An inkjet printer includes a waste ink treatment system and a humidification chamber to separate waste ink produced by a printhead maintenance station into solid ink pigment particles and a solvent stream and use the solvent stream to maintain inkjets in the printheads of the inkjet printer in operational status. The waste ink treatment system mixes the waste ink with a metal salt to precipitate the solid ink pigment particles out of the waste ink. The solvent stream remaining after the precipitation of the pigment particles is humidified and directed to air baffles positioned on opposite sides of each printhead in every other printhead module in the process direction. A kit is provided to retroactively modify an existing inkjet printer to treat the waste ink and use the solvent stream to maintain the operational status of the inkjets in the printheads of the inkjet printer.