If you notice a foul sewer smell in your basement, here are the five possible causes in order of probability: 1  You have a water trap under a floor drain, laundry tub or wash basin that has dried out from lack of use. Water in any trap under unused drains will eventually evaporate. 2  Check for a cleanout plug inside the floor drain.
https://www.familyhandyman.com/plumbing/drain-repair/how-to-eliminate-basement-odor-and-sewer-smells/view-all/
A. Close up the basement , you must dry it out, remove all water, fix leaks, etc. Get a dehumidifier and run it on high. Put a box fan down there and run it 24 hours a day. Get a box of powdered bleach and spread it on the concrete floor for a couple days, then sweep it up. If it still smells spread another box, etc.; keep at it.
https://www.finishing.com/239/22.shtml
Removing Urine from Wood Floors. 1  1. Locate the source of the smell. 2  2. Remove as much liquid as possible. 3  3. Blot the area with a damp paper towel.  4. Apply baking soda 1  generously. 5. Vacuum the baking soda 2  up. 6. Soak the area with an enzyme-based cleaner.  7. Blot up any excess 1  cleaner. 8. Repeat the previous two steps as  needed.
http://www.wikihow.com/Get-Dog-Smell-Out-of-a-Basement
If you are going to do the job of taking care of the musty smell in the basement, make sure that you wear a face mask before you tackle a cleaning job. Use a mixture of bleach and water and scrub the walls. The bleach and water combination will get rid of the musty smell and mold. I don't know what can be done with the ceiling. What your aunt's basement needs is a dehumidifier which will remove the dampness.
http://www.thriftyfun.com/Getting-Rid-of-a-Musty-Smell-in-the-Basement.html
Removing Urine Smells from Carpet and Upholstery. 1  1. Locate the source of the smell. 2  2. Blot the urine-soaked area. 3  3. Soak with an enzymatic solution.  4. Blot up the 1  solution. 5. Sprinkle baking soda over the spot.  6. Apply a deodorizing 1  solution. 7. Scrub the 2  area. 8. Vacuum the  area.
http://www.wikihow.com/Get-Dog-Smell-Out-of-a-Basement
Finding the source of the basement smell. If you notice a foul sewer smell in your basement, here are the five possible causes in order of probability: You have a water trap under a floor drain, laundry tub or wash basin that has dried out from lack of use. Water in any trap under unused drains will eventually evaporate.
https://www.familyhandyman.com/plumbing/drain-repair/how-to-eliminate-basement-odor-and-sewer-smells/view-all/
Here is how to KILL the mold: FIRST: get some kerosene (or citronella-mosquito oil will work fine too) and pour small amounts (maybe 1/2 cup) on the floor (2-3 inches from a corner) in each room that has a carpet. If no carpet, pour on a pillow, cushion, or any textile-type product.
https://www.finishing.com/239/22.shtml
This combination should eradicate any odors, although you may still need to install some form of basement ventilation. In any case, you should end up with a more functional storage area. For basements with concrete floors, the solution may be a little trickier. Some form of waterproofing may be necessary.
http://www.homeadvisor.com/r/basement-moldy-smell/
Mold in Basement. Of course a moldy odor in your basement usually means you have mold in the basement. Depending on the extent of your mold problem, you may need to hire a mold removal professional. Mold can eat through wood framing, basement insulation, and a number of other materials and structures.
http://www.homeadvisor.com/r/basement-moldy-smell/
Locate the source of the smell. Urine is one of the most common pet odor problems. For people whose dog spends a lot of time in their basement, figuring out how to remove the urine smell from concrete or cement can be tricky. The first thing you’ll need to do is locate the source of the urine smell.
http://www.wikihow.com/Get-Dog-Smell-Out-of-a-Basement
how to get the smell out of your basement
To get rid of the mushy smell and mold in a basement use a mixture of bleach and water and scrub the walls.