Improvement of tangential microfiltration of gelatin solution using a permanent magnetic field.

Membrane technology is an interesting alternative to conventional gelatin clarification methods, resulting in the elimination of refining chemical agents. In this work, the application of a permanent magnetic field as a pre-treatment of the gelatin solutions was proposed as a strategy to improve the microfiltration (MF) performance. Filtration tests were performed using a 1.5% swine gelatin solution at 40 °C through cellulose acetate membranes in a tangential flow module. Prior to the filtrations, the feed solutions were pretreated by the circulation of the solution through magnetic fields with different flux densities, 0.7 T and 1.34 T, for 2 h. The magnetic induction of the solution significantly increased the permeate flux and the recovery of hydraulic permeance by 63% and 122%, respectively, showing the application of the magnetic field in the solution of gelatin is an attractive alternative to improve the performance of the process.

Use of membranes for the treatment and reuse of water from the pre-cooling system of chicken carcasses.

Poultry processing plants generate large amounts of wastewater in the many steps necessary to provide high quality and safe products. Carcass chilling is one of these steps, where the temperature of the carcass is reduced from 40°C to 4°C, for reducing the growth rate of microorganisms and affecting flavour, texture and appearance. In this operation, carcasses are continually displaced through a series of two tanks (called pre-chiller and chiller) filled with cold water, thus being responsible for a considerable amount of wastewater generation. This work aimed to regenerate the wastewater of the pre-chiller tank employing microfiltration (pore size 0.10 and 0.20 µm) and ultrafiltration (UF; MWCO 10 and 50 kDa) polymeric membranes in bench and pilot scales, with the final purpose of reuse. Membrane performance was evaluated in terms of the capacity of removing the contaminants and producing sufficient permeate flux in different working pressures. Bench-scale UF membrane presented the highest initial permeate flux of 112.1 L/m2h at 200 kPa. The four membranes tested presented good retention of microorganisms, with apparent rejection of up to 100%. Pilot-scale membranes presented better apparent rejection, with retentions above 99% for turbidity, apparent colour and fat content. Moreover, organic matter retention was also very high, up to 94% for chemical oxygen demand and 92% for total organic carbon. The use of membranes seems to be a promising approach for recycling and reuse of poultry pre-chiller wastewater.

Impact of MWCO and Dopamine/Polyethyleneimine Concentrations on Surface Properties and Filtration Performance of Modified Membranes.

The mussel-inspired method has been investigated to modify commercial ultrafiltration membranes to induce antifouling characteristics. Such features are essential to improve the feasibility of using membrane processes in protein recovery from waste streams, wastewater treatment, and reuse. However, some issues still need to be clarified, such as the influence of membrane pore size and the polymer concentration used in modifying the solution. The aim of the present work is to study a one-step deposition of dopamine (DA) and polyethyleneimine (PEI) on ultrafiltration membrane surfaces. The effects of different membrane molecular weight cut-offs (MWCO, 20, 30, and 50 kDa) and DA/PEI concentrations on membrane performance were assessed by surface characterization (FTIR, AFM, zeta potential, contact angle, protein adsorption) and permeation of protein solution. Results indicate that larger MWCO membranes (50 kDa) are most benefited by modification using DA and PEI. Moreover, PEI is primarily responsible for improving membrane performance in protein solution filtration. The membrane modified with 0.5:4.0 mg mL-1 (DA: PEI) presented a better performance in protein solution filtration, with only 15% of permeate flux drop after 2 h of filtration. The modified membrane can thus be potentially applied to the recovery of proteins from waste streams.

Magnetic field on fouling control of ultrafiltration membranes applied in treatment of a synthetic textile effluent.

Membrane performance is decreased by fouling, reducing permeate flux and membrane lifespan. This paper assesses ultrafiltration of a model textile effluent assisted by permanent magnetic field as an alternative to improve the water permeability recovery. Ultrafiltration was performed in a tangential module and model solutions, composed of carboxymethylcellulose (CMC) and sodium sulphate (Na2SO4). The feed was permeated through 30 kDa polysulphone membrane with and without the presence of a permanent magnetic field of 0.41 T, perpendicular to the membrane surface. Magnetic induction (MI) of feed solution was also investigated by recirculation of the feed stream through the magnetic field for 3 h. The increase in feed concentration did not affect permeate flux, while the presence of salt resulted in a severe flux decline. Effective water permeability recovery was obtained when the magnetic field was applied in the ultrafiltration process, although the MI of the CMC and Na2SO4 solutions also caused some enhancement in permeability recovery. Scanning electron microscopy images showed differences between the assays done with and without the presence of magnetic field. The magnetic field application in ultrafiltration of CMC and Na2SO4 solutions has proved to be an attractive alternative for improving the permeability recovery.