On-site Sanitation Systems Research Articles

Being shown samples of composted, granulated faecal sludge strongly influences acceptability of its use in peri-urban subsistence agriculture

Using human excreta derived fertiliser (HEDF) in agriculture reduces dependence on diminishing phosphorus rock reserves, improves soil health, and facilitates sustainable nutrient recycling. Such schemes have particular scope for expansion in peri-urban areas of low-income countries, where large quantities of faecal sludge from on-site sanitation systems are available. However, public acceptability is a critical unknown factor. This study used surveys of 534 peri-urban subsistence farmers in Blantyre, Malawi, to investigate the public acceptability of HEDF. Two factors are highlighted as having a particularly strong association with acceptability: showing a sample of composted, granulated faecal sludge to participants at the start of the survey, and having heard of HEDF before. For instance, almost all participants who were shown the composted, granulated sample and had prior knowledge of HEDF were willing to buy maize grown in HEDF (96%). Conversely, less than a third of participants who had not heard of HEDF before and were not shown the composted, granulated sample were willing to do so (30%). Maize was the most widely accepted crop for use with HEDF, as there is perceived to be little contact between the edible parts and the ground. This suggests that HEDF has the potential to be widely accepted by subsistence maize farmers and the general public in Malawi. However, uptake rates could be substantially improved with public engagement campaigns involving demonstrations or samples of a visually appealing product, and by promoting the concept through channels such as farmer radio programmes or agricultural extension workers.

Comparative evaluation of urban versus agricultural nitrate sources and sinks in an unconfined aquifer by isotopic and multivariate analyses

Nitrate (NO3−) is one of the most widespread contaminants in groundwater primarily due to agricultural activities utilizing N-containing fertilizers and the presence of animal wastes. Hydrochemical and nitrate isotope data (δ15N-NO3− and δ18O-NO3−) from the unconfined aquifer in the urban area of Del Campillo city and its surrounding rural area with different land-use types, i.e. individual sanitation systems, agricultural areas and livestock breeding facilities, were generated to investigate the impact of nitrogen pollution sources and to assess N-biogeochemical processes. The Principal Component Analysis of hydrochemical and isotopic data were used to compare the factors that control the groundwater quality and particularly the nitrate concentrations in the urban and the rural area. The results showed that nitrate pollution in the urban area of Del Campillo city originated mainly from the on-site sanitation systems and/or animal domestic wastes, whereas in the rural area nitrate pollution was mostly attributed to a combination of urea-based fertilizers and manure from livestock breeding activities. The aquifer is under oxic to suboxic conditions in the rural area and becomes suboxic in the urban area where the higher supply of organic matter consumes oxygen. As a result, denitrification was more significant in the urban area compared to the rural area, as evidenced by the higher N and O isotope enrichment factor (ε). This work will be used to benchmark the current nitrate contamination status in the region and evaluate effective planning of environmental measures and remediation strategies.

Urbanisation and emerging economies: Issues and potential solutions for water and food security

Urbanisation will be one of the 21st century's most transformative trends. By 2050, it will increase from 55% to 68%, more than doubling the urban population in South Asia and Sub-Saharan Africa. Urbanisation has multifarious (positive as well as negative) impacts on the wellbeing of humans and the environment. The 17 UN Sustainable Development Goals (SDGs) form the blueprint to achieve a sustainable future for all. Clean Water and Sanitation is a specific goal (SDG 6) within the suite of 17 interconnected goals. Here we provide an overview of some of the challenges that urbanisation poses in relation to SDG 6, especially in developing economies. Worldwide, several cities are on the verge of water crisis. Water distribution to informal settlements or slums in megacities (e.g. >50% population in the megacities of India) is essentially non-existent and limits access to adequate safe water supply. Besides due to poor sewer connectivity in the emerging economies, there is a heavy reliance on septic tanks, and other on-site sanitation (OSS) system and by 2030, 4.9 billion people are expected to rely on OSS. About 62–93% of the urban population in Vietnam, Sri Lanka, the Philippines and Indonesia rely on septic tanks, where septage treatment is rare. Globally, over 80% of wastewater is released to the environment without adequate treatment. About 11% of all irrigated croplands is irrigated with such untreated or poorly treated wastewater. In addition to acute and chronic health effects, this also results in significant pollution of often-limited surface and groundwater resources in Sub-Saharan Africa and Asia. Direct and indirect water reuse plays a key role in global water and food security. Here we offer several suggestions to mitigate water and food insecurity in emerging economies.

