Transforming Fecal Sludge into an Affordable Biofuel Alternative: A Sustainable Solution for Developing Countries

Justification In Sub-Saharan Africa, excreta and wastewater disposal is characterised primarily by on-site sanitation systems. This sanitation option is more likely to increase as governments, municipalities, communities, private operators and donor agencies strive to reach the Millennium Development Goals aimed at reducing by half the proportion of people without access to basic sanitation facilities. Due to increased urban population growth in Sub-Saharan Africa, the faecal sludge volumes will increase to alarming quantities in the coming decades. An evaluation of faecal sludge management practices reveals that the main shortcomings relate to the widespread lack of involvement and foresight by the municipalities, the paucity of effective legal provisions and organization, and the absence of stakeholder coordination. Stakeholder involvement for planning and implementing faecal sludge management is virtually inexistent or excluded from urban sanitation planning processes. In the majority of situations, faecal sludge management is financially not viable. This is a major cause of the indiscriminate dumping of faecal sludge in urban areas or its untreated use in urban agriculture. These practices not only pose permanent and serious health risks but also contaminate both scarce ground and surface water. Objective and general approach On the basis of these facts, which present a real challenge to sector specialists, the overall objective of our research is to develop an innovative strategic planning approach for sustainable faecal sludge management in urban areas which allows minimising public health and environmental risks. Focus is placed on developing a reproducible methodology for stakeholder involvement, on enhancing population awareness for improved faecal sludge disposal and attributing a leading role to the dynamic private faecal sludge emptying and transport operators. These aspects form the three pillars of our search for a comprehensive methodological approach. The municipality of Ouahigouya in Burkina Faso with a population of about 65'000 inhabitants was used as pilot site to launch, implement and scientifically validate the approach. Analysis and stakeholder involvement The stakeholder-based planning approach developed in Ouahigouya relies on a combination of stakeholder identification and analysis, and participatory planning techniques (focus groups, workshops, informal meetings, all-stakeholder workshops). A quantitative survey among households allowed collecting stakeholders' proposals and evaluating suggestions for improvement of faecal sludge management and neighbourhood hygiene proposed by the population. The main steps in the stakeholder involvement approach include: Jointly clarifying the objectives of the planning process together with the stakeholders; Identifying stakeholders and their interests; Classifying stakeholders according to their importance and influence based on defined criteria and confirmed by the stakeholders themselves; Identifying the interactions between the stakeholders; Verifying the results of the stakeholder analysis by the stakeholders themselves; Choosing stakeholder involvement techniques; Implementing the chosen method of stakeholder involvement: development of faecal sludge management scenarios, acceptance of the scenarios by the stakeholders in focus groups, choice and acceptance of a basic scenario for development of the future strategy in an all-stakeholder workshop; Evaluating the chosen involvement process by the stakeholders. The experience gained with the planning methods developed and implemented in Ouahigouya reveals that the "Stakeholder analysis" method is efficient and provides answers to questions such as: Who are the important and influential stakeholders? Who should participate in the planning process and in which manner? This experience also revealed the need for capacity building of certain stakeholder categories (emptying operators, women's associations, etc.) to increase their degree of involvement in the planning process. Improvement in stakeholder involvement was achieved thanks to a combination of workshops, focus groups and other informal meetings allowing less influential stakeholders (associations of local women, horticulturists, emptiers) to share information and to freely express their opinions and concern and to defend their interests. Thus, providing an excellent example of local democracy appreciated by all stakeholders of Ouahigouya. The approach developed provides tools for policy-makers and planners to ensure an effective stakeholder involvement in the process of developing a common vision and implementation of improved urban sanitation measures. The conditions for replicating the approach developed and tested in Ouahigouya are due to participatory democracy, great commitment of the local authorities and the high motivation of the stakeholders involved. Levers for the willingness-to-improve faecal sludge management and neighbourhood hygiene The evaluation method of the willingness to improve faecal sludge management by the population was based on a combination of the planned behavior model of Ajzen and the contingent valuation method, financial analysis of the pit emptying and faecal sludge enterprise, and on focus groups of stakeholders. By focusing on local practices, perceptions and individual behavior, this method revealed that financial viability – often reduced to willingness-to-pay – is not the only factor to consider when planning improvement of sanitation practices. Willingness-to-improve is highly dependant on psycho-sociological factors such as attitude towards and beliefs in an improved neighbourhood environment, social pressure on the households by the neighbourhood as well as the subjective costs and benefits expected from improved faecal sludge management. These factors therefore present levers allowing planners and decision-makers to encourage, increase and develop the demand for improved latrine emptying services, e.g. though social marketing. Promoting private entrepreneurs According to market analysis of emptying services and stakeholders involved, small private and mainly informal enterprises play a leading role in faecal sludge management in most cities of Sub-Saharan Africa. These operators, dynamic but fragile, require an appropriate institutional, jurisdictional and economic environment based on a balanced partnership between the municipality (public) and the private sector. Our study reveals that for a company truck to be profitable, about 1'000 trips per year (at 6'000 FCFA per trip) are required or the equivalent of a city of 56'000 inhabitants. In the case of Ouahigouya, profitability is increased if the emptying operators apply the latest management and professional tools and techniques, and manage to provide emptying services in neighbouring towns. Decision support tools The research led to developing decision support tools for professionals and policy-makers. These tools facilitate the development of a tariff-oriented policy to avoid uncontrolled faecal sludge discharge into the environment, to render investments by private operators profitable, and still make emptying services accessible to low-income households. This involves: Analysis of the cost structure of 3 pit emptying companies has revealed that fuel, maintenance/repair and personnel costs make up 45%, 20% and 30%, respectively, of an enterprise's operating expenses. An Excel programme was developed to allow municipalities and private operators to determine the operating costs of emptying services. This allowed to establish a sustainable money flux between the different stakeholders involved and to define the tariffs. To prevent faecal sludge discharges in the immediate residential environment or on unauthorised sites, it might under specific circumstances prove necessary and feasible to reimburse rather than charge entrepreneurs for delivering faecal sludge to the treatment sites, hence, create a strong incentive for good emptying and haulage practice. Evaluation methods of the sludge quantities to be disposed of have been developed to allow faecal sludge planning by the municipal authorities, assessment of the potential market and return on investment by the private operators. Advantages of the approach for the population of Ouahigouya Based on the results of our study, it was possible to formulate practical recommendations for the organisation of the urban sanitation sector for the municipality of Ouahigouya – now in possession of a sustainable faecal sludge management strategy. Our study has also contributed to promoting local consultation and raising the awareness of the role and contribution of each stakeholder group, in particular the previously neglected manual emptiers in their daily efforts to improve the living conditions of the urban inhabitants. The "Strategic Excreta and Wastewater Sanitation Plan", that was developed and supported by the "Office National de l'Eau et de l'Assainissement - National Water and Sanitation Agency", provides an excellent framework for the implementation of the elaborated faecal sludge management model (as part of the this strategic plan).

