You probably found this:
I used one of them and it worked pretty well. Only problem i found was that it was not very precise, especially at short distances. Maybe it was the way i used it.
I don't know if it is possible for Arduino to control 10 of them, but i guess it is.
One thing you should consider very carefully is that the sensor has an angle in wich it will detect an object. If you place 10 of them on a wall it will be very difficult to avoid the angels to overlap. This will make more than one sensor detect the same person. This will be a potential problem no matter which sensor you choose.