NOVELTY - Treating solid waste material, comprises: (a) preparing a slurry comprising particles of the solid waste material in a liquid carrier; (b) subjecting a decomposable fraction of the solid waste material to a fermentation process in a solids digestion vessel; (c) removing some of the liquid from the vessel to leave a compostable fermented solid waste material; (d) removing the compostable solid waste material from the vessel; (e) feeding the liquid to a liquid digestion vessel; and (f) subjecting the liquid in the liquid digestion vessel to anaerobic bacterial digestion.    USE - The process is useful for treating solid waste material (claimed) including farm waste, food and catering wastes, trade, garden and local authority wastes.    ADVANTAGE - The process: allows much faster throughput because the solids digestion vessel is ready to accept a new batch of solids waste material within five days; and does not exhibits any danger of an explosive mixture formed in the event that air is drawn in to the solids digestion vessel, due to the occurrence of little or no methane-producing anaerobic digestion. The process and plant are designed to be easy to operate, require low maintenance, relatively odorless, clean and compact. The vessels are preferably enclosed to prevent cross-contamination and disease risk from birds, rodents and insects.    DETAILED DESCRIPTION - Process for treating solid waste material, comprises: (a) preparing a slurry comprising particles of the solid waste material in a liquid carrier, where the particles has sizes less than a predetermined maximum size; (b) subjecting a decomposable fraction of the solid waste material to a fermentation process in a solids digestion vessel to produce a compostable material and a fermentation gas comprising mainly carbon dioxide; (c) before the fermentation gas from the slurry contains as much as 1% of methane by volume, removing at least some of the liquid from the solids digestion vessel to leave a compostable fermented solid waste material; (d) removing at least some of the compostable solid waste material from the solids digestion vessel; (e) feeding at least some of the liquid from step (c) to a liquid digestion vessel; and (f) subjecting the liquid in the liquid digestion vessel to anaerobic bacterial digestion to produce a liquid fraction containing active anaerobic bacteria and a methane-rich gas fraction. An INDEPENDENT CLAIM is included for an apparatus for digesting a solids waste material, comprising a mixing vessel, a solids digestion vessel, and a liquid digestion vessel, where the mixing vessel is connected to the solids digestion vessel by a slurry pump, and the solids digestion vessel having a fluid connection to the liquid digestion vessel for transferring liquid from the solids digestion vessel to the liquid digestion vessel.    DESCRIPTION OF DRAWING(S) - The figure shows the apparatus for digesting solid waste.