which contains less nitrogeneous waste? - renal vein or renal artery?

@Seeno:- Aastha is absolutely  right- renal artery contains large amount of waste .

Renal artery brings oxygenated blood to the kidneys from the aorta which arises out of heart but this blood is not pure and has nitrogenous waste in it while renal vein carries deoxygenated but filtered blood to the heart from where it is again pumped to the entire body.

@Aastha:- Good answer, keep contributing!!