Conventional and Advanced Processes for the Removal of Pharmaceuticals and Their Human Metabolites from Wastewater

Lignocellulosic pruning waste adsorbents to remove emerging contaminants from tyre wear and pharmaceuticals present in wastewater in circular economy scenario

The following work explores a sustainable approach to repurpose organic waste from poplar pruning into lignocellulosic waste-based activated carbons (LPWACs) through environmentally friendly thermochemical processes and in line with circular economy principles. The developed LPWACs, activated by potassium hydroxide (KOH) at two different temperatures and weight ratios, exhibited promising textural properties with BET surface area (SBET) and total pore volume (VTOT) reaching up to 1336 m2·g-1 and 0.588 cm3·g-1, respectively. In addition, they displayed a developed microporous structure with a significant oxygen content (up to 11 %). These activated carbons were used to remove five emerging organic pollutants from the leaching of tyre wear particles (TWPs) and pharmaceuticals present in water. The increase in oxygen groups had a negative effect on the adsorption capacity of 1H-benzotriazole (BZTL), while electrostatic influences hindered diatrizoic acid (DZT) adsorption. LPWACs effectively remove pharmaceutical and tyre contaminants, supporting the circular economy in water treatment.

A combined experimental and density functional theory study of metformin oxy-cracking for pharmaceutical wastewater treatment

Pharmaceutical compounds are emerging contaminants that have been detected in surface water across the world. Because conventional wastewater treatment plants are not designed to treat such pollutants, new technologies are needed to degrade and oxidize such contaminants. The newly developed oxy-cracking process was utilized to treat the antidiabetic drug, metformin. The process, which involved partial oxidation of metformin in alkaline aqueous medium, proved to decompose the drug into small organic molecules, with minimum emission of CO₂, therefore, increasing its biodegradability and removal from industrial treatment plants. The reaction gaseous products were probed by online gas chromatography. The liquid phase before and after oxy-cracking was analyzed for total carbon content by TOC and gas chromatography mass spectrometry. The products formed from the nitrogen-rich drug included ammonia, amines, amidines, and urea derivatives. A reaction mechanism for the oxy-cracking process is proposed. Because the hydroxyl radical (˙OH) is believed to play a central role in the oxy-cracking process, the mechanism is initiated by ˙OH attacks on metformin, followed by single decomposition or isomerization steps into stable products. The reactions were investigated using density functional theory calculations and validated using high quality 2^nd order Møller–Plesset perturbation theory energy calculations.

Pharmaceutical compounds are emerging contaminants that have been detected in surface water across the world.