The present invention is a system for processing organic waste using insect larvae, which has the advantage of being able to process large quantities of organic fecal waste material. The system includes a plurality of substantially flat reaction vessels stacked one on top of the other in parallel arrangement to form a processing blocks 11. Each of the reaction vessels in the processing block 11 are dimensioned and configured to contain a quantity of organic waste, each reaction vessel having front and back ends and side edges, the reaction vessels each being separated from the reaction vessel above by an air space 23, the processing block being contained in a plant enclosure having side walls. At least one of the side walls of the plant enclosure (plenum wall 38) is positioned adjacent the processing block such that the plenum wall is adjacent one of the side edges of the reaction vessels. The plenum wall has a plurality of openings which open to the air spaces and the openings positioned on the plenum walls such that openings are immediately adjacent air spaces. The system further includes an air circulation system for circulating purified and adjusted air through the air spaces by passing air through each of the openings in the plenum wall. The system also includes a feeder system for loading raw organic waste onto the reaction vessels and a discharge system for removing processed organic waste from the reaction vessels.