Bricks, Masonry, Asphalt and Concrete - Refilling trenches in basement floor

I broke my basement concrete floor for sewage ejector pump pit and DWV pipes trenches. The pit is about 34" deep and troches are about 16" deep. I carefully collected all broken concrete debris into one trash bug and sand and dirt from deeper layers into another trash bag. I put about 2" of gravel to the bottom of pit and trenches and then put pipes and pipe basin on the gravel. Now I need to refill the pit and trenches and make them smooth with basement floor level. What's the right way to do this? I never dealt with concrete before so detailed advise of technique and materials would be greatly appreciated. Of cause I would like to reuse concrete debris that I collected as much as possible.