A SINGLE COPY OF THIS ARTICLE MAY BE DOWNLOADED FOR PERSONAL AND NGO USE. THE DISTRIBUTION OF MULTIPLE COPIES, OR ANY COMMERCIAL USE, MAY RESULT IN A COPYRIGHT VIOLATION. PLEASE TAKE CARE TO CITE THE SOURCE WHEN USING ANY OF THE MATERIAL.

THANK YOU

REUSE OF WASTE FOR FOOD PRODUCTION IN ASIAN CITIES:
HEALTH AND ECONOMIC PERSPECTIVES

Dr. Christine Furedy, Urban Studies Program, York University
Dr. Virginia Maclaren, Department of Geography, University of Toronto
Emeritus Professor Joseph Whitney, Department of Geography, University of Toronto

Abstract

Asian communities have many practices of reusing organic wastes in agriculture and aquaculture, even in urban areas, in a sustainable manner. Improvements in organic waste reuse in the context of modern urbanization requires attention to health and economic considerations. This paper discusses these aspects of the reuse of organics from municipal wastes in South and Southeast Asia, referring to some recent research and projects in Bangkok, Bandung, Bangalore, Hanoi, Ho Chi Minh City, Jakarta and Manila. The major theme of this paper is that an important constraint on the reuse of organic wastes is contamination that has both health and economic impacts. The paper suggests strategies for minimizing these constraints to improve the marketability of organic wastes.

KEYWORDS: South Asia, Southeast Asia, organic waste, wastewater, organic waste recycling, composting, aquaculture, waste reuse, urban agriculture, health risks, contamination, source separation, economic viability.

A. Introduction

Food production based on the principles of sustainable development in and around cities can be enhanced if the nutrients and organic residues resulting from urban consumption can be safely reused. There is a substantial interest in linking waste management and sustainable food production: municipal waste managers have for decades hoped that composting could reduce the costs of waste disposal, while current proponents of urban agriculture mention the potential of composting urban organics for application to urban and peri-urban plots or using human excreta in fish farming (Smit et al. 1996 ; Hart, ‘t and Pluijmers 1996; Lardinois and van de Klundert 1993; van der Bliek 1992).

Although reliable comparative studies have not been done, it is clear that the organic portion of municipal solid wastes in most Asian cities is relatively high even today, averaging well over 50% in most cases (see Stentiford et al. 1996). Traditionally, substantial amounts of wastes (including human excreta) have been diverted for use in farming and aquaculture. These practices have been supported by factors such as: diversity in farming in and around cities, large numbers of poor farmers, scarcity and expense of chemical fertilizers, and peri-urban farmers' ready access to urban garbage (due to casual supervision of solid waste transportation and disposal). Municipal authorities have often endorsed waste reuse (cf. investments in compost plants in most metropolitan cities, 1970s-1990s)(see Jalan et al. 1995; Stentiford et al. 1996).

Waste reuse in agriculture is everywhere under-researched, but, considering how widespread waste reuse is in the region, the paucity of research (as against merely observational) data for Asian cities is notable. Furthermore, apart from projects on waste-fed aquaculture (cf., Edwards & Pullin 1990; Edwards 1992), there are few projects supported by international agencies, especially for South and Southeast Asia. This paper briefly discusses health concerns and economic viability, two aspects that are thought to provide constraints on waste reuse in urban agriculture (WRUA). The urban wastes referred to here are: the organics in municipal waste streams, human and animal excreta, and wastewaters and sewage sludges. The discussion is of municipal wastes rather than commercial wastes that are sold for processing.