Estimation of fuel potential of faecal sludge in a water scarce city, a case study of Jaipur Urban, India

Abstract Non-sewer sanitation systems are widely implemented for treatment and management of faecal sludge (FS) and septage in developing nations. India became an open defecation free (ODF) country in 2019, with more than 90 million toilets at rural and urban level constructed to achieve this ODF status. Government of India also initiated a faecal sludge and septage management (FSSM) policy in 2017. This paper highlights the policy vision for the state of Rajasthan and predicts options for a safely managed sanitation system through exploring the fuel potential of faecal sludge generated in the city. The intended study is an attempt to valorize faecal sludge into a marketable product through determining the heat capacity of dried faecal sludge from different sources such as pit toilets, septic tanks etc. In the present work in urban Jaipur, which is already a water scarce city, various onsite sanitation systems were targeted to collect FS samples from different locations. It was observed that the FS generated has a high heating value of 13.96 MJ/kg, with total solids ranges from 7 to 9%. For a pragmatic resource recovery option, the experimental data observed is validated with a literature review.

Economic analysis and probability of benefit of implementing onsite septic tank and resource-oriented sanitation systems in Seoul, South Korea

Abstract Most sanitation provisions cater to toilet infrastructures alone. Little consideration is given to requirements before and after toilets, such as the availability of water supply along with safe and sustainable methods for the disposal, treatment, and recycling of sanitary wastes after the toilet. Implementing communal onsite sanitation practices can be more feasible for societies suffering from a lack of adequate sanitation systems. This study presents a lifetime cost analysis of two onsite sanitation systems, one septic tank, and one resource-oriented sanitation (ROS) system. Both systems are considered to be implemented in a suburban area of Seoul to offer public hygiene services. The lifetime cost and probability of benefit were evaluated based on the capital, operation, maintenance, and disposal costs for one year. Results show that although the septic tank sanitation system requires a lower initial capital cost, its annual operation and maintenance costs are higher than the ROS systems’. The economic analysis shows how ignoring pre-toilet and post-toilet infrastructure can mislead the decision-making process by resulting in a higher capital and maintenance cost for the ROS system. Accordingly, the sanitation system should be considered not only to be a toilet but also to contain the required pre-toilet and post-toilet steps.

Evaluating the feasibility of human excreta-derived material for the production of hydroponically grown tomato plants - Part II: Growth and yield

Disposal of human excreta derived materials (HEDM), particularly domestic wastewater, presents a challenge in areas served with on-site sanitation systems, most particular in informal settlements. The use of HEDM for agricultural food production represents a couple of opportunities such as improved sanitation, household food security as well as the generation of informal income. In this study, tomato seedlings ‘Monica’ cv were grown in a hydroponic system and irrigated with HEDM (effluents from decentralized wastewater treatment system and nitrified urine concentrate). A commercial hydroponic fertilizer mixture was used concurrently as a control treatment. All the treatments were applied to the plants through fertigation using a drip irrigation system. Plant growth (plant height, stem diameter, leaf area index, root:shoot ratio and plant dry matter), physiological (photosynthesis and chlorophyll), yield components (fruit number, fruit mass, harvest index and crop yield), leaf nutrient composition (N, P, K, Mg, Ca, Cu, Mn, Fe, Zn and Na) and microbiological (Aerobic count, coliforms and faecal coliforms) parameters were measured to assess the potential of these HEDMs as nutrient sources for hydroponically produced tomatoes. The results showed that irrigating the tomatoes with HEDM increased harvest index relative to crops irrigated with a commercial hydroponic fertilizer mix. Tomato plants irrigated with a commercial hydroponic fertilizer mix achieved the highest growth and yield, however, irrigation with human excreta based sources improved plant physiological performance and leaf nutrient composition compared to crops irrigated with commercial fertilizer mix. In terms of microbiological analysis, tomatoes harvested from plants treated with HEDM recorded the highest population of bacterial count as compared to the commercial hydroponic fertilizer mix.These results showed that nutrients derived from human excreta can be a good source of nutrients for hydroponically grown tomatoes. Moreover this practice can effectively address the challenges of human waste disposal while at the same time providing the much-needed resources for increased food production through urban agriculture. However, further research on the effect of heavy metals, pathogens on tomato fruit quality is still needed for the adaptation of wastewater as nutrients sources for hydroponically grown tomatoes.

