都市污水與醫院廢水之抗生素抗性基因組成以及臭氧微米氣泡於廢水處理之應用

Abstract

抗生素抗藥性對全球人類健康之威脅日益嚴重，由於污水收集未被代謝之抗生素及抗生素抗性基因(Antibiotic Resistance Genes, ARGs)，且污水下水道及污水處理廠可作為ARGs傳播之熱點，若未經過適當之處理流程，將使ARGs透過放流水進入自然水體中，已被視為環境中ARGs之主要來源。醫院為高度使用抗生素之環境，且醫院廢水收集病患之排泄物及其他化學物質，故其廢水含有高濃度之抗生素、病原菌及機會性病原菌，其中亦可能含有抗生素抗性細菌及抗性基因，因此其相較於一般都市污水具有更高之傳播風險。為了解醫院廢水對下水道及其下游環境之影響，本研究先藉由比較污水下水道、都市污水處理廠與醫院廢水處理廠中ARGs之濃度差異，並選擇對應六大類抗生素之9種ARGs及1種移動遺傳因子進行分析，結果顯示醫院廢水可能是下水道ARGs之主要貢獻者，尤其是對應醫院用藥之mcr-1，且僅採用生物處理方法作為醫院廢水之處理流程，將可能導致ARGs在處理流程中擴增，因此本研究建立臭氧微米氣泡處理方法以改善處理流程對於ARGs之去除率。在經過ARG與COD降解測試後，確認使用臭氧微米氣泡於實際醫院廢水作用20分鐘可以有效降解ARGs，其對於sul1、intⅠ1、tetA、blaTEM及mcr-1之平均去除率約為3.82 ± 0.67 log，並可以透過串聯生物處理提高其COD去除率，為醫院廢水建立一個節能且有效之處理流程。

Antibiotic resistance poses a serious threat to global public health. Antibiotics, their metabolites, and antibiotic resistance genes (ARGs) will be introduced into wastewaters via human urine and feces; sewer systems and wastewater treatment plants (WWTPs) are believed to be potential hotspots for antibiotic resistance dissemination. If ARGs are not appropriately removed through wastewater treatment, they will be discharged into natural aquatic systems through effluent of WWTPs, and become significant contributors to ARGs in the environment. Because the highest consumption of antibiotics mainly occurs in hospitals, hospital wastewaters have been the focus as one of the high-risk point sources of antibiotics, pathogens, and opportunistic pathogens, which may also contain antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs). Therefore, the risk potential of hospital wastewater is further increased and higher than municipal wastewater. This study collected samples from a sewer system that receives hospital wastewater, a municipal WWTP, as well as an on-site hospital WWTP. It then quantified 9 ARGs and one mobile genetic element to learn more about the impact of hospital wastewater on its downstream environment. Results showed that the release of untreated hospital wastewater could increase ARG prevalence in sewer systems, especially mcr-1 corresponding to the last-resort antibiotics; in addition, the limited removal of ARGs through conventional biological wastewater treatment process might increase the concentration of certain ARGs in effluents. Accordingly, it is necessary to develop new technological solutions which will help to reduce ARGs in WWTP effluents. This study has confirmed that ozone microbubble technology can reduce ARGs in hospital wastewater within 20 minutes; the average removal of 5 target genes (sul1, intⅠ1, tetA, blaTEM, and mcr-1) is 3.82 ± 0.67 log. Furthermore, ozone microbubble technology followed by a biological treatment process can be applied to increase COD removal efficiencies and develop an energy-saving and practical treatment process for hospital wastewaters.