- Human waste contains significant amounts of organic material that can be digested by specific bacteria in oxygen-free environments.
- The byproducts from this digestion process can be used as energy for cooking, lighting, and generating electricity.
- Revenue or savings from the sale or use of these products provides financing to pay back up-front capital costs.
Access to sanitation has proved to be one of the toughest nuts to crack in international development, as evidenced by the fact that the Millennium Development Goal (MDG) target for sanitation, to reduce the number of people in low and middle-income countries without access to adequate sanitation by 50 percent, was the furthest off track of any MDG at the end of 2015. Slightly less than one billion people around the world practice open defecation—that is, they do not use any toilet facilities—and 2.4 billion do not have access to improved sanitation facilities.1 This has environmental, social, and economic implications. Environmental implications are a result of pathogens and nutrients in feces, which are aesthetically unpleasant and contaminate water sources. In large water bodies, these nutrients cause eutrophication, an overgrowth of algae that eventually deoxygenates the water, leaving it as a dead zone for fish and other aquatic animals. This ‘dead zone’ is referred to as hypoxia, which is increasing in lakes and oceans because of sewage contamination, in addition to agricultural runoff and water temperature changes linked to climate change.2 Social impacts include lack of dignity, respect, and safety, particularly for women and girls. The lack of toilets appropriate for menstrual hygiene in schools means that post-pubescent girls and female teachers can be absent up to one week every month, affecting their educational achievement. For 650 million people around the world without access to improved drinking water sources, or the almost two billion without access to potable water,1,3 pathogens in water cause significant burdens of diarrheal and nematode diseases that affect cognitive and physical development in young children, affecting school attendance, individual productivity (whether at school or work), and creating a preventable burden on the healthcare system. As a result, economic costs have been estimated at USD$260 billion annually (1.5 percent of global GDP) in the countries that are most significantly affected by lack of sanitation.4
There are three main reasons for lagging progress towards the 2015 MDG sanitation target: 1) sanitation and managing bodily wastes is not appealing to some donors who would prefer to invest in "sexier" development infrastructure;5 2) many national governments cannot afford to invest in scaling up sanitation at the level required to meet this target; and 3) sanitation is not simply an infrastructure issue but also a behavior change issue, and 4) large gaps exist between data on access to and use of toilet facilities. A final challenge in providing sanitation facilities is what to do with the end product—human waste, consisting of urine and fecal sludge. Urine contains large amounts of nitrogen, phosphorous, and potassium. When diluted, it makes an excellent fertilizer and is ready to use fairly quickly, as it contains few, if any, pathogens. The problem here lies in separating urine from the fecal sludge, and one solution is to separate the two at the source. EcoSan (ecological sanitation) toilets use this principle of urine diversion to maximize the use of both urine and fecal sludge. Fecal sludge is also high in nutrients, but most pathogens in human waste are shed through it, making it extremely dangerous to human health when first excreted. In EcoSan solutions, this solid waste is captured and stored for several months, with a significant period of this time spent out in the sun in order to kill off pathogens through heat and solar processes. After this process is complete, the waste product is used as fertilizer. To reduce health concerns, the World Health Organization (WHO), as well as many countries have guidelines and laws on pathogen levels for human-waste fertilizer and the types of crops that can be grown with it. While pathogens can be removed, heavy metals and chemical contaminants, which can be mixed with human waste in some wastewater effluents, are more difficult to remove, and become an additional threat to human health.
A Proven Solution
Anaerobic digestion (AD) is a technology that has been commercialized for decades. Many large urban centers in Europe and North America use AD in municipal wastewater treatment plants. The process of AD is relatively straightforward: waste is captured in a sealed container that prevents any oxygen from entering, thus creating anaerobic conditions. The waste is then broken down (digested) by bacteria that flourish in these oxygen-free environments. The by-products of this process are a gas that is approximately 60 to 70 percent methane (biogas) and a liquid slurry that is high in nutrients and low in pathogens. In large municipal treatment plants, the gas is used to generate electricity in order to offset the energy costs associated with treatment. More and more, this type of technology is being developed for household use, particularly in small rural communities where families raise cows and grow crops. In this context, animal manure is utilized as the primary feedstock for AD, and the gas produced is used directly for cooking and lighting, replacing wood-based fuels, while the slurry is used to fertilize crops.
