Field experiments on remediation of coastal sediments using granulated coal ash

- Granulated Coal Ash (GCA) was applied to deteriorated coastal sediments.
- GCA effectively removed phosphate and hydrogen sulfide from the sediments.
- GCA led to an increase in the number of benthic organisms.
- GCA decreased hydrogen sulfide concentration by suppressing its formation.
- GCA is an effective material for remediating organically enriched coastal sediment.

Field experiments were carried out to evaluate the effect of Granulated Coal Ash (GCA) on remediation of coastal sediments in terms of removing phosphates and hydrogen sulfide. Phosphate concentrations in the sediment were kept below 0.2 mg/l after the application of GCA, whereas those in the control sites increased up to 1.0 mg/l. The concentration of hydrogen sulfide in the sediment was maintained at almost zero in the experimental sites (GCA application sites) for over one year, whereas it ranged 0.1-2.4 mg S L−1 in control sites. Meanwhile, individual number of benthos increased in the experimental sites by several orders of magnitude compared to the control sites. The major process involved in hydrogen sulfide removal by GCA was thought to be the increase in pH, which suppresses hydrogen sulfide formation. From our findings, we concluded that GCA is an effective material for remediating organically enriched coastal sediment.