Rice husk and fecal sludge are significant waste management challenges in Ghana, often leading to sanitation and environmental issues. Given their complementary nutrient profiles (rice husk: potassium, organic carbon; fecal sludge: nitrogen, phosphorus), co-composting these bio-wastes presents a promising agricultural application. These biowastes, while rich in nutrients, can contribute to pollution when improperly managed. This study aimed to mitigate these issues by co-composting rice husk and fecal sludge to produce a nutrient-rich compost suitable for agricultural applications. This study aimed to optimize rice husk compost through co-composting with fecal sludge. A Completely Randomized Design (CRD) experiment was conducted at the University of Skill Training and Entrepreneurial Development (AAMUSTED) Mampong campus. Rice husk (R) and fecal sludge (F) were mixed in varying ratios (RF 1:0.5, 1:1, and 1:2) and subjected to aerobic composting. Results indicated that raw rice husk was nutrient-deficient compared to fecal sludge. However, co-composting significantly enhanced nutrient content. The RF 1:2 ratio yielded the highest total nitrogen (21,000 mg/kg), phosphorus (9,300 mg/kg), and mineralized nutrients. Pathogen reduction was also observed, with RF 1:2 demonstrating the lowest levels of total and fecal coliforms. Based on these findings, co-composting rice husk and fecal sludge in a 1:2 ratio is recommended for producing high-quality compost that can be used to improve agricultural productivity while mitigating waste management challenges.

Biofuel characteristics of non-charred briquettes from dried fecal sludge blended with food market waste: Suggesting a waste-to-biofuel enterprise as a win–win strategy to solve energy and sanitation problems in slums settlements

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

This study aims to evaluate the physical and thermal properties of briquettes made of faecal sludge (FS) charcoal. FS charcoal was produced by pyrolysis of the dry FS at 400°C and subsequently was briquetted with rice starch and different ratios of rice husk (RH) powder, corncob powder (CP), wheat powder (WP) and cow dung (CD). The ratios of FS charcoal and binding materials were chosen as 80 : 20, 75 : 25 and 70 : 30 for RH, CP and WP briquettes. For CD briquettes, the ratios were 70 : 30, 50 : 50 and 30 : 70. The bulk density and the compressive strength of all briquettes were in the ranges 1990–2150 kg/m3 and 172–815 kPa, respectively. The moisture contents of all briquette samples achieved 5–8%. The ash content in briquettes was comparatively higher, achieving 29–46%. The energy contents of all briquette samples were above 12.0 MJ/kg. The briquettes made of FS charcoal and CD were found to be suitable, having a low cost (US$0.18–0.28 per kg), sufficient compressive strength (>375 kPa) and desirable energy content (>13.40 MJ/kg). The FS charcoal briquettes showed a potential alternative to manage human waste for sustainable environmental protection.

