204 CHRISTINE FUREDY
dumps. Even with high levels of informal reuse, however, substantial amounts of
organics remain in the municipal waste flow, material that solid waste managers wish
to treat and to divert from disposal.
9.4. ISSUES IN COMPOSTING OF URBAN ORGANICS
Although organic wastes can be exploited for energy – formally, by anaerobic diges-
tion to produce gases, pelletisation and briquetting (Furedy and Doig, 2002), and
informally for domestic fuel – the use of decomposed biomass in food and plant
production (in agriculture, horticulture, forestry and aquaculture) remains the means
by which the greatest amount of urban organic wastes are reused. Composting
(controlled decomposition of organics by numerous micro-organisms) is the preferred
method of processing. The experience with composting of urban organics, however,
has been fraught with multiple problems: of feedstock; of plant operation; of the
quality and price of the product; of marketing; of consumer understanding; and of
institutional support.
Motivations for composting
From the point of view of solid waste management composting is a means of both
treating and reducing the amount of waste requiring final disposal. Backyard
composters are concerned with recovering resources, but most households cannot
reuse their organics and must put them out for collection. They thus have no incentive
for keeping organics separate from other wastes. Pilot projects in composting often try
to integrate general environmental, health and specific social concerns (Lardinois and
Furedy, 1999). Private fertilizer companies may undertake composting from urban
wastes to enhance their ‘green’ image rather than to make a profit on that line (Patel,
2000). A major issue for solid waste managers is what will motivate household and
institutional waste generators to undertake and keep up the difficult task of carefully
separating wet wastes. The long run success of urban organic solid waste composting
would seem to depend on such separation.
City experiences with mechanized compost plants
The failures, inadequacies, and high cost of large, mechanized compost plants have
been noted in many countries (see Rosenberg and Furedy, 1996:124, 317; Lardinois
and Marchand, 2000; Etuah-Jackson et al., 2001). As well as problems with inappro-
priate machinery, lack of expertise, high operating costs, difficulties in developing
markets and so on, such plants have produced poor quality compost because they
usually used mixed municipal wastes as feedstock. The problem of contamination is
increasing as municipal wastes contain more glass, biomedical wastes, and plastics.
City governments find it hard to acquire convenient sites for large plants. A few
large-to-medium plants are still operating with simpler technology, and with govern-