SATPC0040861 Tab 04 4 SOW.pdf

STATEMENT OF WORK

1. Objective/Requirements The International Space Station Water Recovery System (WRS) achieves near total recovery of potable water via the combined processes of the Urine Processor Assembly (UPA) and the Water Processor Assembly (WPA). However, biofouling in a wastewater holding tank at the start of the WPA process, particularly in the form of biofilm formation, can accumulate to a point of disrupting system operation by causing interruptions or blockages of flow within lines and valves surrounding the accumulated growth. The National Aeronautics and Space Administration (NASA) seeks to develop biofilm mitigation technology including continued research of nutrient removal with resin technologies, continued biocide research, and assessment of biofilm transfer to nearby hardware and small apertures. This research will inform the Mars Campaign Office (MCO) of the technology success or pain points and deliver hardware for future use.

2. Characteristics, Scope, and Specs

A. Sustain Meeting Support and Reporting

CBE Task 1.1: Sustain meeting support and reporting.

Provide technical assistance in meetings, emails and calls through the PoP at minimum by joining bi-weekly group meetings and responding to technical questions.

Providing expertise in biofilm mitigations and test planning.

CBE Task 1.2: Support MSFC engineers to assess biocide delivery methods.

Utilizing knowledge from the biocide synthesis and writeup task (Task 3.1), CBE will provide expertise and technical support to MSFC engineers familiar with the ISS architecture working on biocide delivery tasks.

B. Upstream Mitigation - Resin Testing

Resin testing during CBE’s Phase 1 Resin Screen/Down-Selection and MSFC’s Biofilm Test Stand have both used a sterile MTN feed and assessed resins very early in predicted resin lifetime (within the first 0.5%). Resins have optimal flow ranges based on equipment architecture and fluid flow around resin particles and resin performance may additionally be impacted by colonization of resin particles with biofilm (reducing active site availability) or due to possible channeling through the resin bed due to biofilm accumulation.

CBE Task 2.1: Assess nutrient removal efficiency and clogging potential in microbially-colonized resin beds.

Test resin performance with a microbial load (1 month of continuous flow at mean WPA tank fill rate): CBE will run BFR300 vs a control column filled with glass beads of the same diameter for a target operation time of one month (pending earlier clogging or pressure buildup) with a specific focus on biofilm within the column and released through column effluents. Resin beds will be inoculated with the 5-species consortium in Microbial Ersatz MTN for an initial batch period (ie 24hrs), then continuous flow of Microbial Ersatz MTN will start at the mean WPA fill rate (30.5mL/min or 307L/week per column). The column will be monitored via pressure drop and the column effluent will be monitored for chemical removal efficiency (TOC, IC, pH) and microbial release (viable counts and FlowCam analysis of total biomass, and biomass aggregate distribution), with endpoint assessment of biofilm in the resin beds (microbial assessment and microscopy). The column effluent from the BFR-300 column will be filter-sterilized and collected for feed carboys for tasks 3.2 and 4.1 to compare upstream resin mitigation effects on biofilm in the tank and downstream components.

CBE will use two existing resin column setups from a previous MSFC contract (Phase 1 Resin Screen) consisting of two 1” glass resin column (12” bed depth) setups with compression fittings (~1/3 scale of MSFC resin canisters). This system was built to Dupont recommendations for resin testing, will improve comparison to previous sterile testing, and reduce cost of manufacturing/purchasing flight canisters ($5712/each). At this scale, P-breakthrough is captured in this test and is predicted at 19.9 days of the one-month test. Previous CBE testing used 30.5mL/min but assessed optimal initial performance capturing 2L for analysis. Previous MSFC testing used 0.1mL/min over 9 weeks (9L total of a predicted 1915 L to phosphate breakthrough). This platform is well-suited to deliver the key information of how microbial presence affects resin performance.

Deliverable: Resin performance with a microbial load in the feed water, addressing nutrient removal efficiency of a microbially colonized resin bed and clogging assessment.

Reporting: Bi-weekly update presentations. Final report with images, data and text detailing results, conclusions, and technical achievements shall be delivered.

Results will be included and submitted for publication with the initial screen of resins for biofilm mitigation.

C. Tank Mitigation - Biocides The CBE has performed multiple biocide studies addressing biofilm in the WPA through MSFC contracts, a three-year MT NASA EPSCoR grant, and a one-year MT NASA EPSCoR R3 grant. This task aims to provide a writeup of work to date, to provide new biocide testing of an identified knowledge gap (effective biocide treatment at entry to dormancy), and to consult on biocide delivery efforts.

CBE Task 3.1: Biocide writeup.

