This study aimed to evaluate the waste cooking oil (WCO) hydrolysis in ultrasonic system using lipase as catalyst. Lipase was produced by the fungus Aspergillus niger via solid state fermentation (SSF) using canola meal as substrate. Prior to the hydrolysis reaction, the lipase behavior when subjected to ultrasound was evaluated by varying the temperature of the ultrasonic bath, the exposure time and the equipment power. Having optimized the treatment on ultrasound, the WCO hydrolysis reaction was carried out by evaluating the oil:water ratio and the lipase concentration. For a greater homogenization of the reaction medium, a mechanical stirrer at 170rpm was used. All steps were analyzed by experimental design technique. The lipase treatment in ultrasound generated an increase of about 320% in its hydrolytic activity using 50% of ultrasonic power for 25min. at 45°C. The results of the experimental design conducted for ultrasound-assisted hydrolysis showed that the best condition was using an oil:water ratio of 1:3 (v:v) and enzyme concentration of 15% (v/v), generating 62.67μmol/mL of free fatty acids (FFA) in 12h of reaction. Thus, the use of Aspergillus niger lipase as a catalyst for hydrolysis reaction of WCO can be considered as a possible pretreatment technique of the oil in order to accelerate its degradation.

After years of pesticide application, often indiscriminately, damage has been caused to the environment, as well as to agronomic crops grown in contaminated areas. In water treatment, techniques based on physical and/or physicochemical processes are used, being formed secondary oxidizing agents responsible for the mineralization of contaminants present in the herbicides, thus causing the degradation process. However, few studies have demonstrated the effectiveness of these techniques in soils. The aim of this study was to review the existing studies, presenting the main techniques used for remediation of soils contaminated with pesticides. Emphasis was placed on electrokinetics, advanced oxidative processes, soil washing, chemical or solvent extraction, and combinations of these methods. According to the results of several studies, the combination of techniques, such as electrokinetics and soil washing processes, allows achieving a high efficiency when it is applied for the degradation of agricultural contaminants. The combination of electrolysis with other methods, such as the Fenton’s reagent, ultrasound irradiation, and UV light, also present satisfactory results in removing pesticides in soil treatment. However, Fenton technology used alone is the most promising of the assessed techniques since it can be used for the remediation of several contaminants, especially pesticides, not harming the environment and allowing soil recovery.

This study aimed at evaluating the activity of peroxidases after ultrasound and microwave radiation exposure as an alternative to the wastewater treatment improvement. The results showed that after treatment with ultrasound using a power of 30% and a temperature of 55 °C was obtained an increase in relative activity, 129.5% in the enzyme from rice bran, 147.9% in the enzyme from soybean meal and 102.4% in the enzyme from horseradish. Using microwave radiation, the highest relative activity (107.4%) was observed for the peroxidase extracted from rice bran with 10 seconds of reaction time and a reaction temperature of about 50 °C. The data obtained in this study suggest that the ultrasonic bath and microwave are adequate for conducting reactions catalyzed by peroxidases because it was possible to increase their activity during the performed tests. Preliminary tests of enzyme application showed that the highest color removal occurred using 3 mL of the enzyme extract from rice bran and H 2 O 2 concentrations of 40 mg L -1 . This condition resulted in a color removal of about 40%.

We evaluated the effect of ultrasound radiation on lipase activity. The experiments were conducted using a low‐cost crude enzyme extract. We then used this lipase to treat dairy effluent. The results of our study presented an increase of approximately 430% in the concentration of free fatty acids.

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