Author(s)

R López, M D Hurtado & F Cabrera

Abstract

Several properties (pH, electrical conductivity, contents of organic matter, nutrients, heavy metals, glass and impurities) were determined in different particle size fractions (0-0.5, 0.5-2, 2-5, 5-10, 10-25 and >25 mm) of various MSW composts produced in two composting facilities located at SW Spain (Montemarta-Sevilla and Villarrasa-Huelva). Mean percentages of the first five fractions were 9.6, 22.7, 29.2, 23.4 and 15.1 respective1y. The MSW compost properties depended on particle size. Fine fractions (<2 mm) shown better quality than the mean compost: lower EC, Na content, C/N ratio, less glass and impurities indicated higher maturity and cleanness. Though this fine fraction had lower nutrient contents and the 0.5-2 mm fraction accumulated heavy metals, separation of the fine fraction would produce a compost more suitable for applications which require high stability compost, such as component for pot substrates. On the other hand, the >2 mm fractions tended to be richer in fertilizing elements, probably in relation with OM mineralization. Introduction Composting has been adopted in Spain as the main alternative for municipal solid waste (MSW) treatment, being soil improvement and fertilization the main uses for these composts. The beneficial effects of composts on crop production and soil properties are directly related to the physical, chemical and biological properties of the composts. New markets and uses are needed to absorb the increasing amounts of MSW compost but at the same time, stricter regulations appear to fulfil quality requirements for new uses and to guarantee environmental protection [1].

Keywords