Framework Enables Systematic Evaluation of Innovative Ammonia Removal Technologies

SUMMARY
This paper introduces a technology evaluation framework developed by the Philadelphia Water Department (PWD) to assess emerging technologies as viable alternatives to conventional methods. A case study identified cost-effective ammonia removal technologies for PWD's water pollution control plants (WPCPs), with mobile organic biofilm (MOB) and Microvi MicroNiche Engineering (Microvi) standing out for their significant life-cycle cost-saving potential. The presentation will outline the systematic methodology used and discuss ongoing desktop and demonstration testing efforts.

1. TECHNOLOGY EVALUATION APPROACH DRIVERS PWD operates three WPCPs: two with conventional activated sludge (CAS) and one with high-purity oxygen (HPO). Recently proposed effluent ammonia limits of 1.5 mg/L for all three facilities have increased the need for a structured approach to technology evaluation. Historically, PWD relied on established or like-kind technologies due to familiarity, perceived risks, and testing constraints, which limited innovation. Recognizing this gap, PWD developed a framework to systematically vet new technologies, mitigating risks and enabling innovative solutions to complement or replace conventional methods effectively.

2. TECHNOLOGY EVALUATION FRAMEWORK PWD's framework systematically identifies, assesses, and implements technologies through these steps (Figure 1):
- Discovery: Identification of promising emerging technologies. Ideas brought to PWD's Applied Research Group are screened for advancement to the initiation phase.
- Initiation: Desktop analysis comparing selected technologies to established alternatives.
- Planning: Development of a detailed demonstration plan, including testing design and budget.
- Execution: Bench-, pilot-, or full-scale testing with performance checkpoints to guide further investment.
- Handoff: Documenting findings and lessons learned to guide potential full-scale implementation.
Each step includes pass/fail criteria established by key stakeholders to determine progress.

3. CASE STUDY: AMMONIA REMOVAL TECHNOLOGY EVALUATION
PWD applied its framework to identify mainstream innovative and cost-saving alternatives capable of increasing nitrification capacity to meet the proposed ammonia limit:
Discovery: Thirteen innovative and emerging technologies (Figure 2) were identified and scored against stake-holder-weighted non-economic criteria (Figure 3).
- MOB and Microvi received the highest scores and proceeded to the next step (Figure 4). MOB use plant-based media for biofilm growth and an activated sludge ballast to enhance settling. Configurations include Integrated Fixed Film Activated Sludge (MOB-IFAS) for secondary treatment or Moving Bed Biofilm Reactor (MOB-MBBR) for tertiary applications (Figure 5).
- Microvi employs highly efficient microorganisms encapsulated in polymeric capsules. Designed for nitrification, utilizing heterotrophic nitrifying organisms and can be configured as Integrated Microvi Activated Sludge (IMAS) or Microvi Tertiary MBBR (Figure 6).

Initiation: A desktop analysis compared MOB and Microvi configurations against the CAS expansion and tertiary biological aerated filter (BAF) as the baseline. MOB media from two manufacturers, Nuvoda and Arxtera, were evaluated based on differences in their physical characteristics, which impacted facility requirements and associated costs.

Desktop Analysis Findings:
- Upgrading WPCPs with secondary treatment options, MOB-IFAS and IMAS offered 37% - 64% cost savings compared to CAS depending on WPCP.
- Tertiary MBBR configurations for MOB and Microvi were less favorable due to higher footprint, capital, and O&M costs.
- IMAS emerged as another viable option, particularly for the HPO system, due to 60% saving in capital cost reductions (Figure 7).

Limitations of the Analysis:
- Aeration and mixing requirements for MOB media require further evaluation. Tertiary MOB clarifiers were designed based on discrete settling. Further testing is required to assess the MOB media settleability.
- Microvi is an emerging technology that has not been applied in utilities as large as PWD.
- The effect of pumping shear on Microvi polymeric capsules requires evaluation.

Planning: A research and testing program was developed for MOB, including proof-of-concept and demonstration phases (Figure 8). Stakeholders were engaged to refine testing plans and secure organizational support. PWD is currently procuring a mobile pilot setup designed to further investigate MOB and Microvi.

Execution: Bench testing in 2022 demonstrated MOB's ability to sustain nitrification under challenging conditions (Figure 9), paving the way for pilot testing in Spring 2026. The pilot will evaluate removal efficiency, establish design parameters, and refine operating strategies.

4. KEY TAKEAWAY
The developed evaluation methodology empowers utilities to systematically assess and adopt innovative technologies:
- Provides a structured pathway to explore emerging ammonia removal technologies.
- Reduces reliance on established or like-kind methods and avoids ad-hoc selection of alternatives.
- Enables utilities to balance innovation with risk management through comprehensive evaluation.
Participants will gain practical insights into leveraging technology evaluation frameworks to unlock the benefits of innovative solutions, showcasing their role in addressing critical treatment challenges.