B. Waste reuse practices in South and Southeast Asian cities

The table (bottom of page) summarizes the main practices of waste reuse in urban agriculture (WRUA) in developing countries. Almost every conceivable reuse of organics from urban consumption can be found in Asia. In both South and Southeast Asia, large and small peri-urban integrated farming systems using wastes are found. Fish farms draw on human and animal excreta; rice, vegetable and fruit tree cultivation are irrigated with wastewaters, and livestock and poultry derive some feed from aquatic plants grown in wastewaters (see Ghosh 1990; Edwards & Pullin 1990; Edwards 1996b). Urban areas can be ranked along a continuum from intensive to restricted waste-reusing economies. In places ranked at the intense end, traditions of reuse persist, supported by low wages for agricultural labour, scarcity of chemical fertilizers, easy access to organic wastes, the acceptability (if only to certain social groups) of waste handling, and little concern about health risks (e.g., Calcutta). In restricted reuse economies, contamination of organics, availability of chemical fertilizers, transportation expense, and labour costs have led to a decline in traditional reuse practices and a concomitant increase in solid wastes requiring disposal (e.g., Bangkok). International health research is raising awareness about health risks associated with waste reuse. Regulations may be enacted, particularly in rapidly changing societies, that may limit WRUA.

C. Areas of Concern

To persist in the vicinity of large cities, WRUA must ultimately be economical, safe and acceptable (to urban authorities, farmers/farm workers, and the public). Currently, economic factors affecting the availability and cost of inputs (chemical fertilizers, organic wastes, water, labour) are more important in the persistence or decline of WRUA than public health considerations. Better urban management, higher levels of education, and more international attention to occupational health and consumer safety will, however, increase attention to the health aspects of reusing urban organic wastes and human excreta or sewage.

i) Health Concerns

Health concerns are always mentioned in discussions of waste reuse (see Smit et. al., 1996; Lardinois & van de Klundert 1993; Hart, ‘t and Pluijmers 1996; Furedy 1996; Cointreau-Levine et al. 1997; Edwards 1992, 1996a; Allison & Harris 1996; Khouri et al. 1994, Mara and Cairncross 1989; Shuval 1996). While the general health risks for both wastewater reuse and organic wastes are well known (see below), only in wastewater irrigation and waste-fed aquaculture has there been any substantial environmental health research (Mexico, Indonesia, Israel, Pakistan: Shuval 1996; Blumenthal et al. 1989,1991; Vietnam: Edwards 1996b). There is very little health risk research for organic solid waste reuse in developing countries. Among the possible reasons for this may be that: the extent of waste reuse is not known; disease outbreaks can rarely be traced to specific practices; there are few experts able to do the research; and developing countries have many other health research targets.

Multiple health problems can occur when mixed solid wastes are processed, human excreta is applied to fruit and vegetable farms and wastewaters are used for irrigation or fish farming. Pathogens, viruses, and parasites in wastes can cause enteric infections, helminthic infestation, and skin ulcers. Fish farmers using sewage can be exposed to the whole range of water-borne diseases. Poor management of compost piles increases disease-causing vectors. Particulates and gases are responsible for chronic bronchitis, TB, dysentery, chronic cough, headaches, and cancers. Leachates may increase the mobility of heavy metals (Olaniya and Bhide 1995). Workers are exposed to sharps such as glass splinters in compost. Handlers and consumers of produce can be affected by crop contamination disease links such as diarrhea from faecal matter in wastewater irrigation and cancers from heavy metal take up by crops via soil or wastewater. The food chain path of transmission is also involved when animal-feeding disease links occur ( e.g., enteric infections, whipworm infestation, "mad cow disease" linked to feed produced from animal parts) (see Cointreau-Levine et al. forthcoming 1997; Giroult et al. 1996; Shuval et al. 1986).

We can assume that some health risks are increasing as industrialization and modern consumerism change the nature of both solid and liquid urban wastes. While legislation governing the disposal of industrial wastes is improving throughout Asia, there are few special industrial or bio-medical dumps or cells within dumps, and small industries are often not covered by the legislation (Cointreau-Levine et al. 1997). Pollution of wastewaters is frequently mentioned in aquaculture research (see Krishnamoorthi 1990; Zhang 1990). Peter Edwards (1996a) has recently argued that industrial pollution may pose an even greater threat to public health than pathogens and parasites. Hundreds of factories discharge effluents, including highly toxic chromium from tanneries, into Calcutta’s wastewaters,. One wastewater-fed fishpond system in Calcutta receives 70% industrial sewage. Hanoi sewage also contains about 30% industrial waste (Edwards 1996b). Both cities have extensive sewage-fed fish farming systems.

