Banca de DEFESA: FABIANA LOUREIRO DOS REIS

MATURITY ANALYSIS FOR AGRONOMIC USE OF PRODUCT GENERATED FROM THERMAL AND MECHANICAL DEHYDRATION OF FOOD WASTE

Substrate, Food waste, Composting, Germination Index,  Compost Maturity Index

The environmental impact of the annual production of wasted food scraps is significant and causes several negative impacts on the environment, soil erosion and greenhouse gas emissions. An alternative for reusing this waste is to use it as raw material for composting or as substrates after stabilization, returning nutrients and carbon to the soil and vegetable crops. In this sense, it is important to carry out stability and maturity analyzes of the waste to ensure its efficiency as a substrate. This work aims to analyze the maturity of mechanically and thermally processed food waste (RAP) for use as substrate and organic compost. For this, laboratory analyzes were carried out to determine the pH, Electrical Conductivity, and chemical composition of the biochar and RAP to determine the carbon, nitrogen, phosphorus, potassium, calcium and magnesium contents. To analyze stability and maturity, tests were carried out on solid materials, namely: RAP and biochar, commercial substrate carolina, the organic compound organosoil and vermiculite. Germination tests with cucumber seeds (Cucumis sativus) were carried out in two stages, first using seedbeds with 36 cells with four treatments: T1: vermiculite, vermiculite + RAP, carolina; T2) vermiculite, vermiculite + RAP + biochar 400 ° C + carolina; T3:) vermiculite, vermiculite + organosol, carolina. Subsequently, Germination Indices were observed through the number of germinated seeds. The experimental design was completely randomized, with three treatments and three replications. The second germination test was carried out in Petri dishes, which is based on the analysis of cucumber seed germination in the compost extract, where the Germination indices are analyzed based on the number of seedlings. Finally, the stability of the compounds was analyzed through the respirometry test, which determined CO2 and NH3 emissions from solid materials in NaOH and H3BO3. Laboratory tests demonstrated that the EC and pH values of RAP presented undesirable chemical and physical characteristics as an organic compound. Significant differences were observed in the GI% (GI% weight, length and leaf area) of the T1 and T2 treatments, where RAP was used alone and with biochar at 400°C. In the sowing test, there was no seed emergence, indicating that the product has phytotoxicity. In Petri dish tests, the GI% of RAP presented a value of 88% germination, indicating maturity, In-vitro germination and root elongation, however the GI% weight and length presented percentages that are considered low. In the stability test, the RAP showed no CO2 emissions. The RAP material presented phytotoxicity and undesirable chemical characteristics for an organic fertilizer or plant seedling substrate, that is, the material is unsuitable for use as a substrate in nurseries and presents limitations for application to agricultural soil as an organic fertilizer.