NOVELTY - Process for the enzymatic hydrolysis of cellulose comprises: (a) providing an aqueous slurry of a pre-treated cellulosic feedstock; (b) introducing the aqueous slurry at the bottom of a hydrolysis reactor; (c) adding cellulase to the aqueous slurry; and (d) removing an aqueous stream comprising hydrolysis product (comprising glucose, cellobiose and/or glucose oligomers) and unhydrolyzed solids.    USE - The invention deals with the enzymatic hydrolysis of cellulose to provide the hydrolysis products such as glucose, cellobiose and/or glucose oligomers (claimed).    ADVANTAGE - The process is an improved process and has high conversion efficiency at loss cost. The use of an upflow settling hydrolysis reactor addresses the improved process over the conventional processes, and results in a higher degree of conversion of the cellulose to glucose. The reactor results in a lower requirement for cellulases than conventional hydrolysis systems. The improved hydrolysis is achieved without the expense of mixing of the slurry within the hydrolysis reactor and without adding intense shear to the system.    DETAILED DESCRIPTION - Process for the enzymatic hydrolysis of cellulose to produce a hydrolysis product from a pre-treated cellulosic feedstock, comprises:    (a) providing an aqueous slurry of the pre-treated cellulosic feedstock, where the slurry comprises 3-30% of undissolved solids (comprising at least 20% of cellulose) in a liquid;    (b) introducing the aqueous slurry at the bottom of a hydrolysis reactor, limiting axial dispersion in the reactor by avoiding mixing, and maintaining an average slurry flow velocity of 0.1-20 feet/hour, so that the undissolved solids flow upward at a rate slower than that of the liquid;    (c) adding cellulase to the aqueous slurry before and/or during introducing the aqueous slurry; and    (d) removing an aqueous stream comprising hydrolysis product (comprising glucose, cellobiose and/or glucose oligomers) and unhydrolyzed solids from the hydrolysis reactor.    INDEPENDENT CLAIMS are also included for:    (1) an enzyme composition comprising cellulase enzymes and one or more flocculant, for hydrolyzing cellulose to glucose, cellobiose and/or glucose oligomers, by the new method;    (2) a kit comprising cellulase enzymes, one or more flocculant, and instructions for hydrolyzing cellulose to produce the hydrolysis product from the pre-treated cellulosic feedstock;    (3) a system for hydrolyzing cellulose to glucose, cellobiose and/or glucose oligomers, comprising the feedstock slurry supply line in fluid communication with an input to an upflow hydrolysis reactor and a solids-liquid separator in fluid communication with the upflow hydrolysis reactor and comprising a first output for withdrawing a slurry comprising unhydrolyzed solids and a second output for withdrawing a stream comprising the hydrolysis product, where the feedstock supply line and/or the upflow hydrolysis reactor comprise an enzyme composition comprising cellulase enzymes and one or more than one flocculent; and    (4) a method for preparing an enzyme composition for use in hydrolyzing cellulose to produce the hydrolysis product from the pre-treated cellulosic feedstock, comprising obtaining cellulase enzymes from a plant, fungal or microbial source, and combining the cellulase enzymes with one or more than one flocculent to produce the enzyme composition.