Microplastics in Toulon area:occurrence and efficiency of wastewater treatment plants

The occurrence of microplastics in the environment is a growing concern. Their presence in the ocean and in sea water has been documented since the early 1970s. The sources of microplastics emissions are numerous and related to human activities. Wastewater treatment plants (WWTPs) are sometimes reported as sources of microplastics while a growing number of studies demonstrate high removal performances of microplastics during wastewater treatment. The first studies focused on microplastics above 300 μm that could be analyzed by simple techniques (optical microscopy in particular) commonly used in laboratories. The development of more powerful analytical tools has led to a lower detection limit of a few micrometers. However, the lack of harmonized analytical protocols (sampling strategy, sample preparation, etc.) still renders the comparison of results from different studies difficult. The MEDIPLAST project studies the occurrence of microplastics in the water cycle of the Toulon metropolitan area using a robust and reproducible analytical method on all the samples. Microplastics down to 10 μm are qualified and quantified in four WWTPs composed with different treatment processes. Measurement campaigns were also carried out in the marine environment at six locations in Toulon bay to assess the impact of discharge from WWTPs or harbor activities. Results show a very good performance of WWTPs with a removal of microplastics higher than 99.4%. The primary treatment is the most efficient step but biofilters and disc filters enable an additional elimination of the remaining microplastics up to 69%. Offshore measurements do not show a significant increase of microplastics at the WWTPs discharge points compared to the aquatic environment not impacted by the discharges

Towards an Aircraft with Reduced Lateral Static Stability Using Differential Thrust

In the context of aircraft drag reduction, we study the possibility of reducing the area of the vertical tail using Distributed Electric Propulsion (DEP) while maintaining lateral stability with active Differential Thrust (DT). Distributed Electric Propulsion is usually thought of as a mean to increase aerodynamic efficiency by exploiting the benefic effects of accelerating air around key parts of the aircraft. However, it can also be seen as a collection of actuation devices generating additional moments through Differential Thrust. When the engines are distributed along the lateral axis, the aircraft designer may take advantage of the increase of control authority on yaw to reduce the static stability or the control authority provided by the Vertical Tail (VT). This in turn would allow a reduction of vertical tail surface area. In order to explore and assess this idea, we suggest a framework to compare flight qualities of a traditional configuration versus a configuration using Distributed Electric Propulsion and Differential Thrust. The framework provides information on the flight envelop and stability of the aircraft by computing a map of the equilibriums. Thanks to a global approach, it allows to study any aircraft or DEP configurations in any flight phase. In addition, a key feature of the framework is the inclusion of the VeDSC[1] method to compute analytically the contribution of the vertical tail to lateral stability. It allows to study effects of a 30% reduction of VT surface area. Here are presented the first results and potential of using differential thrust to reduce the area of the vertical tail and the reasons for us to continue developing this framework