The impact of gasification wastewater on soil microorganisms and the growth of oat and red clover

Process water generated during the biomass gasification is abundant in organic compounds such as polycyclic aromatic hydrocarbons (PAHs). Doses of wastes used in the study were the following: 10, 20, 40, 80, and 160 cm³ of process water per 100 g of dry soil mass. Obtained results showed, that, analyzed wastes can be classified as acute toxicity compounds. Cytometric analysis showed that with the wastewater concentrations of 40 and 80 cm³ per 100 g of soil, the number of microorganisms during the initial days after the contamination was markedly increased; however after 16 days it dropped to the quantity similar to the initial number. Regarding plants the contamination of soil with small volumes (10 cm³/100 g of soil and 20 cm³/100 g of soil) led to the stimulation of the oat aboveground part's growth by 6 and 23% compared to the control sample, respectively. The use of higher concentrations weakened the plants growth or arrested it completely. As a result it was also concluded, that red clover can be a better bioindicator in the analyses of toxicity of this type of wastes than oat.