In the event of a flood, there is a great possibility that you will experience a sewer backup. This cleaning job is not the most pleasant but it can be done without causing more damage when done correctly.
Pump out Water
Before you can clean out solid particles and sludge, you need to pump out the standing water. Use at least two submersible pumps to make this job go faster and to not overload either pump. Place pumps in the lowest part of the basement with a hose going out a basement window.
After you have pumped the water out, remove the items in the basement. This should include both damaged and undamaged items.
Clean up Remaining Water
A wet dry vacuum will help you get the rest of the remaining moisture off the floor. It will also pick up some of the smaller pieces of solid wastes. Keep the vacuum from filling up completely by emptying it frequently.
Remove Carpet and Dehumidify
Remove the carpet by rolling it up and wrapping in plastic to keep from dripping on other areas. Mop the floor with a water and bleach solution. Set up fans in the windows to keep the air circulating and use a dehumidifier to soak out the remaining moisture from the room.