top of page

YPIE Scientist: Rania Khan

Updated: May 31

Research: Combined Sewer Overflow Neutralizing Agent Sodium Hypochlorite’s Ramifications on the Vitality of the Phytoplankton Population of the Hudson River

Awards: STS Top 300 Scholars, 2nd Place in Environmental Science JSHS 2024, Mayor Spano’s Proclamation - “ February 28: Rania Khan Day”, US Junior Stockholm Water Prize: WESEF 2023


When rainwater and wastewater combine within the pipes of a combined sewer system, it overflows because the water capacity of the system is surpassed. This surplus water becomes filled with contaminants and fecal matter, which is then released into bodies of water. This occurrence is known as a combined sewer overflow (CSO). This research was conducted on CSOs in the Hudson River, located adjacent to the city of Yonkers. The river firstly becomes unusable because of the combined sewer water and then secondly because of the sodium hypochlorite which is a chemical cleaner used by the EPA to neutralize contaminants in the river after a combined sewer overflow. Sodium hypochlorite accomplishes its goal but the responses of this chemical cleaner on phytoplankton are unclear due to a lack of research. This study examined how this sewer overflow cleaner, sodium hypochlorite affects phytoplankton. The hypothesis was that sodium hypochlorite exposure may harm phytoplankton health, cellular growth, count, and photosynthetic capacities. The Science Barge, a floating greenhouse in Yonkers, on the Hudson River, hosted the experiment. A phytoplankton culture, Tetraselmis, was grown. It was then treated with 0.5, 1, 1.5, and 2 mL solutions of sodium hypochlorite at a 5% concentration. The higher dosages (1.5 and 2 mL) for cell count (p < .05), pH levels (p < .01), and temperature (p < .01) had p-values that were statistically significant, however the weight (p < .36) was insignificant. Exposure reduced hemocytometer cell count by 100,000 minimum from a 550,000 normal cell count range. The color chart showed phytoplankton photosynthetic impairment. The hypothesis was confirmed. This research fills the gap of understanding the neutralizing agent sodium hypochlorite ramifications on the vitality of the phytoplankton population.

About this Scientist:

Rania Khan is a senior at Charles E. Gorton High School and will be graduating as the salutatorian of her class. She has achieved significant success in science research and academia, earning recognition in various newspapers including the New York Times, Yonkers Rising, and The Ledger, among others, which can be found online. In the fall, Rania will be attending Wesleyan University as a biology and behavioral neuroscience double major with a minor in human rights advocacy. She plans to continue her research in college and aims to publish her own papers in the near future. After college, she plans to attend medical school and pursue a career as an emergency surgeon or gynecologist.

8 views0 comments

Recent Posts

See All


bottom of page