Home composting of household biodegradable wastes under the tropical conditions of Guadeloupe (French Antilles)

Because of the collapse of landfill sites, reduction and recycling of municipal solid wastes is a crucial concern in the small island states of the Caribbean region. This study is part of a project promoted by the General Council of Guadeloupe about home composting of household biodegradable wastes, and concerned 60 volunteer households from 10 municipalities with different pedoclimatic conditions. The aim was to examine the problems observed during home composting, and to assess compost quality. Only 32% of households experienced at least one problem during composting, including the presence of cockroaches and scolopendra (23%), rodents (12%), bad smells and excess leachate (8%). Despite these problems no one stopped composting. Most of these difficulties were not severe and slight changes in the composting procedure should be sufficient to solve them; e.g. to wear gloves when handling composts, to control harmful animals outside the composter, and to increase the stable to labile waste ratio. Neither Escherichia coli nor Salmonella sp. were present in the composts. Organic matter (OM, mean 46%), nitrogen (N, 2.2%), potassium (K, 2.1%), and lignin (20%) contents were much greater than those observed for industrial compost produced in Guadeloupe. Temperature inside the composters during the thermophilic phase (∼43 °C) was lower than that currently reported for industrial composting, which reduced OM decomposition and favoured the conservation of the more stable organic compounds such as lignin. Also, nutrient leaching was lower in the closed home composting system, which favoured the conservation of N and K. Differences between municipalities concerned the contents of calcium (greatest for the municipalities with calcareous soils) and OM (lowest for the warmer municipalities). These results indicated that home composts may be helpful to improve OM content and nutrient availability in infertile tropical soils. This study highlighted that home composting may be a suitable alternative to help local authorities to achieve targets to divert wastes from landfill.