Your-garbage-disposal won't harm your-septic-tank,
but the liquid & solid waste coming out of your-garbage-disposal
will cause your-septic-tank to back/fill-up faster,
requiring you to have your-septic-tank pumped out more-frequently.
Septic-tank-systems are designed/sized based on your-(pre-existing)-plumbing-fixtures.
You are better-off composting & mulching such food/kitchen-(fruit/vegetable)-waste,
rather than using an in-sink-garbage-disposal.