The citrus pulp obtained from orange (Citrus sinensis) in industrial process is an important residue in countries where orange juice is produced. Enzyme production from this waste can reduce costs of biotechnological processes for the production of food and bioenergy since this residue is not expensive. In this book the citrus pulp was evaluated as substrate for the production of polygalacturonases, cellulases, reduced sugars, and protein for feed by Trichoderma reesei or Aspergillus niger in a cell recycle Batch process. The crude protein in the solid residue after this culture was also evaluated. Good levels of enzymes and protein enrichment of this residue are possible to obtain with the proposed technology.