Scheduled Faecal Sludge Service (SFSS) for Sustainable Faecal Sludge Management in Cilacap

In accordance with the 6’th Sustainable Development Goals (SDG's), that ensurin availability and sustainable management of water and sanitation for all and with the launch of the 100-0-100 movement by Indonesian Government, which is a program to achieve the 100% accesss for water, 0% for slums, and 100% accesss to proper sanitation, Cilacap government need to work harder to achieve 100% accesss to proper sanitation especially in faecal sludge management that still needs to be improved. More than 98% households in Cilacap are using on-site sanitation system, without periodicaly emptied, and its causing problems in public health, and has impact for environmental and economic nearby communities. This study was held in Cilacap, a municipal in Central Java, Indonesia, using secondary data and literature review. This study aims to analyze feseability of the plan of implementation Scheduled Faecal Sludge Service (SFSS). Based on analysis, Cilacap are feasible to implementing SFSS as long as Cilacap could ensure to repair all gaps that shown in Gap analysis. Data of sludge service areas in cilacap, operating patterns, SFSS implementation procedures, and financial calculations must be made on preparation stage of SFSS.

A simple anaerobic and filtration combined system for domestic wastewater treatment

Anaerobic treatment of domestic wastewater can only partially treat the effluent and still contains concentration of organic matter, suspended solids, nutrients and pathogens beyond the recommended safe limit. This study aims to observe the effect of sand filter as a low cost post treatment solution. A 250 L pilot scale upflow anaerobic sludge blanket (UASB) reactor was fed septic tank effluent and operated at an average ambient temperature of 19 °C. The reactor was fed intermittently at 6 h hydraulic retention time and the performance was monitored. The UASB effluent was filtered in a 1 m3 sand filter unit. The removal efficiencies of Total Suspended Solid, Chemical Oxygen Demand and Faecal Coliform for combined system were 93%, 87% and 93%, respectively. However, the top layer of the sand in the filter needs to be replaced in every two to three months to maintain acceptable filtration capacity performance. The tested combined anaerobic and filtration system was sufficient to treat effluents from a typical Nepalese family and the result could be useful to design and develop a suitable compact, low cost onsite sanitation system in developing countries like Nepal. The result should encourage investigating on the establishment of a safe route of sand replacement and handling as well as alternative low cost filtration media in order to avoid frequent replacement of the sand.

Field testing of an onsite sanitation system on apartment building blackwater using biological treatment and electrochemical disinfection

Demonstration of an electrochemical toilet wastewater treatment and disinfection technology at the scale of an apartment building and translation of the system into a commercial product.

Innovative Approach for the Management of Faecal Sludge Accumulated in Ventilated Improved Pit Latrine: A Case Study of eThekwini Municipality in Durban South Africa

The provision of sustainable sanitation service to all South Africans has become one of the government national priorities. This is because the government recognizes that all citizens of the country has the right to basic sanitation that is affordable, appropriate, socially acceptable and sustainable in the long run. Ventilated Improved Pit latrines (VIP) has been considered to be the minimum acceptable level of sanitation service. However, the provision of appropriate sanitation service in the form of VIP latrines to all goes beyond building the toilets, plans should be put in place by municipalities are for adequate operation and maintenance of the toilets before and when the toilets reaches their capacity. Major challenges faced by many of this municipalities which is also common in many developing countries is that, this on-site sanitation systems eventually becomes full to their capacity and if there is no long-term maintenance plan in place, this system becomes unusable and eventually leaves the household without an effective basic sanitation system again. This paper present innovative approaches that have been considered for the operation and maintenance of Ventilated Improved Pit latrine in and around eThekwini Municipality in Durban, South Africa.

