Bioremediation of n-alkanes, polycyclic aromatic hydrocarbons, and heavy metals from wastewater using seaweeds

Abstract

The removal of n-alkanes, polycyclic aromatic hydrocarbons, and heavy metals from wastewater using three dried seaweeds Ulva intestinalis Linnaeus (green alga), Sargassum latifolium (Turner) C.Agardh (brown alga), and Corallina officinalis Kützing (red alga) has been shown to evaluate their potential usage as inexpensive adsorbents. Under natural environmental conditions, numerous analytical methods, including zeta potential, energy dispersive X-ray spectroscopy (EDX), SEM, and FT-IR, are used in this study. The results showed that n-alkanes and polycyclic aromatic hydrocarbons adsorption increased with increasing contact time for all three selected algae, with a large removal observed after 15 days, while the optimal contact time for heavy metal removal was 3 h. S. latifolium dry biomass had more potential as bioadsorbent, followed by C. officinalis and then U. intestinalis. S. latifolium attained removal percentages of 65.14%, 72.50%, and 78.92% for light n-alkanes, heavy n-alkanes, and polycyclic aromatic hydrocarbons (PAHs), respectively, after 15 days. Furthermore, it achieved removal percentages of 94.14, 92.62, 89.54, 87.54, 82.76, 80.95, 77.78, 73.02, and 71.62% for Mg, Zn, Cu, Fe, Cr, Pb, Cd, Mn, and Ni, respectively, after 3 h. Carboxyl and hydroxyl from FTIR analysis took part in wastewater treatment. The zeta potentials revealed that algal cells have a negatively charged surface, and the cell surface of S. latifolium has a more negative surface charge than U. intestinalis and C. officinalis. Our study suggests that seaweeds could play an important role in wastewater treatment and thus help as an economical, effective, and ecofriendly bioremediation system for ecological health and life protection.

Keywords: Adsorption; Heavy metals; Marine macroalgae; Polycyclic romatic hydrocarbons; n-Alkanes.

Fig. 1

El Amia drain at El-Tabia Region in Alexandria

Fig. 2

Removal percentage of light n-alkanes, heavy n-alkanes, and polycyclic aromatic hydrocarbons (PAHs) from wastewater at different time intervals using Ulva intestinalis, Sargassum latifolium, and Corallina officinalis dry biomass

Fig. 3

Removal percentage of heavy metals (Ni, Mn, Cd, Pb, Cr, Fe, Cu, Zn, and Mg) from wastewater at different time intervals using Ulva intestinalis, Sargassum latifolium, and Corallina officinalis dry biomass

Fig. 4

FTIR of Ulva intestinalis, before (b) and after (a) adsorption experiments

Fig. 5

FTIR of Saragassum latifolium before (b) and after (a) adsorption experiments

Fig. 6

FTIR of Corallina officinalis before (b) and after (a) adsorption experiments

Fig. 7

EDX of the surface of U. intestinalis (E), S. latifolium (S), and C. officinalis before (b) and after (a) adsorption experiments

Fig. 7

EDX of the surface of U. intestinalis (E), S. latifolium (S), and C. officinalis before (b) and after (a) adsorption experiments

Fig. 8

Scanning electron microscopy of the surface of U. intestinalis (E), S. latifolium (S), and C. officinalis before (b) and after (a) adsorption experiments

Fig. 9

Zeta potential of U. intestinalis, S. latifolium, and C. officinalis