pH Pivoting for Algae Coagulation: Bench Scale Experimentation
Abstract
Harmful algal blooms (HABs) threaten recreational waters and public supplies across the US, causing detrimental economic and environmental effects to communities. HABs can be mitigated with dissolved air flotation (DAF) treatment, which requires addition of pH-sensitive charged chemicals to neutralize algae, allowing them to attach to microbubbles and float to the surface. During HAB events and photosynthesis, algae raise the pH to levels that are not ideal for DAF. Traditionally, pH is reduced with a strong acid; however, this adds operational cost and permanently adjusts the waters pH. This study assessed an approach that might allow for infusing CO from diesel-powered electricity generators into the water prior to DAF treatment. It was hypothesized that formation of carbonic acid could temporarily reduce the pH. Results showed that 2.5 percent - 5.0 percent CO2 mixed within compressed air can achieve pH levels between 67 in algal water with an initial pH of 9-11 and alkalinity of 150 mg/L as CaCO3. Further, dosing CO2 before chemical addition yielded a 31 percent improvement in water clarification. Returning the pH back to natural levels was not achieved using ambient air microbubbles; however, coarse bubble air spargers should be tested to provide more volumetric capacity for CO2 absorption.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 31, 2024
- Accession Number
- AD1229089
Entities
People
- Amanda M. Chisholm
- Julia Miazek
- Marissa A. Campobasso
- Martin A. Page
- Musa M. Ibrahim
Organizations
- Engineer Research and Development Center
- United States Army Corps of Engineers
- United States Department of Energy
- University of Illinois Urbana–Champaign