Water Hyacinth E. crassipes
SUSTAINABLE STRATEGIES FOR URBAN WASTE
Introduction Sanitation development projects have the potential to be a decentralised and low-technology intervention, yet problems are often encountered when it comes to the management and financing of the construction and ongoing use of the infrastructure. Given these limitations of ‘front-end’ user-targeted programs, which also tend to be expensive and technically difficult to introduce, this paper will investigate and present cases where existing approaches to waste treatment and reuse have been successful and sustainable. The examples present ‘bottom up’ economic and social strategies which could be applied in both poorer and more developed economies. In rapidly growing urban areas, international development funding is generally aligned towards expensive and technically complex back-end projects. Furthermore, in prioritising spending on development projects to attract international investment, local governments may place low priority on providing infrastructure in poorer urban areas, meaning many parts of cities miss out on sanitation provision. When addressing the overall sustainability of urban sanitation systems, Balkema, Preisiga, Otterpohlb and Lamberta argue that: “…probably the most important question today is whether it is possible to attain more sustainable urban water management through improving the existing centralised systems or whether it is necessary to switch to new decentralised systems. 1” There may be advantages both to decentralized or centralized systems, or a hybrid of the two, when it comes to social and financial sustainability. This paper will discuss how examples of both centralized and decentralized systems at different scales have managed to operate sustainably, and what might be a possible system for more extensive adaptation in urban areas. Centralised systems Some of the problems with associated with conventional sewer disposal systems begin from their very conceptual basis in the desire to remove waste materials from the city using clean water. Among various other factors, this turn of events was linked to the development of industrial (chemical) farming and the ability to pump large volumes of water. In an account of colonial
Balkema Annelies J., Preisiga Heinz A., Otterpohlb Ralf and Lamberta Fred J. D., ‘Indicators for the sustainability assessment of wastewater treatment systems’ Alastair Upton MUNDUS URBANO Technische Universität Darmstadt 2011
development in Kenya, Nilsson 2 describes the process by which a centralised water supply system, installed initially, created the demand for waste water and sewage removal systems. Traditional methods of rainwater harvesting and collection of ‘night soil’ to be used in agriculture were not considered as avenues for development as there conflicts with the collector’s health, and altogether with the making of the city’s ‘modern’ image. We can now say that the main drawbacks of the water-borne waste system are their expensiveness to build and run, and the wastefulness of their method of conveying waste with water. This process removes nutrients from the food production cycle, which has in turn led to the prevalence of chemical fertilizers in industrial food production. These fertilisers are very intensive to manufacture and create downstream ecological impacts. They also offer few benefits of nutrient re-use at the ‘end of the pipe’, for two main reasons: “Even where sewage sludge is put to agricultural use only a small fraction of the nutrients are reintroduced into the living soil layer. Most are either destroyed (e.g. nitrogen elimination) or enter the water balance, where they pollute the environment. … Frequently, the use of sewage sludge from central wastewater systems is also restricted as it contains too high a concentration of heavy metals and other hazardous substances, often as a result of intermixing household with commercial/industrial wastewater and with rainwater from contaminated streets. 3” Integrating Reuse into Centralised Systems Currently, wastewater is reused in the growing of an estimated 10% of the world’s food. It is either used directly from sewer systems or from waterways containing sewage 4. Growers who can utilise waste water are at advantage to their mainstream irrigating competitors in the dry season. Wastewater can in some cases be an opportunistic strategy – for example where piped infrastructure has failed or where waterways are used as final disposable points, it can also form a highly sophisticated and planned part of a re-use scheme. In Kolkata, India, Dr N. C. Nandeesha studied fish farms - ‘bheries’ - which form a vital part of the wastewater treatment system. It is an end of pipe solution as a part of a centralised system, and it is self-sustaining. There are a variety of levels of productive output and social organisation implicated in the bheries, with few other inputs other than human labour and fish seed stocks. Wastewater is treated using solar energy to remove most pathogens 5. The nutrient-rich sludge are then fed into a rotational fish pond which sustains a large population of operators, fish seed growers, fishers, delivery persons and vendors in the city of Kolkata, whose population relies on them as a food source. The operation is managed by farming collectives, who sustain reasonable working conditions for their 2
