水力停留时间对猪粪厌氧发酵残留物中磺胺类抗生素分布的影响

针对厌氧消化中磺胺类抗生素(SAs)残留及在沼渣、沼液中分配特征不清等问题,以猪粪为发酵原料,采用完全混合式反应器(CSTR)在中温(37±1℃)条件下进行室内模拟试验,探讨不同水力停留时间(HRT)对磺胺嘧啶(SD)、磺胺二甲嘧啶(SM)和磺胺氯哒嗪(SCP)的去除及其在固/液相中分配的影响。研究结果表明:厌氧消化对3种SAs的去除率表现为SMSDSCP。水力停留时间(HRT)=20 d时,猪粪中3种SAs的去除率均达90%以上;HRT=15 d时,三者的去除率均有所下降,特别是SCP去除率降为72.8%左右。厌氧发酵后残留的抗生素主要分布在猪粪沼渣中,其中SCP在沼渣中占有绝对优势。同时,HRT=15 d的处理中,SM和SCP的固/液分配比率明显高于HRT=20 d的处理。厌氧消化过程中不同磺胺类抗生素的降解过程和影响因子存在差异,延长反应体系中抗生素与厌氧微生物作用的反应时间,对中温厌氧消化过程中SAs的去除有积极的作用。为降低其环境危害,猪粪沼渣在还田利用前应进一步消减其中残留的SAs。

Effects of hydraulic retention time on sulfonamides distributions in anaerobic digestates of swine manure

Intensive animal husbandry is believed to be a major contributor to the increased environmental burden of antibiotics. Anaerobic digestion(AD)is an effective way to deal with manure and wastewater in intensive animal farms. Despite the volume of sulfonamides(SAs) in swine manure in China, little information is available regarding the degradation characteristics of SAs during the AD process using swine manure. In this study, bench-scale completely stirred tank reactors(CSTRs)were chosen to degrade sulfadiazine(SD), sulfadimidine(SM) and sulfachlorpyridazine(SCP)in swine manure mixed with rice straw at mesophilic condition(37±1)℃and two hydraulic retention times (HRT), i.e., 20 d and 15 d. The removal rates of SD, SM and SCP and their content distribution in solid and liquid digestates were analyzedduring AD. Results showed that the removal rates followed the trend of SM>SD>SCP. The removal rates of the three SAs were more than 90%at HRT of 20-d;while the rates decreased at HRT of 15-d, especially for SCP, which removal rate was lower than 72.8%. The residual SAs mainly existed in solid digestate during AD of swine manure, especially for SCP. Meanwhile, the distribution ratio of SAs in solid and liquid digestate was higher at HRT of 15-d compared with HRT of 20-d. Different SAs presented extinct degradation characteristics during AD. Increasing the reaction time between SAs in swine manure and substrates in digester was a key factor to stimulate SAs degradation dur-ing AD. Meanwhile, residual SAs in solid digestate of swine manure need to further remove during their land application with purpose of en-vironmental safety.