Filterability and Filtration Experiences of Viscous Complex Food Salting Solutions

Abstract

The main focus of this study was to find out the suitable coupling for the regeneration of a complex concentrated ternary brine (salt/corn syrup/water) after fish fillet salting using separation technologies. Experiments were designed for analytical purposes with three selected waste brines originating from different clean solutions and salting process conditions, and processing as well as plant parameters (for example, economics, environment, technical availabilities) were considered. In this regard, several chemical and physical pretreatments were first conducted to increase the size of suspended solids (SS) and to reduce the proteinaceous matters in the suspension. Treated suspensions and their separated phases after settling were subjected to various filtration experiments. Crossflow micro- and ultra-filtration pilot trials (tubular ceramic membranes) showed their inefficiency in terms of permeation flux density, even at high temperature. This was mainly because of the high viscosity of solutions which in turn lowered the shear stress near the membrane. Laboratory-and industrial-scale cake filtration experiments using a rotary vacuum precoat filter (RVPF) were also conducted to find the optimal filtration conditions with the help of a unifying filterability parameter. The best coupling appeared to be pH pretreatment, followed by a settling time adjusted to the salting process conditions. Using body feed for the SS-rich phase, a differential RVPF filtration of the settled phases allowed the regeneration of solution with minimal filter-aid consumption.