Mainstream Anammox: New Frontiers in Superefficient Biological Nitrogen Removal from PN/A to PdN/A

Presentation Description: As more WRRFs in California implement potable reuse schemes, and the impact of nutrients on coastal waters is recognized, biological nitrogen removal is expected to expand dramatically along the coast. Upgrading to nitrogen removal can significantly increase the cost, energy use, operational complexity, footprint requirement and climate impact of these facilities, and so determining the most efficient and sustainable treatment strategy is critical. Anammox is a unique biology that has been widely implemented in sidestream treatment to reduce costs and improve sustainability and efficiency, but this technology has not yet been implemented widely in mainstream secondary trains. This presentation will review two new technological developments that promise to bring the benefits of Anammox biology to mainstream secondary treatment.

First, we will describe the challenge of adapting the partial-nitration/Anammox process (PN/A) from hot, concentrated centrate treatment to dilute, cool secondary treatment. This strategy boasts the highest potential reductions in aeration energy, carbon requirements and sludge production, but is also the most challenging to operate and maintain. Challenges associated with NOB inhibition will be discussed, and a novel strategy, developed by Tomorrow Water and demonstrated with Black & Veatch at the Hyperion Water Recovery Plant in LA, will be described. We will share data from lab and pilot-scale facilities, highlighting the newest developments in process design and the relationship of critical control variables (inhibition frequency, temperature, nitrogen species ratio, etc.) We will also discuss the knowledge gaps that remain in order to bring this novel strategy into wide implementation.

Secondly, we will describe an alternative strategy for mainstream Anammox implementation: partial denitrification/Anammox (PdN/A). This strategy was developed in plants in the mid-Atlantic, and is now being commercialized for deployment in California (and worldwide). The process uses the same Anammox biology, but in concert with different supporting organisms (heterotrophic denitrifiers instead of ammonia-oxidizing bacteria.) This presentation will compare PN/A and PdN/A strategies, explaining the differences in process design, control, and achievable efficiency gains between the two different strategies. Participants will be provided with hypothetical plant scenarios and polled to determine which of the two strategies would be more applicable in a given context.