Oops! Sorry, I did not realize that it was a virtual ground. Circuit makes more sense now. Could not figure out why there were differing ground symbols.Do you need mean the virtual ground? The virtual ground gives the op amps the illusion of a dual tracking power supply.
That "virtual ground", which makes indeed an effective equal of a split power supply, is actually better than using a voltage divider and filter capacitors because the effective impedance of that source is the output of the op-amp used, quite low and independent of frequencies over a wide range.One of my standard design features.