Characterization of Sewage Sludge Hydrochar for Use as a Heavy Metal Adsorbent

Wieckowski, Hunter

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Characterization of Sewage Sludge Hydrochar for Use as a Heavy Metal Adsorbent

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Alternative methods of managing sewage sludge have become a topic of increasing interest as traditional disposal methods are becoming more regulated and costly due to environmental concerns. One promising alternative treatment method is hydrothermal carbonization, a thermochemical process that can convert wet biomass to a higher energy-dense solid known as hydrochar. Hydrochar produced by SoMax Circular Solutions was characterized and the adsorption of Cu(II) ions was measured and compared to designer glucose hydrochar whose structure is more well-understood. Multiple analysis methods including FTIR, Raman spectroscopy XRD, and Boehm titration were employed. The high ash content of the hydrochar was found to influence the results making a direct comparison to other hydrochar difficult. The maximum absorption capacity of the SoMax hydrochar was found to increase from 22.6 to 49.0 mg Cu(II) g-1 following chemical treatment with Potassium Hydroxide. Chemical activation was found to change the best fit adsorption model from Langmuir to a non-interacting dual-site Langmuir. Sewage sludge hydrochar was determined to be a potentially promising Cu(II) adsorbent as secondary treatment was not required for detectable adsorption.

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