  The elemental abundances of symbiotic giants are essential to address the
role of chemical composition in the evolution of symbiotic binaries, to map
their parent population, and to trace their mass transfer history. However, the
number of symbiotic giants with fairly well determined photospheric composition
is still insufficient for statistical analyses. This is the third in a series
of papers on the chemical composition of symbiotic giants determined from high
resolution (R ~ 50000), near-IR spectra. Here we present results for 24 S-type
systems. Spectrum synthesis methods employing standard local thermal
equilibrium analysis and atmosphere models were used to obtain photospheric
abundances of CNO and elements around the iron peak (Fe, Ti, Ni, and Sc). Our
analysis reveals metallicities distributed in a wide range from slightly
supersolar ([Fe/H] ~ +0.35 dex) to significantly subsolar ([Fe/H] ~ -0.8 dex)
but principally with near-solar and slightly subsolar metallicity ([Fe/H] ~
-0.4 to -0.3 dex). The enrichment in 14N isotope, found in all these objects,
indicates that the giants have experienced the first dredge-up. This was
confirmed in a number of objects by the low 12C/13C ratio (5-23). We found that
the relative abundance of [Ti/Fe] is generally large in red symbiotic systems.
