Is it permissible to submit studies for beneficial projects (such as water purification or waste-to-energy conversion) if these projects are to be financed by usurious loans, knowing that my work does not directly involve banks and I do not approve of usurious dealings?

If your work is permissible in itself and is not connected to usury or assisting with it, then there is no harm in you providing studies. However, if obtaining usurious loans depends on those studies, then it is not permissible to provide them, as this falls under cooperation in sin and aggression.