Your time limit could be a problem. If you need to eat 'normally' in ten days you should not fast right up until that time. If your deadline is not a date which requires you to eat normally then it is possible, otherwise you will need to fast for 5 days and then eat minimal raw foods for the next five bringing you up to your deadline.
If you are healthy to begin with you may be able to exercise enough to ensure extra weight loss in this time, but if your eating habits have been highly toxic then you may find that your body has too much work to do removing those toxins to allow you the energy to exercise. It is still possible you will lose the amount you want regardless though, but there are no guarentees.
seltzer is not okay. Carbonated water is okay but you need to make it yourself using pure water to start with. Don't drink tap water or mineral water if you can avoid it, only pure H2o with nothing added to it.