Permeate flux and fouling resistance in ultrafiltration of depectinized apple juice using ceramic membranes

Raw depectinized apple juice was clarified in a laboratory scale ultrafiltration system using ceramic tubular membranes (Tech-Sep Carbosep) with a molecular weight cut-off of 300,000, 50,000, and 30,000 Da. The experiments have been carried out over a wide range of transmembrane pressures (100–400 kPa), temperatures (20–55 °C), and feed flow rates (100–900 ml/min). Permeate flux significantly decreased with time until a steady-state was established. The steady-state permeate flux reached a maximum at a transmembrane pressure of about 200 kPa. Higher permeate flux was obtained at higher temperatures due to lower permeate viscosity. The steady-state permeate flux was proportional to the feed flow rate raised to powers ranging between 0.22 and 0.31. All the membranes studied produced the clarified juice with a satisfactory clarity and color intensity value

Clarification of red raspberry juice using microfiltration with gas backwashing: a viable strategy to maximize permeate flux and minimize a loss of anthocyanins

Red raspberry (Rubus idaeus) juice was produced by maceration of raspberry pulp at 50 °C for 2 h using 400 mg kg Klerzyme150 enzymatic pectolitic preparation followed by raw juice clarification with gelatin and bentonite or cross-flow membrane filtration. A minimal loss of anthocyanins from 630 to 540 mg l was obtained when the juice was clarified using a ceramic multichannel microfilter (MF) with a pore size of 0.2 μm. A light transmission at 625 nm in MF permeate was above 85% and the residual pectin (900 mg l) was completely removed. During ultrafiltration through ceramic or polysulfone membranes with a molecular weight cut-off of 30-300 kDa, the content of anthocyanins was reduced to 220-370 mg l, but a light transmission at 625 nm was as high as 96%. The permeate flux in MF was maintained at high values above 170 l m h at 3 bar for more than 2 h by backwashing the membrane with a compressed air every 6 min for 1 min. The cake compression at high pressures was avoided by short filtration times between backwashing

Investigations of hydrodynamic permeability of ceramic and polysulfone membranes for microfiltration and ultrafiltration

The aim of this research was to compare the hydraulic resistance of several commercial ultrafiltration and microfiltration membranes. The hydraulic resistance for each membrane was calculated from the pure water permeation data collected at various transmembrane pressures and temperatures to check the effects of these parameters on the membrane resistance. The experiments have been carried out in a laboratory crossflow UF/MF equipment for clarification of fruit juices. This paper introduces the experimental results showing the influence of operating parameters, such as feed flow rate, temperature, pressure difference in the microfiltration and ultrafiltration through the ceramic Kerasep membrane (pore size 0.2 μm, Tech-Sep, Miribel, France), Carbosep M9 and M7 membrane (molecular weight cut-off of 300 and 30 kg/mol, Tech-Sep, Miribel, France) and polysulfone membranes (molecular weight cut-off of 30 kg/mol, Frenesius, Germany). The results confirmed our earlier work [1] but we provide here many additional results. The hydraulic resistance Rm was 0.65, 3.56, and 0.05 × 1013 1/m for Carbosep M7, Carbosep M9 and Kerasep membrane, respectively. The hydraulic resistance of these membranes does not depend on the operating pressure, which means that the membranes are incompressible. The hydraulic resistance of a polysulfone hollow fiber membrane slightly increased with increasing the applied pressure difference. The Rm values were in the range of (0.61 – 0.92) ⋅1013 1/m, and the applied pressure difference was in the range of (0.225 – 0.900) bar, which is an indication that this membrane was compressible