Quantification and characterization of faecal sludge from a tropical urban area: the case study of Douala, Cameroon

Faecal sludge (FS) management is a challenging problem in low-income countries where the majority of the urban population relies on on-site sanitation systems. The design of treatment plants relies on accurate knowledge on FS quantities and characteristics. Due to the lack of information on the quality and quantity of FS in the Cameroonian context, this study aims at evaluating the quantity and the quality of FS produced at the city scale by mechanical trucks at the dumping site of “Bois des singes” in Douala. Quantification was done through enumeration of emptying trucks and emptying truck capacities during one-week period while in the laboratory, analyses of composite samples were performed by the determination of physico-chemical, bacteriological and parasitological parameters in samples according to the standard protocols. Results on the quantification of FS in the city of Douala revealed that the weekly volume of faecal sludge dumped in natural environment at “ Bois de singe ” is estimated at about 2,890 m 3 with an average of 50 discharges per day by mechanical emptying trucks. Concerning the characterization of FS samples, FS exhibited high strength because of its higher concentration of organic, bacterial and helminth eggs loads. Therefore, there is need for proper health and environmental protection measures to prevent threats due to dumping of untreated faecal sludge into the environment after on-site sanitation technologies emptying by the construction of a treatment plant. © 2019 International Formulae Group. All rights reserved Keywords: Faecal sludge management, treatment plant, FS quantification, FS characterization, tropical urban area, Cameroon

Wastewater management in urban Bhutan: Assessing the current practices and challenges

This study reviews the current wastewater management practices and their challenges in urban Bhutan. The study data was collected from the local authorities of 35 classified towns, and the field survey was conducted for the two representative towns of Thimphu City and Khuruthang town. The study observed that only eight of the 35 classified towns (22.8%) have public sewerage systems, with an average coverage of 19.7% of Bhutan’s total urban population, or 7.4% of Bhutan’s entire population. The imported modular wastewater treatment technology was significantly more expensive than alternative options; however, approximately six towns have already adopted this technology, due to a lack of space for a much cheaper waste stabilisation ponds. Currently, over 80% of Bhutan’s urban population depends on the on-site sanitation system for their domestic wastewater disposal; however, over 40% of these properties lacked a soak-pit system for the safe disposal of septic tank effluent. Therefore, this study indicates that urban settlements in Bhutan are potentially subjected to overflow of significant amount of hazardous septic tank effluents directly into the environment posing significant risk to public and the environment. A critical urban plot space analysis indicates that the current system of on-site sanitation is inadequate and unsuitable for the current urban settings. Since it is impractical for the government to provide public sewerage system to all the towns, a low-cost public sewerage system, or an alternative and improved on-site treatment system, needs to be explored and promoted to achieve long-term environmental objectives.

Dynamics of nitrate degradation along an alternative latrine improved by a sawdust permeable reactive barrier (PRB) installed in an irregular settlement in the municipality of São Paulo (Brazil)

Nutrients, like nitrate and phosphate, and pathogens are the primary contaminants released into groundwater by on-site sanitation systems, which are an effluent disposal outcome for regions not covered by sanitation infrastructure, as periurban communities in developing countries. As appropriate setback distances between pit latrines and supply wells often cannot be met to avoid groundwater contamination, especially in a densely-populated situation, efficient, low-cost and accessible technologies are extremely necessary to protect water resources and surpass critical and persistent public health problems. This paper presents 1-year field-testing of an alternative latrine (AL) that incorporates two waste materials as permeable reactive barriers (PRB) in an irregular settlement at the municipality of São Paulo (Brazil). Basic oxygen furnace (BOF) slag in contact with wastewater effluent increases its pH level, which causes pathogens inactivation and phosphate adsorption. Sawdust under water saturation creates reducing conditions that encourage the growth of denitrifying bacteria that remove nitrate. A control latrine (CL) was constructed 90 m apart from AL with similar hydraulic characteristics and nonreactive materials for hydrochemical comparison. It was evident for AL the formation of well-defined nitrification and denitrification reaction zones, whereas CL overall presented nitrogen in its ammoniacal form, with incipient nitrate production at CL bottom, indicating that nitrification is probably boosted below that. BOF slag had attenuated microorganisms and phosphate almost completely, but nitrate removal average efficiency was 42%. The high pH effluent generated in BOF media may have also affected in the short-term the denitrifying bacteria in sawdust barrier 1 m below. The inverted position of the reactive barriers, i.e., sawdust PRB overlying BOF slag PRB, should be a more suitable design to achieve nitrate and pathogens removal. This kind of sanitation solution employing cheap and accessible waste materials have never been applied in the design proposed in this paper and also was a novelty for Brazilian context, proving to be a suitable technology to meet local needs.

