Ecotoxicity of Tar from Coffee Grounds and Pine Pellet Gasification Process

This study determined the toxicity of the condensates produced during the gasification of two waste types. Coffee grounds, pine pellets, and a mixture of both substrates at a ratio of 1:1 were used in the study. Two microbiotests were applied for soil plants and aquatic macrophytes, and quantitative analysis of the soil microbiome for primary taxonomic groups of microorganisms was conducted. Three contamination rates were used in the Phytotoxkit test and the microbiological tests, 100, 1000, and 10,000 mg·kg −1 d.m. of soil, while in the aquatic organism studies, successive two-fold serial dilutions of condensates were used. The presence of liquid waste from the gasification process adversely affected the germination and development of terrestrial plants and the vegetative growth of aquatic plants. The condensate components modified the composition of the soil microbiome, adversely affecting soil fertility. The negative impact increased with increasing levels of contamination and primarily depended on the type of substrate from which the gasification process produced the liquid waste.