To evaluate their abilities to remove colour from textile-plant effluents, tests were run using several low cost natural adsorbent materials including vermiculite, sawdust, barbecue charcoal, maize stalks, sand, rice husks and peatmoss. With the exception of vermiculite, more than 50% of the colour was removed from the wastewater, with barbecue charcoal and rice husks showing the best adsorptive qualities (67% and 65% respectively). Under simulated industrial conditions on a laboratory scale a fixed-bed reactor was used to investigate the adsorption capacity of barbecue charcoal with respect to colour removal. An average of 28% of colour was removed at a hydraulic retention time (HRT) of 1.6 h over a period of 25 days. The effect of pH on the adsorptive capacity with respect to colour removal and represents a relatively cheap adsorbent material compared to conventionally used granular activated carbon.

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