Aplicação de microrganismos eficientes em vermicompostagem visando eliminação de patógenos

Abstract

Vermicomposting has been widely used as a technique to treat and stabilize organic matter. It is considered a form of treatment that does not harm the environment, prevents the contamination of soil and water by chemicals, makes the soil rich in nutrients, helps control soil toxicity and generates fertilizer for gardens and vegetable gardens. It is a low-cost process that involves the action of earthworms and microorganisms capable of making nutrients available from animal waste, food waste, tree trimmings, grass, etc. However, the poor conduction of the processes can cause the non-elimination of pathogens present in the waste, so that the compost can offer risks of contamination. Thus, this research aimed to evaluate the microbial composition of the original waste, as well as, to add efficient microorganisms in different concentrations during the vermicomposting process, in order to assess their efficiency in removing pathogenic microorganisms. Vegetable stalks and peels such as carrots, coffee powder leftovers, grass clippings and bovine manure were used to compose the pre-composting mixture (20 days). Then the precompost was sent to vermicomposting with the addition of efficient microorganisms in all treatments and worms of the species Eisenia foetida. For the analysis of Escherichia coli the most probable number technique (NMP/gMS) or multiple tube technique was used. For the identification of Salmonella sp. and Shigella sp. the ISO 6579-1 was used. The bovine manure and grass waste presented the highest values for thermotolerant coliforms (>1100 and 810.57 and NMP/gMS). The precompost showed thermotolerant coliforms in numbers higher (1100 NMP/gMS) than allowed by legislation, and after vermicomposting these values were reduced in all treatments, including the control, being generated a compost with acceptable number of coliforms. Salmonella spp., Shigella spp. and Staphylococcus spp. were present in all treatments and were maintained during the pre-composting until the end of vermicomposting, so that the final compost did not meet the legislation. Treatment 4 (dose equivalent to 8 mL/L of MSs) was able to reduce the number of thermotolerant Coliforms in the vermicompost by about 85%.