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Three different process alternatives for the production of soybean oil by supercritical carbon dioxide extraction were analyzed. The first two processes were organized according to the classical scheme, based on high-pressure extraction followed by separation induced by pressure reduction. Different techniques were used to recover the solvent in these two schemes, in the liquid and in the gas phases, respectively. The third alternative was based on an isobaric scheme--the oil, extracted at high pressure, was separated by changing the temperature in the separator. In a further improvement, a technique for the heat transfer network integration was added to all the process schemes. The different schemes were used to establish the process configuration that can produce a lower operating cost for soybean oil extraction. Operating costs were considered on an industrial scale to carry out a screening of the different alternatives. The operating cost of these plants were then compared with the hexane extraction process. A substantial reduction in the specific costs was obtained in the case of heat transfer integration, and the operating costs fell in the same range as conventional extraction plants.

Waste cooking oil (WCO) can be a useful secondary raw material, if properly managed. On the contrary, uncontrolled disposal generates negative environmental impacts as well as economic loss. Therefore, improving WCO recovery rate, with the cooperation of citizens and effective collection programs, is fundamental. The aim of the study was to investigate the reason for the low recovery of WCO in those areas suffering serious waste management problems such as the Campania region in Southern Italy. For this purpose, the case of a WCO collection program adopted in Angri, a town of around 34,000 people with a high population density, was studied. In 2015, the collection program was managed by a social cooperative, while, in 2016, after the change of the local government, the collection of WCO was entrusted to a private company. In 2015, the households’ participation in the collection program was surveyed through a structured questionnaire. The results revealed that the collection of WCO was practiced by 53% of the respondents. Among those not collecting WCO, 76% of the sample wrongly disposed of WCO in their home (kitchen or toilet). Misinformation was the main reason why they did not adhere to the collection program. Therefore, it was suggested to support information and environmental education campaigns to promote environmental awareness of citizens. Unfortunately, the change of management, together with serious problems in the collection of municipal waste in the whole region, due to the continuous closures of the mechanical and biological plants, produced a sharp decline in the collection from 7730 kg in 2015 to an average of 3800 kg for the period 2016–2019, with a loss of more than 15,000 kg of WCO wrongly disposed with consequent environmental and economic damage. Therefore, information and awareness campaigns are important but the form of entrusting the collection service is equally important, especially in areas with long-standing waste management problems.