Cleaning of Microfiltration Membranes for Filtration of Aqueous Extract of Marsh Mallow

Abstract

Cleaning of a microfiltration membrane was studied using various chemicals. The activation energy and cleaning constant were estimated for alkaline cleaning.Baromembrane filtration methods (microfiltration, ultrafiltration, nanofiltration, and reverse osmosis) are widely used in processing of synthetic and natural high-molecular-weight compounds for their concentration, desalination (removal of low-molecular-weight compounds from solutions of macromolecules), and fractionation [1].Among the most important problems arising in using membrane filtration in biotechnology and food and pharmaceutical industries is that the membrane throughput decreases in the course of filtration [23 4], which is caused by such factors as increase in the concentration of components retained at the membrane surface [5, 6] and adsorption of colloids, microorganisms, and organic compounds on the surface and in the pores of the membrane [6,7]. Both these factors reduce the effective pore size, thus increasing the resistance of the membrane to the flux [8].The problems arising from membrane fouling started to be manifested in full measure upon accumulation of data on operation of industrial units [9]. Fouling with organic contaminants plays an especially significant role in filtration of macromolecular compounds, which can form a gel layer on the membrane surface [10]. Studies concerned with the problem of fouling are being conducted in various areas including development of cleaning methods [9]. Chemical cleaning involves treatment of filters with various agents, allowing regeneration of a membrane without disassembling of a membrane unit (cleaning-in-place) [11]. To optimize chemical cleaning, specific features of a given process and the type of the membrane used should be taken into account.The goal of this study was to optimize the chemical cleaning of a membrane contaminated during microfiltration of the extract of marsh mallow. EXPERIMENTALIn the study we used an Alpma microfiltration system (Germany) (Fig. 1) equipped with two membrane units (Kerasep, France). Each unit consisted of nine cylindrical membranes fabricated from TiO 2 with the Al 2 O 3 / TiO 2 active layer (nominal pore size 0.2 mm). Membranes of this type are thermally and chemically resistant over the pH range 1314 at 2933358 K.The water flux across an unused membrane at a transmembrane pressure P TM = 85 kPa was 1650 l m !2 h !1 , and the resistance, R m = 1.96 0 10 11 m !1 . Fig. 1. Microfiltration flowsheet.

Separation of metal ions by complexation-microfiltration process

“…Ovo je posebno tačno kada je u pitanju neorgansko onečišćenje. Rastvore za čišćenje potrebno je propuštati kroz sistem pod uslovima turbulentnog toka [89]. Posle svake faze čišćenja potrebno je isprati membrane pri čemu je najbolje koristiti meku vodu.…”