Your web browser is out of date. Update your browser for more security, speed and the best experience on this site.

Update your browser

all things water®

Contact Us

498 Seventh Ave, 11th Floor
New York, NY 10018

(212) 539-7000

Applied Research

Erik Rosenfeldt, PhD, PE
Wendell Khunjar, PhD, PE

Founded by water science pioneers, discovery and progress continue to define Hazen to this day. Our ongoing applied exploration program has led us to hold the largest water research portfolio in the industry and contribute firsthand to new approaches to remove pollutants and pathogens, augment natural resources, and manage water most efficiently and effectively.

I Stock 1310269671

For decades, we have advanced the science behind environmental engineering, from designing the first declining-rate filtration system to influencing regulations on the disinfection contact time necessary to meet permit requirements a century later.

By knowing what’s possible, Hazen can continue to deliver the best of what's practical.

Hazen and Sawyer remains a haven for those who see that the best today can be made better tomorrow, and who are driven to push for scientific and operational breakthroughs each and every day.

Our Work

Hazen is the leader in applied water research and advancing new water science technologies.

Recent Areas of Research


  • Supply and demand challenges from climate change and extreme weather events
  • Operation support tools
  • Advanced oxidation processes for taste and odor compounds, groundwater contaminants, and emerging contaminants
  • Treatment strategies for contaminants such as arsenic and chromium


  • Process optimization and intensification
  • Next-generation nutrient removal and recovery technologies
  • Co-digestion for biogas production and energy recovery
  • Machine learning and digital twins

Recycled Water

  • Potable reuse treatment processes including full advanced treatment and new alternatives such as ozone and biologically active carbon (BAC)
  • Communication tools to aid stakeholder education and acceptance
  • Decentralized, community- and building-scale reuse systems
  • Energy outcomes of recycled water, desalinated water, and alternative water supply options


  • Green infrastructure feasibility studies
  • Stormwater pilot projects
  • Watershed modeling
  • Rainwater harvesting