Regency, Central Java, Indonesia

Nitrate (NO3-) pollution in groundwater is generally caused by chemical fertilizers from the agricultural sector and wastewater from onsite sanitation. Magelang Regency, Central Java, Indonesia, is a large food estate that has 206 km2 paddy fields. In addition, this area is inhabited by 1.3 million people who produce onsite sanitary waste every day. Due to the concentration and intensity of fertilization and sanitary waste, which are quite high, Magelang Regency is susceptible to groundwater pollution by nitrate. This study aims to determine the characteristics of nitrate in the groundwater of the west side Magelang Regency, Central Java, Indonesia. The research was carried out by testing groundwater samples taken from several springs, dug wells, and drilled wells used by society for their daily needs. Groundwater sampling was carried out in the wet season and tested using the ion chromatography method to determine the level of nitrate in groundwater and know the chemical characteristics to analyze dominant ions in groundwater. The results showed that the average nitrate was 3.9 mg/l; the deviation standard was 5.12; minimum nitrate was 0 mg/l; and maximum nitrat was 20.78 mg/l. The origin of nitrate content may come come from feces but still in small quantities. Facies of groundwater are Ca-HCO3 and Na-Cl. It can be concluded that the groundwater of the west side Magelang Regency is not yet polluted by nitrate. However, there is still a possibility in the future, so that necessary to apply for groundwater protection immediately.

Nitrate contamination level in groundwater of the randublatung basin and its surroundings

The community of Randublatung basin and its surroundings (Grobogan, Blora, and Bojonegoro Regencies) using groundwater for agricultural, farming, and daily needs. However, these activities can contaminate the groundwater through nitrate and chloride in fertilizers, pesticides, animal waste, and household waste. Therefore, it is crucial to know the amount of nitrate and chloride content in the groundwater of The Randublatung basin and its surroundings. This research aims to analyze nitrate and chloride content and the ratio between ions in the groundwater of The Randublatung basin and its surroundings to find contaminant resources. The method to analyze the nitrate and chloride content is using Ion Chromatography. The analysis result from 35 samples of groundwater shows that the average nitrate content in dug wells samples is 10.06 mg/L, while the average from pump wells is 6.31 mg/L. The average chloride in dug wells samples is 43.65 mg/L, and the average from pump wells is 54.57 mg/L. These nitrate and chloride level are still in safe category based on Health Ministry Indonesia and WHO. The nitrate: chloride ratio in dug wells is 1:5, 1:9 from pump wells. The ratios indicate that the nitrate’s resource is associated with the on-site sanitation and will increase if there is no mitigation action to the contaminant resource.

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.

Fecal Sludge Management in Low Income Settlements: Case Study of Nakuru, Kenya.

Introduction: In order to meet the sustainable development goals targets of sanitation, countries aim to increase access to safely managed sanitation services for its citizens. Safely managed sanitation services refers to improved sanitation technologies that are not shared with other households and where excreta is treated and disposed; or stored, transported and treated off-site. In most Sub-Saharan Africa (SSA) countries, on-site sanitation facilities such as latrines and septic tanks are common, with low-income urban settlements mainly using pit latrines. However, little is documented about the management of sludge from these facilities, especially in low income settlements in secondary and emerging cities. This lack of data is a major hindrance to public health, development and planning efforts by governments and planning agencies. This study specifically assesses practices and challenges along the sanitation value chain related to containment, emptying, transportation, treatment and recycling of fecal sludge.Methods: The study was carried out in low income settlements in Nakuru, a secondary city in Kenya. Over half the population in Nakuru live in low income areas and majority of these residents use pit latrines. A case study design was selected for this study and data was collected using qualitative methods. Data was collected through In-depth interviews and Focus Group Discussions using in depth interview guide and focus group discussion guides that had questions on sanitation practices along the value chain, challenges, opportunities available, and recommendations for improvement. Analysis was done through content analysis by reading the transcripts multiple times to gain a sense of the flow of the discussion. Thereafter, coding was done by following emergent issues and thereafter categories were identified which formed the basis for providing a picture of FWM practices in the settlements.Results: On site sanitation facilities are dominant in the settlements, but they are few and are shared by several households. These facilities were unclean, and they filled up at a fast rate because of the high number of users. The latrines were emptied by manual emptiers who used mechanized equipment but complemented with manual emptying using buckets. Sludge was transported to a central collection point using large and small scale means of transportation, before transfer to the treatment site for final treatment and disposal. Various stakeholders are involved in capacity building of emptiers as well as in the transportation, treatment and disposal of fecal sludge in the settlements. Challenges along the stages of the value chain included negative community perceptions and attitudes toward fecal sludge management.Conclusion: The results highlight the need to address the challenges along the chain by involvement of state and non-state actors. Low income areas have high populations and thus contribute huge amounts of fecal sludge. Deliberate efforts to consolidate such data from low income areas will result in availability of data, and informed decision making for stakeholders at national and international levels.