Assessment of nutrient recovery, air emission and farmers’ perceptions of indigenous mound burning practice using animal and human wastes in Myanmar

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.

This work studied the effect of varying ratios of substrates on biogas production from rice husk and cow dung and was carried out using different slurry concentration of 1:4 and 1:12 solid to water ratios and monitored over 48 days. The results from daily production show that all the digesters started biogas production in day 1, with rice husk recording the highest biogas of (400 cm3), while most of the digesters recorded their highest biogas production in the early days. It was observed that rice husk stopped production in day 29 and 38 with biogas yield of 10 cm3 and 5 cm3 respectively. The weekly biogas production for the digesters in 1:4 and 1:12 ratios shows that hydrolysis of rice husk takes place faster than cow dung, were rice husk produces the highest biogas of (2190 cm3) in week 1 and rice husk plus cow dung with the highest biogas yield of (580 cm3) in week 4. It was also observed that only cow dung was producing biogas steadily at an average temperature of 35 °C. The effect of slurry concentration on the substrates used shows that; less dilute slurry is better for biogas production, D1>D4 and D2>D5 for Rice husk and cow dung respectively, while for the combination of rice husk and cow dung shows the reverse case D6>D3. proximate analysis shows the % moisture content for rice husk (10 %), cow dung (15 %) and %Organic matter content for rice husk (5 %), and cow dung (10 %), this indicates both samples can make a better substrate for biogas production with the trend cow dung > rice husk. From the search conducted, it may be concluded that slurry concentration plays a vital role in biogas production than substrate combination ratios with less slurry concentration showing a promising trend for optimum biogas yield as a sustainable energy sources.

In view of environmental problems generated by large-scale production of fly ash, increasing attention is now being paid to the recycling fly ash as a source of plant nutrients in agriculture. However, the low amount of nitrogen in such materials forms a major constraint for such application. In the present study, the possibility of improving the N status in mixtures of fly ash and organic matter was investigated by adopting vermicomposting technology. Different combinations of fly ash and cow (Bos taurus) dung; namely fly ash alone, cow dung alone and fly ash + cow dung at 1:1, 1:3 and 3:1 ratios were incubated with and without epigeic earthworms (Eisenia fetida) for 50 days. The occurrence of N in different bio-available forms; namely easily mineralizable, NH4+ and NO3- tended to increase considerably in the series treated with earthworms. This behaviour was attributed primarily to increased microbiological activity in the vermicomposted samples and also to a considerable rise in the concentration of nitrogen-fixing bacteria in this series. Among the three combinations of vermicomposted fly ash and cow dung, the 1:1 mixture appeared to exhibit the highest availability of nitrogen.

Lumpur tinja merupakan sumber pencemar yang mengandung padatan, material organik dan mikroorganisme patogen. Lumpur tinja memiliki karakteristik umum seperti TSS 4.000-100.000 mg/L, COD 20.000-50.000 mg/L, BOD5 6.000-7.600 mg/L, dan total coliform 105-1010 CFU/100 mL. Tangki septik kedap air merupakan salah satu solusi yang digunakan oleh masyarakat dalam pengolahan lumpur tinja. Tangki septik mengendapkan padatan dan mendegradasi lumpur tinja secara anaerobic, tetapi hasil degradasi masih mengandung zat organik maupun patogen yang membahayakan lingkungan. Salah satu unit pengolahan lumpur tinja dari tangki septik adalah Solid Separation Chamber (SSC) yang memisahkan padatan dan cairan. Proses di dalam unit SSC dipengaruhi oleh ketebalan lumpur, media filter, maupun konsentrasi TS. Hasil penelitian menunjukkan bahwa pada ketebalan 30 cm konsentrasi TS mempengaruhi proses di dalam unit SSC. Semakin besar konsentrasi TS yang masuk akan mempengaruhi besarnya filtrat yang dihasilkan dan penyisihan bahan organik, padatan tersuspensi, dan total coliform.

