Heavy metal content in compost and earthworms from home composters

Abstract

Abstract The paper presents the results of compost tests from home composters and earthworms living there, that treating waste into compost. The samples were taken from home composters and allotment gardens from Opole Region. The composting material was green waste. The total content of heavy metals (Cd, Pb, Cu, Zn, Ni Cr) in compost and compost earthworms’ samples were determined. It was found that the compost samples were not contaminated with heavy metals. According to the Polish classification of composts from municipal wastes, the composts met the requirements for first class of quality. The composts did not exceed the limits of heavy metals specified in the Polish law for solid organic fertilizers. The degree of metal accumulation by compost earthworms depended on the type of metal. The high value of the bioaccumulation factor (BAF) was obtained for Cd, Pb and Zn. No accumulation of other metals (Ni, Cr, Cu) in earthworm bodies was found. It has been found that earthworm species, naturally occurring in Poland, can also be used as potential bioindicators of metals in the environment, such as the species Eisenia fetida. The aim of the study was to evaluate the heavy metal content in composts from home composters and ability to accumulate metals by compost earthworms.