Sewage pump sounds like running dry
Check the sump where the pump is located.  It's likely getting a trickle of water from somewhere, filling very slowly until it trips the float switch and pumps the water out.  You may have a leaky stool, water seepage from under the floor, a dripping faucet, a de/humidifier, or condensing furnace draining into it.  Your next steps, if any, depend on where the water is coming from.