Several countries in Asia have embarked on large-scale programs for biogas production, including China, India, and Nepal.5 These systems vary in size from small household AD units to large-scale units that use a variety of feedstocks as a source of biomass. The development of the biogas sector in Nepal is particularly instructive.5 With financial support from the Netherlands Directorate-General for International Cooperation, a Biogas Support Program was started in Nepal in 1992. In the beginning, there was only one, state-owned company producing biogas and only one state-owned financial institution providing loans to biogas entrepreneurs. However, by the end of 2007, over 180,000 units had been installed in Nepal, attributable to the following developments:
- Establishment of the Nepal Biogas Promotion Association in 1994 to promote commercial interests
- Establishment of an apex body under the Ministry of Science and Technology in 1996 to support biogas and other alternative energy applications in Nepal at a policy level
- More than 60 qualified private biogas installation companies operating by the end of 2007
- 15 qualified biogas appliances manufacturers
- 120 financial institutions (in addition to the state-owned bank) deliver loans to biogas entrepreneurs
- 30 local and international nongovernmental organizations (NGOs) promoting biogas technologies in Nepal
In India, biogas plants are set up at the domestic (family) level, community level, and in large industrial facilities. Feedstocks vary from animal manure and food waste (used primarily in family units), to agriculture and forestry waste, food processing waste, and municipal wastewater. By 2010, 4.3 million small domestic biogas plants (1–10 m3) had been set up in India under the National Biogas Manure Management Program.7 Also by 2010, there were 14 large biogas fertilizer plants operating in India, collectively producing more than 23,000 m3 of biogas per day.6 This represents an energy equivalent of 138,000 kWh per day. A portion of this energy is lost when converted to electricity, but according to the World Energy Council, global average annual household consumption is just over 3,000 kWh. Even if two-thirds of energy is lost in converting to electricity, the daily capacity will satisfy annual demand for 30 average households. In countries with the lowest annual energy demand, such as Nepal, it would satisfy annual demand for more than 300 households. Biogas generation in India is augmented by over 200 community-based public toilet biogas plants of intermediate size that are currently operating in India that were commissioned by Sulabh International.5 The "Sulabh Model" is an intermediate capacity biogas plant (35–60 m3) that uses human fecal material as the primary feedstock.
While AD has proven successful in Asia, the story is different in Africa. A review of biogas generation facilities in Africa indicates that while there are small-scale biogas systems in many African countries, a relatively small proportion of these are operational.8 There are large-scale biogas generation facilities (i.e. >100 m3) with a high level of technology development in a small number of sub-Saharan African countries, including Burundi, Kenya, Mali, Rwanda, Tanzania, and South Africa. These AD systems utilize a variety of feedstocks, including slaughterhouse waste, waste from sugar factories, water hyacinths, animal dung, and human fecal waste. Medium-scale biodigestors have been installed in chicken and dairy farms in Burundi, a public latrine block in Kibera, Kenya, prisons in Rwanda, and health clinics and hospitals in Tanzania. Some of the challenges to biogas commercialization in Africa include the following:7
- Lack of experienced contractors and consultants for construction, operation, maintenance, and repair
- Lack of reliable information to reduce investment risks for financial institutions
- Absence of resources and supporting infrastructure (academic, bureaucratic, legislative, and commercial)
- Lack of community acceptance and responsible ownership
- Lack of appropriate government energy policies to support the sector
- Lack of pilot, demonstration, and full-scale systems
Thus, notwithstanding technical capacity, it appears that the keys to success in the biogas sector are not based on technology alone, but are dependent on having the right organizational, financial, and governance structures in place to support the development of the sector. Affordability was a key barrier addressed in India through multiple options to secure loans, which has not been replicated in Africa. Both financial and technical capacities require government interventions that do not appear to have been as concerted in Africa to date.
