Document Type : Original Article
Abstract
Synthetic envelopes have been found to be highly effective filters for numerous applications and are currently replacing gravel envelopes. The growth of petrochemical and textile industries in Iran offers the possibility of manufacturing these products domestically. The objective of this study was to assess the mineral clogging potential of two non-woven synthetic envelopes (pre-wrapped loose materials, PLM) manufactured in Iran in comparison with similar imported envelopes. Two physical permeameter models designed according to ASTM D-5101 were used to carry out a series of permeability tests on varying envelope types. The study was conducted on soil and water provided from the Khorramshahr area, Khouzestan province, in southern Iran. A distinctive aspect of this research is the use of highly salt-affected drainage water (EC= 22.2 dS/m and SAR= 45.18) in contrast to non-saline water (EC= 0.78 dS/m) and Khoramshahr saline-sodic soil. Permeability tests were done at five hydraulic gradients (1, 2.5, 5, 7.5, 10). Variations in discharge, hydraulic conductivity and gradient ratio (GR) were measured and investigated statistically in fully randomized factorial experiments. The results indicated that the greater the salinity, the lower the hydraulic conductivity and flow discharge rate for all envelope samples. The average hydraulic conductivity for domestic products 1 and 2 decreased 19% and 28%, respectively, in comparison to the imported envelope for non-saline water. For saline water, these percentages reached 28% and 33%, respectively. The gradient ratio revealed that the imported sample was not sensitive to mineral clogging. However, the two domestic specimen gradient ratios were greater than that for the imported envelope for the application of saline and non-saline water.
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