On-site Sanitation Research Articles

Situational assessment for fecal sludge management in major cities of Pakistan.

With enhanced focus on global sanitation, access to toilets at the household level is increasing in developing countries although the provision of sewer networks is not expanding at the same pace. This is resulting in the adaptation of on-site sanitation facilities to contain the fecal sludge. The fecal sludge generated by the on-site sanitation facilities requires emptying, treatment, and safe end-use or disposal. In this study, the sanitation situation and need for fecal sludge management was evaluated in major cities of Pakistan including Karachi (provincial capital), Lahore (provincial capital), and Islamabad (national capital). Primary and secondary data were collected from key informant interviews of the stakeholders, national and international reports, research, and review articles. Infographics on wastewater and fecal sludge from origin to disposal were developed using a shit flow diagram tool and enabling environment was evaluated with a modified service delivery assessment tool. The results indicate that sewerage network coverage exists for 60%, 63%, and 50% of the areas in Karachi, Lahore, and Islamabad respectively. The sewerage network in major cities is old, leaking, and insufficient, thus a limited amount of wastewater reaches the treatment plants. Total wastewater treatment in Karachi and Islamabad is 10% and 9% respectively whereas, in Lahore, there is no infrastructure for the same. The safe sanitation in Lahore (8%) and Islamabad (25%) is coming from on-site sanitation systems with fecal sludge buried safely onsite. National level sanitation programs exist in the country but are limited to reducing open defecation and containments of fecal sludge only. The inclusion of complete fecal sludge management related framework, guidelines, and policies can help achieve the goal of safe sanitation for all.

Evaluation of an on-site sanitation intervention against childhood diarrhea and acute respiratory infection 1 to 3.5 years after implementation: Extended follow-up of a cluster-randomized controlled trial in rural Bangladesh.

Diarrhea and acute respiratory infection (ARI) are leading causes of death in children. The WASH Benefits Bangladesh trial implemented a multicomponent sanitation intervention that led to a 39% reduction in the prevalence of diarrhea among children and a 25% reduction for ARI, measured 1 to 2 years after intervention implementation. We measured longer-term intervention effects on these outcomes between 1 to 3.5 years after intervention implementation, including periods with differing intensity of behavioral promotion. WASH Benefits Bangladesh was a cluster-randomized controlled trial of water, sanitation, hygiene, and nutrition interventions (NCT01590095). The sanitation intervention included provision of or upgrades to improved latrines, sani-scoops for feces removal, children's potties, and in-person behavioral promotion. Promotion was intensive up to 2 years after intervention initiation, decreased in intensity between years 2 to 3, and stopped after 3 years. Access to and reported use of latrines was high in both arms, and latrine quality was significantly improved by the intervention, while use of child feces management tools was low. We enrolled a random subset of households from the sanitation and control arms into a longitudinal substudy, which measured child health with quarterly visits between 1 to 3.5 years after intervention implementation. The study period therefore included approximately 1 year of high-intensity promotion, 1 year of low-intensity promotion, and 6 months with no promotion. We assessed intervention effects on diarrhea and ARI prevalence among children <5 years through intention-to-treat analysis using generalized linear models with robust standard errors. Masking was not possible during data collection, but data analysis was masked. We enrolled 720 households (360 per arm) from the parent trial and made 9,800 child observations between June 2014 and December 2016. Over the entire study period, diarrheal prevalence was lower among children in the sanitation arm (11.9%) compared to the control arm (14.5%) (prevalence ratio [PR] = 0.81, 95% CI 0.66, 1.00, p = 0.05; prevalence difference [PD] = -0.027, 95% CI -0.053, 0, p = 0.05). ARI prevalence did not differ between sanitation (21.3%) and control (22.7%) arms (PR = 0.93, 95% CI 0.82, 1.05, p = 0.23; PD = -0.016, 95% CI -0.043, 0.010, p = 0.23). There were no significant differences in intervention effects between periods with high-intensity versus low-intensity/no promotion. Study limitations include use of caregiver-reported symptoms to define health outcomes and limited data collected after promotion ceased. The observed effect of the WASH Benefits Bangladesh sanitation intervention on diarrhea in children appeared to be sustained for at least 3.5 years after implementation, including 1.5 years after heavy promotion ceased. Existing latrine access was high in the study setting, suggesting that improving on-site latrine quality can deliver health benefits when latrine use practices are in place. Further work is needed to understand how latrine adoption can be achieved and sustained in settings with low existing access and how sanitation programs can adopt transformative approaches of excreta management, including safe disposal of child and animal feces, to generate a hygienic home environment. ClinicalTrials.gov; NCT01590095; https://clinicaltrials.gov/ct2/show/NCT01590095.

