Removal of Metformin and Clarithromycin from aqueous media using Magnetic Brewery Spent Grain

Student thesis: Doctoral ThesisDoctor of Philosophy (awarded by UHI)


Conventional treatment plants have demonstrated to be ineffective in the removal of a range of ‘emerging contaminants’ from wastewater streams. The presence of contaminants such as human pharmaceuticals in natural and potable waters has highlighted the need for new modes of treatment. While adsorption has proven to be effective in many applications, conventional adsorbents such as activated carbon (AC) can be expensive to produce. Consequently, there is significant need for novel and low-cost adsorbents for the removal of priority contaminants from aqueous media. In this work, adsorbents derived from brewery/distillery and shellfish waste were developed and evaluated for their ability in the removal of prioritised pharmaceutical contaminants from aqueous media.
Prioritisation studies were conducted to identify seven target compounds and four raw materials for further investigation. Subsequently, selected raw materials were evaluated and modified through encapsulation and magnetisation techniques with the aim of enhancing removal efficiencies for two prioritised pharmaceuticals, metformin (MF) and clarithromycin (CLR). Response surface methodology (RSM) was applied to identify optimal adsorption parameters for the most promising material, magnetic brewery spent-grain biochar (MBSG). Under these optimal conditions removal efficiencies of 100% and 99% were recorded for MF and CLR respectively. Techniques including Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were used in conjunction with kinetic, isotherm and thermodynamic studies to determine that H-bonding and π-π interactions (so-called for MF) were the predominant mechanisms involved in the adsorption processes.
This work suggested that brewery spent grain could be developed into an effective adsorbent, MBSG, for the removal of the pharmaceuticals targeted here. A techno-economic assessment (TEA) was undertaken to assess the feasibility of the approach in relation to the principles of the ‘circular economy’. However, TEA revealed that a large-scale on-site facility was the only feasible option for the production of this novel adsorbent.
Date of Award17 Oct 2022
Original languageEnglish
Awarding Institution
  • University of the Highlands and Islands
SponsorsESF studentship

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