The Uganda Context
In Uganda, about 80 percent of the population lives in rural areas, and more than 70 percent of the national disease burden results from diseases linked to poor sanitation and hygiene.8 This is tied to the fact that 70 percent of Ugandans do not have access to proper toilet facilities. Diarrhea associated with this lack of sanitation kills approximately 23,000 Ugandans every year, with 85 percent being children under five years of age.1 In addition, more than 90 percent of the citizens of Uganda use wood, charcoal, or animal dung for cooking and heating, which contributes to high rates of pneumonia and acute respiratory infections—additional child killers.9 The annual social and health care costs associated with poor sanitation in Uganda are estimated to be 389 billion Ugandan shillings or USD$177 million.10
A lack of toilets and wastewater treatment also results in poor water quality in lakes and rivers. This threatens improvements in drinking water access, especially for Ugandans who depend on untreated sources for domestic needs. Meanwhile, tree cover reduction to create firewood and charcoal and increased land area under agricultural cultivation continues in Uganda at unsustainable rates, further affecting water quality as well as degrading soils. In a country where more than three quarters of the population depend on agriculture for their main source of livelihood,11 this threatens health and financial wellbeing as well as the environment.
A critical barrier to progress is the insufficient funding currently available to achieve both the MDG targets (and therefore universal access to drinking water and sanitation as called for under the proposed Sustainable Development Goals) and National Development Plan objectives, especially given rapid population growth.10 In order to increase access to drinking water and sanitation facilities, the Ministry of Water and Environment in Uganda is encouraging the implementation of community self-supply models, wherein management of the water and/or sanitation facilities is borne by the community. However, even when management is devolved to the community, finding sufficient funds for upfront capital costs can be prohibitive to national governments and rural communities alike.
Waste to Wealth
To address these issues, Waste to Wealth is a Ugandan initiative created in partnership with the Ministry of Water and Environment, its water and wastewater utility (the National Water and Sewerage Corporation), and other government, NGO, and academic partners. The concept is simple—to use modern bioenergy technologies to convert human and other organic wastes into resources that will provide economic benefits and improved environment and human health. The biogas and slurry left from energy conversion will be used as a resource with economic value to provide a return on the investment in AD technology. The concept is an innovative and transformative technology-based approach to managing human wastes and providing sanitation services in low income countries. The approach is innovative because it harnesses the revenue from waste by-products to finance the operation, maintenance, and expansion of sanitation services. Further, it is transformative because it involves the creation of a new national economic sector through multistakeholder collaboration using technologies that have been tested and proven in other developing countries. A recent application to assess the global value in waste calculated that the energy from the annual waste of those practicing open defecation alone (2.4 billion people) would be sufficient to power 10 million homes for a year, and is valued at more than USD$200 million (natural gas equivalent on the global market).12
One potential barrier to uptake of AD byproduct use, particularly when the feedstock is human waste, is the associated "yuck" factor, a fear of food contamination, and cultural taboos. In a limited survey conducted by UNU–INWEH within a cross-section of the public in the Lyantonde District of Uganda, about 40 percent of respondents did not own their own sanitation or toilet facilities. Among the respondents, there was interest in using a community-based sanitation facility, especially if access was provided for free, and even more so if the users received residue byproducts (e.g. briquettes and fertilizer/compost) as a benefit of using the facility. The respondents also expressed a strong interest in producing the byproducts as a source of employment. It is not clear whether there would be widespread acceptance by the public for the use of the dried slurry as a solid fuel. There was initial skepticism among respondents about the use of the solid byproducts from AD, but acceptance improved once safety issues were directly addressed by the interviewer. Any marketing strategy for the residual byproducts of biogas production would thus have to include a public education component to ensure acceptance of the products.
Currently, the partners are working to catalyze the development of the Ugandan water and sanitation subsector implementation of the national decentralized (on site) fecal waste management framework in order to contribute to bridging the finance gap for sanitation. Ultimately, it is anticipated that the initiative will progress to the development of a decentralized system for wastewater management and sanitation in Uganda that will require little direct government investment.
A Business Opportunity
The business opportunities for the bioenergy sector are varied, depending upon the feedstocks that are available for use in bioenergy conversion, the size of the AD facilities, the level of investment in infrastructure, and access to markets. For instance, entrepreneurs could use relatively small AD systems to produce biogas from human waste that generates electricity for charging cell phones or car batteries on a local fee-for-service basis. Entrepreneurs or community cooperatives that have access to investment capital could develop larger AD systems that use human waste, food waste, industrial waste (e.g. brewery or dairy waste), and animal waste to generate sufficient amounts of biogas to purify, compress, and bottle for distribution to markets far from the site of generation. The economic benefits of AD systems at large institutions would mainly be from offsets against the costs of fuel and electricity within the facilities.
