污泥超高温(65℃)厌氧消化系统启动方案

Start-up strategy for hyperthermophilic anaerobic digestion system of sewage sludge

以高温(55℃)厌氧消化反应器的污泥为接种泥,以不同比例的牛粪和脱水污泥为基质,通过产甲烷潜力测试实验,对污泥超高温(65℃)厌氧消化系统的启动策略进行了初步的探讨.实验结果表明:污泥超高温(65℃)厌氧消化系统具有其可行性;65℃条件下,由于水解酸化过程加快,易发生VFAs(尤其是乙酸和丙酸)的累积.同时,与中温(37℃)和高温(55℃)污泥厌氧消化系统相比,超高温(65℃)系统的产气量虽然较低,但所产沼气中CH4含量明显升高,可以达到79.0%.对系统细菌和古菌进行的多样性分析结果表明:超高温(65℃)条件下,反应器中的细菌以Coprothermobacter、Caldicoprobacter、Ruminiclostridium等极端嗜热的蛋白质水解菌和木质纤维素水解菌为主,不同反应器之间细菌种群多样性的差异是由所投加物料的不同造成的;所有反应器的古菌中,嗜热的氢营养型产甲烷菌Methanothermabactor成为绝对优势菌群,占古菌的比例均超过96%.在超高温反应器(65℃)的启动初期,可适当提高投加基质中牛粪的比例,加快对嗜热产甲烷菌(氢利用型产甲烷菌)的富集,同时避免系统中的VFAs的积累,保证反应器顺利启动.

The feasibility of hyperthermophilic anaerobic digestion system of sewage sludge is evaluated in the study,which is conducted with biochemical methane potential experiments using thermophilic anaerobic digestate as inoculums and cow dung and dewatered sludge as substrate.The results show that:①the start-up of hyperthermophilic sludge anaerobic digestion system is practicable;②the accumulation of VFAs(particularly propionic acid)is easy to occur due to the acceleration of hydrolysis and acidification process under65℃;③compared with mesophilic(37℃)and thermophilic(55℃)anaerobic digestion systems,the total gas production of hyperthermophilic(65℃)system is relatively lower,while the methane content is elevated significantly,even reaching79.0%;④under hyperthermophilic(65℃)condition,the extremely thermophilic bacteria responsible for lignocellulose and protein degradation such as Coprothermobacter、Caldicoprobacter、Ruminiclostridiumwere dominant,the difference of which is due to the different substrate addition;hydrogenotrophic methanogens-Methanothermobacter accounted for nearly96%of archaea in all the digesters.Thus,in the start-up period,the addition of cow dung can not only accelerate the accumulation of hyperthermophilic methanogens(Hydrogenotrophic methanogens),but also avoid the accumulation of VFAs,particularly the accumulation of propionic acids,ensuring successful start-up of the system.