Wastewater filtration performance of multilayer glassy microporous filters

The glassy composition (quartz, clinoptilolite and frit glass mixture) provides a filter having glassy pore wall microstructure and thus enables easily cleaning through the filter recovery by back flushing. The filter was obtained as multilayer compaction by one step slip cast-processing where a cylindrical filter, consisting of filtration layer on granular assemblies with specific interlayer was shaped by a fine particle migration phenomenon. The multilayer compaction has low resistance to liquid flow and thus the filter great potential to use for wastewater filtration. It is known that high capacity filtration also requires correct pore size/interval with respect to filtered particles. In this study, a wastewater overflow from marble factory (0.035 wt.% of solid with a size distribution of 0.58-1.46 mu m) was filtered by different pore sizes of the glassy filters (pore size intervals: 0.4-10 mu m, 0.2-4 mu m, 0.1-1.5 mu m and 0.04-2 mu m) and significantly different filtering capacities was obtained; the irreversible fouling capacities were determined between 2.9 and 8.5 m(3) of filtrate per m(2) of the filter area through the filtration produced 5 min intervals. The filtration pressure was 5 bar and backflushing was achieved at I bar. The high filterability (8.1 m(3)/m(2) in 5 mm) with high filtrate clarity (similar to 0.5 nephelometric turbidity units) could be obtained using finer pore sized filters. The large size filter was seriously clogged during the filtration. (C) 2011 Published by Elsevier Ltd and Techna Group S.r.l.