Field investigation of antibiotic removal efficacies in different hospital wastewater treatment processes in Thailand

Abstract

The removal efficacies of 19 antibiotics in different hospital wastewater treatment processes (WWTP) were investigated at various sizes of 60 hospitals across Thailand. The results showed slight differences in the total antibiotic removals (79–84%) among WWTP sizes. High antibiotics loading to all WWTP were amoxicillin, ciprofloxacin, tetracycline ampicillin, and norfloxacin, respectively. Amoxicillin and ampicillin were eliminated highly (90–99%) in every size of WWTP, while various efficacies showed for other antibiotics (0–93%). According to process comparison, activated sludge (CAS), oxidation ditch (OD), and sequencing batch reactor (SBR) systems showed similar removals of overall antibiotics (P>0.05). The attached growth systems such as submerged aerated fixed-film (SAFF) demonstrated relatively lower antibiotic removals. The natural processes such as aerated lagoon (AL), facultative pond (FP), and constructed wetland (CW) presented substantial biodegradation of some recalcitrant antibiotics such as fluoroquinolones, sulfamethoxazole, and trimethoprim. Post -chlorination provided additional elimination of some antibiotics such as amoxicillin and ampicillin. Finally, the top-five of antibiotics released into the water environment via discharged effluent are amoxicillin, tetracycline, ampicillin, ciprofloxacin, and imipenem, respectively, which mainly from the suspended growth systems.