+ POOL
Pier 35 Water Filtration Testing
+ POOL Filtration System
Official Water Filtration Testing near Pier 35: August – October 2024
Friends of + POOL and the global sustainable development consultancy, Arup, engineered a filtration system that brought raw river water to an acceptable microbiological standard for swimming. The filtration system was installed onsite at Pier 35. While not accessible to the public, the floating prototype platform was used daily by Water Quality Engineers and System Operators to track water quality and demonstrate the effectiveness of the system. The system was designed to reduce turbidity in the raw water, reduce particulate organics, and reduce pathogenic organisms (bacteria, viruses, protozoa). The public demonstration of the system that summer was intended to provide New York State and Friends of + POOL with the final data needed to move forward with the installation of NYC’s first water-filtering floating swimming pool.
Depositing clean water back into the East River.
The scaled version of the filtration system was mounted on a 110 ft. x 36 ft. floating barge, moored in the waters south of Pier 35. It was composed of the following:
- Intake Pump. A submersible pump was suspended in the East River to abstract the raw water for the pilot facility at 22 gallons per minute. The pump discharged into a 500-gallon feed tank fitted with an overflow back to the river. The submersible pump was fitted with an intake strainer basket (0.5”) to protect against fish passage and larger debris.
- Pre-filtration. The containerized filtration unit was fitted with a feed pump to draw water from the feed tank to the filtration plant. Prior to the filtration plant, the water was pumped through a 200-micron automatic washing strainer to remove material that could damage or block the membrane filter.
- Membrane filtration. The pre-filtered water was fed into the polymeric ultrafiltration membranes, which treated the water for turbidity, bacteria, particulate organics, and some viruses.
- UV Disinfection. The final treatment step was the disinfection process, achieved by exposing the filtered water to ultraviolet (UV) irradiation.
- Test Pool. Friends of + POOL installed a mock-up pool scaled to the dimensions of the future Stage 1B (+ POOL Mini) designed to be open to the public for swimming. Treated water was fed to the pool and constantly refreshed to mimic the future Stage 1B pool. To test the growth of biofilms, algae and any other surface deposits, a series of 3 inches x1 inch coupons were placed in the pool, mounted on backboards. There were three board types – daily, weekly, monthly, which reflect the frequency of cleaning the coupon boards. Before cleaning, one coupon was taken from each board for analysis by Heterotrophic Plate Count (HPC) and Chlorophyll.
- Cleaning System. The membranes required periodic washing, and spent washwater was returned to the East River. The membranes also required chemical backwashing (CIP and maintenance cleans). The chemical backwash water was stored on board the floating platform for safe disposal at the end of the testing period.
The ultrafiltration system was certified for 4-log removal of Giardia and Cryptosporidium and 1-log removal of viruses. The unit was certified to NSF/ANSI 419 to comply with the EPA Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR). Water quality in the river was continually monitored with a submersible multi-parameter immersed sonde probe, which relayed water quality data via telemetry.
Pre-filter for the system.
Membrane filtration unit.
Device for UV Disinfection
Data was submitted to the NYC Health Department and other city agencies. The results from the study validated the suitability of the patented system and informed the full-scale system design to achieve the required water quality conditions. Results demonstrated how the +POOL, and its innovative filtration system, met water quality standards recently detailed by City and State health departments for “novel” and “nontraditional” beaches, without the use of chemical disinfectants, while providing consistent recirculation of filtered water sourced from the river.
About Arup
Dedicated to sustainable development, Arup is a collective of 20,000 designers, advisors and experts working across 140 countries. Founded to strive for humanity and excellence in everything that we do, we collaborate with our clients and partners, using imagination, technology and rigor to shape a better world.
Visit https://www.arup.com/.
