Effect of pre-treatment and conditions on the appearance of long chain fatty acids in treatment of wastewater containing oil

The aim of the research was to increase the efficiency of treatment of wastewater containing edible oil. In order to increase the bioavailability of this wastewater, ultrasound method was proposed, as a pre-treatment of wastewater before the biological treatment. An emulsification oil in wastewater by ultrasound has initiated the process of oil hydrolysis and resulted in the appearance of free fatty acids in the water phase (saturated acids: palmitic, stearic; and unsaturated acids: oleic, linoleic). Degradation of oil and the formation of dissolved substrates were also favoured by the application of elevated temperature of 30°C. While at the temperature of 15°C, the oil emulsion maintained its stability through the first hours of the research. The effectiveness of the treatment was compared on three types of wastewater: wastewater containing edible oil (0.1% + wastewater), wastewater containing oil changed by ultrasound (0.1% + ultr + wastewater) and wastewater which also contained other organic compounds (peptone and meat extract, urea, sodium acetate and starch) apart from oil (0.1% + ultr + wastewater). The introduction of co-substrate caused a decrease in the frequency of unfavourable phenomena in system – outflow of activated sludge.