Removal of anionic surfactant from wastewater by alumina: a case study

The adsorption characteristics of sodium dodecyl sulfate (SDS) on neutral alumina were studied in detail. Alumina was found to be an efficient adsorbent for SDS and could be used for the removal of anionic surfactant (AS) from wastewater when it is present in high concentration (several thousand ppm). In the present work the actual laundry wastewater was treated by both batch and continuous mode. The initial AS concentration in wastewater was 8068 ppm. The optimum adsorbent dose and equilibrium time found were 120 g/l and 1 h, respectively. Under optimised conditions the removal efficiency was found to be 94%. The removal of SDS by alumina follows the pseudo-second order reaction kinetics. In column study the flow rate was maintained at 1.63 m3/m2/h. The breakthrough and exhaust time were found to be 48 and 86 min, respectively, using 10 cm column depth. Height of adsorption zone was found to be 5.5 cm and the rate at which the adsorption zone was moving through the bed was 9.42 cm/h. The percentage of the total column saturated at breakthrough was found 75.5%. The value of adsorption rate coefficient (K) and adsorption capacity coefficient (N) were obtained as 0.000824 l/(mg h) and 143460 mg/l, respectively. After exhaustion, aqueous NaOH could efficiently regenerate alumina.