Investigation of sanitary and chemical indicators of soil pollution by biodegradation products of plastic without resins based on non-wood plant raw materials

The purpose of this study was to get plastic without resin (PWR) based on plant fillers of non-wood origin in the form of wheat husks and rice husks using piezothermal treatment in a sealed mold and to perform tests on the biodegradability of these materials in the soil, followed by an assessment of the level of chemical contamination of soils as a result of their destruction. PWR samples based on fractionated wheat husk and rice husk were produced. The samples were obtained by compression pressing in an airtight mold at a pressure of 40 MPa and a temperature of 170 °C, followed by its cooling without pressure relief to 40 °C. The physico-mechanical parameters of the samples were determined (density, modulus of elasticity when bending along the deflection of the disk sample, hardness after indentation of the ball, elasticity number, water absorption, swelling, wetting edge angle). After conducting studies of the physico-mechanical properties, the samples were subjected to biodegradability tests in relation to soil for 84 days. After the biodegradability tests were completed, the soil was examined for the level of chemical contamination with heavy metals. The results of the tests showed that plastic obtained from wheat and rice husks can be classified as a fully biodegradable material. During the destruction of these materials, inorganic compounds migrate into the soil environment, while the level of heavy metals does not exceed the established environmental and sanitary standards for the soil. According to the results of a comprehensive assessment of chemical contamination of soils by degradation products of a biodegradable composite material without a binder based on plant raw materials, the category of contamination of the studied soil was classified as "acceptable". Nevertheless, given the existing level of environmental pollution, when using the raw materials in question, an initial assessment of their quality is required, including the content of pollutants.

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