Textile wastewater treatment using granular activated carbon adsorption in fixed beds

This work involved the treatment of industrial wastewater from a nylon carpet printing plant which currently receives no treatment and is discharged to sea. As nylon is particularly difficult to dye, acid dyes are required for successful coloration and cause major problems with the plant's effluent disposal in terms of color removal. Granular activated carbon Filtrasorb 400 was used to treat a ternary solution of acid dyes and the process plant effluent containing the dyes in a fixed-bed column system. Experimental data were correlated using the bed depth service time (BDST) model to previously published work by the authors for single dye adsorption. The results were expressed in terms of the BDST adsorption capacity, in milligrams of adsorbate per gram of adsorbent, and indicated that there was a 12-25% decrease iri adsorption capacity in the ternary system compared to the single component system; This reduction has been attributed to competitive adsorption occurring in the ternary component system. Dye adsorption from the process plant effluent showed an approximate 65% decrease in adsorption capacity compared to the ternary solution system. This has been attributed to interference caused by the other colorless textile effluent pollutants found in the process wastewater. A chemical oxygen demand analysis on these components indicated that the dyes accounted for only 14% of the total oxygen demand.

Granular fertilizer drying and agglomeration in storage

In the manufacture of granular NPK fertilizer the product is cooled before packaging and storage in moisture-proof bags. It has been shown that the temperature of the fertilizer prior to packing is significant in that at high temperatures, drying of the granules takes place in the bag which causes an increase in the humidity of the air surrounding the granules and thus an increase in moisture content at the granule - granule interface. This surface moisture was shown to increase the likelihood of agglomeration in the fertilizer by a capillary adhesion/unconfined yield stress model. An iterative model was set up to establish conditions that would prevent drying occurring, which takes into account fertilizer drying rate, fertilizer cooling rate cooling rate and the effect of coating oils on the drying mechanism.

Analysis and comparison of displacement granular pile anchors

Granular piles can resist only compressive and shear loads owing to their inherent nature. By a simple modification of providing a pedestal/geogrid at the bottom and attaching a cable to the same, they are made to resist pullout/uplift forces. This paper presents an analysis of granular pile anchor (GPA), considering it and the in situ soil to behave linearly and the in situ ground to be semi-infinite. A parametric study presents results in the form of variations of normalised shear stress, displacement influence coefficient and axial uplift force with depth with relative stiffness factor. Two methods for the estimation of deformation moduli of the GPA and the in situ soil are proposed. Based on the estimated values of the moduli, the displacements of GPA were estimated and the results compared with test results of Kumar (2002). The predicted displacements compare well with the measured ones.

The removal of bromate from potable water using granular activated carbon

Bromate in drinking water, at a level of microgrammes/litre, is a problem in ozonated waters but can be adsorbed, to a certain extent, by granular activated carbon. The adsorption capacity of granular activated carbon for bromate is significantly lowered when there are high concentrations of other anions, most notably chloride and sulphate, present in the water.