Study of the recovery in agriculture of the waste resulted from baker’s yeast industry

The baker’s yeast industry generates large amounts of waste, rich in mineral and organic substances. The reintegration into the natural cycle of these wastes, as a biological fertilizer, is one of the ways to reuse them and also represents a model for achieving the circular economy in the baker’s yeast industry. This paper presents the quality of the sewage sludge and the waste resulted from the separation of the yeast biomass from the spent molasses resulted from a baker’s yeast processing plant and the possibility of using them in agriculture. The content of heavy metals as well as the main parameters were assessed in accordance with the requirements of the national Order 344/2004 concerning the protection of the environment and especially of soils, when using sewage sludge in agriculture. These products were used in order to increase the agrochemical soil parameters for the cultivation of some vegetables (eggplant and pepper) in the field. We considered a garden soil poor in humus (1.16% d.m.) and with nitrogen (N), potasium (P) and potassium (K) values below the optimal soil agrochemical parameters, which condition the potential state of its fertility. The products were dosed according to the soil quality, and biometric measurements were made both on plants and harvested fruits. The results were compared with the untreated vegetables cultivated on the soil that was not treated with these products. These preliminary experiments showed that these two products have potential to be used as a source of mineral and organic soil fertilization.