Evaluation of the environmental burden of Co/CoMnK catalytic synthesis wastewater employing acute toxicity tests as a methodological framework

Contaminated wastewater is produced as an inevitable by-product in many industrial applications. This paper thoroughly investigates the toxicity and environmental burden of wastewater from the Fischer-Tropsch catalytic synthesis process. This significant by-product was analysed through the means of root growth inhibition of Sinapis alba, acute lethal effects on Eisenia andrei, chromatography on organic compounds, and determination of the content of metals. Two samples based on Co and CoMnK fixed bed catalytic synthesis using a standard range of parameters (250–280 °C; 1.5 MPa; 1145 h^–1) were prepared. The results showed a severe toxicological effect in all investigated means. Significant Co, Mn, and K occurrences were detected in wastewater in amounts of 0.40–0.57, 0.83, and 0.13 mg·l^–1, respectively. The root growth inhibition test proved that only 9.85 % solution is necessary to reach a 50 % growth inhibition in the case of Co synthesis. CoMnK synthesis presented slightly less toxic results – 11.75 % solution for 50 % growth inhibition. Similarly, Wastewater Co with lethal concentration LC50 87.74 % was more toxic to earthworms than Wastewater CoMnK with LC50 95.99 %. The level of toxicity of this widely produced substance was surprisingly high. Rising environmental protection activity is expected to prove problematic for the current or future industrial applications, and a need to adopt treatment processes discussed in this study or upgrade the existing ones might be of the essence. The issue of wastewater toxicity and its environmental impact are discussed and evaluated hereby.