If concern about health risks of WRUA increases, there is a range of options to reduce risks to workers and consumers (Furedy 1996). Major interventions, for instance, are to:

• reduce the contamination of the wastes being used (e.g., limit industrial wastes in sewage, increase source separation of organics);
• modify agri-aquacultural practices (e.g., prohibit irrigation of leafy vegetables with untreated sewage; use holding ponds for fish);
• monitor compost for pathogen inactivation
regulate human consumption of certain products; and,
educate handlers and consumers in protective practices.

ii) Economic Viability

There are numerous economic constraints which may limit increased use of organic wastes in urban agriculture. We illustrate some of the issues by referring to two important considerations in the making and use of compost: contamination and the cost of production.

The most common problem is that of contamination. Contamination is mainly due to the almost universal practice in the region of mixed refuse collection and the subsequent composting of mixed wastes. Even with elaborate sifting of compost, the product usually contains many splinters of glass and hard plastics, shredded plastic film, and toxic substances. Such contamination affects farmers' demand, mainly because farm workers suffer injuries, skin problems and respiratory diseases (see Allison and Harris 1996). Producers fear for the health of their animals if food wastes are contaminated. Another consideration is that contaminated compost is a poor soil conditioner over a period of time. Research in Hanoi and Bangkok has shown that farmers are unwilling to pay for contaminated compost no matter how cheap it is (Le 1995; Kim 1995). Farmers in Vietnam have noted that plastic film is leading to soil problems (Midmore 1994). Food chain disease links, however, seem not to affect farmers' demand.

The relatively high cost of standard compost production is also cited as a constraint. This is particularly so where chemical fertilizers are available and (often) subsidized. Just how much more costly properly-produced compost is estimated to be, compared to chemical fertilizers, however, depends on the scope of the analysis used. If WRUA is considered as a waste reduction strategy (less cost for municipal disposal), the overall economic assessment would differ from a simple cost analysis. Using an economic appraisal approach Le (1995) demonstrated that the costs of composting in Hanoi were almost half the costs of disposal in dumps. The efficiency of plant management (including marketing strategies) is important. Small-scale compost plants and private enterprises have met costs or been profitable in several places (Lardinois 1997; Rosenberg & Furedy 1996; Sharma 1995).

Both of these related constraints can be ameliorated by interventions to minimize contamination, which are also necessary to address health problems. The main options are discussed in the following section.

D. Minimizing contamination

Minimizing the contamination of organic wastes and wastewaters helps both health considerations and economic viability. By obtaining pure organics, many public health risks can be reduced and the end product is more marketable.

There are two main procedures for obtaining relatively pure organic wastes:

• separate collection from special generation points (fruit, vegetable and flower markets; restaurants, canteens);
• collection of segregated organics from domestic and institutional waste generators
.

In intensive reuse urban areas, the first option is widely practised: municipal crews deliver the market wastes to compost plants or directly to farms; livestock farmers arrange for collection of food wastes (see Rosenberg & Furedy 1996, p. 72; Furedy 1995; Giri 1995). Many places, however, could better exploit the relative purity of wastes from these generation points.

Since market wastes are usually not sufficient to meet the demand for organic matter, especially in intensive reuse areas, and limiting reuse to this category does not substantially reduce the quantities that municipal authorities must dispose of, a major challenge for improved composting is to persuade large numbers of waste generators to cooperate in separating larger quantities of organics. This is an area requiring a great deal of research and pilot projects (from which case study information can be obtained). Examples of projects undertaken so far in South and Southeast Asia include:

• small-scale projects for the separation of "wet" and "dry" wastes at the neighbourhood level in Bandung (Woolveridge 1995) Jakarta (HIID 1992, Wawolumaya and Maclaren, in
progress), Bangalore (Waste Wise 1995, Lardinois 1997), Ho Chi Minh City (Du 1995);
divided street bins for "wet" and "dry" wastes in Bangkok and Surabaya(Furedy 1994);
composting of organics in schools, Manila (Comacho 1994);
composting at a waste recovery station, Sta Maria, Philippines (Lardinois 1997).

