Catalyzes the NAD(+)-dependent dehydrogenation of 2-dehydro-3-deoxy-L-rhamnonate to 2,4-didehydro-3-deoxy-L-rhamnonate. Also has weak dehydrogenase activity on butane-2,3-diol. Does not show any detectable activity in the presence of NADP(+). 2-dehydro-3-deoxy-L-rhamnonate + NAD(+) = 2,4-didehydro-3-deoxy-L-rhamnonate + H(+) + NADH Binds 2 Zn(2+) ions per subunit. Optimum pH is 9.5. Optimum temperature is 50 degrees Celsius. Carbohydrate degradation; L-rhamnose degradation. Belongs to the zinc-containing alcohol dehydrogenase family. The sequence shown here has been extracted from the Sulfobacillus thermosulfidooxidans DSM 9293 genome sequencing BioProject (Accession PRJNA61271, JGI sequencing center).