Abstract
To evaluate the contamination of coastal sediments along the Fongafale Islet, Tuvalu, Central Pacific, a field survey was conducted along the lagoon-side coast, near a densely populated area. Gray and white layers were obtained in the sediment core samples, whereas relatively high acid-volatile sulfide was detected in the gray layer. Considering that the leakage of domestic wastewater from poorly constructed sanitary facilities flows into the coastal lagoon through groundwater during ebb tides, the gray layer was considered to be the runoff pathway of the leaked domestic wastewater. Sediment contamination indices were applied to estimate the contamination level of the sediments. The result shows that heavy metal pollution exists in both colored sediment samples. Then, assuming that an existing septic tank system is used, heavy metal removal method was investigated by operating a 6-L-scale sequencing batch reactor with domestic wastewater as the feed. By this treatment, over 68% removal rate of Pb, Zn, and Cu was achieved, largely owing to the formation of metal-sulfide.
