There’s a lavandería-tintorería, on the American way, in Sevilla city centre at calle Castelar nº 2, just 100 metres from Cathedral and Avenida de la Constitución, that is 5-10 minutes on foot from Triana bridge. The lavandería is called “Roma”. Telephone 954.21.05.35 and it is round the corner from the American Institute of Sevilla (Calle Harinas).
As you are going to be in Triana, I recommend you to have some tapas in Bar Salomón, at López de Gomara Street 11. Do have: patatas a la brava, calabacines rellenos, berenjenas fritas con miel,....
Have a good time!