2005 Winning Projects                                                                              

 Evaluation of Ozone and Ultraviolet Light
Clinton, Massachusetts

  GRAND PRIZE — RESEARCH

ENTRANT: Black & Veatch Corp.
ENGINEER IN CHARGE: Gerald B. Benson, P.E., DEE

Project Role
Black & Veatch, serving as project manager and co-principal investigator for the project, was responsible for providing overall project management; developing the experimental test program; designing and overseeing construction of the experimental facilities; analyzing and evaluating data from the pilot and field studies; and developing guidance for the industry, the Massachusetts Water Resources Authority (MWRA) and the Town of Concord, Massachusetts.

Role of Other Consultants & Agencies
Participating Consultants
Black & Veatch assembled a unique, collaborative team for this project, including nationally recognized experts from specific and relevant disciplines. Robert Hulsey, Black & Veatch, and Dr. James Malley of the University of New Hampshire served as co-principal investigators. Dr. Malley is one of the world’s foremost researchers in ultraviolet disinfection. Dr. Malley’s team wrote the literature review of ultraviolet light (UV) applications for disinfection, conducted bench-scale work with other sub-consultants, led the field challenge trials, and performed specific analyses.

Dr. David Reckhow of the University of Massachusetts studied disinfection by-products and performed other analyses on raw, irradiated, and ozonated water throughout the study. Dr. Anne Camper of Montana State University and Center for Biofilm Engineering performed all bulk water and attached microbial analyses for the simulated distribution system studies of ozonated and non-ozonated waters subject to UV disinfection. Clancy Environmental of St. Albans, Vermont, and Dr. Marilyn Marshall of the University of Arizona performed the bench-scale Cryptosporidium inactivation work. Finally, Dr. Giovanni Widmar of Tufts University Veterinary School, MA, performed the bench-scale Giardia lamblia inactivation work with the University of New Hampshire.

Other Key Participants
The active participation of water utilities and manufacturers provided other key roles on the team. Sponsoring agency MWRA constructed and operated the pilot facilities including raw water pumping, UV disinfection, ozonating a portion of the water, post-treatment corrosion control, and testing through a simulated distribution system. MWRA collected and analyzed daily samples and helped with field trials. Concord built and operated the full-scale one-million-gallon-per-day ozone-UV disinfection scheme. Financial assistance and technical review was provided by the Southern Nevada Water Authority (SNWA) and the Portland Water Bureau, Oregon. Ozone and UV systems manufacturers Mitsubishi Electric Power Products and Trojan Technologies donated vital equipment. The American Water Works Association Research Foundation (AwwaRF) directed the overall effort, providing an expert panel to guide and review the final product.

Project Description - An Intriguing Possible Solution for an Urgent
Public Health Problem
In response to the threat of waterborne diseases caused by Cryptosporidium, Giardia lamblia, E. coli, and other pathogens, the U.S. Environmental Protection Agency formulated more stringent regulations requiring a higher level of water disinfection yet lower levels of harmful disinfection byproducts. The Interim Enhanced Surface Water Treatment Rule requires 2 log inactivation or removal of Cryptosporidium, a chlorine-resistant protozoan parasite. Prior research indicated that ozone cannot cost-effectively inactivate Cryptosporidium at cold water temperatures. Fearing a major capital investment, water utilities nationwide sought a solution that would enable cost-efficient compliance with the new regulations. The combination of ozone and UV was an exciting possibility but little was known about their interaction between the two. Credible research was needed to determine whether the combination could inactivate target pathogens without adversely affecting distributed water quality.

Innovative Technologies
This research was the first project to examine the sequential treatment of raw water with ozone and UV with an emphasis on disinfection effectiveness and disinfection byproducts. This information will be vitally important to water professionals in reaching compliance with emerging Stage 2 Disinfectants/Disinfection By-Product regulations.
This is the first comprehensive ozone and UV light research program in the world for consumer water quality assessment. MWRA built the largest ozone and ultraviolet light testing facility, while the Town of Concord built the first full-scale system to deliver ozone+UV-treated water to U.S. consumers. The pilot operation demonstrated process reliability and ease of operation as well as design elements that enhanced efficiency and effectiveness.

Also, this project was the first UV project to study distribution system effects with seasoned, well-characterized century-old pipe loops that are being treated with corrosion control measures and chloramines. These pipe loops mimic the distribution system of the MWRA extremely well from the AwwaRF Red Water Project.
 
Technical Value
The research provided evidence that combining the strengths of ozone (oxidation, taste, odor reduction and virus inactivation) with UV (Cryptosporidium inactivation) and chlorine or chloramines (bacterial inactivation and protection within the distribution system) provided a highly cost-effective treatment benefit. From a regulatory perspective, ultraviolet light in concert with ozone presents a multiple disinfection barrier approach to protecting public health.

Complexity
Increasing microbial risks in drinking water, particularly resistant pathogens such as Giardia lamblia, Cryptosporidium, and other organisms on the Contaminant Candidates List, dictate a growing need for multiple-barrier disinfection. The study of multiple disinfectants, each with distinct actions and effectiveness for specific pathogens, is a fundamentally sound strategy because it utilizes the most cost-effective treatment for each target organism. Results from this project will prepare water treatment specialists for the next millennium through heightened knowledge of multiple-barrier disinfectant principles with ozone, UV and chloramines in a single treatment train.

Equally important, this research demonstrates how to achieve the conflicting and complex goals of improving disinfection without increasing levels of halogenated disinfection byproducts or other adverse effects on water quality in the distribution system.

Social and Economic Benefits
For MWRA and similar large unfiltered surface water systems, knowledge gained from the study will directly impact the public, enabling delivery of quality potable water at a reasonable cost. Placing ultraviolet light after ozone results in capital cost savings of 19% to 21% compared to stand-alone ultraviolet light. Savings in operating costs have also proven impressive, with 29% to 32% lower operations costs with an optimum ozone sequence.

For water systems that rely on disinfection processes alone, the study demonstrates how the combined benefits of ozone followed by UV disinfection provide the most cost-effective microbial inactivation (protozoa, bacteria and viruses) above and beyond regulatory guidelines, thus providing a means to reach the very highest levels of water quality.