Physico-chemical properties of waste derived biochar from community scale faecal sludge treatment plants

Background: The dumping of untreated faecal sludge from non-sewered onsite sanitation facilities causes environmental pollution and exacerbates poor public health outcomes across developing nations. Long-term mechanisms to treat faecal sludge generated from these facilities are needed to resolve the global sanitation crisis and realize the Sustainable Development Goal (SDG) 6 “ensure availability and sustainable management of water and sanitation for all” by 2030. Pyrolysis of faecal sludge removes pathogens and generates biochar, which can be used as a soil enhancer. Methods: The properties of faecal sludge biochars from three full-scale treatment plants in India were determined via Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy dispersive x-ray (EDX) spectroscopy, crystal x-ray diffraction (XRD), proximate analyses, and BET surface area porosimetry. Results: Results showed that all three biochars had low specific surface area, high alkaline pH values, high ash content, and negative surface charge. Fourier transform infrared spectra showed the same surface functional groups present in each biochar. X-ray diffraction analysis showed the mineral composition of each biochar differed slightly. Scanning electron microscopy analysis indicated a porous structure of each biochar with ash particles evident. Conclusions: Slight differences in the ash content, surface area, pH and mineral content was observed between the three biochars.

Household waste management practices from the CGEDA / DST era at SGDS in Cotonou (Republic of Benin)

The problem of household waste management is acute in Cotonou. From the era of COGEDA / DST to SGDS, the unsanitary conditions of household living and neighborhoods are still noticeable. This work aims to describe the household waste management practices in Cotonou from the era of COGEDA / DST to SGDS. The method adopted consisted of conducting questionnaire surveys administered to households in the study area as well as interviews with institutional stakeholders in the management of DMS in Cotonou. At the end of the field work, it was noticed that in the era of COGEDA / DST 34% of households have trash cans, and only 16 % have their garbage removed by the NGOs / SMEs pre-collection of the DSM, against 78 % in the era of SGDS. Regarding the management of wastewater and excreta, nearly half of the households in Cotonou (45%) discharge their domestic wastewater in the courtyard of houses. On-site sanitation is the main mode of excreta collection, with ventilated pit latrines representing the largest percentage (56%). 93% of respondents believe that there is no policy for public sanitation. Hence the notorious insalubrity in certain districts of Cotonou subject to increasing environmental and health risks.

Elucidating the role of extracellular polymeric substances (EPS) in dewaterability of fecal sludge from onsite sanitation systems, and changes during anaerobic storage.

As the importance of fecal sludge management (FSM) is increasingly being realized, the need for adequately designed and functioning fecal sludge (FS) treatment plants is also increasing. Research to fill this gap is only emerging and dewatering is a key challenge for developing sustainable treatment solutions. This study evaluated the effect of extracellular polymeric substances (EPS) on dewaterability of FS, and how EPS and dewaterability change during anaerobic storage (as a proxy for time in onsite containment). EPS was extracted from FS and activated sludge using Na2CO3 and sonication and added to sludge samples to determine the effect on dewaterability. The results confirmed that an increase in EPS had a direct impact of decreasing FS dewaterability (as capillary suction time). In this context, we evaluated FS degradation during anaerobic storage, the effect of anaerobic storage time on EPS, EPS fractions and particle size distribution, and the effect of variations in these factors on FS dewaterability. Variations in EPS, EPS fraction and particle size distribution during anaerobic storage were less than expected and average VS reduction of 20% was recorded over 7 weeks. Although anaerobic digestion was verified (biogas production), the results indicate that kinetics of degradation of FS is different from wastewater sludges. Comparatively, EPS fractions in FS were 70 – 75% lower and with higher fractions of humic-like substances than wastewater sludges. Although EPS significantly affects FS dewaterability, anaerobic storage time is not a predictor of dewaterability.

