Waste Reuse in Agriculture

Urban Agriculture in the Context of Human and Organic Municipal Waste Management

Demographic and urban growth is one of the major challenges of the next decade. In 1994, 45% of the world population lived in cities, and this figure will have risen to 65% by 2025. The most rapid change occurs in the developing world, where urban populations grow 3.5% annually. In 1988, about 25% of the urban population ranked among the absolute poor. By 2000, this figure rose to about 56%. Historically, cities were the driving force in the field of economic and social development. However, urbanisation not only offers advantages, but poses also environmental and social problem, including inadequate water supplies, poor environmental sanitation services and food insecurity.

In environmental sanitation and urban agriculture, these problems should be faced by a holistic approach. Human and municipal solid waste contains significant amounts of nutrients for the production of food and non-food crop. Reuse of municipal wastewater and solid waste in urban agriculture can effectively reduce waste treatment and disposal, provided public health is not impaired.

In our opinion , all human and organic municipal solid waste can be recycled and used in urban and peri-urban agriculture. However, our knowledge of the quantity of reusable waste required is limited. In addition to human and organic municipal solid waste, other waste such as from industrialised livestock production or from food-processing industries is also generated and has to compete with mineral fertilisers in urban and peri-urban areas. Some of these products (i.e. human waste) are used by farmers, however, they contain pathogens and have to be pretreaded prior to their agricultural use. Other waste products have only a low nutrient content and/or are liquid and, thus, require special transport and application methods.

Integration of urban and peri-urban agriculture into urban environmental sanitation planning is therefore of utmost importance. The reuse potential of different waste products as a function of crops, soil and climate conditions, including health, socio-cultural, economic, and reuse policy aspects have to form an integral part of future environmental sanitation strategies.