Screening the toxicity of phosphorous-removal adsorbents using a bioluminescence inhibition test

Abstract

When found in excess, phosphorus (P) has been linked to surface water eutrophication. As a result, adsorbents are now used in P remediation efforts. However, possible secondary toxicological impacts on the use of new materials for P removal from surface water have not been reported. This study evaluated the toxicity of adsorbent materials used in the removal of P from surface water including: fly ash, bottom ash, alum sludge, a proprietary mix of adsorbents, and a proprietary engineered material. Toxicity screening was conducted by performing solid-liquid extractions (SLEs) followed by the bacterial bioluminescence inhibition test with a Microtox® M500. Of the materials tested, the samples extracted at lower pH levels demonstrated higher toxicity. The material exhibiting the most toxic response was the iron and aluminum oxide coated engineered material registering a 66-67% 15-min EC50 level for pH 4 and 5 SLEs, respectively. However, for SLEs prepared at pH 7, toxic effects were not detected for this engineered material. Fly ash and bottom ash demonstrated between 82 and 84% 15-min EC50 level, respectively, for pH 4 SLE conditions. Dried alum sludge and the proprietary mix of adsorbents were classified as having little to no toxicity.

Halloysite Nanotubes as Adsorptive Material for Phosphate Removal from Aqueous Solution

“…Heavily phosphate-laden waters impose hazardous risk to aquatic ecosystems [1][2][3][4]. Although phosphorus concentrations in runoff from agricultural fields are, in general, below 1 mg L −1 , the elimination of phosphorus is considered a crucial environmental sustainability concern to halt rapid degradation of water quality [4][5][6][7][8]. A wide range of phosphorus concentrations has been investigated in phosphorus adsorption studies [1,6,9].…”