Evaluation of the Use of Pyrolysis Oil from Municipal Solid Waste in the Germination and Development of Lettuce (Lactuca sativa), Biochemical Properties, and Level of Contaminants.

Pyrolysis oil, one of the products of the pyrolysis process of different wastes, due to its diverse chemical composition, may have biological activity of interest for agricultural areas. However, the safety of using these products must be adequately evaluated to verify the applicability of pyrolysis oil from municipal solid waste (MSW) on agricultural crops. This study carried out the quantitative chemical characterization of MSW pyrolysis oil and evaluated the germination inhibition potential of this material on lettuce seeds in a laboratory test carried out at the concentrations of zero (control), 0.1%, 0.5%, 1.0%, 1.5%, and 2.0% v/v. Moreover, the pyrolysis oil was sprayed on lettuce plants, with a weekly application of pyrolysis oil for 4 weeks, at concentrations of zero (control), 25%, 50%, 75%, and 100% v/v, and the plants' growth was assessed. The main constituents identified in MSW pyrolysis oil were hydrocarbons, phenols, esters, amides, and organic acids. The pyrolysis oil showed satisfactory germination control with increasing concentrations, did not cause toxicity effects in plants, and did not cause significant changes in the levels of phenolic compounds and flavonoids in plant tissue. The levels of heavy metals remained within the maximum limits established by legislation for fresh food. The pyrolysis oil from municipal solid waste showed promising results in the exploratory tests, demonstrating its suitability for studies and its use within the agricultural sector.