Investigation of soil fertility affected by biodiesel by-product in microcosm experiment

László TOLNER, ¹ – Brigitta BONDOR ¹ - Imre CZINKOTA ¹ - Zsolt VADKERTI ¹ - Attila KOVÁCS ¹

1 Szent István University, Department of Soil Science and Agrochemistry, Gödöllő, tolner.laszlo@mkk.szie.hu

Abstract: On the grounds of expedience, versatile investigation of industrial by-products has to be considered to protect the environment. This consideration has been revealed the field of biodiesel production. Glycerol, which is a by-product from biodiesel production is available in such a large amount, that it can not be disposed in the traditional utilization ways. This glycerol is contaminated and the cleaning process is rather expensive. The pollutants originated from oil seed proteins, containing carbohydrates, as useful plant nutrients, and also potassium hydroxide is used as catalyser and methanol used for transesterification, which ingredient can be utilisable. There is a noticeable tendency, where manufacturers try to recover methanol during the process in order to reach a higher technological efficiency. Potassium content of potassium hydroxide is a plant nutrient. In addition alkalinity can be important in compensation of soil acidity.

According to our previous investigations on hygroscopic ability of crude glycerol influences the germination of plant seeds. As an easily degradable organic matter stimulates microbial activity in the soil and alters the C/N ratio, which can cause a temporary nitrogen deficiency. The nutrient supplying capacity of soil influenced by glycerol was examined in microcosm experiment. Approximate observation is capable to monitor the complex ecological effect for a small scaled soil-plant-animal system. The soils were treated by glycerol and potassium nitrate. Lolium perenne as indicator plant and eisenia fetida as indicator animal were applied for this investigation.

Keywords: glycerol, biodiesel, by-product, microcosm experiment, eisenia fetida