Protein separation from alkaline process water of shrimp waste processing industry using membrane filtration

The recovery of protein and caustic soda solution from shrimp waste alkaline process water was experimentally investigated by a two-step filtration process with polymer membranes of different molecular weight cut-offs. Experiments for nine combinations of microfiltration/ultrafiltration and nanofiltration membranes were conducted in batch-mode using a stainless steel stirred cell with a membrane area of 38.5 cm². It could be shown that this process concept is capable of separating protein and dissolved organic carbon from the alkaline hydrolysis of shrimp waste. Totally, more than 30 % of protein was fractionated by the first step filtration while the second step reached a higher protein rejection of more than 88 %. The protein concentrate could be reused as animal feeding and the recovered sodium hydroxide solution couldbe recycled to the production process. Keywords : Membrane filtration, protein recovery, alkaline process water.