纳米零价铁对厌氧消化影响的反应动力学模型

Kinetic modeling of nano-zero valent iron(NZVI) on sludge anaerobic digestion

污泥厌氧消化是污水处理厂实现"碳中和"的关键环节。然而传统厌氧消化技术普遍存在水解不充分、产甲烷效率低的问题,在工程中表现为污泥的甲烷潜势(B0)低、产甲烷速率(k)低等,从而使得获得的甲烷气通常不能达到量和质的要求。纳米级零价铁(NZVI)基于能够在厌氧条件下析氢(H2)腐蚀为产甲烷菌提供电子供体及更有利的厌氧环境,而被认为在厌氧消化领域具有潜在的应用前景。就此,通过在厌氧消化体系中投加不同剂量的NZVI(0、100、300、600和1000 mg·L^(-1)),以甲烷潜势(B0)和产甲烷速率(k)为主要评价指标,并基于一级反应动力学模型探讨了NZVI对厌氧消化过程的主要作用机理。研究结果表明,NZVI能够强化厌氧消化过程产甲烷,主要作用机制在于促进微生物细胞破壁,从而提高污泥的水解酸化程度,得到更高的甲烷潜势(B0)。

Anaerobic digestion of excess sludge is the key node to achieve ＂carbon neural＂ in wastewater treatment plants. Conventional anaerobic digestion technology is limited by insufficient hydrolysis and low methanogenesis. Therefore, both quantity and quality of the produced methane cannot meet the standard for the practical engineering application because of low biochemical methanogenesis potential （B0） of waste activated sludge and methanogenesis rate （k）. Nanozero valent iron （NZVI） has been considered to have a great application potential in enhancing sludge anaerobic digestion since NZVI addition can lower oxidation reduction potential （ORP）, and thus create a more favorable condition for methanogens; NZVI also served as an electron donor to improve methane product rate. In this study, effects of different dosages of NZVI （0,100,300,600,1000 mg·L^-1） on methane production in anaerobic digestion was evaluated based on B0 and k via first order kinetics. The results demonstrated that NZVI can improve methane production mainly through enhancing refractory organics degradation to improve B0 rather than methanogensis rate （k）.