A review of rural and peri-urban sanitation infrastructure in South-East Asia and the Western Pacific: Highlighting regional inequalities and limited data.

Rural and peri-urban communities in developing countries rely on sanitation systems which are often unsafely managed. One of the major barriers to assess safely managed sanitation is a lack of data about the existing sanitation infrastructure and levels of containment safety. The aim was to review rural and peri-urban on-site sanitation studies in order to understand different infrastructure types, associated management practices and any impacts on human health. The scope was limited to South-East Asia and Western Pacific regions in order to better identify regional inequalities. Among the 155 reviewed articles, 73 studies (47%) linked sanitation infrastructure to poor human health. Nearly all articles reported latrine ownership (n=149, 96%) while sanitation infrastructure types were covered less frequently (n=104, 67%). In particular, there was a lack of published literature describing back-end characteristics (dimension and materials) (n=12, 8%) and/or management practices (n=4, 3%). This stems from a limited application of research methodologies that characterise sanitation infrastructure and faecal sludge management (containment, emptying and on-site treatment). Inequality between regions was prevalent with three quarters of the studies on latrine back-end infrastructure from Bangladesh and India in South-East Asia. A strategic research approach is needed to address the current knowledge gaps regarding sanitation infrastructure and safe faecal sludge management.

Assessment of nitrate contamination and its factors in the urban area of Yogyakarta, Indonesia

Population growth in urban areas increases rapidly due to improving economic conditions. However, this growth is not always followed by the addition of public facilities such as clean water facilities and sewage water system networks, especially in developing countries. There are still many people who use on-site sanitation systems that will cause groundwater pollution problems. In addition, many people in urban areas still depend on groundwater for drinking water. The quality of groundwater becomes an essential factor for this purpose. One of the common groundwater problems in urban areas is nitrate concentration. Therefore, this study aimed to determine the potential groundwater contamination, the primary source of nitrate contamination in groundwater, and their influencing factor in the study area. The research method used the Cl/NO&lt;sub&gt;3&lt;/sub&gt; ratio and Cl/Br ratio to determine the source of nitrate in the study area. The groundwater contamination potential was evaluated based on depth to the groundwater table, sorption capacity above the groundwater table, permeability, groundwater table gradient, and horizontal distance from the contaminant source. In addition, the total of family members, age of the settlement, the distance of the well from the septic tank, and groundwater table depth were correlated with nitrate concentration. The results showed that nitrate levels in the research area generally exceed the maximum drinking water limit by WHO, with the maximum concentration reaching 167 mg/L. The high concentration of nitrate in the groundwater is due to contamination. According to the diagrams of nitrate versus chloride and the Cl/Br ratio analysis, the primary source of groundwater nitrate contamination is a septic tank. The higher family member and age of the settlement have a positive correlation with increasing nitrate concentration. Besides, distance from the septic tank and depth of the groundwater table is negatively correlated with nitrate concentration.

ONE WAY ANALYSIS OF VARIANCE OF CRITICAL PARAMETERSOF ON SITE SANITATION SYSTEM – A CASE STUDY

In the present study three periurban areas were selected to study the effect of onsite sanitation on borewell water quality. Bore well samples were collected from the peri urban areas and were analysed for critical onsite sanitation parameters like nitrate, chloride and total count. Minitabversion 17 was used to run One way Analysis of Variance (ANOVA) at 95% confidence interval. To determine the significance levels of parameters in both spatial (between bore wells and pitlatrines) and seasonal variations. In the study areas it was observed from one way analysis of variance test that chloride concentration varied with distance and season and was significant with both distance and season, while distance had highest significant effect. It was observed from the analysis of variance test that both season and distance has significant effect on nitrate concentration. Between the two, distance had higher significant effect when compared with season. Both season and distance had significant effect on total count concentration and was affected more by season than distance.

