This study investigates the use of the microwave thermo-ethanol method to recover cuprous oxide from waste liquid that contains heavy metals, formed by the leaching of acid from sludge of printed circuit boards. An XRD analysis yields main peaks of cuprous oxide 2θ = 36.45° and 42.35°. SEM analysis indicates that the cuprous oxide was octahedral when 0.1 M glucose, or a higher concentration, was added to the waste liquid. The purity of prepared powder of cuprous oxide was analyzed using an inductively coupled plasma-optical emission spectrometer (ICP-OES), and the purity of the prepared powder of cuprous oxide was found to exceed 70%. Accordingly, in this study, metallic resources were regenerated.