TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The apparatus further comprises: a fluid connection for transferring liquid from the liquid digestion vessel to the mixing vessel; and a pump for recycling liquid from a lower part of the solids digestion vessel to an upper part of the solids digestion vessel. The slurry pump is a chopper pump, or a self-cleaning or macerating pump.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The process further comprises: subjecting the compostable solid waste material removed from the solids digestion vessel to a composting process to produce a composted material suitable for use as a soil conditioner; using at least some of the liquid fraction from the liquid digestion vessel in the preparation of the slurry; agitating the slurry in the solids digestion vessel; and reforming a slurry from liquid remaining in the solids digestion vessel and solids at or near the bottom of the vessel, and pumping the reformed slurry out of the solids digestion vessel. The decomposable fraction of the solid waste material undergoes acid hydrolysis prior to or during the fermentation process. The pH of liquid in the solids digestion vessel is maintained at 6-7. The pH of liquid in the liquid digestion vessel is maintained at 7-8. The slurry is prepared by mixing solid waste materials and a liquid in a mixing vessel and pumping the mixture to the solids digestion vessel using a comminuter or slurry pump which breaks up particles of the solid waste material larger than the predetermined maximum size. In the process, most of the mass of the solid waste material comprises particles having a size of 5-15 mm. The slurry is agitated by recycling liquid from a lower part of the vessel to an upper part of the vessel. The step of recycling is carried out by means of a chopper pump, or a self-cleaning or macerating pump. The solids digestion vessel is open to the atmosphere during the fermentation process. The fermentation step (b) is carried out for 2-3 days. The step of removing at least some of the compostable solid waste material from the solids digestion vessel comprises using a moving curtain to push floating solid waste material out of the solids digestion vessel. Preferred Components: The maximum size of the particles of the solid waste material is 15 mm. The weight ratio of solids to liquids in the slurry fed to the solids digestion vessel is 50:50.