Understanding the Microbial Internal Storage Turnover in Wastewater Treatment: Retrospect, Prospect, and Challenge

Abstract

Biological wastewater treatment processes usually occur under dynamic conditions involving a dynamic regime with respect to carbon substrate, which results in different microbial internal storage processes. These storage processes play important roles in pollutant removal (e.g., chemical oxygen demand, nitrogen and phosphate removal) and resource recovery (e.g., anaerobic digestion for methane production). This review focuses on two different internal storage processes: microbial storage for shock loading of electron donor and another for separate electron donor and acceptor. The review gives the up-to-date status on several essential microbial internal storage issues: their formation and consumption, the kinetics of these processes, the key factors governing microbial storage, their relationship to microbial growth and other important microbial products, their role in nitrous oxides emissions, and their implications in biological wastewater treatment systems. Although previous research in microbial internal storage has undoubtedly improved our level of understanding, it is clear that much remains to be learned about the processes, as many unanswered questions still remain; some of these important future research areas are then outlined. One of the challenges appears to be the competitions for carbon substrate by these microbial internal storage groups when they encounter the same dynamic regimes.