Nilsson, David ‘A heritage of unsustainability? Reviewing the origin of the large-scale water and sanitation system in Kampala’, Uganda Environment and Urbanization 2006, pg 377 3 Schlick Jana, Werner Christine, ‘ecosan –– Introduction of closed-loop approaches in wastewater management and sanitation –– a new supra-regional GTZ – project’ Gesellschaft für Technische Zusammenarbeit Eschborn 2002 pg 2 4 Parkinson, Jonathan and Tayler, Kevin, ‘Decentralized wastewater management in peri-urban areas in lowincome countries’ Environment and Urbanization 2003 15: 75 5 Nandeesha, Dr. M.C, ‘Sewage Fed Aquaculture Systems of Kolkata A Century-old Innovation of Farmers’, Aquaculture Asia, April-June 2002 (Vol. VII No. 2) pg 28 Alastair Upton MUNDUS URBANO Technische Universität Darmstadt 2011
members. The fish farms are operational almost year-round, and can yield up to 5 tonnes of fish per hectare per year. Once water has been used for farming fish, it is channelled into food growing areas where the nutrients from the fish faeces fertilise yet more food crops. It is then released almost completely clean into the river system. Dykes separating ponds are used to filter the water and grow food trees. Plant species such as water hyacinth grow quickly in the wastewater and are used as a nutrient transfer and detoxification system when harvested to compost on agricultural land 6. One drawback is that the bheries themselves are a very low density and land hungry operation: one farm Dr Nandeesha studied employed 200 employees on an area of 120 hectares; that is less than two persons per hectare. Other disadvantages include potential poor health effects of contamination from heavy metals due to mixing of storm water with sewage and industrial wastes, which may find their way into the food chain. However, when one considers the scale and variety of productivity of the ponds, the ecological and climatic benefit to the city and waterways, and the number of ‘downstream’ means of economic activity they generate, they form a remarkable and sustainable part of Kolkata’s economy. At the same time they perform a vital sanitation service for the city free of cost. Many cities dedicate large areas of peri-urban or rural land to waste treatment facilities which could be converted at least in part to emulate bheries. Decentralised strategies Around the world, neoliberalisation of economic governance has led to the weakening of the role of governments in basic service provision. Further, many governments lack the governance ability to manage or extend sanitation systems to large areas of cities. In many places, the World Bank has backed policies of decentralization and privatization to counter this trend, relying instead on private investment in the marketplace of infrastructure provision, a system that has been shown to work very poorly or not at all in many cases 7. Alternative models which are managed in a decentralized way do exist; however, as seen in Burra, Patel and Kerr’s description of the difficulties and successes in establishing community run sanitation facilities in various cities throughout India. They detail the experiences of communities who mobilized in the form of women’s groups to provide themselves with community-managed toilet blocks. These were successful where outside funded or pay-and-use systems had proved too expensive. The authors point out the difficulty in getting noticed or securing funding when proposing such projects: “When women’s groups suggested improvements to municipalities, they were laughed at….International donors were approached for support but they lacked the mechanisms to fund such a project. Accepting these kinds of solutions is never easy for official donors, in part because the projects are so simple and so cheap. 8” Furthermore, projects which were funded and built by the government were implemented 6
Ibid. cit. pg 30
Castro, José Esteban ‘Neoliberal water and sanitation policies as a failed development strategy: lessons from developing countries’ Progress in Development Studies 2008 vol 8, pg 65 8 Burra Sundar, Patel Sheela and Kerr Thomas, ‘Community-designed, built and managed toilet blocks in Indian cities’ Environment and Urbanization 2003 15: 11 pg 12 Alastair Upton MUNDUS URBANO Technische Universität Darmstadt 2011
