An overview of the strategies for the deammonification process start-up and recovery after accidental operational failures

The deammonification process has been universally acknowledged as an energy-efficient technology for sewage disposal. In contrast with traditional biological nitrogen removal technology, the deammonification process is able to remove ammonia from wastewater with the simplest nitrogen removal process because of its advantages of lower operating expenses, no organic carbon consumption, lower biomass production, lower carbon dioxide and no nitrous oxide emissions. This review paper provides an overview of the current state of research and development of deammonification in terms of strategies for the process start-up and recovery after accidental failures as well as model-based developments of those strategies. The paper discusses the following issues: (1) current status of research and development of the deammonification process; (2) functional microbial groups involved in the process and their synergistic and competitive relationships; (3) influence of the operational factors, such as the substrates such as nitrite, ammonium and toxic compounds, dissolved oxygen (DO) concentration, aeration patterns temperature, inorganic carbon (IC), pH/free ammonia (FA)/free nitrous acid (FNA) and hydraulic retention time (HRT)/solids retention time (SRT); (4) strategies for the process start-up; (5) strategies for the process recovery after accidental failures; (6) model-based developments of the start-up and recovery strategies; and (7) perspectives on the future trends in the technological applications and developments of deammonification.