Dataset Information

Modified Crushed Oyster Shells for Fluoride Removal from Water.

ABSTRACT: Elevated concentrations of fluoride ions (F-) in natural groundwater are a worldwide problem. Discarded oyster shells were ground to ?100?µm particle size to produce oyster shell powder (OS). A subset of the OS was heated to produce calcined oyster shell (COS). A subset of the COS was further treated with 1?M phosphoric acid to produce phosphoric-acid-treated oyster shell (POS). OS and COS were combined with phosphoric acid (1.6?mM and 3.2?mM) to produce OS?+?P (oyster shell with phosphoric acid) and COS?+?P (calcined oyster shell with phosphoric acid). OS and COS removed 46% and 50% (10?g/L of sorbent dose) but POS, OS?+?P and COS?+?P removed 96%, 100% and 76% (1?g/L of sorbent dose) when the initial concentration of fluoride was 10?mg/L. The sorption kinetics of POS, OS?+?P and COS?+?P followed second-order reaction rates, and sorption isotherms of all sorbents were well-described by the Freundlich sorption isotherm. These results indicate that oyster shells can be an effective sorbent for fluoride removal, with the added benefit of re-use of a waste product.

SUBMITTER: Kim W

PROVIDER: S-EPMC7113297 | biostudies-literature | 2020 Apr

REPOSITORIES: biostudies-literature

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Modified Crushed Oyster Shells for Fluoride Removal from Water.

Kim Woohang W Singh Rekha R Smith James A JA

Scientific reports 20200401 1

Elevated concentrations of fluoride ions (F<sup>-</sup>) in natural groundwater are a worldwide problem. Discarded oyster shells were ground to ≤100 µm particle size to produce oyster shell powder (OS). A subset of the OS was heated to produce calcined oyster shell (COS). A subset of the COS was further treated with 1 M phosphoric acid to produce phosphoric-acid-treated oyster shell (POS). OS and COS were combined with phosphoric acid (1.6 mM and 3.2 mM) to produce OS + P (oyster shell with phos ...[more]

PMID: 32238852

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Project description:The Pacific oyster, Crassostrea gigas (Thunberg), is the main bivalve species cultivated in the world. With global warming enabling its reproduction and larval survival at higher latitudes, this species is now recognized as invasive and creates wild oyster reefs globally. In this study, the spatial distribution of photosynthetic assemblages colonizing the shells of wild C. gigas was investigated on both a large scale (two contrasting types of reefs found in mudflats and rocky areas) and a small scale (within individual shells) using a hyperspectral imager. The microspatial distribution of all phototrophs was obtained by mapping the Normalized Difference Vegetation Index (NDVI). Second derivative (??) analyses of hyperspectral images at 462, 524, 571 and 647 nm were subsequently applied to map diatoms, cyanobacteria, rhodophytes and chlorophytes, respectively. A concomitant pigment analysis was carried out by high performance liquid chromatography and completed by taxonomic observations. This study showed that there was high microalgal diversity associated with wild oyster shells and that there were differences in the structure of the phototropic assemblages depending on the type of reef. Namely, vertically-growing oysters in mudflat areas had a higher biomass of epizoic diatoms (hyperspectral proxy at ??462 nm) and were mainly colonized by species of the genera Navicula, Nitzschia and Hippodonta, which are epipelic or motile epipsammic. The assemblages on the horizontal oysters contained more tychoplanktonic diatoms (e.g. Thalassiosira pseudonana, T. proschkinae and Plagiogrammopsis vanheurckii). Three species of boring cyanobacteria were observed for both types of reef: Mastigocoleus testarum, Leptolyngbya terrebrans, and Hyella caespistosa, but the second derivative analysis at 524 nm showed a significantly higher biomass for the horizontally-growing oysters. There was no biomass difference for the boring chlorophyte assemblages (??647 nm), with two species: Eugomontia testarum and Ostreobium quekettii observed for both types of reef. This study shows that oyster shells are an idiosyncratic but ubiquitous habitat for phototrophic assemblages. The contribution of these assemblages in terms of biomass and production to the functioning of coastal areas, and particularly to shellfish ecosystems, remains to be evaluated.

Dataset Information

Modified Crushed Oyster Shells for Fluoride Removal from Water.

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Modified Crushed Oyster Shells for Fluoride Removal from Water.

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