Wastewater-based epidemiological surveillance to monitor the prevalence of SARS-CoV-2 in developing countries with onsite sanitation facilities

Wastewater-based epidemiology (WBE) has emerged as a valuable approach for forecasting disease outbreaks in developed countries with a centralized sewage infrastructure. On the other hand, due to the absence of well-defined and systematic sewage networks, WBE is challenging to implement in developing countries like Bangladesh where most people live in rural areas. Identification of appropriate locations for rural Hotspot Based Sampling (HBS) and urban Drain Based Sampling (DBS) are critical to enable WBE based monitoring system. We investigated the best sampling locations from both urban and rural areas in Bangladesh after evaluating the sanitation infrastructure for forecasting COVID-19 prevalence. A total of 168 wastewater samples were collected from 14 districts of Bangladesh during each of the two peak pandemic seasons. RT-qPCR commercial kits were used to target ORF1ab and N genes. The presence of SARS-CoV-2 genetic materials was found in 98% (165/168) and 95% (160/168) wastewater samples in the first and second round sampling, respectively. Although wastewater effluents from both the marketplace and isolation center drains were found with the highest amount of genetic materials according to the mixed model, quantifiable SARS-CoV-2 RNAs were also identified in the other four sampling sites. Hence, wastewater samples of the marketplace in rural areas and isolation centers in urban areas can be considered the appropriate sampling sites to detect contagion hotspots. This is the first complete study to detect SARS-CoV-2 genetic components in wastewater samples collected from rural and urban areas for monitoring the COVID-19 pandemic. The results based on the study revealed a correlation between viral copy numbers in wastewater samples and SARS-CoV-2 positive cases reported by the Directorate General of Health Services (DGHS) as part of the national surveillance program for COVID-19 prevention. The findings of this study will help in setting strategies and guidelines for the selection of appropriate sampling sites, which will facilitate in development of comprehensive wastewater-based epidemiological systems for surveillance of rural and urban areas of low-income countries with inadequate sewage infrastructure.

Hydrogeology of an urban weathered basement aquifer in Kampala, Uganda

Weathered basement aquifers are vital sources of drinking water in Africa. In order to better understand their role in the urban water balance, in a weathered basement aquifer in Kampala, Uganda, this study installed a transect of monitoring piezometers, carried out spring flow and high-frequency groundwater level monitoring, slug tests and hydrochemical analyses, including stable isotopes and groundwater residence time indicators. Findings showed a typical weathered basement aquifer with a 20–50-m thickness. Groundwater recharge was 3–50 mm/year, occurring during sustained rainfall. Recharge to a deep groundwater system within the saprock was slow and prolonged, while recharge to the springs on the valley slopes was quick and episodic, responding rapidly to precipitation. Springs discharged shallow groundwater, mixed with wastewater infiltrating from onsite sanitation practices and contributions from the deeper aquifer and were characterised by low flow rates (< 0.001 m3/s), low pH (<5), high nitrate values (61–190 mg/L as NO3), and residence times of <30 years. The deeper groundwater system occurred in the saprolite/saprock, had low transmissivity (< 1 × 10−5 m2/s), lower nitrate values (<20 mg/L as NO3), pH 6–6.5 and longer residence times (40–60 years). Confined groundwater conditions in the valleys were created by the presence of clay-rich alluvium and gave rise to artesian conditions where groundwater had lower nitrate concentrations. The findings provide new insights into weathered basement aquifers in the urban tropics and show that small-scale abstractions are more sustainable in the deeper groundwater system in the valleys, where confined conditions are present.

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.

Application of Financial Flow Simulator (eSOSView™) for Analyzing Financial Viability and Developing a Sustainable Fecal Sludge Management Business Model in Kushtia, Bangladesh

To achieve SDG 6.2.1 (a) on safely managed sanitation services, several financial flow models (FFMs) and business models for the sanitation value chain have been implemented in Bangladesh and elsewhere; however, there is limited research on financial viability and sustainability of business models. Bangladesh has attained 99% sanitation coverage, mostly with onsite sanitation systems; however, the country is facing a second-generation sanitation challenge, fecal sludge management, encompassing the entire sanitation chain. Kushtia Municipality in Bangladesh is entirely served by onsite systems; the fecal sludge emptying service is provided by the municipality, and the fecal sludge treatment plant is managed by a private entity. This study investigated sustainability of FFMs in Kushtia by using the financial, institutional, environmental, technical, and social (FIETS) sustainability approach and applying the financial flow simulator (eSOSView™) tool to analyze financial viability. Several criteria in each aspect of the FIETS approach were developed, scored, and validated by stakeholders to determine sustainability. The study found that the financial aspect is the most important criteria for sustainability and “modified parallel tax and discharge fee” is the most sustainable business model for Kushtia.

