The interaction between biofuel ashes and the oxygen carrier in chemical looping combustion (CLC) and chemical looping with oxygen uncoupling (CLOU) processes will be a key factor for the future implementation of these processes on an industrial scale. This is important if the biofuel used is a waste product with a high ash content, as much as 30 wt %, as is dry swine manure. The main components of swine manure ash are Ca (17 wt %) and P (13 wt %). The present work studies the interactions between three different oxygen carriers, two synthetic magnetic Cu-based CLOU oxygen carriers (Cu30MnFekao7.5 and Cu30MnFe_Mag) and ilmenite, and swine manure ash. CLOU and CLC cycles were performed in a batch fluidized-bed reactor under harsh conditions using up to 33.3 wt % ash. For both CLOU oxygen carriers, the concentration of O