A tank or bed has a plurality of sidewalls that create a bed cavity and a Fresnel panel frame that includes at least one Fresnel panel. The Fresnel panel frame may be adjacent to the bed cavity and may cover at least a portion of the bed cavity. An amount of sludge may be contained within the bed cavity. When placed in sunlight, the heat enhanced by the Fresnel panels may heat the sludge sufficiently for the sludge to be used as fertilizer.