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<br /> . treating it, and selling it to farmers in the mettopol- for vegetable produce in this way."
<br /> itan area. Industrial countries rea~cle sewage New York has recently launched several efforts
<br /> sludge, the solid by-product of wastewater treat- to capture the benefits of composting. The pilot
<br /> ment. F god Waste Composting Facility on Bikers Island, a
<br /> One particularly promising technology for recy- prison facility with 15,000 inmates and 10,000
<br /> cling human wastes produced by cities also provides guards and otxcers, represents the city's first larcc-
<br /> an important source of Food. For m~~e than SO scale attempt to compost a concentrated food waste
<br /> - years, wastewater-fed aquaculture in Calcutta, India, stream. The facility processes 20 cons of food waste
<br /> has produced fish for the city. A natural wetland and corrugated cardboazd per day, and hopes to
<br /> east of the city has been modified into a 12,000 eventually use the compost for the island's farm pro-
<br /> hectare cluster of ponds that grow fish on sewage; gram. Smaller projects to compost several hundred
<br /> ' the sewage provides nutrients for the algae the fish pounds each day are underway at a hospital in
<br /> eat, and the process in turn dilutes the high concen- Queens and on the City College campus. Robert
<br /> [ration of fecal coliform bacteria present in sewage. LaValva, the current Director of Composting, notes
<br /> The resulting effluent can then be safely used to irri- that these smaller-scale projects probably make
<br /> gate fields. Each day, 22 tons offish-mainly carp- more sense and have a better chance of succeeding
<br /> are produced in the course of treating 150 million since composting, unlike most other kinds of recy-
<br /> gallons of Calcutta's wastewater. The ponds pro- cling, can be done locally and the end-product can
<br /> vide at least 10 percent of the city's daily consume- be utilized locally. As his analysis suggesu, it may be
<br /> lion offish, which are the primary source of protein easier co keep the loop closed when both ends of It
<br /> for Calcutta's residents. It has been estimated that aze kept in the same locality.
<br /> the output could be doubled.
<br /> Wastewater-fed aquaculture provides benefits
<br /> other than tiood to cities. It also represents acost- A St7rViVa1 Technlglle
<br /> effective way to treat the wastes that aze now dis- More than five billion people wrill live in cities
<br /> chazged direcdy into the local environment-pollee- by 2025, and if present trends continue, almost hall
<br /> ing rivers, esruaries, and seas. A 1990 proposal to of them-as many as the whole population of the
<br /> construct fish ponds similar to Calcutta's in other world afrer World War II-wRll live in chaotically
<br /> Indian cities estimated that ponds with a capacin~ to growing districts that are increasingly polluted and
<br /> treat 30 million liters per day could be built for one- afflicted by poverty and social and economic insta-
<br /> fourth the cost of a conventional mechanical treat- bitty. Under such conditions, the problems associ-
<br /> • ment plant with a comparable capacity. Not only are ated with feeding those cities and managing their
<br /> the aquaculture ponds cheaper, but the produce wastes seem almost insurmountable. Yer in many
<br /> can also be sold for a profit, reducing coca! costs fur- ways, living in tides is the most sustainable option
<br /> Cher. In Lima, Peru, fish farms fed by partially treat- people have, since high population densities mini-
<br /> ed wastewater are expected to recover 100 percent mize transportation needs and energy consumption
<br /> of the wastewater treatment costs through fish sales. and reduce each individual's impact on the larger
<br /> Duclc~veed ponds can also be used co treat waste- environment.
<br /> water: in Kochcice, Poland, a duckweed pond treats While most experts agree that urban farming is
<br /> wastewater from 3,000 residents at a cost far lower now both ~Rable and desirable, they are contentious
<br /> than that of a treatment plant, and the biomass pro- about its potential contribution to feeding the
<br /> duced is hazvested twice a year and Fed to livestock. world's population. Jac Smit, president of The
<br /> Solid waste management can also be facilitated Urban Agriculture Network (TUAN) and co-
<br /> by diverting organic wastes from landfills or dumps author of Urban Agriculture: Food, Jobt, and
<br /> and converting them to compost. Of the 26,000 Sustainable Cities, recently released by TUA.~I and
<br /> tons of solid waste thrown out by Ne~v York City the UN Development Programme, claims that
<br /> each day, some 20 to 40 percent is organic matter. urban agriculture already produces 15 percent of
<br /> Composting such material could reduce disposal the world's food, and that it has the potential "to
<br /> ' costs and provide rich soil for urban agriculture. In produce one-quarter of the nutritional needs of the
<br /> addition, the three principal by-products of the global population where they live." Rachel Nugent,
<br /> composting process-heat, carbon dioxide, and the economist who wrote the chapter on urban agri-
<br /> water-together with the compost itself, can be culture in the 1996 State of Food and Agrie:~lnere,
<br /> used fot intensive greenhouse agriculture. As published by the UN Food and Agriculture
<br /> Thomas Outerbridge, the city's former Director of Organization (FAO) in October, takes a more cur
<br /> Composting, noted several years ago in Tlie cious view: urban agriculture, while potenciall}'
<br /> Ecologist, °According to some estimates, New York viable and productive, takes much more planning
<br /> City could eventually meet much of its own demand than exisn in the cities of most developine coun-
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