Removal of antibiotics from wastewater using a novel combined adsorption and regeneration process

Abstract

The presence of antibiotics in (waste) waters worldwide is an emerging concern, particularly given that, apart from many life-threatening toxic side effects to human and aquatic lives, its presence can cause/enhance antibiotic resistance resulting in the death of millions of people each year. As conventional water treatment methods have a poor performance record when it comes to the removal of antibiotic pollution there is an urgent need to develop and test new technologies that can effectively and safely remove these from (waste) waters. Arvia Technology Ltd recently developed a novel water treatment technique, the Nyex Rosalox™ (NR) process, which makes use of an adsorption and electrochemical regeneration process, to meet the increasing demands of higher water quality. The key to this technique is a unique graphite-based adsorbent media, Nyex™2000. However, although it has been successfully used to remove a variety of organic pollutants, it remains unclear to what extent it can be used to safely remove a wide range of antibiotics. Therefore, the overall aim of the present study was to assess if a range of globally prescribed model antibiotic pollutants can be adsorbed on the Nyex media and to evaluate the efficiency of the NR process on the removal of these pollutants from (waste) waters under a range of effluent conditions. Analyses indicated that all antibiotics can efficiently be adsorbed by the Nyex media, but the adsorption rate is antibiotic specific with a higher adsorption speed being observed for tetracyclines and quinolones if compared to the beta-lactams. The lab-scaled NR process analyses indicated that all assessed antibiotics can be effectively destroyed (up to 95% overall removal within 24 hours) without the generation of any detectable, harmful breakdown products. The addition of the electrochemical regeneration process using a minimum electrical energy input boosted the removal efficiency in comparison to adsorption only, but any further increase in energy input proved to be inefficient and potentially costly. Moreover, results from the repeat analyses using the same Nyex media indicated that the adsorbent can be consistently regenerated and reused up to (at least) eight cycles without loss of efficiency. Analyses further indicated that, although antibiotic specific, effluent conditions have a clear impact on both the adsorption of antibiotics on the Nyex media as well as the overall efficiency of the NR process. Both antibiotic adsorption and the removal efficiency of the whole NR process generally increase with elevated temperature or a lowered pH. In contrast, salinity had the least impact on adsorption but the highest impact on electrochemical regeneration, indicating that the addition of small amounts of sodium chloride (up to 1g/L) can improve removal efficiency although no additional impact was observed when the salinity was increased further. The presence of other organics, e.g. natural amounts of dissolved organic carbon, can reduce the amounts of antibiotics adsorbed but has a minimal impact on the performance of the NR process. Combined these results suggest that antibiotics can be effectively and safely removed using the NR process without any formation of harmful by-products and the removal efficiency is affected in varying degrees by effluent conditions and energy input. This highlights that the NR process could be a promising and reliable treatment method to solve the tough antibiotic removal issue.

Date of Award	23 Apr 2024
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Bart Van Dongen (Main Supervisor), David Polya (Co Supervisor) & Stephen Boult (Co Supervisor)