A combined technological scheme for purification of undiluted high-strength wastewater produced in the shale oil industry was proposed. The initial values of chemical oxygen demand (COD), biological oxygen demand (BOD₇) and phenols in the studied pyrogenic wastewater samples were up to 45, 35 and 1 g/L, respectively. Furthermore, the wastewater had a high toxicity to indicator organism Daphnia Magna (EC₅₀ = 0.34%) and caused inhibition of oxygen uptake rate (IC₅₀ = 3.4%) and nitrification rate (IC₅₀ = 0.7%) in activated sludge treatment. The combination of air strip­ping, coagulation-flocculation, batch distillation, activated sludge and the Fenton oxidation processes reduced all measured parameters more than 95%. Consequently, a treatment scheme applicable to pyrogenic wastewater was developed.