Valorização de resíduos orgânicos a partir da compostagem e vermicompostagem com adição de microrganismos eficientes

Abstract

The growing production of waste is a result of the country's population and economic growth, as well as the consumption of goods and services. Furthermore, the lack of effective public policies for waste management and treatment also contributes to the problem. To the detriment of this, composting and vermicomposting emerge as attractive, low-cost and effective ways to stabilize domestic and industrial organic solid waste. The microbiological biooxidative action promotes the production of a stable compound that can be used as an organic fertilizer. In this work, the performance in stabilizing organic matter was evaluated, applying pre-composting followed by vermicomposting on a small scale, with the addition of efficient microorganisms (ME) in different concentrations with the aim of optimizing the process. 70 kg of food waste (RA), 37 kg of fresh cattle manure (DB), 11 kg of grass clippings (PG) and 2 kg of gall cuttings (AG) were used. The total mass of the windrow was 120 kg in proportions of 58%, 31%, 9% and 2% for RA, DB, PG and AG, respectively, aiming to start the process with a C/N ratio of 30/1. Vermicomposting was prepared with pre-composted waste aiming at the metabolic and reproductive activities of 10 adult earthworms of the species Eisenia andrei (California red) containing visible signs of sexual maturity. In preparing the ME culture, the methodology recommended by the Ministry of Agriculture and Livestock of Brazil (2009) was observed; in the quantification, the method for calculating colony-forming units according to the American Public Health Association (APHA, 2021) was applied and the inoculation of the ME on the pre-composed substrate was considered the adaptation of the methodology proposed and applied in research by Panisson (2017). 5 treatments were tested in quadruplicate to evaluate the effect of adding ME on the agronomic quality of vermicompost, with control D0 and doses D3, D4, D5 and D6, totaling 20 vermicomposts. In the composition of treatments from D3 to D6, the ME doses were progressively increased by adding 3, 4, 5 and 6 mLME/L of residue, respectively. During pre-composting, the microbiological and physicochemical parameters [pH, electrical conductivity (EC), volatile solids (SV), total solids (TS), total Kjeldahl nitrogen (NTK), carbon and nitrogen ratio (C/N)] were monitored weekly, except temperature and humidity, recorded daily. In vermicomposting, microbiological, morphological (Dickson Quality Index, IQD), phytometric and physicochemical parameters were monitored [pH, EC, ST SV, C/N, NTK, potassium (k) and total phosphorus (Ptotal)]. In vermicomposting, the final evaluation indicated pH in the range of 8.7 to 9.5 while the C/N ratio was between 12 and 13. SV values were between 22.5 and 32%ST and NTK reached values close to 3 .1% in treatment D3. The EC reached values between 2.7 and 3.9 mS cm-1. It was found that treatment D3 presented better Ptotal and K values, phytotoxicity parameters and germination index (GI) among all treatments evaluated. Considering the parameters evaluated in vermicomposting, the D3 treatment reveals greater maturity and agronomic relevance.