Degradation by high frequency ultrasound (US) of the endocrine disruptor, benzophenone-3 (BP-3) is a promising treatment process as it does not need additives and does not generate waste. In this paper the variables affecting this process were studied. The frequency effect on initial degradation rates was analyzed for various frequencies between 215 and 1,134 kHz, and an optimum frequency of 574 kHz was found in this range. Power density had a positive effect on degradation rates over the whole work range. Kinetics adjusted statistically well to a pseudolinear kinetic model. According to these results and those for degradation in presence of radical scavengers, a conclusion was made that US BP-3 degradation was taking place in the bubble/liquid interphase. Toxicity test was conducted by Microtox methods, finding an $E{C}_{50}$ for 5 min of $1.7\mathrm{mg}/\mathrm{L}$ , and for 15 min of $2.07\mathrm{mg}/\mathrm{L}$ . Toxicity profile along degradation path showed a decrease at the beginning growing after 30% of BP-3 degradation. Four possible degradation byproducts were found by gas chromatography–mass spectrometry (GC-MS) analysis, and a degradation path was proposed.

Response Surface Methodology was used for optimizing operating variables for a multi-frequency ultrasound reactor using BP-3 as a model compound. The response variable was the Triclosan degradation percent after 10 sonication min. Frequency at levels from 574, 856 and 1134 kHz were used. Power density, pulse time (PT), silent time (ST) and PT/ST ratio effects were also analyzed. 22 and 23 experimental designs were used for screening purposes and a central composite design was used for optimization. An optimum value of 79.2% was obtained for a frequency of 574 kHz, a power density of 200 W/L, and a PT/ST ratio of 10. Significant variables were frequency and power level, the first having an optimum value after which degradation decreases while power density level had a strong positive effect on the whole operational range. PT, ST, and PT/ST ratio were not significant variables although it was shown that pulsed mode ultrasound has better degradation rates than continuous mode ultrasound; the effect less significant at higher power levels.

This paper aims to make a bibliographic literature review about the current and potential uses of geothermal energy within the food industry, which uses a third of the world’s energy during production in all the processes involved. Fossil fuels are the most common sources for generating electrical energy for the food industry. However, it is known that they cause adverse environmental effects such as atmospheric pollution, ecosystem disturbances and natural resource depletion. Due to the lack of published studies about this subject, this review was carried out using different databases. Of the 77 documents published between 2010 and 2020, more than 70 % of them were written in English by researchers from 67 institutions from around the world. These documents allow us to analyze a sample of countries where the implementation of geotermal energy has a greater advance in processes implementing geothermal energy in the food industry; such as heating and cooling systems for the drying of fruits and vegetables, and producing various foods, achieving energy coverage close to 10 % in this industry.