Apart from the school projects, the only place where a degree of success has been reported, is Bangalore, on very small scale. Other projects are not succeeding in source separation. The assistance given to these efforts, however, has been minimal. Considerable investment in public education and further commitment from urban authorities is needed to achieve suitable levels of co-operation with source separation.

Background research is also necessary. A limited amount of research on waste generators' practices and attitudes in Hanoi, Ho Chi Min City and Bangalore has found:

• the more that residents are aware of farmers' need for organic matter, the more they are willing to source-separate (Rosario 1994);
• more frequent and separate collection of organics could be an important incentive to extend source separation (Le 1995);


• where animals are raised in the household, food wastes are extensively used. Animal raising may be significant for a household's income in places like Hanoi (Le 1995);


• up to 35% of householders are currently separating food wastes (and some organics) for animal feeding or sale (Ho Chi Minh City) (Du 1995);


• up to 15% of organic waste is used for compost or animal feed in Hanoi (Grégoire 1997);


• lack of space in the living unit is a constraint on thorough source separation in cities like Hanoi (Le 1995).

There is scope for much more research on attitudes and behaviours important to consumption and source separation of organics (see Lardinois 1997; Allison and Harris 1996). Economic analyses, including costs and benefits of composting compared with landfilling of wastes, are needed for all places where composting is being considered. Means of testing compost for pathogens should be disseminated (see Stentiford et al. 1996).

With regard to wastewaters and sewage sludges, the main contamination problem is urban authorities' inability to control the disposal of liquid wastes into sewers and canals. More emphasis needs to be placed on ameliorative production methods, such as crop selection, holding ponds, and careful monitoring. Bioremediation is relevant also.

E. Conclusion

At present the potential of waste reuse for food production is limited by concerns that derive from health risks and skepticism about the economic viability of municipal waste derived compost. There are, however, feasible ways of reducing risks: by reducing the contamination of the organics through source separation, by amending agri-aquacultural practices, and by educating workers and consumers. Composting less contaminated organic wastes should assist the marketability of this compost.

Recent research, although limited in scope, is laying the basis for better understanding of waste reuse. More integration of research in related fields (for instance, of the findings from wastewater research with work on solid wastes) can strengthen the research effort.

Asian cities cannot be complacent about their waste reuse practices, however, as higher urban densities, more industrialization and waste-producing consumerism usually reduce urban and peri-urban food production and contaminate organic resources. On the other hand, the prospects for WRUA contributing to sustainable urban food production are strengthened by improvements in urban management, higher levels of education, greater environmental awareness, and more community participation in environmental management.

F. Reference List

Allison, M.; Harris P. 1996. A review of the use of urban waste in peri-urban interface production systems. Overseas Development Administration, The Peri-urban Interface Production System, Natural Resources Systems Programme, Renewable Natural Resources Research Strategy. African Studies Centre, Coventry University, Coventry, U.K.

Bliek, van der, J. 1992. Urban agriculture: possibilities for ecological agriculture in urban environments as a strategy for sustainable cities. ETC Foundation, Leusden, Netherlands.

Blumenthal, U. J.; Strauss, M.; Mara, D.D.; Cairncross, S. 1989. Generalized model for the effect of different control measures in reducing health risks from waste reuse.Water science and technology, 21, 567-577.

Blumenthal, U. J.; Abiaudjak, B.; Bennet, S. 1991. The risk of diarrhoeal disease associated with the use of excreta in aquaculture in Indonesia, and evaluation of microbiological guidelines for use of human wastes in aquaculture. Proceedings of Third Conference of the International Society for Environmental Epidemiology. ISEP, Jerusalem, Israel.

