Protein recovery by selective separation using ceramic membranes

Abstract

Processing of shrimp shells for the production of chitin makes commercial use of shell waste with economic benefits. Although chitin possesses the valuable properties of a biopolymer, with many useful applications, significant environmental pollution during its production hampers growth opportunities for industrial processing. In this study, a filtration process at different molecular weight cut-offs is assessed for protein recovery from the discharged alkaline processing stream of an industrial chitin manufacturing unit. Three tubular ceramic membranes (0.1 μm, 450 D and <300 D) have been investigated under a constant temperature of 70 °C, at chosen trans-membrane pressures of 1.3–5 bar, high cross flow velocities of 3.3–3.5 m/s, and at a volumetric concentration factor of 5. Results of concentration runs indicate a significant increase of recovered proteins, between 7 and 16%, can be achieved in the concentrate stream by reducing the chosen membrane cut-offs. A second product the permeate stream – solid-free hydroxide sodium solution – can be re-utilized in the chitin production line. Retention of the organic load led to a 56% decrease of chemical oxygen demand and total bound nitrogen in the permeate stream.