Field performance of two on-site wastewater treatment systems using reactive media layers for nutrient and pathogen removal

Sparsely populated or peri-urban areas commonly lack access to public water supply and sewerage systems. The inhabitants must make use of excavated wells to meet their water needs and septic systems or pit latrines for domestic wastewater disposal, which can release pathogens and nutrients (nitrate and phosphate) into shallow groundwater. This study compares two on-site sanitation systems improved with permeable reactors for removal of nutrients and pathogens: a lateral flow design at Maryhill site (Canada) and a downflow design at Parelheiros site (Brazil). Both alternative latrines employed two reactive materials: BOF (Basic Oxygen Furnace) slag for pathogen removal and sawdust for nitrate removal. At Maryhill, the sawdust tank was emplaced before the BOF slag tank, and at Parelheiros, the BOF slag layer was emplaced before the sawdust layer. Maryhill latrine was able to oxidize up to 98% of ammonium to nitrate and to remove 99% of nitrate, phosphate, and E. coli from the effluent. Parelheiros latrine was more efficient in promoting nitrification, with almost complete ammonium oxidation, but nitrate removal by denitrification ranged between 13 and 57%, while phosphate and E. coli were completely removed. The BOF slag overlying sawdust layer in Parelheiros design may have negatively affected the performance in denitrifying bacteria due to the high pH created in BOF slag. The Maryhill latrine proved to be a more satisfactory design for nitrate removal. The combined use of sawdust and BOF slag in differing subsurface environments has shown considerable potential for mitigating impacts of on-site sanitation systems on groundwater.

Statistical analysis of the effluent quality of 231 on-site sanitation facilities in France monitored during a 6-year period.

On-site wastewater treatment systems are approved by the French regulation based on the results of platform tests following the European standard NF EN 12566-3. In addition to this approval for the treatment system, at least 90% of outlet concentrations have to be below 30 mg L-1 for total suspended solids (TSS) and 35 mg L-1 for biochemical oxygen demand. The aim of this study is to evaluate the effluent quality of these treatment systems on site, i.e. under real operating conditions, and to assess their performances. Between 2011 and 2016, 1,286 treated wastewater samples were taken from 231 on-site sanitation facilities in France. Data collected are heterogeneous and a robust statistical methodology (using a generalized log-linear model) was used to study the effects of four explanatory variables (treatment systems, loading rate, aging and sampling methods) on the distribution of treated wastewater concentrations. The model calculates median outlet concentrations depending on the effects identified. Its application allowed studying and comparing the outlet median concentrations of 21 on-site sanitation systems classified into nine categories and three groups. Four treatment systems out of the 21 monitored showed TSS median outlet concentrations below 10 mg L-1 and four treatment systems have TSS medians higher than the regulatory threshold of 30 mg L-1.

A Comprehensive Study on the Physicochemical Characteristics of Faecal Sludge in Greater Accra Region and Analysis of Its Potential Use as Feedstock for Green Energy

Design of treatment plants for faecal sludge management systems relies on a comprehensive accurate knowledge of FS (faecal sludge) characteristics, but this information is lacking. Developing countries like Ghana, where large proportion of the urban population (Accra) rely on onsite sanitation systems, face a lot of FSM (faecal sludge management) design challenges as a result of lack of a comprehensive study data on physicochemical characteristics of raw faecal sludge after primary dewatering. Achieving a fully operational FSM chain would imply a well understanding of the characteristics of the FS and its dynamics after primary dewatering. A study was carried out to determine the characteristics of faecal sludge brought to the Lavender Hill treatment plant, Accra Metropolis, and environs to ensure the treatability and uses of the products after treatment. The treatment plant receives an average of 150 trucks (1350m3) a day with 58% coming from private homes and 42% from public toilets. Composite samples were made from both public and private toilets facilities. Samples were taken from a reservoir holding faecal sludge from both public and private facilities, examined on daily basis and characterized. The values obtained showed high concentrations of BOD and COD values. The COD: BOD ratios showed that the faecal sludge is not stabilized yet and can be further degraded. The calorific value for the dry sludge was found to be 15.16-15.82 MJ/kg and 16.39–18.31 MJ/kg for the wet sludge. The calorific value of the sludge is adequate enough to be used as potential feedstock for green energy generation. The high concentrations of COD and organic matter of the faecal sludge make it suitable enough for biogas generation. A good correlation (r=0.909,R2=82.6%) between the calorific value and the TVS was found to be CV=0.122TVS+7.44. Heavy metal concentrations were low and satisfied the EPA Ghana guidelines for sludge. Thus products from the treatment can be used for agricultural purposes.