without any form of community involvement, and with the government showing reluctance to maintain them. In fact, the communities even had to pay extra to for cleaners already paid by the municipality. This led to toilet blocks falling into disuse 9. The communities found success where they had a say in the physical design of facilities, could design the payment and maintenance system, and could secure small and unconditional loans from donor charities. These toilets still needed to be connected to a centralised system and therefore required the cooperation, engineering capacity and goodwill of the municipality, something that was not always available 10. It is clear from the examples described above that the operation and maintenance of sanitation systems can be problematic, but there are other alternative decentralized and financially autonomous modes. Ashley Murray and Isha Ray note that: “[t]he key to incorporating back-end users into the long-term O&M plan of a sanitation facility is, of course, designing sanitation schemes for reuse. To capture back-end user demand requires targeting potential customers before the system is designed and tailoring sanitation schemes such that the outputs meet the specific needs of those customers in terms of their final location, quality, and state. 11” By experimenting with decentralized ‘pit’ or composting toilet systems, researchers and NGOs have explored the ways sanitation by-products can be seen as profitable commodities such as fertilizers or biofuels, which provide cheap and available alternatives to chemical fertilizers and non-renewable fuel sources. A successful example of this is the Sulabh International system of twin-pit toilets installed in several Indian cities, which are used to generate biogas and fertilizer with very sound economic benefits 12. Conclusion What could be drawn from these examples? It is clear that to be successful there needs to be a sound social and economic integration into the urban setting. Any alternative sanitation strategies will be difficult to implement, and due social and political unwillingness to address alternatives to waterborne waste treatment systems, innovation may be difficult. “A lack of local knowledge with respect to different wastewater treatment technologies and their end-products, and thus a tendency to choose those that are known, calls for decision-making 13.” The case for alternatives may yet be stronger if knowledge about potential economic benefits was more widely available. Technical or infrastructural integration is perhaps not so important in the case of decentralised systems, where networks of supply and distribution of newly valorised products could be largely 9
Burra Sundar, Patel Sheela and Kerr Thomas, ‘Community-designed, built and managed toilet blocks in Indian cities’ Environment and Urbanization 2003 15: 11 pg 12 10 Ibid. Cit. pg 18. 11 Murray, Ashley and Ray, Isha Back-End Users: ‘The Unrecognized Stakeholders in Demand-Driven Sanitation’, Journal of Planning Education and Research 2010 30: 98 12 http://www.sulabhinternational.org/st/economic_environmentalbenefit_sulabh_technologies.php: accessed 29 Nov 2010 13 Murray, Ashley and Ray, Isha Back-End Users: ‘The Unrecognized Stakeholders in Demand-Driven Sanitation’, Journal of Planning Education and Research 2010 30: 98 Alastair Upton MUNDUS URBANO Technische Universität Darmstadt 2011
informal. Opposing this there are barriers to social acceptance of human waste, and it is also clear that projects need to be scaled and to the specific conditions they are addressing. Privatisation of services can be successful in the form of local collectives, down-the line commodity production and the use of cooperatives. These can be more effective than simple privatised back-end service provision. Significant technical barriers exist to front-end separation systems, but a creative combination of centralised and decentralised treatment methods may begin to overcome this trend. While highly sophisticated technical options exist, more attention needs to be paid to the ways waste can be reinterpreted in the urban society and economy, and how simple synergies between systems such as those in the examples can help to overcome other urban resource problems. Therefore the realignment of planning of the technical social and economic dimensions of waste is vital in the success of financially viable sanitation systems.
Alastair Upton MUNDUS URBANO Technische Universit채t Darmstadt 2011
Sanitation development projects have the potential to be decentralised and low-technology interventions, yet problems are often encountered...
Published on Feb 9, 2012
Sanitation development projects have the potential to be decentralised and low-technology interventions, yet problems are often encountered...