热碱解-中温两相厌氧消化工艺运行效能及抗生素抗性基因(ARGs)变化研究

为实现剩余污泥稳定化,并评估剩余污泥的生态环境风险,本研究采用热碱解-中温两相厌氧消化(Thermal-Alkaline Pretreatment-Mesophilic Two Phase Anaerobic Digestion,taMTPAD)工艺处理剩余污泥.考察了热碱解条件及在20、16和10 d 3个不同的总水力停留时间(Total Hydraulic Retention Time,tHRT)下,taMTPAD工艺的运行效果及消化前后抗生素抗性基因(ARGs)的变化.结果表明,对于taMTPAD工艺,当tHRT=10 d时,产酸相的挥发性脂肪酸(VFA)积累量和产甲烷相的日产气量达到最大值,但对ARGs的控制效果最差;tHRT=16 d时反应器的运行效果与tHRT=20 d时接近,但对磺胺类ARGs的控制效果不如tHRT=20 d时;当tHRT=20 d时,挥发性固体(VS)去除率和ARGs的削减效果最好.对比tHRT=10 d时的taMTPAD工艺和MTPAD(两相厌氧消化)工艺,发现对剩余污泥进行热碱预处理能提升产酸相150.32%的VFA产量和产甲烷相89.3%的甲烷产率,但同时热碱解却使得厌氧消化后污泥部分ARGs(sul1、tetO、tetW、tetX)相对丰度回升.研究表明,延长tHRT有利于taMTPAD工艺削减ARGs和VS,而缩短tHRT则有利于产气.

Efficiency and the change of antibiotic resistance genes during thermal-alkaline hydrolysis and mesophilic two-phase anaerobic digestion of excess sludge

In order to stabilize the excess sludge and assess its ecological environment risks, the thermal-alkaline hydrolysis integrated mesophilic two-phase anaerobic digestion(taMTPAD) system was constructed. The effects of the thermal-alkaline hydrolysis conditions and the total hydraulic retention time (tHRT) of 20, 16 and 10 d on the performance of taMTPAD and the removal of antibiotic resistance genes (ARGs) was investigated. Results show that volatile fatty acid(VFA) accumulation in acidogenic phase and the daily biogas production in methanogenic phase reached the maximum at the HRT of 10 d, but the worst removal efficiency of ARGs was found. With regarding to HRT of 16 and 20 d, the reactor performance was similar, but the removal of sulfonamide ARGs was lower than that with the HRT of 20 d. Hence, the maximal removal rate of volatile solid(VS) and ARGs was achieved at tHRT=20 d. Compared with MTPAD (two-phase anaerobic digestion) under tHRT=10 d, thermal-alkaline hydrolysis could increase the VFA production in AP by 150.32% and the methane yield in MP of 89.3% in taMTPAD. However, the ARGs(sul1, tetO, tetW, tetX) were partially recovered after thermal-alkaline hydrolysis. Overall, prolonging tHRT was beneficial to taMTPAD process to reduce ARGs and VS, while shortening tHRT was beneficial to biogas production.