Recovery of carbohydrates from nixtamalization wastewaters (Nejayote) by ultrafiltration

Nejayote extract is a polluting by-product from Nixtamalization of maize; therefore in this study was evaluated a membrane operation for the treatment and recovery of industrial usable compounds. Nejayote extract was processed by ultrafiltration (UF) membrane on laboratory scale. In experimental tests performed according to the total recycle mode, the e ect of transmembrane pressure (TMP) on permeate flux has been studied. The permeate flux no showed a considerable increase for TMP values higher than 1.3 bar, which is considered as limiting TMP (TMPlim) that provides the maximum permeate flux. Filtrated Nejayote extract has been produced in experimental test carried out according to the batch concentration mode working in optimal operating conditions. The extract was analyzed in terms of total soluble solids (TSS), total solids content (TSC), pH, electrical conductivity, turbidity, total polyphenols, total carbohydrates, total organic carbon (TOC) and calcium content. The UF process permitted a good level of recovery; it was corroborated with the removal of 95.3 % on turbidity, 22.0 % on TSC, 37.0 % on TSS, 14.7 % on Calcium and 29.3 % on TOC on Nejayote. From retentate was recovered considerable sugar content (rejection of 46.6 % in total carbohydrates). Finally, high fouling index in the membrane (87 %) was determined after treatment of Nejayote; however, the total of the initial water permeability was recovered by enzymatic cleaning (cleaning eciency 100 %).