J. Lora

Treatment of whey effluents from dairy industries by nanofiltration membranes

Abstract Membrane separation processes are based on the principle of concentration-fractionation treatment of solutions without phase change. Ultrafiltration (UF) and reverse osmosis (RO) are well established pressure-driven membrane processes that are widely used in the dairy and other food industries throughout the world. Recent developments in the membrane technology have expanded the range of applicability of these traditional processes offering the processing industry new alternatives to the more traditional technological approaches. One such new development is nanofiltration (NF). Nanofiltration (NF) membrane processing was investigated as a method of deacidifying and demineralizing acid cheese whey as a function of temperature, pressure and pH. This study was focused on improving the demineralization rate achieved by commercial nanofiltration membranes by using laboratory-manufactured membranes. Model solutions of whey were applied as well as model solutions for each salt (single-salt solutions), allowing us in this way to study the performance and transport of salts when each salt is treated alone and when all are together (whey salts) in the feed solution

Effect of oxidation agents on reverse osmosis membrane performance to brackish water desalination

Currently, the polyamide (PA) membranes by reverse osmosis (RO) are highly effective in their applications for water desalination and water reuse. However, they offer poor resistance to strong oxidants such as chlorine, resulting in chain deformation. In this work, we have studied the RO performance of membranes, which were made from a copolymer of two different aromatic polyamide (poly-terephtalamide diphenyl sulphone (PTDS) and poly-isophtalamide diphenyl sulphone (PIDS)) by using the phase-inversion method. The membranes were tested before and after treatment with a sodium hypochlorite solution. The results showed a remarkable tolerance of these membranes to a chloration test.

Modelling of a low-pressure reverse osmosis system with concentrate recirculation to obtain high recovery levels

A big problem for the desalination plants situated far from the sea is the elimination of the concentrated brines. The volume reduction of the final concentrate could allow an economic transport and a high recovery level. In order to solve this problem, a reverse osmosis system with recirculation (RRO) is proposed. In this system, a part of the final concentrate is recirculated in order to obtain high concentration ratios at low applied pressure. The recirculated stream flows in the permeate side in counter-current reducing the osmotic pressure difference, which is the driving force for solute transport. In this way, a low pressure is needed to establish the water flux. Formally, the RRO system is similar to a continuous distillation or a liquid-liquid extraction, and the flow recirculation ratio, defined as the relation between the flows of product and recirculated stream, is the main operative parameter. In this work a model of the system is used to evaluate the efficiency and to determine the situations where it can be preferable compared to other configurations or unit operations.