We live in the west where there is no Islamic banks. So we use normal banks here and give the riba we get to a organization that can receive it and use it for something halal. This organization has its own capital saved up for its charitable work. Does this organization that can receive others riba, have to give the riba that comes from their own capital in the bank, to another organization, or can it spend it on the same halal causes it spends riba given by other Muslims who want to get rid of their riba?

All praise be to Allah, and may His blessings and peace be on His last messenger, Muhammad,

It is not permissible to keep one’s money in an interest generating account. One may take their money out of those accounts and deposit it in checking accounts. You should keep the minimum needed for various needs in those accounts and any surplus of money should be invested in halal, including in the stock market.

As for the charitable organization, they don’t need to separate the money they get through riba transactions since all the money will be spent on charitable causes.

Allah knows best.