Vertical pipe under kitchen sink. What is it and can I use it?

[Dmytro Zhosan]

Hi, I have a single drain kitchen sink with a garbage disposer. I’m trying to install an RO system, and need to connect the drain line somewhere (Y-connector through a dishwasher drain in the disposer is not an option due to space constraints).
So, I have a question: anybody knows the purpose of the vertical pipe in the photo between the disposer and the wall? Can I just use a saddle tap to connect my RO drain line to that pipe?
Thank you in advance.

 

[frodo]

show an image of the drains under the sink

back up..take another pic.

you can possibly use a wye branch at the sink.

 

[Dmytro Zhosan]

Thank you for your response. Here are some more pictures. Basically there is no other possible part a pipe to tap, as tapping after the garbage disposer means the drain line will constantly get clogged.

An update: I was told this is an auto vent (The sink is in the island). If I’m understanding it correctly, that means I can tap into it with a saddle tap. Can anyone who knows the stuff confirm that this is correct?

thank you.

 

[voletl]

Thats your vent for your kitchen sink you cannot tap anything into that and if you're going to connect anything to a drain line you should do it before the Trap