+ POOL
November 19, 2024
10:18 AM
What We Learned From Our Filtration Prototype
This summer, we put a scaled version of our filtration system on a construction barge and floated it to Pier 35, where we began testing the system following new City and State protocols. We tested the water quality along six different points of our treatment train (choo! choo!) so we could see what happens as the water flows from one filtration process to the next. The combination of these test results are being examined to determine 1) that the system is performing as expected, and 2) the O&M considerations that need to be made for the full sized system (such as optimal flux, backwash timing, etc.). We learned a lot and will have a detailed report coming out soon, but here are a few of our key takeaways.
Pure Progress
When the system is in full operation, the water quality standards we set to achieve were met! This included samples tested for physical/chemical water parameters (such as temperature, turbidity, pH, salinity, etc.) and microbiological parameters (such as enterococci, e. coli, etc.). Our system achieves WQ standards that exceed beach standards and gets to what’s called a 4-log reduction (ie. 99.99%) of viruses.
It was a bit of a bummer that we were not able to test the system against major storms and rain events, because there simply were not any major storm events during the testing period. That said, record breaking temperatures in October showed us an extended swim season could be really appealing! Climate change means we ride the wave and prepare for all scenarios.
New Friends Underwater!
We contracted the team at Roux to assist in preparing a sanitary survey developed in accordance with the newly developed New York State Department of Health requirements for the design of a novel bathing facility. The sanitary survey is an assessment of the East River, which was the water source for this project, to review the current conditions of the water source as well as outline potential scenarios which could adversely affect the incoming raw water quality.
As part of the survey, Roux conducted an underwater survey of the river bottom in the proposed location of the future pool utilizing a FiFish underwater drone. The underwater survey consisted of photographic and video recordings of the area for signs of sensitive aquatic life which could be adversely affected by construction of the floating structure. And guess what? The findings included blue crabs, black sea bass, red beard sponges, and various red and green algae species.
Seaweed Diaries
One thing we didn’t quite expect was how much seaweed would be pulled into our prefilter, which required regular manual cleaning; and how much seaweed would grow in our mock up pool. Since we didn’t have swimmers in our mockup pool, we did not schedule regular cleanings and allowed algae to grow so we could assess cleaning frequencies for the full scale section we are building for next summer. This was a great learning experience, as it wasn’t an insurmountable task, but rather one that required a little shift in our approach.
This sent us all down a rabbit hole of conversations with ChatGPT on how we could potentially, down the line, recycle/reuse seaweed. There are quite a few ways folks reuse seaweed we didn’t know about – East River seaweed ice cream anyone? (Maybe not quite yet!)
Rinse, Refresh, Repeat
One of the main things we wanted to learn was how frequently we needed to backwash our filters. The good news is, fouling of the membranes due to suspended solids and organics in the river occurred more slowly than expected. That means a reduced need for periodic cleaning of the filters.
Of course, our swimmable water will remain chemical-free and we will be discharging clean water back to the source. But just like your bathtub, our filters will need a deep clean here and there. We plan to clean the filters periodically with chemicals and were able to determine that frequency needed through this testing phase.
Dream Team
Getting this filtration system prototype in the river was an incredible collaboration among so many awesome innovators who have never done this kind of thing before! We’ve been in a sprint since Governor Hochul first announced + POOL R&D in her State of the State, and so far, we have stayed on an aggressive timeline to make sure we can bring river swimming to New Yorkers safely as soon as possible.
Our next steps are detailing the program design atop our custom barge (currently under construction in the shipyard!) and the operational protocols based on everything we learned. We’ll start training facility operators and prepping for a final season of testing in summer 2025 (this time, with a fully built out section of + POOL!)
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