In one aspect of the invention, a method recovers oil from a concentrated byproduct, such as evaporated thin stillage formed during a dry milling process used for producing ethanol. A cleaningfluid-feeding head integrates a cleaning head portion and a fluid-feeding head portion. The optical device is operable to direct the beam to illuminate a sequence of specified regions of a surface. The third malware pattern is a second permutation of the second malware pattern and is different than the second malware pattern.