高负荷厌氧生物反应器的三元酸碱缓冲体系特征与调控

高负荷是升流式(Up-flow Anaerobic Sludge Bed, UASB)、内循环厌氧反应器(internal circulation, IC)和厌氧膜生物反应器(anaerobic membrane bioreactor, AnMBR)等厌氧生物反应器发展的趋势,也是实现"沼气升级(biogas upgrading)"的难点.挥发性有机酸(volatile fatty acids, VFAs)和溶解性无机碳(total inorganic carbon, TIC)既是厌氧消化必经的中间产物,又与氨氮等弱碱共同影响高负荷厌氧消化过程的pH变化,并决定着沼气中的甲烷含量.VFAs、TIC和氨氮构成的三元pH酸碱缓冲体系是高负荷厌氧消化"沼气升级"的关键操作条件.本文总结了高负荷厌氧消化过程中pH变化规律和影响,针对不同VFAs/氨氮关系的形成机制,分析了高负荷厌氧消化碳酸盐缓冲体系特征及其对沼气CH_4/CO_2构成的影响.以厌氧膜生物反应器为例,讨论了近年来基于pH在线监测和调控方法、理论模型方面的研究进展,同时对未来的重点研究方向提出展望,以期为今后的高负荷AnMBR研发提供参考.

Formation and regulation of ternary pH buffer system for anaerobic bioreactor at high loading rate

High loading rate is a tendency for anaerobic bioreactor for UASB (upflow anaerobic sludge blanket), IC (internal circulation) and AnMBR (anaerobic membrane bioreactor), and it is also a bottleneck for "biogas upgrading". As intermediate products and buffer capacity contributors, the volatile fatty acids (VFAs) and total inorganic carbon (TIC) are the primary endogenous driving forces for pH evolution for anaerobic bioreactor at high loading rate. Meanwhile, ammonia also plays an important role in pH evolution and methanogenesis pathway. The VFAs, TIC and ammonia form a ternary pH buffer system which determines the "biogas upgrading" for anaerobic bioreactor at high loading rate. The purposes of this paper are to summarize the pH evolution for anaerobic bioreactor at high loading rate, to thoroughly review the ternary pH buffer system driven by VFAs and TIC, the advances of pH based online monitoring and automation control strategies, and to propose the future research directions for anaerobic membrane bioreactor at high loading rate.