The influence of dissolved oxygen on partial nitritation/anammox performance and microbial community of the 200,000 m/d activated sludge process at the Changi water reclamation plant (2011 to 2016).

Mainstream partial nitritation/anammox (PN/A), coupled with excess biological phosphorus removal, in a 200,000 m/d step-feed activated sludge process (Train 2) in the Changi Water Reclamation Plant (WRP), Singapore, has been studied and reported. This paper presents an overview of process performance and the microbial community during the period from 2011 to 2016. The site data showed that, along with the reduction of dissolved oxygen (DO) from 1.

The occurrence of enhanced biological phosphorus removal in a 200,000 m/day partial nitration and Anammox activated sludge process at the Changi water reclamation plant, Singapore.

Mainstream partial nitritation and Anammox (PN/A) has been observed and studied in the step-feed activated sludge process at the Changi water reclamation plant (WRP), which is the largest WRP (800,000 m/d) in Singapore. This paper presents the study results for enhanced biological phosphorus removal (EBPR) co-existing with PN/A in the activated sludge process. Both the in-situ EBPR efficiency and ex-situ activities of phosphorus release and uptake were high.

Non-denitrifying polyphosphate accumulating organisms obviate requirement for anaerobic condition.

Enhanced biological phosphorus removal (EBPR) is a widely used process in wastewater treatment that requires anaerobic/aerobic or anaerobic/anoxic cycling. Surprisingly, phosphorus (P) release was observed in the presence of nitrate in the anoxic compartment of the activated sludge tank in a full-scale treatment plant with the Modified Ludzack Ettinger configuration. We therefore studied the potential of this full-scale activated sludge community to perform EBPR under anoxic/aerobic cycling.

Mainstream partial nitritation-anammox in municipal wastewater treatment: status, bottlenecks, and further studies.

Driven by energy neutral/positive of wastewater treatment plants, significant efforts have been made on the research and development of mainstream partial nitritation and anaerobic ammonium oxidation (anammox) (PN/A) (deammonification) process since the early 2010s. To date, feasibility of mainstream PN/A process has been demonstrated and proven by experimental results at various scales although with the low loading rates and elevated nitrogen concentration in the effluent at low temperatures (15-10 °C). This review paper provides an overview of the current state of research and development of mainstream PN/A process and critically analyzes the bottlenecks for its full-scale application.

Simultaneous nitrification, denitrification and phosphorus removal (SNDPR) in a full-scale water reclamation plant located in warm climate.

The combination of simultaneous nitrification-denitrification (SND) with enhanced biological phosphorus removal (EBPR) provides a more efficient and economically viable option for nutrient removal from municipal wastewater compared to conventional two-step nitrification-denitrification. This study analyzed the nutrients (N and P) profiles in a full-scale municipal wastewater reclamation plant (WRP) located in the tropical region, in which more than 90% of nitrogen was removed. Interestingly, average SND efficiency in aerobic zones was found to be up to 50%, whereas phosphorus profile displayed a clear cyclic release and uptake pattern with a phosphorus removal efficiency of up to 76%.

Mainstream partial nitritation and anammox in a 200,000 m3/day activated sludge process in Singapore: scale-down by using laboratory fed-batch reactor.

A laboratory fed-batch reactor has been used to study under controlled conditions the performance of partial nitritation/anammox for the 200,000 m(3)/day step-feed activated sludge process at the Changi Water Reclamation Plant, Singapore. The similarity of the concentrations of NH(4), NO(2), NO(3), PO(4), suspended chemical oxygen demand (sCOD), pH, and alkalinity (ALK) between the on-site process and laboratory reactor illustrates that the laboratory fed-batch reactor can be used to simulate the site performance. The performance of the reactor fed by primary effluent illustrated the existence of anammox and heterotrophic denitrification and apparent excessive biological phosphorus removal as observed from the site.

The challenges of mainstream deammonification process for municipal used water treatment.

The deammonification process combining partial nitritation and anaerobic ammonium oxidation has been considered as a viable option for energy-efficient used water treatment. So far, many full-scale sidestream deammonification plants handling high-ammonia used water have been in successful operation since Anammox bacteria were first discovered in the 1990s. However, large-scale application of this process for treating municipal used water with low ammonia concentration has rarely been reported.