Adequacy of vacuum and non-vacuum technologies for emptying faecal sludge from informal settlements of Kampala City

Over 90% of the population in Kampala Informal settlements is served by onsite sanitation facilities (septic tanks and pit latrines). These fill up fast, leaving emptying as the most viable option for their sustained reuse. This study fills the gap for the limited information about different emptying technologies suitable for informal settlements and limitations they face while carrying out operations. The study compared adequacy of vacuum and non-vacuum emptying technologies used in informal settlements of Kampala. 111 questionnaires (78 for vacuum and 33 for non-vacuum) were administered to obtain data about faecal sludge (FS) source and time estimates, while an additional 37 samples were used in characterising emptied FS. The results showed that FS emptied by vacuum trucks was 43.6% from lined pits, of which 28.2% are from informal settlements. 56.4% is emptied from septic tanks by vacuum technology, where informal settlements contribute 12.8%. FS emptied by non-vacuum technologies was 9.1% from lined pit latrines, 30.3% septic tanks and 60.6% unlined pit latrines (42.4% from informal settlements). Vacuum trucks of capacity 3.6 m3 were the mostly used in informal settlements, while large vacuum trucks (7.2–14 m3) exclusively operated outside informal settlements. The most critical event is the time spent during containment emptying, where non-vacuum can take up to 3 h and less than an hour for vacuum technologies. Such longer emptying times by non-vacuum technologies can be reduced through enforcing minimum standards of containment facilities and preventing dumping of solid wastes in pits. In addition, there is a need to sanction non-compliant operators in observation of PPEs and SOPs in order to improve their safety.

Barriers and Enablers to the Regulation of Sanitation Services: A Framework for Emptying and Transport Services in Sub-Saharan African Cities

Onsite sanitation is the dominant form of sanitation in Sub-Saharan African cities. Services for emptying the fecal sludge from these facilities and transporting it to safe disposal or treatment plants are crucial to public and environmental health. While these services are becoming increasingly regulated, implementation of the regulation remains a challenge. Through a multiple-case study anchored in the Contextual Interaction Theory, this research investigated the barriers and enablers to regulating emptying and transport services for fecal sludge. Looking at the cases of Kampala, Lusaka, and Freetown, this research found that both the content of the regulation and the regulatory process (initiation, creation or reform through to implementation) play a key role in the extent to which the regulation is or can be implemented. New elements relating to the knowledge, motivation, and resources of all stakeholders are identified as crucial to achieve regulated services. The findings have resulted in a framework that identifies the key elements to consider when regulating services. This framework would prove useful to practitioners and researchers engaged through all stages of creating, implementing, and evaluating regulatory practices.

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.

Antibiotics in shallow groundwater underlying urban informal settlements in developing countries: influence of on-site sanitation practices and risk assessment

ABSTRACT This study investigated the influence of on-site sanitation practices (OSS) on antibiotics in shallow groundwater underlying an informal settlement in Kampala City (Uganda) and the resulting antibiotic resistance risks. Ten antibiotics (including sulfonamides, fluoroquinolones, quinolones, penicillins and tetracyclines) were investigated in 17 groundwater sources in relation to physico-chemical and bacteriological water quality parameters. Seven antibiotics were detected, at a maximum total concentration of 1,400 ng/L during the dry season and 730 ng/L during the wet season. A significant positive correlation was observed between sulfathiazole and Escherichia coli (p < 0.001), supported by principal component analysis. Hierarchical cluster analysis showed grouping of antibiotics with parameters usually associated with OSS (E. coli, chlorides, nitrates, sodium and sulphates). Over 65% of the locations presented a high risk for antibiotic resistance during the dry season. This study showed that the population in informal settlements is exposed to a high risk of antibiotic resistance, influenced by OSS.

