Enhanced Removal of the Xenobiotic Surfactant Sodium Dodecyl Sulfate from Actual Nondomestic Wastewaters Using Immobilized Mixed Bacterial Cells

A. A.Najim, Z. Ismail and K. K. Hummadi

Abstract
Cell immobilization has been proven to offer noticeable benefits over conventional biological systems using free cells, particularly for recalcitrant compounds. In this study, mixed bacterial cells were alternatively immobilized in sodium alginate (SA) and in sodium alginate-polyvinyl alcohol (SA – PVA) for biodegradation of sodium dodecyl sulfate (SDS). Synthetically prepared SDS-bearing aqueous solution (SWW), as well as actual automobile service station wastewater (AWW) and laundry wastewater (LWW) were used. The results revealed that high removal efficiencies were achieved after 48 h for both types of beads. When SDS concentration in SWW increased from 10 to 1000 mg L–1, SDS degradation using both types of beads were decreased from 99.71 % to 85.12 % using SA beads, and from 99.63 % to 83.29 % using SA-PVA beads. The removal efficiency of SDS in the actual (AWW) were 94.91 % and 93.82 % using SA beads and SA-PVA beads, respectively. While, for SDS-bearing laundry (LWW), the removal efficiencies were 94.39 % and 92.04 % using SA beads and SA-PVA beads, respectively. No decline in the biodegradation capacity of immobilized consortium was noted over its recycling and reuse. Both hydrogel matrices lasted for up to five cycles in the actual wastewaters. These promising results confirmed the validity of using immobilized mixed cells as an efficient and cost-effective approach for SDS biodegradation in real industrial wastewaters.

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Keywords
immobilization, hydrogel matrices, sodium dodecyl sulfate, biodegradation, sodium alginate