Approximately 75% of the Tanzanian population depends on inadequate sanitation management services, with urban areas facing significant challenges due to the improper handling of faecal sludge (FS), leading to contamination of water sources and a considerable public health risk. This trend is evident in Arusha City, where over 70% of the population relies on onsite sanitation systems, generating substantial quantities of FS that surpass the capacity of available treatment infrastructure. Given Arusha's status as a key tourist hub in Tanzania, improving faecal sludge management (FSM) is crucial for ensuring public health and environmental sustainability. This study examined the role of stakeholder engagement and social network mapping in enhancing FSM in urban settings, using Arusha City as a case study. Stakeholders involved in FSM were identified through key informant interviews, facilitated by the snowball sampling technique. The information gathered was supplemented by document reviews. Stakeholder influence and interest were analyzed using a ranking method in conjunction with a Power vs. Interest matrix, while social network relationships among stakeholders were visualized using Social Network Visualizer version 3.1 software. The results indicate that key stakeholders with significant power and interest (>80%) in FSM include the Ministry of Water (MoW), the President’s Office - Regional Administration and Local Government (PO-RALG), the Ministry of Health (MoH), the Ministry of Education (MoE), and the Ministry of Finance and Planning (MoF). However, the Arusha Urban Water and Sanitation Authority (AUWSA) and the Arusha City Council (ACC) are central institutions responsible for FSM within the city. Additionally, 97% of interlocutors highlighted the importance of effective social relationships among stakeholders for improving FSM outcomes. The study concludes that involving all relevant stakeholders in both the planning and project implementation promotes a sense of ownership and accountability, thereby enhancing the effectiveness of FSM initiatives and reducing the risk of misconduct.

This research tested the viability of using faecal sludge (FS) as solid fuel – an end use that could unlock an environmentally and financially beneficial replacement for disposal-oriented FS management, while replacing fossil energy. FS samples were collected from pit latrines, septic tanks, drying beds and stabilization ponds in three cities, Kumasi, Dakar and Kampala. For each sample, the average calorific value, solids and water content, and their variation with source and age were determined. The average calorific value of untreated FS across the three cities was 17.3 MJ/kg total solids (TS), which compares well with other biomass fuels. The age of FS did not affect its calorific value, nor did the reduction in chemical oxygen demand (COD) that occurred while it was in drying beds. The TS content of FS depended on its source but ranged from 1 to 6% for sludge from septic tanks and pit latrines, respectively. Harnessing net energy from FS requires partial drying. The results indicate that sufficient drying occurs within two weeks in open-air drying beds, or in a matter of days with simple drying bed innovations.

The present study investigated the optimum time and temperature for inactivation of bacteria and parasites in cow dung and pit faecal sludge, a forthcoming fertilizer. Samples were collected from different areas of Bangladesh and were examined through modified centrifugal flotation and conventional culture techniques to isolate parasites and bacteria respectively. A cow dung sample from Gopalganj and a pit sample from Dohar that were found to be the most contaminated among the samples tested were heated to annihilate the pathogens present there. After 30 min of exposure at 60°C, all bacteria lost their ability to grow on culture media except enterococci. Among the parasites found in the pit sample, Entamoeba histolytica was the least heat resistant, which was killed at 60°C within 30 min followed by Ancylostoma duodenale larva, Strongyloides stercoralis larva, Trichuris trichiura, Ancylostoma duodenale eggs and Strongyloides stercoralis egg. Ascaris lumbricoides and Hymenolepis nana were the most resistant to heat, inactivated at 75°C within 15 min. In cow dung, Paramphistomum was the most resistant, became inactivated at 65°C within 60 min whereas Haemonchus at 65°C within 30 min. The study findings showed the best time dependent temperature to deactivate the pathogens present in faecal sludge in Bangladesh context.

The study reports on the influence of nitrogen source on the biogas yield from cow (N'Dama) dung and rice husk. The digester performance for both feedstocks were evaluated using standard parameters such as; initial PH, water dilution, nitrogen source (guano and poultry droppings) and heavy metals. The source of innoculum used was cow rumen fluid. The result show that for feedstock to water dilution ratio of 1:6 w/v and initial pH of 7.0, the maximum biogas yield for rice husk was 430 mL/day and 350 mL/day for cow dung. The heavy metals (Ni2+ and Zn2+) increased the biogas yield while Fe2+ (100 ppm) shows no effect. Addition of guano results in maximum production rate of 85 mL/day and 60 mL/day in rice husk and cow dung respectively. The use of guano indicates more biogas production rate in both feedstocks compared to poultry droppings.

Valorization of faecal and sewage sludge via pyrolysis for application as crop organic fertilizer