Constant pressure filtration of lime water (nejayote) used to cook kernels in maize processing Original Research Article

The purpose of this work is to establish the operating conditions of an intermittent filtration cell running at constant pressure, designed to treat nejayote – the liquor left after the separating cooked kernels by reducing the solid content as an alternative to reusing this liquid waste directly. The X-ray results and scanning electron microscope analysis shows that calcite (CaCO3) is the major inorganic component in nejayote, although there is also the presence of fibers and starch. The nejayote filtration process without precoat is slow; the results indicated that a precoat of 3.17 mm exhibits a higher filtration rate and therefore this condition has been selected to perform the filtration tests in the cell. The graphs of filtrate volume versus time, corresponding to diatomite dosage level 1:0.5, significant fluctuation in nejayote filtration. This could be due to the random manner in which the pores are interconnected. As a result, the diatomite, at dosage of 1:0.25, has to form paths through the cake in order to allow filtered nejayote to flow. However, at a dosage of 1:0.5 some diatomite and solids can form clusters, which decreases filtration rate. Filtration represents an alternative method to separate insoluble solids and nejayote filtrate.