Evaluating the viability of establishing container-based sanitation in low-income settlements

Container-based sanitation (CBS) services operate in a number of low-income urban settlements across the globe, providing sanitation services where other on-site and off-site sanitation systems face logistical and environmental restrictions. The viability of each CBS service is influenced by a number of location specific factors. Drawing on an initial review of existing CBS services, this paper identifies and evaluates these factors in relation to establishing CBS in a new service location. By applying a weighted scoring matrix to these factors, the potential viability of CBS services has been assessed for urban informal settlements in Kathmandu Valley, Nepal. The viability of CBS services in these settlements was found to be most influenced by the current availability of basic sanitation facilities, the unfamiliarity with paying for sanitation services and the universally adopted practice of anal cleansing with water. The process and scoring matrix developed and subsequently applied in Nepal, are recommended as part of the pre-feasibility stage assessment where a CBS service is being considered as a sanitation option in new locations.

Material Flow Analysis as a Decision Supporting Tool for Faecal Sludge Resource Recovery: Mathematical Formulation and Quantification

In this work, a conceptual framework for faecal sludge (FS) management and resource recovery in Dar es Salaam city was developed. Material Flow Analysis (MFA) approach was used to assess and quantify the current materials and nutrients to support on decisions for nutrient recovery and minimize environmental pollution in three unplanned settlements of Manzese, Keko and Kipawa in Dar es Salaam city. Nitrogen and Phosphorus were chosen as indicators for the evaluation of the process. The results showed that about 75% of the Dar es Salaam city population relies on pit latrines and 15% connected to septic tanks, translating to a large amount of faecal sludge being contained onsite. The situational analysis study on faecal sludge management (FSM) showed that the collection, treatment and proper disposal of FS are the major challenges that pose risks to public health. Currently, 57% of faecal sludge generated in Dar es Salaam is disposed to the environment inappropriately. Onsite Sanitation Systems in all study areas are the main polluters, discharging large quantity of nutrients to the environment. About 37.7% of faecal sludge is with large amount of nutrients emptied from onsite sanitation systems discharged to the environment and through seepage to the groundwater.

Prevalence of water-related diseases and groundwater (drinking-water) contamination in the suburban municipality of Mont Ngafula, Kinshasa (Democratic Republic of the Congo)

An epidemiological survey conducted among users of water points and medical institutions in the N'djili Kilambu neighborhood of Kinshasa in Democratic Republic of the Congo, indicates that waterborne diseases have already affected more than 60% of the patients admitted to local clinics between 2013 and 2017. In order to raise public and political awareness about this hazardous health issue resulting from the lack of safely managed sanitation systems, this study investigates the microbial quality of drinking water from local water resources. Water samples were collected from nine wells and streams used as drinking sources, and analyzed for Fecal Indicator Bacteria (FIB), including Escherichia coli, Enterococcus, and Total Coliforms. Physicochemical parameters (pH, electrical conductivity, O2, and soluble ions (Na+, K+, PO43–, SO42–, NO3–, NO2–) were also analyzed. Except for NO3– and NO2–, the average concentrations of the physicochemical parameters and dissolved ions generally meet the guidelines for drinking/domestic water quality. By contrast, the results reveal high levels of FIB in the water samples collected during both dry and wet seasons. The contamination is significantly higher during the wet season compared to dry season, due to increased runoff, open defecation practices, and more frequent overflow of onsite sanitation systems and septic tanks.

Assessing the sustainability of on-site sanitation systems using multi-criteria analysis

Integrated approach to assess the sustainability of on-site sanitation systems.