Cointreau-Levine, S.; Listorti, J.; Furedy, C. 1997. Occupational health issues of solid waste management. In Herzstein, J., et al., eds., International occupational and environmental medicine, first edition. Mosby Year Book Inc., St Louis, Miss., USA.

Comacho, L. 1994. Personal communication.

Du, P-T. 1995. The determinants of solid waste generation, reuse and recycling by households in Ho Chi Minh City, Vietnam: A case study of District No. 3. Asian Institute of Technology. Unpublished Masters thesis, Bangkok.
Edwards, P. 1996a. Wastewater-fed aquaculture systems: status and prospects. Naga, Jan. 1996, 33-35.

________ 1996b. Wastewater reuse in aquaculture: socially and environmentally appropriate wastewater treatment for Vietnam. Naga, Jan. 1996, 36-37.

________ 1992. Reuse of human wastes in aquaculture: a technical review. Water and Sanitation Report 2. World Bank, Washington, DC. USA.

________; Pullin, R., eds. 1990. Wastewater-fed aquaculture. Asian Institute of Technology, Bangkok, Thailand.

Furedy, C. 1996. Solid waste reuse and urban agriculture: dilemmas in developing countries: the bad news and the good news. Paper presented at Joint Congress of the Association of Collegiate Schools of Planning and Association of European Schools of Planning, Toronto, June. (Unpublished).

________ 1995. One world of waste: should countries like India solve solid waste problems through source separation?. In Tepper, E.; Wood. J.R., eds., Enriched by South Asia: celebrating 25 years of scholarship. Vol. Two: Social sciences. Canadian Asian Studies Association, Montreal, Canada, pp.87-107.

Ghosh, D. 1990. Wastewater-fed aquaculture in the wetlands of Calcutta. In Edwards, P.; Pullin, R., eds., Wastewater-fed aquaculture. Asian Institute of Technology, Bangkok, Thailand, pp. 251-266.

Giri, P. 1995. Urban agriculture: waste recycling and aquaculture in East Calcutta. Paper presented to the International Workshop on Urban Agriculture and Sustainable Development. Centre for Built Environment, Calcutta, India.
Giroult, E., Christen, J., Brown, A. 1996. Public health aspects of municipal solid waste management. In Rosenberg, L.; Furedy, C., eds. 1996. International source book on environmentally sound technologies for municipal solid waste management. International Environmental Technology Centre, United Nations Environment Program, Osaka, Japan, pp. 395-406.

Grégoire, I. 1997. From waste generation to food production: development of a composting strategy for Hanoi, Vietnam. Unpublished M.A. research paper, Department of Geography, University of Toronto, Toronto, Canada.

Hart, ‘t, D. and J. Pluijmers. 1996. Wasted agriculture: the use of compost in urban agriculture. WASTE, Gouda, Netherlands.

HIID (Harvard Institute for International Development). 1992. Enterprises for the recycling and composting of municipal solid waste in Jakarta, Indonesia. A discussion paper. HIID, Cambridge, Mass., USA.

Jalan, R.K.; Sushil, D.; Srivastava, V.K. 1995. The emerging priority for disposal, use and recycling of MSW in India. Wastes Management, April, 17-18.

Khouri, N.; Kalbermatten, J.M.; Bartone, C.R. 1994. The reuse of wastewater in agriculture: a guide for planners. UNDP-World Bank Water and Sanitation Program. Washington, DC., USA.

Kim, S?M. 1995. Demand and supply of waste derived compost in Bangkok Metropolitan Region, Thailand. Unpublished M.S. thesis, Asian Institute of Technology, Bangkok, Thailand.

Krishnamoorthi, K.P. 1990. Present status of sewage-fed fish culture in India. In Edwards, P.; Pullin, R., eds., Wastewater-fed aquaculture. Asian Institute of Technology, Bangkok, Thailand, pp. 99-103.
Lardinois, I. 1997. Organic waste recycling. In Reader for UWEP programme policy meeting. Unpublished. WASTE, Gouda, Netherlands, pp.22-34.

