Technical approaches to evaluate the surfactant-enhanced biodegradation of biodiesel and vegetable oils.

This research compared the effects of biosurfactant on the biodegradation of biodiesel and vegetable oils while validating two conceptually diverging methodologies. The two experimental setups were successfully modeled towards the effects of biosurfactants during biodegradation. We established the equivalence of both methodologies from the data output. As expected, the biosurfactants caused an increased oil uptake, thus increasing biodegradation performance. Cooking oils were favored by the microbial consortium as a carbon source when compared with biodiesel fuel, especially after use in food preparation. However, we found that biodiesel substrate standout with the highest biodegradation rates. Our results might indicate that a rapid metabolic change from the original compound initially favored biodiesels during the assimilation of organic carbon for a set specialized microbial inoculum. The data output was successfully combined with mathematical models and statistical tools to describe and predict the actual environmental behavior of biodiesel and vegetable oils. The models confirmed and predicted the biodegradation effectiveness with biosurfactants and estimated the required timeframe to achieve satisfactory contaminant removal.

Electrolytic treatment of wastewater containing n-phenyl-n'-1,3-dimethylbutyl-p-phenylenediamine.

This study investigated the effects of electrolytic treatment using Dimensionally Stable Anode (DSA, 70%TiO2/30%RuO2) type electrodes in simulated wastewater containing aromatic amine n-phenyl-n'-1,3-dimethylbutyl-p-phenylenediamine (Flexzone 7P). A low direct current density of 0.025 A cm(-2) was applied for periods up to 60 minutes and a 52.6% decrease in Flexzone 7P concentration was observed. Ultraviolet-visible spectra, gas chromatography, toxicity and biodegradation tests were carried out with the aim of verifying the toxic by-products that were formed. Ultraviolet-visible spectra of simulated wastewater exhibited changes in the aromatic amine's molecular structure. Additionally, based on the S. cerevisiae toxicity test, it was observed that detoxification of the wastewater occurred after 15 minutes of electrolysis. It was also observed that five minutes of treatment were sufficient to improve the biodegradation rate, determined through the respirometric Bartha method.