Full-Scale Performance Comparison of Sidestream Nitrogen Removal Processes in the U.S.

Presentation Description: In response to increasingly stringent nutrient regulations, sidestream treatment (SST) processes have entered the U.S. market to meet growing demand. But given a lack of operational familiarity, established design practices, and overall performance outcomes, the process of deciding which technology is the best fit for a given facility is challenging. Owners are reliant on information provided by vendors or published literature for comparing and evaluating tradeoffs between technologies, often basing decisions on nitrogen removal performance, reliability, and cost. To support SST technology decisions, this paper summarizes relevant operating data that the authors solicited from full-scale wastewater facilities with SSTs in the US. The SST processes evaluated include:

1. Conventional nitrification/denitrification (NDN) SST
2. Anaerobic ammonium oxidation (anammox)
a. AnoxKaldnes ANITA™ Mox (Veolia)
b. DEMON® Anammox Treatment Technology (World Water Works)
c. ANAMMOX® (PAQUES)
3. Post-aerobic digestion - DigestivorPAD™ (Ovivo)

1-3 years of full-scale operating data were analyzed from a dozen facilities to calculate and compare the following metrics:
1. Design criteria
2. Performance metrics
3. Alkalinity consumption
4. Chemical addition
5. Energy consumption and air demand
6. Process stability and resilience
7. Capital and estimated O&M costs
8. O&M complexity

The results indicate high ammonia and TIN removal across technologies and installations. In addition, there is significant variance in ammonia/TIN removal within a process category and on an individual plant basis. There are also the occasional outliers of poor performance that could be due to operational upsets. The results for alkalinity consumption are significant in verifying claims that anammox-based processes save alkalinity. The results show alkalinity requirements sometimes exceeding the vendor recommended design ratio of 4:1. This could be explained by unstable deammonification leading to some ammonia removal occurring via conventional nitrification pathways. Though this may be a contributing factor, without operational optimization, it can be expected that anammox-based processes will not result in alkalinity savings. This evaluation highlights the sensitivity of SST processes and the importance of a holistic design approach that properly supports those processes. More needs to be learned as an industry to move closer towards fine-tuned operation and optimal biological performance.

Co-authors: George Kantos and Anton Dapcic