Crossflow filtration of chromium hydroxide suspension by ceramic membranes: fouling and its minimization by backpulsing

Crossflow filtration experiments with Cr(OH)(3) suspension as synthetic electroplating wastewater were performed in turbulent flow regime on a pilot filter unit, equipped with a backpulse device. using porous alumina ceramic membranes of various pore sizes (0.2-5.0 mu m) All membranes are fouled during filtration. Except for the 5.0 mu m pore membrane, the fouling process could not be described by a model considering only one of the pore blocking, pore constriction and cake formation fouling mechanisms reported in literature. However, a model considering all the three fouling mechanisms provides an improved description or the fouling process. Filtration experiments with and without backpulsing show that backpulsing is effective in reducing the fouling phenomenon resulting in up to five-fold increase in steady state permeate flux and 100% flux recovery. The permeate flux increases with increasing transmembrane pressure and crossflow velocity, both in the presence and absence of backpulsing. The membrane cleaning time during backpulse decreases with increasing backpulse amplitude and membrane pore size. However, feed concentration, pulse duration and interval do not have a significant effect. Filtration experiments with various backpulse conditions were conducted to identify the optimum forward and reverse filtration times that yield the maximum steady state permeate flux. (C) 2000 Elsevier Science B.V. All rights reserved.