CBE will prepare a written report and overview of all CBE biocide testing to date. This writeup will synthesize MSFC-supported work along with results from two NASA EPSCoR projects, encompassing a biocide screen of 23 agents against WPA organisms, CDC Biofilm Reactor daily biocide dosing with silver, iodine, and hydrogen peroxide, results of combination nutrient limitation and biocide treatment under continuous flow and with and without flushing under dormant operation, hydrogen peroxide treatment in CDC reactors, results of biocides dosed at shutdown from a 2yr tube dormancy study, and biocide remediation strategies for fouled systems. Possible options for delivery of effective biocide doses will be discussed.

CBE Task 3.2: Biocide testing in dormancy.

CBE will perform a two-month CDC Biofilm Reactor study (2 weeks continuous flow/4 weeks dormant/2 weeks continuous flow) to assess biocide dosing at the time of shutdown (N=1). Biocide and dose will be based on findings from Task 3.1 with final experimental design to be determined with consultation with NASA/MSFC. At current, we propose integrating this task with Task 2.1 to utilize the BFR-300 resin column effluent to assess biocide dosing in the “tank” (reactor) downstream without and with resin mitigation. Two reactors will be fed MTN, two will be fed BFR300 effluent. At two weeks, all reactors will be flushed and one of each reactor feed type will be dosed with biocide (same biocide and concentration). Reactor influents/effluents will be clamped for a one month dormant period. Reactors will then resume continuous flow and will be monitored for two weeks after restart. This experimental design and dormancy timing was previously used to assess dormancy shutdown procedures for the NASA EPSCoR project although flushing and 2ppm AgF biocide doses from that study did not reduce the microbial load and an effective treatment at shutdown has not yet been identified.

Biocide Delivery: Provide consultation and biofilm/biocide expertise for MSFC engineers on this task (see Task 1.2).

Deliverables: Executive summary/report of combinations and iterations of biocide testing during operation and dormancy. Testing of top biocide dosing strategy at the time of shutdown for dormancy. Support of MSFC to identify biocide delivery strategies in the ISS WPA architecture.

Reporting: Bi-weekly update presentations. Biocide testing will be integrated into the biocide writeup. Testing results will be included and submitted for publication with previous results from combined nutrient limitation and biocide dosing under continuous operation and dormant conditions.

D. Downstream Impacts – Clogging Assays and Critical Aperture Testing

Downstream release of biofilm from the WPA tank and clogging of smaller downstream apertures in filters and tubing is a possible criterion for successful biofilm mitigation practices yet current laboratory testing does not address this challenge. To compare biofilm release from reactors under different treatments and to quantify suspended biomass unique to the WPA consortium, the CBE purchased a liquid particle analyzer in 2022 (FlowCam) to compare impacts on suspended biomass (total biomass and aggregate distribution) in bulk fluid and effluent samples, but this equipment is not always available. Lifetime of the EFA flight hardware is on the scale of years and exceeds experimental testing. These tasks aim to develop bench-scale assays for suspended biomass analysis and to address biofilm capture and growth on apertures of varying sizes downstream of reactors.

CBE Task 4.1: Clogging Assay and Critical Aperture Testing

CBE will take an iterative approach in developing these assays. We anticipate testing multiple sizes of filters or mesh as well as filter housing and modifying protocols as the assays are developed.

Our first aim is to develop a basic assay for suspended biomass in reactor bulk fluid or effluent (in absence of a particle analyzer). At current, we propose using the time to filter a designated volume through varying filter sizes under constant vacuum. For development, we intend to analyze the filtered liquid with FlowCam to estimate filter loading, but the aim of the final assay will be based on filtration alone. While critical aperture size of downstream components may be a topic of the second aim, these filters may have smaller pore size to reflect particle counts larger than single cells, or aggregates of different cutoff sizes and to keep this assay within a reasonable time for experimental testing (10-20 min).

Our second aim addresses critical aperture sizes of downstream components and the potential for both captured aggregates and growth on the downstream unit to impact fouling and clogging. Filters containing mesh or filters of varying sizes on the scale of downstream WPA components (1/4” tubing, EFA filter, solenoid valves) will be connected to reactor effluent lines and loaded daily to simulate WPA tank function with stagnant periods between filtrations. Particle analysis and biofilm removal upstream and downstream of the filters (FlowCam), viable cell counts, and fouling assessment (ie time to filter sterile water) will be used to monitor filter function. Endpoint analysis including viable counts and imaging of the filters will characterize the biofilm.

Feed for these filtrations tests may come from Task 3.2. If time to filter clogging for critical aperture testing is sufficiently long, final testing will be considered with daily loading over a duration from a “high-load” reactor fed MTN vs a “low-load” reactor fed BFR300-filtered media.

Deliverables: Testing and development of assays to assess and compare biofilm mitigation impacts on downstream components of small apertures, applicable for use in bench scale technology testing and development.

Reporting: Bi-weekly update presentations. Final report with images, data and text detailing results, conclusions, and technical achievements shall be delivered.

3. Place of Performance

Center for Biofilm Engineering, Montana State University, Bozeman, MT, 59717

4. Period of Performance Testing shall be performed Feb 1, 2026 through January 31, 2027.