Sulfur smell from one side of double sink

[Electron2002]

For several months now, when using one of the two sides of the double sink in our master bathroom, you pick up a bit of a sulfur / rotten egg smell. The other sink has been fine to this point. The two sinks have separate traps and enter the wall separately and I can only assume that their drains are connected within the wall. No other sinks or fixtures have any kind of smell from them.

Since I am not getting any smell from anywhere else, I have eliminated the water supply itself as a possible source. and since it isn't coming back through the second sink's drain, it seemed reasonable that the entire problem was limited to the trap of the smelly drain.

Today I finally got around to pulling the trap and was greeted by the smell. What I also found was a fairly considerable buildup of a black granular substance that I found in the bottom of the Ptrap as well as on the horizontal floor of the drain stub-out coming out of the wall. With the water out of the way, the smell from the substance had more of a burned gunpowder and sulfur smell. (My fiancee almost threw up when she caught a whiff of it)

Do you guys have any ideas what this substance might have been? Or how it might have formed?

I am going to simply replace the trap but also need to clear the buildup from the stub-out, which should at least handle the current situation.

What could be done to keep this from returning?

Thanks,

 

[IFIXH20]

Do you shave in the smelly sink ?

 

[Electron2002]

I used to once upon a time.

 

[FamilyPlumber]

Had the same problem, and after I opened the trap I threw up, right in front of my brother.

If the smell returns, use:

degreasing dishwasing liquid to use through the pipes
chlorine bleach with water to kill every bacteria down there.
baking soda and vinegar mixed with hot water down the drain.

Please do that once a week(I'm always doing it too) just to prevent the smell from ever coming back.