## 1 Introduction  
The use of antibiotics in livestock production has been a cornerstone of modern animal husbandry; this trend is driven mainly by the need to prevent infectious diseases and enhance growth rates [1]. The swine industry is well known for its extensive use of antimicrobial agents, owing to the high density of animals in pig farming and the considerable economic importance of pork products globally [2]. However, this widespread and long-term practice has increased concerns about residual antibiotics in manure and associated wastewater, as these may eventually be discharged into the environment [3; 4; 5]. When antibiotics are administered to pigs, a substantial fraction can remain un-metabolized before being excreted to enter manure and wastewater streams [6]. As these compounds travel through traditional treatment processes, a portion of them may persist, contributing to the development and propagation of antibiotic resistance genes (ARGs) in surrounding ecosystems [7]. Antibiotic resistance has evolved into a pressing public health crisis. Prolonged exposure to sub-inhibitory concentrations of antibiotics in the environment can impose selection pressure on microbial communities, accelerating the emergence of resistant strains [8]. These resistant microorganisms can potentially transfer their resistance genes to other bacteria via horizontal gene transfer (HGT), thereby amplifying the spread of antibiotic resistance across different species and even different ecosystems [9; 10]. The prospect of antibiotic-resistant pathogens has raised global alarm, prompting intensified research, policy-making, and surveillance efforts. However, to effectively mitigate these risks, it is crucial to identify and optimize treatment strategies that can eliminate or substantially reduce antibiotic residues and ARGs in wastewater before environmental discharge [11; 12]. Swing wastewater is complex, containing not only high loads of organic matter and nutrients but also varying concentrations of antibiotics, heavy metals, and other potential stressors [13; 14]. Conventional treatment systems consist of biological and physical/chemical processes. Biological processes can effectively reduce the biochemical oxygen demand (BOD), total suspended solids (TSS), and other classical pollutants. Multiple studies into various wastewater treatment methods have resulted in limited success in fully eliminating antibiotic residues and ARGs. Activated sludge is one of the most widely deployed processes used for treating swine wastewater. Removal of tetracycline analogues can reach up to 95%, depending on plant configuration and compound properties, yet sulfamethoxazole is usually left virtually unchanged [15]. Anaerobic digestion offers an alternative, and has been reported to eliminate up to 98.1% of the oxytetracycline [16]. However, successive investigations have shown that this process fails to curb ARGs and may even facilitate their spread through HGT within the digester sludge [17; 18]. Comparable drawbacks appear in anaerobic membrane bioreactors (AnMBRs). Sulfonamides inhibit extracellular-polymeric substance formation and methanogenesis, and the system requires longer hydraulic-retention times to offset these toxic effects [19; 20]. Even advanced biological treatments may not achieve sufficient reductions, as certain antibiotics and their metabolites are recalcitrant to microbial degradation [21; 22; 23]. Additionally, partial removal of antibiotics can still leave concentrations that are high enough to drive the evolution of resistant bacteria, especially if effluents are released into water where microbial communities can exchange ARGs [24; 25]. Various physico-chemical techniques have been tested as stand-alone or polishing steps used to supplement biological treatment in swine operations. Coagulation with aluminum or ferric salts efficiently removes particle-bound antibiotics and heavy metals, yet proves much less effective with highly soluble compounds [26; 27].