______; van de Klundert, A., eds. 1993. Organic waste: options for small-scale resource recovery. Urban Solid Waste Series No. 1. Technology Transfer for Development and WASTE Consultants, Amsterdam, Netherlands.

Le, T-H. 1995. Urban waste derived compost in Hanoi, Vietnam: factors affecting supply and demand. Unpublished Masters thesis, Asian Institute of Technology, Bangkok, Thailand.

Mara, D.D.; Cairncross, S. 1989. Guidelines for the safe use of wastewater and excreta in agriculture and aquaculture. World Health Organization, Geneva, Switzerland.

Midmore, D. 1994. Social, economic and environmental constraints and opportunities in peri-urban vegetable production systems and related technological interventions. In Richter, J.; Schnitzler, W.H.; Gura, S., eds., Vegetable production in periurban areas in the tropics and subtropics--food, income and quality of life. Deutsche Stiftung fur internationale Entwicklung & Arbeitsgemeinschaft Tropische und Subtropische Agrarforschung (German Foundation for International Development & Council for Tropical and Subtropical Agricultural Research), Feldafing, Germany.

Olaniya, M.S.; Bhide, A.D. 1995. Recycling of municipal solid waste on land and its impact--a case study. Paper presented to the International Workshop on Urban Agriculture and Sustainable Development, Centre for Built Environment, Calcutta, India.

Rosario, A. 1994. Personal communication.

Rosenberg, L.; Furedy, C., eds. 1996. International source book on environmentally sound technologies for municipal solid waste management. Compiled by IETC in collaboration with the Harvard Institute of International Development. International Environmental Technology Centre, United Nations Environment Program, Osaka, Japan.

Sharma, A. A. 1995. A methodology for locating small-scale composting plants with an application to the Kathmandu Valley, Nepal. Unpublished Masters of science thesis, Asian Institute of Technology, Bangkok, Thailand.

Shuval, H. 1996. Do some current health guidelines needlessly limit wastewater recycling? Paper presented to consultative meeting on recycling waste for agriculture: the rural-urban connection. World Bank, Washington, DC. USA.

Shuval, H.I.; Adin, A.; Fattal, B.; Rawitz, E.; Yekutiel, P. 1986. Wastewater irrigation in developing countries: health effects and technical solutions. World Bank Tech. Paper No. 51. World Bank, Washington, DC. USA.

Smit, J.; Ratta, A.; Nasr, J. 1996. Urban agriculture: food, jobs, and sustainable cities. Habitat II Series, UNDP (United Nations Development Program), New York, N.Y., USA.

Stentiford, E.I.; Pereira Neto, J.T.; Mara, D.D. 1996. Low cost composting. Research Monographs in Tropical Public Health Engineering, No. 4. University of Leeds, Leeds, U.K.

Waste Wise (Bangalore). 1995. The execution of field demonstration of small scale composting for the treatment of the organic fraction of municipal refuse. Status report and special report to Mythri Foundation. Bangalore: Mythri. Unpublished.

Wawolumaya, C.; Maclaren, V. (In progress). Community composting in Jakarta, Indonesia. Department of Geography, University of Toronto, and Centre for Human Resources and Environment, University of Indonesia, Jakarta.

Woolveridge, C. 1995. An analysis of critical factors affecting the success of neighbourhood composting projects in Jakarta and Bandung, Indonesia. Unpublished M.A. research paper, Department of Geography, University of Toronto, Toronto.

Zhang, Z. S. 1990. Wastewater-fed fish culture in China. In Edwards, P. and Pullin, R., eds., Wastewater-fed aquaculture. Asian Institute of Technology, Bangkok, Thailand, pp. 3-12.

TABLE: MAIN PRACTICES OF URBAN ORGANIC WASTE REUSE
IN DEVELOPING COUNTRIES

A. LANDBASED