Use of zebra mussel shells as an alternative mineral resource for lime production as a phosphorus precipitant
Zebra mussels are an invasive species to North America and are presently found in many rivers and lakes in prolific numbers. Along with many other issues, zebra mussels present a problem when their shells are deposited on shore, carpeting beaches and reducing beach usability. A possible solution presented in this study is to use the zebra mussel shells as an alternative mineral resource to mined calcium carbonate for the production of lime to remove phosphorus in wastewater. Heat-treated coarse (500 μm-1000 μm) and fine (< 75 μm) zebra mussel shell dosed to 10 mg L-1 phosphorus containing water at 0.50 g L-1 and 0.25 g L-1, removed over 99% phosphorus while maintaining pH levels significantly lower than calcium hydroxide dosed under the same conditions. It was found that ground zebra mussel shells (< 75 μm) heated for 1 hour at temperatures of 600, 700, 800, 900, and 1000 0C were capable of removing varying levels of phosphorus in water. Shells heated at 800 0C and dosed at 1.00 g L-1 reduced phosphorus in collected real effluent wastewater by 99.48%. It was also shown that shells heat treated at 1000 0C achieved 98.7% phosphorus removal when dosed at 0.25 g L-1, while maintaining a final effluent pH of 9.13 and demonstrating the lowest energy costs of any of the effective shell treatments. The results indicate that zebra mussel shells show promise as an alternative resource for phosphorus precipitation in wastewater.
Zebra mussel shells, Phosphorus removal, Calcium carbonate, Calcination, Calcium oxide, Zebra mussel shell reuse