The business case for marketing of the residual slurry also varies, depending upon the AD generation scenario. The simplest business opportunity is to sell residual material for use as fertilizer on agricultural land, but this market generates little revenue and there are cultural barriers to the use of this resource. With an additional investment in infrastructure, the residue can be dried and pressed into solid fuel briquettes that could then be used for industrial purposes (e.g. brick making) or as an alternative to charcoal or wood for domestic cooking and heating.
Currently, based on established business models (Table 1), there is ongoing pre-development for pilot-scale facilities at three locations in Uganda, which will demonstrate the range of business opportunities that can be exploited as well as the economic feasibility of these strategies. However, the scope of business opportunities within the sector will ultimately be driven by the creativity, drive, and business acumen of the entrepreneurial sector within Uganda.
When human waste is broken down through the anaerobic digestion process, the resulting energy and fertilizer products possess more than simply financial value. While the financial value drives the innovation-in-sanitation business models, it is the accrual of additional environmental, health, and economic benefits (Figure 1) that makes this a truly sustainable development solution. Benefits include the following:
- Green energy, reduced greenhouse gas emissions, and a reduced dependency on wood fuels
- Improved soil quality and crop productivity through use of the slurry as fertilizer
- A cleaner environment and healthier people through proper disposal of human waste
The resulting revenue and health benefits increase economic productivity and also relieve burdens currently placed on women, including vulnerabilities associated with finding a safe and dignified location to relieve themselves. The bottom line is that, through Waste to Wealth, we can catalyze and finance social development and economic growth through implementation of AD as a sector response to current challenges facing Uganda and other countries (Figure 1).
Anaerobic digestion, as a source of renewable energy and fertilizer products, is seen to be part of the solution to the linked problems associated with sanitation, energy, and agriculture. In this manner, we see AD as a solution for rural growth areas and small towns—a modular, decentralized approach to providing sanitation facilities, incentivizing the use and maintenance of those facilities, and providing livelihood opportunities in these settings. More importantly, Waste to Wealth is a business case demonstration of integrated sustainable development implementation under Agenda 2030, balancing and benefitting the three P's of a green economy—people, profit (economy), and planet (environment). It is a strategy to improve energy security and waste management while reducing environmental degradation. The benefits to Uganda include improved community health, environment, and economy, and income-generating opportunities.
This paper would not have been possible without financial support from a Government of Canada-funded Grand Challenges Canada Rising Stars in Global Health award. The authors thank Chris Wild for his help in business plan development and Sena Amewu and others for their reviews of the original manuscript.
- UNICEF and WHO. Progress on sanitation and drinking water: 2015 update and MDG Assessment [online] (2015) http://www.wssinfo.org/fileadmin/user_upload/resources/JMP-Update-report....
- Scientific and Technical Advisory Panel. Hypoxia and nutrient reduction in the coastal zone: advice for prevention, remediation and research [online] (2011) https://www.thegef.org/gef/sites/thegef.org/files/publication/STAP_Hypox....
- Onda, K., J. LoBuglio and J. Bartram. Global access to safe water: accounting for water quality and the resulting impact on MDG progress. World Health & Population 14(3), 32–44 (2013) (doi:10.12927/whp.2013.23437).
- Water and Sanitation Program. Economics of Sanitation Initiative [online] (2012) http://www.wsp.org/content/economic-impacts-sanitation#top.
- Harvey, F. Donor aversion to 'unsexy' water projects threatens development goal. The Guardian [online] (2011) http://www.theguardian.com/global-development/poverty-matters/2011/jun/2....
- Sharma, S. and A. Sanghal. Rapid market assessment: waste-derived energy products. Emergent Ventures (2013) (doi: 10.13140/RG.2.1.1335.3129).
- Amigun, B., W. Parawira, J.K. Musango, A.O. Aboyade and A.S. Badmos, in Biogas (ed. Kumar, S.) Ch. 2 (InTech, Croatia, 2012).
- Government of the Republic of Uganda. Uganda Vision 2040 [online] (2014) http://npa.ug/wp-content/themes/npatheme/documents/vision2040.pdf.
- Okello, C., S. Pindozzi, S. Faugno and L. Boccia. Development of bioenergy technologies in Uganda: a review of progress. Renewable and Sustainable Energy Reviews 18, 55–63 (2013).
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- FAO. Uganda and FAO: building resilience and food and nutrition security [online] (2015) http://www.fao.org/3/a-au755e.pdf.
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