COMPOSTING AS ALTERNATIVE TREATMENT OF SOLID WASTES FROM LABORATORY ANIMAL CARE FACILITIES

Abstract

This study evaluated composting as a means of treating wastes from rabbits, guinea pigs, mice and hamsters from animal care facilities and its subsequent use for agricultural purposes. We built six compost windrows with 500kg solid wastes mixed with 221.65kg of cotton waste each, which gave a C:N ratio of nearly 30:1. Chemical, microbiological and parasitological analyses of the wastes and the composts were performed before and after treatment. Temperature and pH were measured inside the windrows throughout the experiment. The initial temperature of 28°C increased to a peak of 60°C and decreased to stabilization within approximately 100 days. The pH values oscillated between 6.5 and 8.0, the range indicated to assure pathogen removal and compost quality. At the end of the experiment, over 90% of Escherichia coli, Salmonella sp, protozoan oocysts and helminth eggs were efficiently eliminated in most of the composts. Chemical analyses detected suitable contents of macro and micronutrients and acceptable levels of heavy metals in the composts. We conclude that composting is an efficient method to treat the solid wastes produced by the studied species held in animal care facilities. It eliminates or reduces microorganism content, producing class B biosolids that can be used with restriction in agricultural practices. Keywords: Environmental pollution, waste treatment, laboratory animals.