A review on decentralized wastewater treatment systems in India

Pollution of water resources and a lack of potable water are two important issues that city dwellers in India encounter. The passage of untreated sewage down municipal drains is one of the most significant sources of water resource pollution. In densely populated areas, effective sanitation and wastewater management is becoming increasingly difficult. In many developing nations, centralized sewage and wastewater treatment facilities serve only a section of big cities, and on-site sanitation is frequently insufficient in heavily populated areas. There is a demand for complementary and intermediate solutions. DEWATS (community-managed anaerobic decentralized wastewater treatment systems) is a good option for the possibility of relatively fast sanitation improvements in high-priority neighbourhoods where the local authority is not providing a full sanitation service. The following technical treatment modules are typically seen in DEWATS. The primary treatment consists of sedimentation ponds, settlers, septic tanks or bio digester, secondary treatment consists of anaerobic baffled reactors, anaerobic filters or anaerobic and facultative pond systems, secondary aerobic/facultative treatment consists of horizontal gravel filters and post-treatment consists of aerobic polishing ponds. The experience of India in establishing community-managed DEWATS on a large scale is examined in this review.

Convective drying kinetics of faecal sludge from VIP latrines

In striving to achieve sustainable sanitation, one challenge is to ensure hygienic treatment of faecal sludge from on-site sanitation. Thermal drying is an important treatment step for moisture removal and disinfection. Improved understanding of the drying process is crucial for the proper design of treatment technologies for faecal sludge. In this study, faecal sludge from ventilated improved pit (VIP) latrines from Durban, South Africa, were dried in a convective drying thermobalance by varying the temperature from 40 to 80 °C, the relative humidity from 0 to 25% and the air velocity from 0.3 to 1.2 mm/s. The faecal sludge samples were in the form of a thin layer and pellets with different diameters from 8 to 14 mm. Kinetic parameters were determined from the experimental data, were compared to classical drying models in literature and were then used to develop a correlative drying model.Drying rates ranged between 1 and 40 g/min/m2, leading to drying times comprised between 100 and 300 min. The drying kinetics increased as temperature was higher, and pellet diameter and relative humidity were lower. Temperature had the greatest influence on the drying kinetics (in both the constant and falling rate periods), followed by the effect of pellet diameter. The drying kinetics were affected in a moderate way by the relative humidity in the constant rate period and part of the falling rate period. The air velocity had a slight effect of drying kinetics during the constant rate period, but this becomes insignificant during the falling rate period. The effective diffusivities increased from 7.81 × 10−8 to 1.97 × 10−7 m2/s by increasing the temperature from 40° to 80 °C, leading to an activation energy of 23 kJ/mol. These values are typical from those found for wastewater sludge. The sludge exhibited a critical moisture content varying between 2.4 and 3.2 g/g db during drying without a clear trend as a function of the operating conditions and suggested that sludge was composed of considerably more bound moisture than unbound.The experimental data fitted the most closely to the Page model and, based on this, a new model was proposed for the prediction of drying times across the range of explored temperatures and pellet diameters in this study. The results of the proposed model fitted the experimental data with acceptable accuracy, so that the developed model could be employed as an analytical tool for the design, operation and optimisation of drying equipment.

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.&#x0D; 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.&#x0D; 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.&#x0D; 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.

Possibilities for changing to resource recovery in Kampala's on-site sanitation regime

Pressure is growing to develop innovative decentralized sanitation systems that protect public health and recover resources. This study evaluates the opportunities for niche technologies focusing on nutrient resource recovery to enter the market in Greater Kampala, Uganda. It applies methodology from sustainability transition studies in a novel way to provide new insights into possibilities for change in the on-site sanitation sector. The study 1) characterizes the existing socio-technical regime for on-site sanitation, 2) identify stress points in the regime and 3) possible advantages for the niches. Assessment of the regime covers technology, epistemic practice, sector values, organisational modes, policy and financing. The niches include urine diversion toilets, on-site resource recovery, and container-based models. The on-site sanitation regime is under performing and the niches all offer advantages for improved service and resource use. However, it will be difficult for the niches to break into a sector in which epistemic practice, organisational modes and financing are heavily dominated by the sewage regime. Recommendations for creating a more open environment for innovation are provided for specific stakeholders.