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.

Assessing inter and intra-variation in the characteristics of faecal sludge from Vadgaon Maval, Maharashtra: For better faecal sludge management in India

Faecal Sludge (FS) produced in developing countries has become a significant source of water pollution. The optimal treatment of FS can lead to a sustainable economy. In India, the second phase of the open defecation free (ODF) initiative (energy recovery by providing city- or town-level centralised FS treatment plants) has begun from 2019 to sustain millions of toilets. However, to achieve this goal, India must address significant knowledge gaps such as the type of available on-site sanitation treatments (OSTs), optimal time of emptying the OSTs, and variations in the FS characteristics with age. Thus, the present study analysed FS samples collected from Vadgaon Maval, Maharashtra, India, to understand the inter- and intra-variation in FS characteristics. The pH, electrical conductivity, total solids (TS), specific gravity (SG), organic matter (OM), chemical oxygen demand (COD), and pathogen content of FS samples were observed to be in the range of 7–7.65, 1.19–4.01 mS/cm, 1–123 g/L, 0.88–1.26, 18.4%–100%, 960–6080 mg/L, and 105–109 number/L of FS, respectively. The inter-variation of FS characteristics exhibited that the pH, EC, TS, and SG increased, whereas OM, settling, and drying capacity decreased with an increase in age. Fresh FS (excreta degraded for ≤3 years) was yellowish-brown in colour and exhibited low TS, low SG, and high OM. On the other hand, older FS (excreta degraded for >3 years) was blackish-brown in colour and exhibited high TS, SG, and pathogen content. This observation indicates that FS vacuum pumping may be difficult in the sludge zone after 3 years of excreta degradation, which may encourage the manual scavenging practice. Additionally, the analysis of FS treatment plant (FSTP) process control parameters (settled sludge volume, sludge volume index, and sludge drying capacity) indicated that the treatment time required for older FS is long, which increases the FSTP cost. Furthermore, FS intra-variation in OST exhibited that effluent FS could be directly sent for effluent treatment without any solid–liquid separation process. Thus, the present study can help practitioners in establishing or modifying FS treatment systems for addressing conditions based on the variation in FS characteristics at the town level in India.

Inhibition of ammonia and hydrogen sulphide as faecal sludge odour control in dry sanitation toilet facilities using plant waste materials

On-site dry sanitation facilities, although cheaper than wet sanitation systems, suffer from high malodour and insect nuisance as well as poor aesthetics. The high odour deters users from utilizing dry sanitation toilets as an improved facility leading to over 20% open defecation in Sub-Saharan Africa. To address this malodour concern, this study first assessed odour levels, using hydrogen sulphide (H2S) and ammonia (NH3) as indicators, on two dry sanitation facilities named T1 and T2. The potential of using biomass (sawdust, rice husk, moringa leaves, neem seeds), ash (coconut husk, cocoa husk) or biochar (sawdust, rice husk, bamboo) as biocovers to remove or suppress odour from fresh faecal sludge (FS) over a 12-day period was investigated. Results showed that the odour levels for H2S in both T1 (3.17 ppm) and T2 (0.22 ppm) were above the threshold limit of 0.05 ppm, for unpleasantness in humans and vice versa for NH3 odour levels (T1 = 6.88 ppm; T2 = 3.16 ppm; threshold limit = 30 ppm limit). The biomasses exhibited low pH (acidic = 5–7) whereas the biochars and ashes had higher pHs (basic = 8–13). Basic biocovers were more effective at H2S emission reduction (80.9% to 96.2%) than acidic biocovers. The effect of pH on suppression of NH3 was determined to be statistically insignificant at 95% confidence limit. In terms of H2S and NH3 removal, sawdust biochar was the most effective biocover with odour abatement values of 96.2% and 74.7%, respectively. The results suggest that biochar produced from locally available waste plant-based materials, like sawdust, can serve as a cost-effective and sustainable way to effectively combat odour-related issues associated with dry sanitation facilities to help stop open defecation.